www/test/0.8.2/src/lib/core.js - master - kopython/_hyperscript

www/test/0.8.2/src/lib/core.js
5 308 строк141 KB
carson
0.8.2 release
02 окт 2021, 03:40
02 окт 2021, 03:40cf8ae97
///=========================================================================
/// This module provides the core runtime and grammar for hyperscript
///=========================================================================
//AMD insanity

/** @var {HyperscriptObject} _hyperscript */

(function (root, factory) {
	if (typeof module != 'undefined') {
		module.exports = factory();
	} else if (typeof this.define === "function" && this.define.amd) {
		// AMD. Register as an anonymous module.
		this.define([], factory);
	} else {
		// Browser globals
		root._hyperscript = factory();
	}
})(typeof self !== "undefined" ? self : this, function () {
	"use strict";

	//====================================================================
	// Utilities
	//====================================================================

	/**
	 * mergeObjects combines the keys from obj2 into obj2, then returns obj1
	 *
	 * @param {object} obj1
	 * @param {object} obj2
	 * @returns object
	 */
	function mergeObjects(obj1, obj2) {
		for (var key in obj2) {
			if (obj2.hasOwnProperty(key)) {
				obj1[key] = obj2[key];
			}
		}
		return obj1;
	}

	function getOrInitObject(root, prop) {
		var value = root[prop];
		if (value) {
			return value;
		} else {
			var newObj = {};
			root[prop] = newObj;
			return newObj;
		}
	}

	/**
	 * parseJSON parses a JSON string into a corresponding value.  If the
	 * value passed in is not valid JSON, then it logs an error and returns `null`.
	 *
	 * @param {string} jString
	 * @returns any
	 */
	function parseJSON(jString) {
		try {
			return JSON.parse(jString);
		} catch (error) {
			logError(error);
			return null;
		}
	}

	/**
	 * logError writes an error message to the Javascript console.  It can take any
	 * value, but msg should commonly be a simple string.
	 * @param {*} msg
	 */
	function logError(msg) {
		if (console.error) {
			console.error(msg);
		} else if (console.log) {
			console.log("ERROR: ", msg);
		}
	}

	// TODO: JSDoc description of what's happening here
	function varargConstructor(Cls, args) {
		return new (Cls.bind.apply(Cls, [Cls].concat(args)))();
	}

	var globalScope = (1, eval)("this");

	//====================================================================
	// Standard library
	//====================================================================

	class ElementCollection {
		constructor(css, relativeToElement) {
			this._css = css;
			this.relativeToElement = relativeToElement;
		}

		get css() {
			return _runtime.escapeSelector(this._css);
		}

		get className() {
			return this._css.substr(1);
		}

		get id() {
			return this.className();
		}

		[Symbol.iterator]() {
			return _runtime.getRootNode(this.relativeToElement)
				.querySelectorAll(this.css)
				[Symbol.iterator]();
		}
	}

	//====================================================================
	// Lexer
	//====================================================================

	/** @type LexerObject */
	var _lexer = (function () {
		var OP_TABLE = {
			"+": "PLUS",
			"-": "MINUS",
			"*": "MULTIPLY",
			"/": "DIVIDE",
			".": "PERIOD",
			"..": "ELLIPSIS",
			"\\": "BACKSLASH",
			":": "COLON",
			"%": "PERCENT",
			"|": "PIPE",
			"!": "EXCLAMATION",
			"?": "QUESTION",
			"#": "POUND",
			"&": "AMPERSAND",
			$: "DOLLAR",
			";": "SEMI",
			",": "COMMA",
			"(": "L_PAREN",
			")": "R_PAREN",
			"<": "L_ANG",
			">": "R_ANG",
			"<=": "LTE_ANG",
			">=": "GTE_ANG",
			"==": "EQ",
			"===": "EQQ",
			"!=": "NEQ",
			"!==": "NEQQ",
			"{": "L_BRACE",
			"}": "R_BRACE",
			"[": "L_BRACKET",
			"]": "R_BRACKET",
			"=": "EQUALS",
		};

		/**
		 * isValidCSSClassChar returns `true` if the provided character is valid in a CSS class.
		 * @param {string} c
		 * @returns boolean
		 */
		function isValidCSSClassChar(c) {
			return isAlpha(c) || isNumeric(c) || c === "-" || c === "_" || c === ":";
		}

		/**
		 * isValidCSSIDChar returns `true` if the provided character is valid in a CSS ID
		 * @param {string} c
		 * @returns boolean
		 */
		function isValidCSSIDChar(c) {
			return isAlpha(c) || isNumeric(c) || c === "-" || c === "_" || c === ":";
		}

		/**
		 * isWhitespace returns `true` if the provided character is whitespace.
		 * @param {string} c
		 * @returns boolean
		 */
		function isWhitespace(c) {
			return c === " " || c === "\t" || isNewline(c);
		}

		/**
		 * positionString returns a string representation of a Token's line and column details.
		 * @param {Token} token
		 * @returns string
		 */
		function positionString(token) {
			return "[Line: " + token.line + ", Column: " + token.column + "]";
		}

		/**
		 * isNewline returns `true` if the provided character is a carrage return or newline
		 * @param {string} c
		 * @returns boolean
		 */
		function isNewline(c) {
			return c === "\r" || c === "\n";
		}

		/**
		 * isNumeric returns `true` if the provided character is a number (0-9)
		 * @param {string} c
		 * @returns boolean
		 */
		function isNumeric(c) {
			return c >= "0" && c <= "9";
		}

		/**
		 * isAlpha returns `true` if the provided character is a letter in the alphabet
		 * @param {string} c
		 * @returns boolean
		 */
		function isAlpha(c) {
			return (c >= "a" && c <= "z") || (c >= "A" && c <= "Z");
		}

		/**
		 * @param {string} c
		 * @param {boolean} [dollarIsOp]
		 * @returns boolean
		 */
		function isIdentifierChar(c, dollarIsOp) {
			return c === "_" || c === "$";
		}

		/**
		 * @param {string} c
		 * @returns boolean
		 */
		function isReservedChar(c) {
			return c === "`" || c === "^";
		}

		/**
		 * @param {Token[]} tokens
		 * @param {Token[]} consumed
		 * @param {string} source
		 * @returns {TokensObject}
		 */
		function makeTokensObject(tokens, consumed, source) {
			consumeWhitespace(); // consume initial whitespace

			/** @type Token | null */
			var _lastConsumed = null;

			function consumeWhitespace() {
				while (token(0, true).type === "WHITESPACE") {
					consumed.push(tokens.shift());
				}
			}

			/**
			 * @param {TokensObject} tokens
			 * @param {*} error
			 */
			function raiseError(tokens, error) {
				_parser.raiseParseError(tokens, error);
			}

			/**
			 * @param {string} value
			 * @returns {Token}
			 */
			function requireOpToken(value) {
				var token = matchOpToken(value);
				if (token) {
					return token;
				} else {
					raiseError(this, "Expected '" + value + "' but found '" + currentToken().value + "'");
				}
			}

			/**
			 * @param {string} op1
			 * @param {string} [op2]
			 * @param {string} [op3]
			 * @returns {Token | void}
			 */
			function matchAnyOpToken(op1, op2, op3) {
				for (var i = 0; i < arguments.length; i++) {
					var opToken = arguments[i];
					var match = matchOpToken(opToken);
					if (match) {
						return match;
					}
				}
			}

			/**
			 * @param {string} op1
			 * @param {string} [op2]
			 * @param {string} [op3]
			 * @returns {Token | void}
			 */
			function matchAnyToken(op1, op2, op3) {
				for (var i = 0; i < arguments.length; i++) {
					var opToken = arguments[i];
					var match = matchToken(opToken);
					if (match) {
						return match;
					}
				}
			}

			/**
			 * @param {string} value
			 * @returns {Token | void}
			 */
			function matchOpToken(value) {
				if (currentToken() && currentToken().op && currentToken().value === value) {
					return consumeToken();
				}
			}

			/**
			 * @param {string} type1
			 * @param {string} [type2]
			 * @param {string} [type3]
			 * @param {string} [type4]
			 * @returns {Token}
			 */
			function requireTokenType(type1, type2, type3, type4) {
				var token = matchTokenType(type1, type2, type3, type4);
				if (token) {
					return token;
				} else {
					raiseError(this, "Expected one of " + JSON.stringify([type1, type2, type3]));
				}
			}

			/**
			 * @param {string} type1
			 * @param {string} [type2]
			 * @param {string} [type3]
			 * @param {string} [type4]
			 * @returns {Token | void}
			 */
			function matchTokenType(type1, type2, type3, type4) {
				if (
					currentToken() &&
					currentToken().type &&
					[type1, type2, type3, type4].indexOf(currentToken().type) >= 0
				) {
					return consumeToken();
				}
			}

			/**
			 * @param {string} value
			 * @param {string} [type]
			 * @returns {Token}
			 */
			function requireToken(value, type) {
				var token = matchToken(value, type);
				if (token) {
					return token;
				} else {
					raiseError(this, "Expected '" + value + "' but found '" + currentToken().value + "'");
				}
			}

			/**
			 * @param {string} value
			 * @param {string} [type]
			 * @returns {Token | void}
			 */
			function matchToken(value, type) {
				if (follows.indexOf(value) !== -1) {
					return; // disallowed token here
				}
				var type = type || "IDENTIFIER";
				if (currentToken() && currentToken().value === value && currentToken().type === type) {
					return consumeToken();
				}
			}

			/**
			 * @returns {Token}
			 */
			function consumeToken() {
				var match = tokens.shift();
				consumed.push(match);
				_lastConsumed = match;
				consumeWhitespace(); // consume any whitespace
				return match;
			}

			/**
			 * @param {string} value
			 * @param {string} [type]
			 * @returns {Token[]}
			 */
			function consumeUntil(value, type) {
				/** @type Token[] */
				var tokenList = [];
				var currentToken = token(0, true);

				while (
					(type == null || currentToken.type !== type) &&
					(value == null || currentToken.value !== value) &&
					currentToken.type !== "EOF"
				) {
					var match = tokens.shift();
					consumed.push(match);
					tokenList.push(currentToken);
					currentToken = token(0, true);
				}
				consumeWhitespace(); // consume any whitespace
				return tokenList;
			}

			/**
			 * @returns {string}
			 */
			function lastWhitespace() {
				if (consumed[consumed.length - 1] && consumed[consumed.length - 1].type === "WHITESPACE") {
					return consumed[consumed.length - 1].value;
				} else {
					return "";
				}
			}

			function consumeUntilWhitespace() {
				return consumeUntil(null, "WHITESPACE");
			}

			/**
			 * @returns {boolean}
			 */
			function hasMore() {
				return tokens.length > 0;
			}

			/**
			 * @param {number} n
			 * @param {boolean} [dontIgnoreWhitespace]
			 * @returns {Token}
			 */
			function token(n, dontIgnoreWhitespace) {
				var /**@type {Token}*/ token;
				var i = 0;
				do {
					if (!dontIgnoreWhitespace) {
						while (tokens[i] && tokens[i].type === "WHITESPACE") {
							i++;
						}
					}
					token = tokens[i];
					n--;
					i++;
				} while (n > -1);
				if (token) {
					return token;
				} else {
					return {
						type: "EOF",
						value: "<<<EOF>>>",
					};
				}
			}

			/**
			 * @returns {Token}
			 */
			function currentToken() {
				return token(0);
			}

			/**
			 * @returns {Token | null}
			 */
			function lastMatch() {
				return _lastConsumed;
			}

			/**
			 * @returns {string}
			 */
			function sourceFor() {
				return source.substring(this.startToken.start, this.endToken.end);
			}

			/**
			 * @returns {string}
			 */
			function lineFor() {
				return source.split("\n")[this.startToken.line - 1];
			}

			var follows = [];

			function pushFollow(str) {
				follows.push(str);
			}

			function popFollow() {
				follows.pop();
			}

			function clearFollows() {
				var tmp = follows;
				follows = [];
				return tmp;
			}

			function restoreFollows(f) {
				follows = f;
			}

			/** @type {TokensObject} */
			return {
				pushFollow: pushFollow,
				popFollow: popFollow,
				clearFollow: clearFollows,
				restoreFollow: restoreFollows,
				matchAnyToken: matchAnyToken,
				matchAnyOpToken: matchAnyOpToken,
				matchOpToken: matchOpToken,
				requireOpToken: requireOpToken,
				matchTokenType: matchTokenType,
				requireTokenType: requireTokenType,
				consumeToken: consumeToken,
				matchToken: matchToken,
				requireToken: requireToken,
				list: tokens,
				consumed: consumed,
				source: source,
				hasMore: hasMore,
				currentToken: currentToken,
				lastMatch: lastMatch,
				token: token,
				consumeUntil: consumeUntil,
				consumeUntilWhitespace: consumeUntilWhitespace,
				lastWhitespace: lastWhitespace,
				sourceFor: sourceFor,
				lineFor: lineFor,
			};
		}

		/**
		 * @param {Token[]} tokens
		 * @returns {boolean}
		 */
		function isValidSingleQuoteStringStart(tokens) {
			if (tokens.length > 0) {
				var previousToken = tokens[tokens.length - 1];
				if (
					previousToken.type === "IDENTIFIER" ||
					previousToken.type === "CLASS_REF" ||
					previousToken.type === "ID_REF"
				) {
					return false;
				}
				if (previousToken.op && (previousToken.value === ">" || previousToken.value === ")")) {
					return false;
				}
			}
			return true;
		}

		/**
		 * @param {string} string
		 * @param {boolean} [template]
		 * @returns {TokensObject}
		 */
		function tokenize(string, template) {
			var tokens = /** @type {Token[]}*/ [];
			var source = string;
			var position = 0;
			var column = 0;
			var line = 1;
			var lastToken = "<START>";
			var templateBraceCount = 0;

			function inTemplate() {
				return template && templateBraceCount === 0;
			}

			while (position < source.length) {
				if (currentChar() === "-" && nextChar() === "-") {
					consumeComment();
				} else {
					if (isWhitespace(currentChar())) {
						tokens.push(consumeWhitespace());
					} else if (
						!possiblePrecedingSymbol() &&
						currentChar() === "." &&
						(isAlpha(nextChar()) || nextChar() === "{")
					) {
						tokens.push(consumeClassReference());
					} else if (
						!possiblePrecedingSymbol() &&
						currentChar() === "#" &&
						(isAlpha(nextChar()) || nextChar() === "{")
					) {
						tokens.push(consumeIdReference());
					} else if (currentChar() === "[" && nextChar() === "@") {
						tokens.push(consumeAttributeReference());
					} else if (currentChar() === "@") {
						tokens.push(consumeShortAttributeReference());
					} else if (isAlpha(currentChar()) || (!inTemplate() && isIdentifierChar(currentChar()))) {
						tokens.push(consumeIdentifier());
					} else if (isNumeric(currentChar())) {
						tokens.push(consumeNumber());
					} else if (!inTemplate() && (currentChar() === '"' || currentChar() === "`")) {
						tokens.push(consumeString());
					} else if (!inTemplate() && currentChar() === "'") {
						if (isValidSingleQuoteStringStart(tokens)) {
							tokens.push(consumeString());
						} else {
							tokens.push(consumeOp());
						}
					} else if (OP_TABLE[currentChar()]) {
						if (lastToken === "$" && currentChar() === "{") {
							templateBraceCount++;
						}
						if (currentChar() === "}") {
							templateBraceCount--;
						}
						tokens.push(consumeOp());
					} else if (inTemplate() || isReservedChar(currentChar())) {
						tokens.push(makeToken("RESERVED", consumeChar()));
					} else {
						if (position < source.length) {
							throw Error("Unknown token: " + currentChar() + " ");
						}
					}
				}
			}

			return makeTokensObject(tokens, [], source);

			/**
			 * @param {string} [type]
			 * @param {string} [value]
			 * @returns {Token}
			 */
			function makeOpToken(type, value) {
				var token = makeToken(type, value);
				token.op = true;
				return token;
			}

			/**
			 * @param {string} [type]
			 * @param {string} [value]
			 * @returns {Token}
			 */
			function makeToken(type, value) {
				return {
					type: type,
					value: value,
					start: position,
					end: position + 1,
					column: column,
					line: line,
				};
			}

			function consumeComment() {
				while (currentChar() && !isNewline(currentChar())) {
					consumeChar();
				}
				consumeChar();
			}

			/**
			 * @returns Token
			 */
			function consumeClassReference() {
				var classRef = makeToken("CLASS_REF");
				var value = consumeChar();
				if (currentChar() === "{") {
					classRef.template = true;
					value += consumeChar();
					while (currentChar() && currentChar() !== "}") {
						value += consumeChar();
					}
					if (currentChar() !== "}") {
						throw Error("Unterminated class reference");
					} else {
						value += consumeChar(); // consume final curly
					}
				} else {
					while (isValidCSSClassChar(currentChar())) {
						value += consumeChar();
					}
				}
				classRef.value = value;
				classRef.end = position;
				return classRef;
			}

			/**
			 * @returns Token
			 */
			function consumeAttributeReference() {
				var attributeRef = makeToken("ATTRIBUTE_REF");
				var value = consumeChar();
				while (position < source.length && currentChar() !== "]") {
					value += consumeChar();
				}
				if (currentChar() === "]") {
					value += consumeChar();
				}
				attributeRef.value = value;
				attributeRef.end = position;
				return attributeRef;
			}

			function consumeShortAttributeReference() {
				var attributeRef = makeToken("ATTRIBUTE_REF");
				var value = consumeChar();
				while (isValidCSSIDChar(currentChar())) {
					value += consumeChar();
				}
				attributeRef.value = value;
				attributeRef.end = position;
				return attributeRef;
			}

			/**
			 * @returns Token
			 */
			function consumeIdReference() {
				var idRef = makeToken("ID_REF");
				var value = consumeChar();
				if (currentChar() === "{") {
					idRef.template = true;
					value += consumeChar();
					while (currentChar() && currentChar() !== "}") {
						value += consumeChar();
					}
					if (currentChar() !== "}") {
						throw Error("Unterminated id reference");
					} else {
						consumeChar(); // consume final quote
					}
				} else {
					while (isValidCSSIDChar(currentChar())) {
						value += consumeChar();
					}
				}
				idRef.value = value;
				idRef.end = position;
				return idRef;
			}

			/**
			 * @returns Token
			 */
			function consumeIdentifier() {
				var identifier = makeToken("IDENTIFIER");
				var value = consumeChar();
				while (isAlpha(currentChar()) || isIdentifierChar(currentChar())) {
					value += consumeChar();
				}
				identifier.value = value;
				identifier.end = position;
				return identifier;
			}

			/**
			 * @returns Token
			 */
			function consumeNumber() {
				var number = makeToken("NUMBER");
				var value = consumeChar();
				while (isNumeric(currentChar())) {
					value += consumeChar();
				}
				if (currentChar() === "." && isNumeric(nextChar())) {
					value += consumeChar();
				}
				while (isNumeric(currentChar())) {
					value += consumeChar();
				}
				number.value = value;
				number.end = position;
				return number;
			}

			/**
			 * @returns Token
			 */
			function consumeOp() {
				var op = makeOpToken();
				var value = consumeChar(); // consume leading char
				while (currentChar() && OP_TABLE[value + currentChar()]) {
					value += consumeChar();
				}
				op.type = OP_TABLE[value];
				op.value = value;
				op.end = position;
				return op;
			}

			/**
			 * @returns Token
			 */
			function consumeString() {
				var string = makeToken("STRING");
				var startChar = consumeChar(); // consume leading quote
				var value = "";
				while (currentChar() && currentChar() !== startChar) {
					if (currentChar() === "\\") {
						consumeChar(); // consume escape char and move on
					}
					value += consumeChar();
				}
				if (currentChar() !== startChar) {
					throw Error("Unterminated string at " + positionString(string));
				} else {
					consumeChar(); // consume final quote
				}
				string.value = value;
				string.end = position;
				string.template = startChar === "`";
				return string;
			}

			/**
			 * @returns string
			 */
			function currentChar() {
				return source.charAt(position);
			}

			/**
			 * @returns string
			 */
			function nextChar() {
				return source.charAt(position + 1);
			}

			/**
			 * @returns string
			 */
			function consumeChar() {
				lastToken = currentChar();
				position++;
				column++;
				return lastToken;
			}

			/**
			 * @returns boolean
			 */
			function possiblePrecedingSymbol() {
				return (
					isAlpha(lastToken) ||
					isNumeric(lastToken) ||
					lastToken === ")" ||
					lastToken === "}" ||
					lastToken === "]"
				);
			}

			/**
			 * @returns Token
			 */
			function consumeWhitespace() {
				var whitespace = makeToken("WHITESPACE");
				var value = "";
				while (currentChar() && isWhitespace(currentChar())) {
					if (isNewline(currentChar())) {
						column = 0;
						line++;
					}
					value += consumeChar();
				}
				whitespace.value = value;
				whitespace.end = position;
				return whitespace;
			}
		}

		return {
			tokenize: tokenize,
			makeTokensObject: makeTokensObject,
		};
	})();

	//====================================================================
	// Parser
	//====================================================================

	/** @type ParserObject */
	var _parser = (function () {
		/** @type {Object<string,GrammarDefinition>} */
		var GRAMMAR = {};

		/** @type {Object<string,GrammarDefinition>} */
		var COMMANDS = {};

		/** @type {Object<string,GrammarDefinition>} */
		var FEATURES = {};

		var LEAF_EXPRESSIONS = [];
		var INDIRECT_EXPRESSIONS = [];

		/**
		 * @param {*} parseElement
		 * @param {*} start
		 * @param {TokensObject} tokens
		 */
		function initElt(parseElement, start, tokens) {
			parseElement.startToken = start;
			parseElement.sourceFor = tokens.sourceFor;
			parseElement.lineFor = tokens.lineFor;
			parseElement.programSource = tokens.source;
		}

		/**
		 * @param {string} type
		 * @param {TokensObject} tokens
		 * @param {GrammarElement?} root
		 * @returns GrammarElement
		 */
		function parseElement(type, tokens, root = undefined) {
			var elementDefinition = GRAMMAR[type];
			if (elementDefinition) {
				var start = tokens.currentToken();
				var parseElement = elementDefinition(_parser, _runtime, tokens, root);
				if (parseElement) {
					initElt(parseElement, start, tokens);
					parseElement.endToken = parseElement.endToken || tokens.lastMatch();
					var root = parseElement.root;
					while (root != null) {
						initElt(root, start, tokens);
						root = root.root;
					}
				}
				return parseElement;
			}
		}

		/**
		 * @param {string} type
		 * @param {TokensObject} tokens
		 * @param {string} [message]
		 * @param {*} [root]
		 * @returns {GrammarElement}
		 */
		function requireElement(type, tokens, message, root) {
			var result = parseElement(type, tokens, root);
			if (!result) raiseParseError(tokens, message || "Expected " + type);
			// @ts-ignore
			return result;
		}

		/**
		 * @param {string[]} types
		 * @param {TokensObject} tokens
		 * @returns {GrammarElement}
		 */
		function parseAnyOf(types, tokens) {
			for (var i = 0; i < types.length; i++) {
				var type = types[i];
				var expression = parseElement(type, tokens);
				if (expression) {
					return expression;
				}
			}
		}

		/**
		 * @param {string} name
		 * @param {GrammarDefinition} definition
		 */
		function addGrammarElement(name, definition) {
			GRAMMAR[name] = definition;
		}

		/**
		 * @param {string} keyword
		 * @param {GrammarDefinition} definition
		 */
		function addCommand(keyword, definition) {
			var commandGrammarType = keyword + "Command";
			var commandDefinitionWrapper = function (parser, runtime, tokens) {
				const commandElement = definition(parser, runtime, tokens);
				if (commandElement) {
					commandElement.type = commandGrammarType;
					commandElement.execute = function (context) {
						context.meta.command = commandElement;
						return runtime.unifiedExec(this, context);
					};
					return commandElement;
				}
			};
			GRAMMAR[commandGrammarType] = commandDefinitionWrapper;
			COMMANDS[keyword] = commandDefinitionWrapper;
		}

		/**
		 * @param {string} keyword
		 * @param {GrammarDefinition} definition
		 */
		function addFeature(keyword, definition) {
			var featureGrammarType = keyword + "Feature";

			/** @type {GrammarDefinition} */
			var featureDefinitionWrapper = function (parser, runtime, tokens) {
				var featureElement = definition(parser, runtime, tokens);
				if (featureElement) {
					featureElement.keyword = keyword;
					featureElement.type = featureGrammarType;
					return featureElement;
				}
			};
			GRAMMAR[featureGrammarType] = featureDefinitionWrapper;
			FEATURES[keyword] = featureDefinitionWrapper;
		}

		/**
		 * @param {string} name
		 * @param {GrammarDefinition} definition
		 */
		function addLeafExpression(name, definition) {
			LEAF_EXPRESSIONS.push(name);
			addGrammarElement(name, definition);
		}

		/**
		 * @param {string} name
		 * @param {GrammarDefinition} definition
		 */
		function addIndirectExpression(name, definition) {
			INDIRECT_EXPRESSIONS.push(name);
			addGrammarElement(name, definition);
		}

		/* ============================================================================================ */
		/* Core hyperscript Grammar Elements                                                            */
		/* ============================================================================================ */
		addGrammarElement("feature", function (parser, runtime, tokens) {
			if (tokens.matchOpToken("(")) {
				var featureElement = parser.requireElement("feature", tokens);
				tokens.requireOpToken(")");
				return featureElement;
			}

			var featureDefinition = FEATURES[tokens.currentToken().value];
			if (featureDefinition) {
				return featureDefinition(parser, runtime, tokens);
			}
		});

		addGrammarElement("command", function (parser, runtime, tokens) {
			if (tokens.matchOpToken("(")) {
				const commandElement = parser.requireElement("command", tokens);
				tokens.requireOpToken(")");
				return commandElement;
			}

			var commandDefinition = COMMANDS[tokens.currentToken().value];
			let commandElement;
			if (commandDefinition) {
				commandElement = commandDefinition(parser, runtime, tokens);
			} else if (tokens.currentToken().type === "IDENTIFIER" && tokens.token(1).value === "(") {
				commandElement = parser.requireElement("pseudoCommand", tokens);
			}
			if (commandElement) {
				return parser.parseElement("indirectStatement", tokens, commandElement);
			}

			return commandElement;
		});

		addGrammarElement("commandList", function (parser, runtime, tokens) {
			var cmd = parser.parseElement("command", tokens);
			if (cmd) {
				tokens.matchToken("then");
				const next = parser.parseElement("commandList", tokens);
				if (next) cmd.next = next;
				return cmd;
			}
		});

		addGrammarElement("leaf", function (parser, runtime, tokens) {
			var result = parseAnyOf(LEAF_EXPRESSIONS, tokens);
			// symbol is last so it doesn't consume any constants
			if (result == null) {
				return parseElement("symbol", tokens);
			}

			return result;
		});

		addGrammarElement("indirectExpression", function (parser, runtime, tokens, root) {
			for (var i = 0; i < INDIRECT_EXPRESSIONS.length; i++) {
				var indirect = INDIRECT_EXPRESSIONS[i];
				root.endToken = tokens.lastMatch();
				var result = parser.parseElement(indirect, tokens, root);
				if (result) {
					return result;
				}
			}
			return root;
		});

		addGrammarElement("indirectStatement", function (parser, runtime, tokens, root) {
			if (tokens.matchToken("unless")) {
				root.endToken = tokens.lastMatch();
				var conditional = parser.requireElement("expression", tokens);
				var unless = {
					type: "unlessStatementModifier",
					args: [conditional],
					op: function (context, conditional) {
						if (conditional) {
							return this.next;
						} else {
							return root;
						}
					},
					execute: function (context) {
						return runtime.unifiedExec(this, context);
					},
				};
				root.parent = unless;
				return unless;
			}
			return root;
		});

		addGrammarElement("primaryExpression", function (parser, runtime, tokens) {
			var leaf = parser.parseElement("leaf", tokens);
			if (leaf) {
				return parser.parseElement("indirectExpression", tokens, leaf);
			}
			parser.raiseParseError(tokens, "Unexpected value: " + tokens.currentToken().value);
		});

		/* ============================================================================================ */
		/* END Core hyperscript Grammar Elements                                                        */

		/* ============================================================================================ */

		/**
		 *
		 * @param {TokensObject} tokens
		 * @returns string
		 */
		function createParserContext(tokens) {
			var currentToken = tokens.currentToken();
			var source = tokens.source;
			var lines = source.split("\n");
			var line = currentToken && currentToken.line ? currentToken.line - 1 : lines.length - 1;
			var contextLine = lines[line];
			var offset = currentToken && currentToken.line ? currentToken.column : contextLine.length - 1;
			return contextLine + "\n" + " ".repeat(offset) + "^^\n\n";
		}

		/**
		 * @param {TokensObject} tokens
		 * @param {string} [message]
		 */
		function raiseParseError(tokens, message) {
			message =
				(message || "Unexpected Token : " + tokens.currentToken().value) + "\n\n" + createParserContext(tokens);
			var error = new Error(message);
			error["tokens"] = tokens;
			throw error;
		}

		/**
		 * @param {TokensObject} tokens
		 * @returns {GrammarElement}
		 */
		function parseHyperScript(tokens) {
			var result = parseElement("hyperscript", tokens);
			if (tokens.hasMore()) raiseParseError(tokens);
			if (result) return result;
		}

		/**
		 * @param {GrammarElement} elt
		 * @param {GrammarElement} parent
		 */
		function setParent(elt, parent) {
			if (elt) {
				elt.parent = parent;
				setParent(elt.next, parent);
			}
		}

		/**
		 * @param {Token} token
		 * @returns {GrammarDefinition}
		 */
		function commandStart(token) {
			return COMMANDS[token.value];
		}

		/**
		 * @param {Token} token
		 * @returns {GrammarDefinition}
		 */
		function featureStart(token) {
			return FEATURES[token.value];
		}

		/**
		 * @param {Token} token
		 * @returns {boolean}
		 */
		function commandBoundary(token) {
			if (
				token.value == "end" ||
				token.value == "then" ||
				token.value == "else" ||
				token.value == ")" ||
				commandStart(token) ||
				featureStart(token) ||
				token.type == "EOF"
			) {
				return true;
			}
			return false;
		}

		/**
		 * @param {TokensObject} tokens
		 * @returns {(string | GrammarElement)[]}
		 */
		function parseStringTemplate(tokens) {
			/** @type {(string | GrammarElement)[]} */
			var returnArr = [""];
			do {
				returnArr.push(tokens.lastWhitespace());
				if (tokens.currentToken().value === "$") {
					tokens.consumeToken();
					var startingBrace = tokens.matchOpToken("{");
					returnArr.push(requireElement("expression", tokens));
					if (startingBrace) {
						tokens.requireOpToken("}");
					}
					returnArr.push("");
				} else if (tokens.currentToken().value === "\\") {
					tokens.consumeToken(); // skip next
					tokens.consumeToken();
				} else {
					var token = tokens.consumeToken();
					returnArr[returnArr.length - 1] += token ? token.value : "";
				}
			} while (tokens.hasMore());
			returnArr.push(tokens.lastWhitespace());
			return returnArr;
		}

		// parser API
		return {
			setParent: setParent,
			requireElement: requireElement,
			parseElement: parseElement,
			featureStart: featureStart,
			commandStart: commandStart,
			commandBoundary: commandBoundary,
			parseAnyOf: parseAnyOf,
			parseHyperScript: parseHyperScript,
			raiseParseError: raiseParseError,
			addGrammarElement: addGrammarElement,
			addCommand: addCommand,
			addFeature: addFeature,
			addLeafExpression: addLeafExpression,
			addIndirectExpression: addIndirectExpression,
			parseStringTemplate: parseStringTemplate,
		};
	})();

	//====================================================================
	// Runtime
	//====================================================================

	var CONVERSIONS = {
		dynamicResolvers: /** @type DynamicConversionFunction[] */ [],
		String: function (val) {
			if (val.toString) {
				return val.toString();
			} else {
				return "" + val;
			}
		},
		Int: function (val) {
			return parseInt(val);
		},
		Float: function (val) {
			return parseFloat(val);
		},
		Number: function (val) {
			console.log(val);
			return Number(val);
		},
		Date: function (val) {
			return new Date(val);
		},
		Array: function (val) {
			return Array.from(val);
		},
		JSON: function (val) {
			return JSON.stringify(val);
		},
		Object: function (val) {
			if (val instanceof String) {
				val = val.toString();
			}
			if (typeof val === "string") {
				return JSON.parse(val);
			} else {
				return mergeObjects({}, val);
			}
		},
	};

	/********************************************
	 * RUNTIME OBJECT
	 ********************************************/

	/** @type {RuntimeObject} */
	var _runtime = (function () {
		/**
		 * @param {HTMLElement} elt
		 * @param {string} selector
		 * @returns boolean
		 */
		function matchesSelector(elt, selector) {
			// noinspection JSUnresolvedVariable
			var matchesFunction =
				// @ts-ignore
				elt.matches || elt.matchesSelector || elt.msMatchesSelector || elt.mozMatchesSelector || elt.webkitMatchesSelector || elt.oMatchesSelector;
			return matchesFunction && matchesFunction.call(elt, selector);
		}

		/**
		 * @param {string} eventName
		 * @param {Object} [detail]
		 * @returns {Event}
		 */
		function makeEvent(eventName, detail) {
			var evt;
			if (window.CustomEvent && typeof window.CustomEvent === "function") {
				evt = new CustomEvent(eventName, {
					bubbles: true,
					cancelable: true,
					detail: detail,
				});
			} else {
				evt = document.createEvent("CustomEvent");
				evt.initCustomEvent(eventName, true, true, detail);
			}
			return evt;
		}

		/**
		 * @param {Element} elt
		 * @param {string} eventName
		 * @param {Object} [detail]
		 * @returns {boolean}
		 */
		function triggerEvent(elt, eventName, detail) {
			detail = detail || {};
			detail["sentBy"] = elt;
			var event = makeEvent(eventName, detail);
			var eventResult = elt.dispatchEvent(event);
			return eventResult;
		}

		/**
		 * isArrayLike returns `true` if the provided value is an array or
		 * a NodeList (which is close enough to being an array for our purposes).
		 *
		 * @param {any} value
		 * @returns {value is Array | NodeList}
		 */
		function isArrayLike(value) {
			return Array.isArray(value) || value instanceof NodeList;
		}

		/**
		 * isIterable returns `true` if the provided value supports the
		 * iterator protocol.
		 *
		 * @param {any} value
		 * @returns {value is Iterable}
		 */
		function isIterable(value) {
			return typeof value === 'object'
				&& Symbol.iterator in value
				&& typeof value[Symbol.iterator] === 'function';
		}

		/**
		 * shouldAutoIterate returns `true` if the provided value
		 * should be implicitly iterated over when accessing properties,
		 * and as the target of some commands.
		 *
		 * Currently, this is when the value is an {ElementCollection}
		 * or {isArrayLike} returns true.
		 *
		 * @param {any} value
		 * @returns {value is any[] | NodeList | ElementCollection}
		 */
		function shouldAutoIterate(value) {
			return value instanceof ElementCollection || isArrayLike(value);
		}

		/**
		 * forEach executes the provided `func` on every item in the `value` array.
		 * if `value` is a single item (and not an array) then `func` is simply called
		 * once.  If `value` is null, then no further actions are taken.
		 *
		 * @template T
		 * @param {T | Iterable<T>} value
		 * @param {(item: T) => void} func
		 */
		function forEach(value, func) {
			if (value == null) {
				// do nothing
			} else if (isIterable(value)) {
				for (const nth of value) {
					func(nth);
				}
			} else if (isArrayLike(value)) {
				for (var i = 0; i < value.length; i++) {
					func(value[i]);
				}
			} else {
				func(value);
			}
		}

		/**
		 * implicitLoop executes the provided `func` on:
		 * - every item of {value}, if {value} should be auto-iterated
		 *   (see {shouldAutoIterate})
		 * - {value} otherwise
		 *
		 * @template T
		 * @param {NodeList | T | T[]} value
		 * @param {(item:Node | T) => void} func
		 */
		function implicitLoop(value, func) {
			if (shouldAutoIterate(value)) {
				for (const x of value) func(x);
			} else {
				func(value);
			}
		}

		var ARRAY_SENTINEL = { array_sentinel: true };

		function linearize(args) {
			var arr = [];
			for (var i = 0; i < args.length; i++) {
				var arg = args[i];
				if (Array.isArray(arg)) {
					arr.push(ARRAY_SENTINEL);
					for (var j = 0; j < arg.length; j++) {
						arr.push(arg[j]);
					}
					arr.push(ARRAY_SENTINEL);
				} else {
					arr.push(arg);
				}
			}
			return arr;
		}

		function delinearize(values) {
			var arr = [];
			for (var i = 0; i < values.length; i++) {
				var value = values[i];
				if (value === ARRAY_SENTINEL) {
					value = values[++i];
					var valueArray = [];
					arr.push(valueArray);
					while (value !== ARRAY_SENTINEL) {
						valueArray.push(value);
						value = values[++i];
					}
				} else {
					arr.push(value);
				}
			}
			return arr;
		}

		function unwrapAsyncs(values) {
			for (var i = 0; i < values.length; i++) {
				var value = values[i];
				if (value.asyncWrapper) {
					values[i] = value.value;
				}
				if (Array.isArray(value)) {
					for (var j = 0; j < value.length; j++) {
						var valueElement = value[j];
						if (valueElement.asyncWrapper) {
							value[j] = valueElement.value;
						}
					}
				}
			}
		}

		var HALT = {};

		/**
		 * @param {GrammarElement} command
		 * @param {Context} ctx
		 */
		function unifiedExec(command, ctx) {
			while (true) {
				try {
					var next = unifiedEval(command, ctx);
				} catch (e) {
					_runtime.registerHyperTrace(ctx, e);
					if (ctx.meta.errorHandler && !ctx.meta.handlingError) {
						ctx.meta.handlingError = true;
						ctx[ctx.meta.errorSymmbol] = e;
						command = ctx.meta.errorHandler;
						continue;
					} else if (ctx.meta.reject) {
						ctx.meta.reject(e);
						next = HALT;
					} else {
						throw e;
					}
				}
				if (next == null) {
					console.error(command, " did not return a next element to execute! context: ", ctx);
					return;
				} else if (next.then) {
					next.then(function (resolvedNext) {
						unifiedExec(resolvedNext, ctx);
					}).catch(function (reason) {
						_runtime.registerHyperTrace(ctx, reason);
						if (ctx.meta.errorHandler && !ctx.meta.handlingError) {
							ctx.meta.handlingError = true;
							ctx[ctx.meta.errorSymmbol] = reason;
							unifiedExec(ctx.meta.errorHandler, ctx);
						} else if (ctx.meta.reject) {
							ctx.meta.reject(reason);
						} else {
							throw reason;
						}
					});
					return;
				} else if (next === HALT) {
					// done
					return;
				} else {
					command = next; // move to the next command
				}
			}
		}

		/**
		 * @param {*} parseElement
		 * @param {Context} ctx
		 * @returns {*}
		 */
		function unifiedEval(parseElement, ctx) {
			/** @type any[] */
			var args = [ctx];
			var async = false;
			var wrappedAsyncs = false;

			if (parseElement.args) {
				for (var i = 0; i < parseElement.args.length; i++) {
					var argument = parseElement.args[i];
					if (argument == null) {
						args.push(null);
					} else if (Array.isArray(argument)) {
						var arr = [];
						for (var j = 0; j < argument.length; j++) {
							var element = argument[j];
							var value = element ? element.evaluate(ctx) : null; // OK
							if (value) {
								if (value.then) {
									async = true;
								} else if (value.asyncWrapper) {
									wrappedAsyncs = true;
								}
							}
							arr.push(value);
						}
						args.push(arr);
					} else if (argument.evaluate) {
						var value = argument.evaluate(ctx); // OK
						if (value) {
							if (value.then) {
								async = true;
							} else if (value.asyncWrapper) {
								wrappedAsyncs = true;
							}
						}
						args.push(value);
					} else {
						args.push(argument);
					}
				}
			}
			if (async) {
				return new Promise(function (resolve, reject) {
					var linearized = linearize(args);
					Promise.all(linearized)
						.then(function (values) {
							values = delinearize(values);
							if (wrappedAsyncs) {
								unwrapAsyncs(values);
							}
							try {
								var apply = parseElement.op.apply(parseElement, values);
								resolve(apply);
							} catch (e) {
								reject(e);
							}
						})
						.catch(function (reason) {
							if (ctx.meta.errorHandler && !ctx.meta.handlingError) {
								ctx.meta.handlingError = true;
								ctx[ctx.meta.errorSymmbol] = reason;
								unifiedExec(ctx.meta.errorHandler, ctx);
							} else if (ctx.meta.reject) {
								ctx.meta.reject(reason);
							} else {
								// TODO: no meta context to reject with, trigger event?
							}
						});
				});
			} else {
				if (wrappedAsyncs) {
					unwrapAsyncs(args);
				}
				return parseElement.op.apply(parseElement, args);
			}
		}

		var _scriptAttrs = null;

		/**
		 * getAttributes returns the attribute name(s) to use when
		 * locating hyperscript scripts in a DOM element.  If no value
		 * has been configured, it defaults to _hyperscript.config.attributes
		 * @returns string[]
		 */
		function getScriptAttributes() {
			if (_scriptAttrs == null) {
				_scriptAttrs = _hyperscript.config.attributes.replace(/ /g, "").split(",");
			}
			return _scriptAttrs;
		}

		/**
		 * @param {Element} elt
		 * @returns {string | null}
		 */
		function getScript(elt) {
			for (var i = 0; i < getScriptAttributes().length; i++) {
				var scriptAttribute = getScriptAttributes()[i];
				if (elt.hasAttribute && elt.hasAttribute(scriptAttribute)) {
					return elt.getAttribute(scriptAttribute);
				}
			}
			if (elt instanceof HTMLScriptElement && elt.type === "text/hyperscript") {
				return elt.innerText;
			}
			return null;
		}

		var hyperscriptFeaturesMap = new WeakMap

		/**
		 * @param {Element} elt
		 * @returns {Object}
		 */
		function getHyperscriptFeatures(elt) {
			var hyperscriptFeatures = hyperscriptFeaturesMap.get(elt);
			if (typeof hyperscriptFeatures === 'undefined') {
				hyperscriptFeaturesMap.set(elt, hyperscriptFeatures = {});
			}
			return hyperscriptFeatures;
		}

		/**
		 * @param {Object} owner
		 * @param {Context} ctx
		 */
		function addFeatures(owner, ctx) {
			if (owner) {
				mergeObjects(ctx, getHyperscriptFeatures(owner));
				addFeatures(owner.parentElement, ctx);
			}
		}

		/**
		 * @param {*} owner
		 * @param {*} feature
		 * @param {*} hyperscriptTarget
		 * @param {*} event
		 * @returns {Context}
		 */
		function makeContext(owner, feature, hyperscriptTarget, event) {
			/** @type {Context} */
			var ctx = {
				meta: {
					parser: _parser,
					lexer: _lexer,
					runtime: _runtime,
					owner: owner,
					feature: feature,
					iterators: {},
				},
				me: hyperscriptTarget,
				event: event,
				target: event ? event.target : null,
				detail: event ? event.detail : null,
				body: "document" in globalScope ? document.body : null,
			};
			ctx.meta.ctx = ctx;
			addFeatures(owner, ctx);
			return ctx;
		}

		/**
		 * @returns string
		 */
		function getScriptSelector() {
			return getScriptAttributes()
				.map(function (attribute) {
					return "[" + attribute + "]";
				})
				.join(", ");
		}

		/**
		 * @param {any} value
		 * @param {string} type
		 * @returns {any}
		 */
		function convertValue(value, type) {
			var dynamicResolvers = CONVERSIONS.dynamicResolvers;
			for (var i = 0; i < dynamicResolvers.length; i++) {
				var dynamicResolver = dynamicResolvers[i];
				var converted = dynamicResolver(type, value);
				if (converted !== undefined) {
					return converted;
				}
			}

			if (value == null) {
				return null;
			}
			var converter = CONVERSIONS[type];
			if (converter) {
				return converter(value);
			}

			throw "Unknown conversion : " + type;
		}

		// TODO: There do not seem to be any references to this function.
		// Is it still in use, or can it be removed?
		function isType(o, type) {
			return Object.prototype.toString.call(o) === "[object " + type + "]";
		}

		/**
		 * @param {string} src
		 * @returns {GrammarElement}
		 */
		function parse(src) {
			var tokens = _lexer.tokenize(src);
			if (_parser.commandStart(tokens.currentToken())) {
				var commandList = _parser.requireElement("commandList", tokens);
				var last = commandList;
				while (last.next) {
					last = last.next;
				}
				last.next = {
					op: function () {
						return HALT;
					},
				};
				return commandList;
			} else if (_parser.featureStart(tokens.currentToken())) {
				var hyperscript = _parser.requireElement("hyperscript", tokens);
				return hyperscript;
			} else {
				var expression = _parser.requireElement("expression", tokens);
				return expression;
			}
		}

		/**
		 * @param {string} src
		 * @param {Context} [ctx]
		 * @returns {any}
		 */
		function evaluate(src, ctx) {
			var body = 'document' in globalScope ? globalScope.document.body : makeModule();
			ctx = mergeObjects(makeContext(body, null, body, null), ctx || {});
			var element = parse(src);
			if (element.execute) {
				return element.execute(ctx);
			} else if (element.apply) {
				element.apply(body, null);
				return getHyperscriptFeatures(body);
			} else {
				return element.evaluate(ctx);
			}

			function makeModule() {
				return {}
			}
		}

		/**
		 * @param {HTMLElement} elt
		 */
		function processNode(elt) {
			var selector = _runtime.getScriptSelector();
			if (matchesSelector(elt, selector)) {
				initElement(elt, elt);
			}
			if (elt instanceof HTMLScriptElement && elt.type === "text/hyperscript") {
				initElement(elt, document.body);
			}
			if (elt.querySelectorAll) {
				forEach(elt.querySelectorAll(selector + ", [type='text/hyperscript']"), function (elt) {
					initElement(elt, elt instanceof HTMLScriptElement && elt.type === "text/hyperscript" ? document.body : elt);
				});
			}
		}

		/**
		 * @param {Element} elt
		 * @param {Element} [target]
		 */
		function initElement(elt, target) {
			if (elt.closest && elt.closest(_hyperscript.config.disableSelector)) {
				return;
			}
			var internalData = getInternalData(elt);
			if (!internalData.initialized) {
				var src = getScript(elt);
				if (src) {
					try {
						internalData.initialized = true;
						internalData.script = src;
						var tokens = _lexer.tokenize(src);
						var hyperScript = _parser.parseHyperScript(tokens);
						if (!hyperScript) return;
						hyperScript.apply(target || elt, elt);
						setTimeout(function () {
							triggerEvent(target || elt, "load", {
								hyperscript: true,
							});
						}, 1);
					} catch (e) {
						_runtime.triggerEvent(elt, "exception", {
							error: e,
						});
						console.error(
							"hyperscript errors were found on the following element:",
							elt,
							"\n\n",
							e.message,
							e.stack
						);
					}
				}
			}
		}

		var internalDataMap = new WeakMap

		/**
		 * @param {Element} elt
		 * @returns {Object}
		 */
		function getInternalData(elt) {
			var internalData = internalDataMap.get(elt);
			if (typeof internalData === 'undefined') {
				internalDataMap.set(elt, internalData = {});
			}
			return internalData;
		}

		/**
		 * @param {any} value
		 * @param {string} typeString
		 * @param {boolean} [nullOk]
		 * @returns {boolean}
		 */
		function typeCheck(value, typeString, nullOk) {
			if (value == null && nullOk) {
				return true;
			}
			var typeName = Object.prototype.toString.call(value).slice(8, -1);
			return typeName === typeString;
		}

		function getElementScope(context) {
			var elt = context.meta && context.meta.owner;
			if (elt) {
				var internalData = getInternalData(elt);
				var scopeName = "elementScope";
				if (context.meta.feature && context.meta.feature.behavior) {
					scopeName = context.meta.feature.behavior + "Scope";
				}
				var elementScope = getOrInitObject(internalData, scopeName);
				return elementScope;
			} else {
				return {}; // no element, return empty scope
			}
		}

		/**
		 * @param {string} str
		 * @param {Context} context
		 * @returns {any}
		 */
		function resolveSymbol(str, context, type) {
			if (str === "me" || str === "my" || str === "I") {
				return context["me"];
			}
			if (str === "it" || str === "its") {
				return context["result"];
			}
			if (str === "you" || str === "your" || str === "yourself") {
				return context["beingTold"];
			} else {
				if (type === "global") {
					return globalScope[str];
				} else if (type === "element") {
					var elementScope = getElementScope(context);
					return elementScope[str];
				} else if (type === "local") {
					return context[str];
				} else {
					// meta scope (used for event conditionals)
					if (context.meta && context.meta.context) {
						var fromMetaContext = context.meta.context[str];
						if (typeof fromMetaContext !== "undefined") {
							return fromMetaContext;
						}
					}
					// local scope
					var fromContext = context[str];
					if (typeof fromContext !== "undefined") {
						return fromContext;
					} else {
						// element scope
						var elementScope = getElementScope(context);
						fromContext = elementScope[str];
						if (typeof fromContext !== "undefined") {
							return fromContext;
						} else {
							// global scope
							return globalScope[str];
						}
					}
				}
			}
		}

		function setSymbol(str, context, type, value) {
			if (type === "global") {
				globalScope[str] = value;
			} else if (type === "element") {
				var elementScope = getElementScope(context);
				elementScope[str] = value;
			} else if (type === "local") {
				context[str] = value;
			} else {
				// local scope
				var fromContext = context[str];
				if (typeof fromContext !== "undefined") {
					context[str] = value;
				} else {
					// element scope
					var elementScope = getElementScope(context);
					fromContext = elementScope[str];
					if (typeof fromContext !== "undefined") {
						elementScope[str] = value;
					} else {
						// global scope
						fromContext = globalScope[str];
						if (typeof fromContext !== "undefined") {
							globalScope[str] = value;
						} else {
							context[str] = value;
						}
					}
				}
			}
		}

		/**
		 * @param {GrammarElement} command
		 * @param {Context} context
		 * @returns {undefined | GrammarElement}
		 */
		function findNext(command, context) {
			if (command) {
				if (command.resolveNext) {
					return command.resolveNext(context);
				} else if (command.next) {
					return command.next;
				} else {
					return findNext(command.parent, context);
				}
			}
		}

		/**
		 * @param {Object<string,any>} root
		 * @param {string} property
		 * @param {boolean} attribute
		 * @returns {any}
		 */
		function resolveProperty(root, property, attribute) {
			if (root != null) {
				var val = attribute && root.getAttribute ? root.getAttribute(property) : root[property];
				if (typeof val !== "undefined") {
					return val;
				}

				if (shouldAutoIterate(root)) {
					// flat map
					var result = [];
					for (var component of root) {
						var componentValue = attribute ? component.getAttribute(property) : component[property];
						if (componentValue) {
							result.push(componentValue);
						}
					}
					return result;
				}
			}
		}

		/**
		 * @param {Element} elt
		 * @param {string[]} nameSpace
		 * @param {string} name
		 * @param {any} value
		 */
		function assignToNamespace(elt, nameSpace, name, value) {
			if (typeof document === "undefined" || elt === document.body) {
				var root = globalScope;
			} else {
				var root = getHyperscriptFeatures(elt);
			}
			while (nameSpace.length > 0) {
				var propertyName = nameSpace.shift();
				var newRoot = root[propertyName];
				if (newRoot == null) {
					newRoot = {};
					root[propertyName] = newRoot;
				}
				root = newRoot;
			}

			root[name] = value;
		}

		function getHyperTrace(ctx, thrown) {
			var trace = [];
			var root = ctx;
			while (root.meta.caller) {
				root = root.meta.caller;
			}
			if (root.meta.traceMap) {
				return root.meta.traceMap.get(thrown, trace);
			}
		}

		function registerHyperTrace(ctx, thrown) {
			var trace = [];
			var root = null;
			while (ctx != null) {
				trace.push(ctx);
				root = ctx;
				ctx = ctx.meta.caller;
			}
			if (root.meta.traceMap == null) {
				root.meta.traceMap = new Map(); // TODO - WeakMap?
			}
			if (!root.meta.traceMap.get(thrown)) {
				var traceEntry = {
					trace: trace,
					print: function (logger) {
						logger = logger || console.error;
						logger("hypertrace /// ");
						var maxLen = 0;
						for (var i = 0; i < trace.length; i++) {
							maxLen = Math.max(maxLen, trace[i].meta.feature.displayName.length);
						}
						for (var i = 0; i < trace.length; i++) {
							var traceElt = trace[i];
							logger(
								"  ->",
								traceElt.meta.feature.displayName.padEnd(maxLen + 2),
								"-",
								traceElt.meta.owner
							);
						}
					},
				};
				root.meta.traceMap.set(thrown, traceEntry);
			}
		}

		/**
		 * @param {string} str
		 * @returns {string}
		 */
		function escapeSelector(str) {
			return str.replace(/:/g, function (str) {
				return "\\" + str;
			});
		}

		/**
		 * @param {any} value
		 * @param {*} elt
		 */
		function nullCheck(value, elt) {
			if (value == null) {
				throw new Error(elt.sourceFor() + " is null");
			}
		}

		/**
		 * @param {any} value
		 * @returns {boolean}
		 */
		function isEmpty(value) {
			return value == undefined || value.length === 0;
		}

		/**
		 * @param {Node} node
		 * @returns {Document|ShadowRoot}
		 */
		function getRootNode(node) {
			var rv = node.getRootNode();
			if (rv instanceof Document || rv instanceof ShadowRoot) return rv;
			else return document;
		}

		/** @type string | null */
		// @ts-ignore
		var hyperscriptUrl = "document" in globalScope ? document.currentScript.src : null;

		/** @type {RuntimeObject} */
		return {
			typeCheck: typeCheck,
			forEach: forEach,
			implicitLoop: implicitLoop,
			triggerEvent: triggerEvent,
			matchesSelector: matchesSelector,
			getScript: getScript,
			processNode: processNode,
			evaluate: evaluate,
			parse: parse,
			getScriptSelector: getScriptSelector,
			resolveSymbol: resolveSymbol,
			setSymbol: setSymbol,
			makeContext: makeContext,
			findNext: findNext,
			unifiedEval: unifiedEval,
			convertValue: convertValue,
			unifiedExec: unifiedExec,
			resolveProperty: resolveProperty,
			assignToNamespace: assignToNamespace,
			registerHyperTrace: registerHyperTrace,
			getHyperTrace: getHyperTrace,
			getInternalData: getInternalData,
			escapeSelector: escapeSelector,
			nullCheck: nullCheck,
			isEmpty: isEmpty,
			getRootNode: getRootNode,
			hyperscriptUrl: hyperscriptUrl,
			HALT: HALT,
		};
	})();

	//====================================================================
	// Grammar
	//====================================================================
	{
		_parser.addLeafExpression("parenthesized", function (parser, _runtime, tokens) {
			if (tokens.matchOpToken("(")) {
				var follows = tokens.clearFollow();
				try {
					var expr = parser.requireElement("expression", tokens);
				} finally {
					tokens.restoreFollow(follows);
				}
				tokens.requireOpToken(")");
				return expr;
			}
		});

		_parser.addLeafExpression("string", function (parser, runtime, tokens) {
			var stringToken = tokens.matchTokenType("STRING");
			if (!stringToken) return;
			var rawValue = stringToken.value;
			/** @type {any[]} */
			var args;
			if (stringToken.template) {
				var innerTokens = _lexer.tokenize(rawValue, true);
				args = parser.parseStringTemplate(innerTokens);
			} else {
				args = [];
			}
			return {
				type: "string",
				token: stringToken,
				args: args,
				op: function (context) {
					var returnStr = "";
					for (var i = 1; i < arguments.length; i++) {
						var val = arguments[i];
						if (val !== undefined) {
							returnStr += val;
						}
					}
					return returnStr;
				},
				evaluate: function (context) {
					if (args.length === 0) {
						return rawValue;
					} else {
						return runtime.unifiedEval(this, context);
					}
				},
			};
		});

		_parser.addGrammarElement("nakedString", function (parser, runtime, tokens) {
			if (tokens.hasMore()) {
				var tokenArr = tokens.consumeUntilWhitespace();
				tokens.matchTokenType("WHITESPACE");
				return {
					type: "nakedString",
					tokens: tokenArr,
					evaluate: function (context) {
						return tokenArr
							.map(function (t) {
								return t.value;
							})
							.join("");
					},
				};
			}
		});

		_parser.addLeafExpression("number", function (parser, runtime, tokens) {
			var number = tokens.matchTokenType("NUMBER");
			if (!number) return;
			var numberToken = number;
			var value = parseFloat(number.value);
			return {
				type: "number",
				value: value,
				numberToken: numberToken,
				evaluate: function () {
					return value;
				},
			};
		});

		_parser.addLeafExpression("idRef", function (parser, runtime, tokens) {
			var elementId = tokens.matchTokenType("ID_REF");
			if (!elementId) return;
			// TODO - unify these two expression types
			if (elementId.template) {
				var templateValue = elementId.value.substr(2, elementId.value.length - 2);
				var innerTokens = _lexer.tokenize(templateValue);
				var innerExpression = parser.requireElement("expression", innerTokens);
				return {
					type: "idRefTemplate",
					args: [innerExpression],
					op: function (context, arg) {
						return runtime.getRootNode(context.me).getElementById(arg);
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
			} else {
				const value = elementId.value.substr(1);
				return {
					type: "idRef",
					css: elementId.value,
					value: value,
					evaluate: function (context) {
						return (
							runtime.getRootNode(context.me).getElementById(value)
						);
					},
				};
			}
		});

		_parser.addLeafExpression("classRef", function (parser, runtime, tokens) {
			var classRef = tokens.matchTokenType("CLASS_REF");

			if (!classRef) return;

			// TODO - unify these two expression types
			if (classRef.template) {
				var templateValue = classRef.value.substr(2, classRef.value.length - 2);
				var innerTokens = _lexer.tokenize(templateValue);
				var innerExpression = parser.requireElement("expression", innerTokens);
				return {
					type: "classRefTemplate",
					args: [innerExpression],
					op: function (context, arg) {
						return new ElementCollection("." + arg, context.me)
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
			} else {
				const css = classRef.value;
				return {
					type: "classRef",
					css: css,
					evaluate: function (context) {
						return new ElementCollection(css, context.me)
					},
				};
			}
		});

		class TemplatedQueryElementCollection extends ElementCollection {
			constructor(css, relativeToElement, templateParts) {
				super(css, relativeToElement);
				this.templateParts = templateParts;
				this.elements = templateParts.filter(elt => elt instanceof Element);
			}

			get css() {
				let rv = "", i = 0
			    for (const val of this.templateParts) {
					if (val instanceof Element) {
						rv += "[data-hs-query-id='" + i++ + "']";
					} else rv += val;
				}
				return rv;
			}

			[Symbol.iterator]() {
				this.elements.forEach((el, i) => el.dataset.hsQueryId = i);
				const rv = super[Symbol.iterator]();
				this.elements.forEach(el => el.removeAttribute('data-hs-query-id'));
				return rv;
			}
		}

		_parser.addLeafExpression("queryRef", function (parser, runtime, tokens) {
			var queryStart = tokens.matchOpToken("<");
			if (!queryStart) return;
			var queryTokens = tokens.consumeUntil("/");
			tokens.requireOpToken("/");
			tokens.requireOpToken(">");
			var queryValue = queryTokens
				.map(function (t) {
					if (t.type === "STRING") {
						return '"' + t.value + '"';
					} else {
						return t.value;
					}
				})
				.join("");

			if (queryValue.indexOf("$") >= 0) {
				var template = true;
				var innerTokens = _lexer.tokenize(queryValue, true);
				var args = parser.parseStringTemplate(innerTokens);
			}

			return {
				type: "queryRef",
				css: queryValue,
				args: args,
				op: function (context, ...args) {
					if (template) {
						return new TemplatedQueryElementCollection(queryValue, context.me, args)
					} else {
						return new ElementCollection(queryValue, context.me)
					}
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addLeafExpression("attributeRef", function (parser, runtime, tokens) {
			var attributeRef = tokens.matchTokenType("ATTRIBUTE_REF");
			if (!attributeRef) return;
			var outerVal = attributeRef.value;
			if (outerVal.indexOf("[") === 0) {
				var innerValue = outerVal.substring(2, outerVal.length - 1);
			} else {
				var innerValue = outerVal.substring(1);
			}
			var css = "[" + innerValue + "]";
			var split = innerValue.split("=");
			var name = split[0];
			var value = split[1];
			if (value) {
				// strip quotes
				if (value.indexOf('"') === 0) {
					value = value.substring(1, value.length - 1);
				}
			}
			return {
				type: "attributeRef",
				name: name,
				css: css,
				value: value,
				op: function (context) {
					var target = context.beingTold || context.me;
					if (target) {
						return target.getAttribute(name);
					}
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addGrammarElement("objectKey", function (parser, runtime, tokens) {
			var token;
			if ((token = tokens.matchTokenType("STRING"))) {
				return {
					type: "objectKey",
					key: token.value,
					evaluate: function () {
						return token.value;
					},
				};
			} else if (tokens.matchOpToken("[")) {
				var expr = parser.parseElement("expression", tokens);
				tokens.requireOpToken("]");
				return {
					type: "objectKey",
					expr: expr,
					args: [expr],
					op: function (ctx, expr) {
						return expr;
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
			} else {
				var key = "";
				do {
					token = tokens.matchTokenType("IDENTIFIER") || tokens.matchOpToken("-");
					if (token) key += token.value;
				} while (token);
				return {
					type: "objectKey",
					key: key,
					evaluate: function () {
						return key;
					},
				};
			}
		});

		_parser.addLeafExpression("objectLiteral", function (parser, runtime, tokens) {
			if (!tokens.matchOpToken("{")) return;
			var keyExpressions = [];
			var valueExpressions = [];
			if (!tokens.matchOpToken("}")) {
				do {
					var name = parser.requireElement("objectKey", tokens);
					tokens.requireOpToken(":");
					var value = parser.requireElement("expression", tokens);
					valueExpressions.push(value);
					keyExpressions.push(name);
				} while (tokens.matchOpToken(","));
				tokens.requireOpToken("}");
			}
			return {
				type: "objectLiteral",
				args: [keyExpressions, valueExpressions],
				op: function (context, keys, values) {
					var returnVal = {};
					for (var i = 0; i < keys.length; i++) {
						returnVal[keys[i]] = values[i];
					}
					return returnVal;
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addGrammarElement("namedArgumentList", function (parser, runtime, tokens) {
			if (!tokens.matchOpToken("(")) return;
			var fields = [];
			var valueExpressions = [];
			if (!tokens.matchOpToken(")")) {
				do {
					var name = tokens.requireTokenType("IDENTIFIER");
					tokens.requireOpToken(":");
					var value = parser.requireElement("expression", tokens);
					valueExpressions.push(value);
					fields.push({ name: name, value: value });
				} while (tokens.matchOpToken(","));
				tokens.requireOpToken(")");
			}
			return {
				type: "namedArgumentList",
				fields: fields,
				args: [valueExpressions],
				op: function (context, values) {
					var returnVal = { _namedArgList_: true };
					for (var i = 0; i < values.length; i++) {
						var field = fields[i];
						returnVal[field.name.value] = values[i];
					}
					return returnVal;
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addGrammarElement("symbol", function (parser, runtime, tokens) {
			/** @type {SymbolScope} */
			var type = "default";
			if (tokens.matchToken("global")) {
				type = "global";
			} else if (tokens.matchToken("element") || tokens.matchToken("module")) {
				type = "element";
				// optional possessive
				if (tokens.matchOpToken("'")) {
					tokens.requireToken("s");
				}
			} else if (tokens.matchToken("local")) {
				type = "local";
			}
			var identifier = tokens.matchTokenType("IDENTIFIER");
			if (identifier) {
				const name = identifier.value;
				return {
					type: "symbol",
					symbolType: type,
					token: identifier,
					name: name,
					evaluate: function (context) {
						return runtime.resolveSymbol(name, context, type);
					},
				};
			}
		});

		_parser.addGrammarElement("implicitMeTarget", function (parser, runtime, tokens) {
			return {
				type: "implicitMeTarget",
				evaluate: function (context) {
					return context.beingTold || context.me;
				},
			};
		});

		_parser.addLeafExpression("boolean", function (parser, runtime, tokens) {
			var booleanLiteral = tokens.matchToken("true") || tokens.matchToken("false");
			if (!booleanLiteral) return;
			const value = booleanLiteral.value === "true";
			return {
				type: "boolean",
				evaluate: function (context) {
					return value;
				},
			};
		});

		_parser.addLeafExpression("null", function (parser, runtime, tokens) {
			if (tokens.matchToken("null")) {
				return {
					type: "null",
					evaluate: function (context) {
						return null;
					},
				};
			}
		});

		_parser.addLeafExpression("arrayLiteral", function (parser, runtime, tokens) {
			if (!tokens.matchOpToken("[")) return;
			var values = [];
			if (!tokens.matchOpToken("]")) {
				do {
					var expr = parser.requireElement("expression", tokens);
					values.push(expr);
				} while (tokens.matchOpToken(","));
				tokens.requireOpToken("]");
			}
			return {
				type: "arrayLiteral",
				values: values,
				args: [values],
				op: function (context, values) {
					return values;
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addLeafExpression("blockLiteral", function (parser, runtime, tokens) {
			if (!tokens.matchOpToken("\\")) return;
			var args = [];
			var arg1 = tokens.matchTokenType("IDENTIFIER");
			if (arg1) {
				args.push(arg1);
				while (tokens.matchOpToken(",")) {
					args.push(tokens.requireTokenType("IDENTIFIER"));
				}
			}
			// TODO compound op token
			tokens.requireOpToken("-");
			tokens.requireOpToken(">");
			var expr = parser.requireElement("expression", tokens);
			return {
				type: "blockLiteral",
				args: args,
				expr: expr,
				evaluate: function (ctx) {
					var returnFunc = function () {
						//TODO - push scope
						for (var i = 0; i < args.length; i++) {
							ctx[args[i].value] = arguments[i];
						}
						return expr.evaluate(ctx); //OK
					};
					return returnFunc;
				},
			};
		});

		_parser.addGrammarElement("timeExpression", function (parser, runtime, tokens) {
			var time = parser.requireElement("expression", tokens);
			var factor = 1;
			if (tokens.matchToken("s") || tokens.matchToken("seconds")) {
				factor = 1000;
			} else if (tokens.matchToken("ms") || tokens.matchToken("milliseconds")) {
				// do nothing
			}
			return {
				type: "timeExpression",
				time: time,
				factor: factor,
				args: [time],
				op: function (_context, val) {
					return val * factor;
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addIndirectExpression("propertyAccess", function (parser, runtime, tokens, root) {
			if (!tokens.matchOpToken(".")) return;
			var prop = tokens.requireTokenType("IDENTIFIER");
			var propertyAccess = {
				type: "propertyAccess",
				root: root,
				prop: prop,
				args: [root],
				op: function (_context, rootVal) {
					var value = runtime.resolveProperty(rootVal, prop.value, false);
					return value;
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
			return parser.parseElement("indirectExpression", tokens, propertyAccess);
		});

		_parser.addIndirectExpression("of", function (parser, runtime, tokens, root) {
			if (!tokens.matchToken("of")) return;
			var newRoot = parser.requireElement("expression", tokens);
			// find the urroot
			var childOfUrRoot = null;
			var urRoot = root;
			while (urRoot.root) {
				childOfUrRoot = urRoot;
				urRoot = urRoot.root;
			}
			if (urRoot.type !== "symbol" && urRoot.type !== "attributeRef") {
				parser.raiseParseError(tokens, "Cannot take a property of a non-symbol: " + urRoot.type);
			}
			var attribute = urRoot.type === "attributeRef";
			var prop = urRoot.name;
			var propertyAccess = {
				type: "ofExpression",
				prop: urRoot.token,
				root: newRoot,
				attribute: attribute,
				expression: root,
				args: [newRoot],
				op: function (context, rootVal) {
					return runtime.resolveProperty(rootVal, prop, attribute);
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};

			if (urRoot.type === "attributeRef") {
				propertyAccess.attribute = urRoot;
			}
			if (childOfUrRoot) {
				childOfUrRoot.root = propertyAccess;
				childOfUrRoot.args = [propertyAccess];
			} else {
				root = propertyAccess;
			}

			return parser.parseElement("indirectExpression", tokens, root);
		});

		_parser.addIndirectExpression("possessive", function (parser, runtime, tokens, root) {
			if (parser.possessivesDisabled) {
				return;
			}
			var apostrophe = tokens.matchOpToken("'");
			if (
				apostrophe ||
				(root.type === "symbol" &&
					(root.name === "my" || root.name === "its" || root.name === "your") &&
					tokens.currentToken().type === "IDENTIFIER")
			) {
				if (apostrophe) {
					tokens.requireToken("s");
				}
				var attribute = parser.parseElement("attributeRef", tokens);
				if (attribute == null) {
					var prop = tokens.requireTokenType("IDENTIFIER");
				}
				var propertyAccess = {
					type: "possessive",
					root: root,
					attribute: attribute,
					prop: prop,
					args: [root],
					op: function (context, rootVal) {
						if (attribute) {
							// @ts-ignore
							var value = runtime.resolveProperty(rootVal, attribute.name, true);
						} else {
							var value = runtime.resolveProperty(rootVal, prop.value, false);
						}
						return value;
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
				return parser.parseElement("indirectExpression", tokens, propertyAccess);
			}
		});

		_parser.addIndirectExpression("inExpression", function (parser, runtime, tokens, root) {
			if (!tokens.matchToken("in")) return;
			if ((root.type !== "idRef" && root.type === "queryRef") || root.type === "classRef") {
				var query = true;
			}
			var target = parser.requireElement("expression", tokens);
			var propertyAccess = {
				type: "inExpression",
				root: root,
				args: [query ? null : root, target],
				op: function (context, rootVal, target) {
					var returnArr = [];
					if (query) {
						runtime.forEach(target, function (targetElt) {
							var results = targetElt.querySelectorAll(root.css);
							for (var i = 0; i < results.length; i++) {
								returnArr.push(results[i]);
							}
						});
					} else {
						runtime.forEach(rootVal, function (rootElt) {
							runtime.forEach(target, function (targetElt) {
								if (rootElt === targetElt) {
									returnArr.push(rootElt);
								}
							});
						});
					}
					if (returnArr.length > 0) {
						return returnArr;
					} else {
						return null;
					}
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
			return parser.parseElement("indirectExpression", tokens, propertyAccess);
		});

		_parser.addIndirectExpression("asExpression", function (parser, runtime, tokens, root) {
			if (!tokens.matchToken("as")) return;
			tokens.matchToken("a") || tokens.matchToken("an");
			var conversion = parser.requireElement("dotOrColonPath", tokens).evaluate(); // OK No promise
			var propertyAccess = {
				type: "asExpression",
				root: root,
				args: [root],
				op: function (context, rootVal) {
					return runtime.convertValue(rootVal, conversion);
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
			return parser.parseElement("indirectExpression", tokens, propertyAccess);
		});

		_parser.addIndirectExpression("functionCall", function (parser, runtime, tokens, root) {
			if (!tokens.matchOpToken("(")) return;
			var args = [];
			if (!tokens.matchOpToken(")")) {
				do {
					args.push(parser.requireElement("expression", tokens));
				} while (tokens.matchOpToken(","));
				tokens.requireOpToken(")");
			}

			if (root.root) {
				var functionCall = {
					type: "functionCall",
					root: root,
					argExressions: args,
					args: [root.root, args],
					op: function (context, rootRoot, args) {
						runtime.nullCheck(rootRoot, root.root);
						var func = rootRoot[root.prop.value];
						runtime.nullCheck(func, root);
						if (func.hyperfunc) {
							args.push(context);
						}
						return func.apply(rootRoot, args);
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
			} else {
				var functionCall = {
					type: "functionCall",
					root: root,
					argExressions: args,
					args: [root, args],
					op: function (context, func, argVals) {
						runtime.nullCheck(func, root);
						if (func.hyperfunc) {
							argVals.push(context);
						}
						var apply = func.apply(null, argVals);
						return apply;
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
			}
			return parser.parseElement("indirectExpression", tokens, functionCall);
		});

		_parser.addIndirectExpression("attributeRefAccess", function (parser, runtime, tokens, root) {
			var attribute = parser.parseElement("attributeRef", tokens);
			if (!attribute) return;
			var attributeAccess = {
				type: "attributeRefAccess",
				root: root,
				attribute: attribute,
				args: [root],
				op: function (_ctx, rootVal) {
					// @ts-ignore
					var value = runtime.resolveProperty(rootVal, attribute.name, true);
					return value;
				},
				evaluate: function (context) {
					return _runtime.unifiedEval(this, context);
				},
			};
			return attributeAccess;
		});

		_parser.addIndirectExpression("arrayIndex", function (parser, runtime, tokens, root) {
			if (!tokens.matchOpToken("[")) return;
			var andBefore = false;
			var andAfter = false;
			var firstIndex = null;
			var secondIndex = null;

			if (tokens.matchOpToken("..")) {
				andBefore = true;
				firstIndex = parser.requireElement("expression", tokens);
			} else {
				firstIndex = parser.requireElement("expression", tokens);

				if (tokens.matchOpToken("..")) {
					andAfter = true;
					var current = tokens.currentToken();
					if (current.type !== "R_BRACKET") {
						secondIndex = parser.parseElement("expression", tokens);
					}
				}
			}
			tokens.requireOpToken("]");

			var arrayIndex = {
				type: "arrayIndex",
				root: root,
				firstIndex: firstIndex,
				secondIndex: secondIndex,
				args: [root, firstIndex, secondIndex],
				op: function (_ctx, root, firstIndex, secondIndex) {
					if (andBefore) {
						return root.slice(0, firstIndex + 1); // returns all items from beginning to firstIndex (inclusive)
					} else if (andAfter) {
						if (secondIndex != null) {
							return root.slice(firstIndex, secondIndex + 1); // returns all items from firstIndex to secondIndex (inclusive)
						} else {
							return root.slice(firstIndex); // returns from firstIndex to end of array
						}
					} else {
						return root[firstIndex];
					}
				},
				evaluate: function (context) {
					return _runtime.unifiedEval(this, context);
				},
			};

			return _parser.parseElement("indirectExpression", tokens, arrayIndex);
		});

		_parser.addGrammarElement("postfixExpression", function (parser, runtime, tokens) {
			var root = parser.parseElement("primaryExpression", tokens);
			if (tokens.matchOpToken(":")) {
				var typeName = tokens.requireTokenType("IDENTIFIER");
				var nullOk = !tokens.matchOpToken("!");
				return {
					type: "typeCheck",
					typeName: typeName,
					nullOk: nullOk,
					args: [root],
					op: function (context, val) {
						var passed = runtime.typeCheck(val, typeName.value, nullOk);
						if (passed) {
							return val;
						} else {
							throw new Error("Typecheck failed!  Expected: " + typeName.value);
						}
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
			} else {
				return root;
			}
		});

		_parser.addGrammarElement("logicalNot", function (parser, runtime, tokens) {
			if (!tokens.matchToken("not")) return;
			var root = parser.requireElement("unaryExpression", tokens);
			return {
				type: "logicalNot",
				root: root,
				args: [root],
				op: function (context, val) {
					return !val;
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addGrammarElement("noExpression", function (parser, runtime, tokens) {
			if (!tokens.matchToken("no")) return;
			var root = parser.requireElement("unaryExpression", tokens);
			return {
				type: "noExpression",
				root: root,
				args: [root],
				op: function (_context, val) {
					return runtime.isEmpty(val);
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addGrammarElement("negativeNumber", function (parser, runtime, tokens) {
			if (!tokens.matchOpToken("-")) return;
			var root = parser.requireElement("unaryExpression", tokens);
			return {
				type: "negativeNumber",
				root: root,
				args: [root],
				op: function (context, value) {
					return -1 * value;
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addGrammarElement("unaryExpression", function (parser, runtime, tokens) {
			return parser.parseAnyOf(
				["logicalNot", "relativePositionalExpression", "positionalExpression", "noExpression", "negativeNumber", "postfixExpression"],
				tokens
			);
		});

		var scanForwardQuery = function(start, root, match, wrap) {
			var results = root.querySelectorAll(match);
			for (var i = 0; i < results.length; i++) {
				var elt = results[i];
				if (elt.compareDocumentPosition(start) === Node.DOCUMENT_POSITION_PRECEDING) {
					return elt;
				}
			}
			if (wrap) {
				return results[0];
			}
		}

		var scanBackwardsQuery = function(start, root, match, wrap) {
			var results = root.querySelectorAll(match);
			for (var i = results.length - 1; i >= 0; i--) {
				var elt = results[i];
				if (elt.compareDocumentPosition(start) === Node.DOCUMENT_POSITION_FOLLOWING) {
					return elt;
				}
			}
			if (wrap) {
				return results[results.length - 1];
			}
		}

		var scanForwardArray = function(start, array, match, wrap) {
			var matches = [];
			_runtime.forEach(array, function(elt){
				if (elt.matches(match) || elt === start) {
					matches.push(elt);
				}
			})
			for (var i = 0; i < matches.length - 1; i++) {
				var elt = matches[i];
				if (elt === start) {
					return matches[i + 1];
				}
			}
			if (wrap) {
				var first = matches[0];
				if (first && first.matches(match)) {
					return first;
				}
			}
		}

		var scanBackwardsArray = function(start, array, match, wrap) {
			return scanForwardArray(start, Array.from(array).reverse(), match, wrap);
		}

		_parser.addGrammarElement("relativePositionalExpression", function (parser, runtime, tokens) {
			var op = tokens.matchAnyToken("next", "previous");
			if (!op) return;
			if (op.value === "next") {
				var forwardSearch = true;
			}

			var thing = parser.parseElement("expression", tokens);

			if (tokens.matchToken("from")) {
				tokens.pushFollow("in");
				try {
					var from = parser.requireElement("expression", tokens);
				} finally {
					tokens.popFollow();
				}
			} else {
				var from = parser.requireElement("implicitMeTarget", tokens);
			}

			var inSearch = false;
			var withinElt;
			if (tokens.matchToken("in")) {
				inSearch = true;
				var inElt = parser.requireElement("expression", tokens);
			} else if (tokens.matchToken("within")) {
				withinElt = parser.requireElement("expression", tokens);
			} else {
				withinElt = document.body;
			}

			var wrapping = false;
			if (tokens.matchToken("with")) {
				tokens.requireToken("wrapping")
				wrapping = true;
			}

			return {
				type: "relativePositionalExpression",
				from: from,
				forwardSearch: forwardSearch,
				inSearch: inSearch,
				wrapping: wrapping,
				inElt: inElt,
				withinElt: withinElt,
				operator: op.value,
				args: [thing, from, inElt, withinElt],
				op: function (context, thing, from, inElt, withinElt) {

					var css = thing.css;
					if (css == null) {
						throw "Expected a CSS value";
					}

					if(inSearch) {
						if (inElt) {
							if (forwardSearch) {
								return scanForwardArray(from, inElt, css, wrapping);
							} else {
								return scanBackwardsArray(from, inElt, css, wrapping);
							}
						}
					} else {
						if (withinElt) {
							if (forwardSearch) {
								return scanForwardQuery(from, withinElt, css, wrapping);
							} else {
								return scanBackwardsQuery(from, withinElt, css, wrapping);
							}
						}
					}
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			}

		});

		_parser.addGrammarElement("positionalExpression", function (parser, runtime, tokens) {
			var op = tokens.matchAnyToken("first", "last", "random");
			if (!op) return;
			tokens.matchAnyToken("in", "from", "of");
			var rhs = parser.requireElement("unaryExpression", tokens);
			const operator = op.value;
			return {
				type: "positionalExpression",
				rhs: rhs,
				operator: op.value,
				args: [rhs],
				op: function (context, rhsVal) {
					if (rhsVal && !Array.isArray(rhsVal)) {
						if (rhsVal.children) {
							rhsVal = rhsVal.children;
						} else {
							rhsVal = Array.from(rhsVal);
						}
					}
					if (rhsVal) {
						if (operator === "first") {
							return rhsVal[0];
						} else if (operator === "last") {
							return rhsVal[rhsVal.length - 1];
						} else if (operator === "random") {
							return rhsVal[Math.floor(Math.random() * rhsVal.length)];
						}
					}
				},
				evaluate: function (context) {
					return runtime.unifiedEval(this, context);
				},
			};
		});

		_parser.addGrammarElement("mathOperator", function (parser, runtime, tokens) {
			var expr = parser.parseElement("unaryExpression", tokens);
			var mathOp,
				initialMathOp = null;
			mathOp = tokens.matchAnyOpToken("+", "-", "*", "/", "%");
			while (mathOp) {
				initialMathOp = initialMathOp || mathOp;
				var operator = mathOp.value;
				if (initialMathOp.value !== operator) {
					parser.raiseParseError(tokens, "You must parenthesize math operations with different operators");
				}
				var rhs = parser.parseElement("unaryExpression", tokens);
				expr = {
					type: "mathOperator",
					lhs: expr,
					rhs: rhs,
					operator: operator,
					args: [expr, rhs],
					op: function (context, lhsVal, rhsVal) {
						if (operator === "+") {
							return lhsVal + rhsVal;
						} else if (operator === "-") {
							return lhsVal - rhsVal;
						} else if (operator === "*") {
							return lhsVal * rhsVal;
						} else if (operator === "/") {
							return lhsVal / rhsVal;
						} else if (operator === "%") {
							return lhsVal % rhsVal;
						}
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
				mathOp = tokens.matchAnyOpToken("+", "-", "*", "/", "%");
			}
			return expr;
		});

		_parser.addGrammarElement("mathExpression", function (parser, runtime, tokens) {
			return parser.parseAnyOf(["mathOperator", "unaryExpression"], tokens);
		});

		_parser.addGrammarElement("comparisonOperator", function (parser, runtime, tokens) {
			var expr = parser.parseElement("mathExpression", tokens);
			var comparisonToken = tokens.matchAnyOpToken("<", ">", "<=", ">=", "==", "===", "!=", "!==");
			var operator = comparisonToken ? comparisonToken.value : null;
			var hasRightValue = true; // By default, most comparisons require two values, but there are some exceptions.
			var typeCheck = false;

			if (operator == null) {
				if (tokens.matchToken("is") || tokens.matchToken("am")) {
					if (tokens.matchToken("not")) {
						if (tokens.matchToken("in")) {
							operator = "not in";
						} else if (tokens.matchToken("a")) {
							operator = "not a";
							typeCheck = true;
						} else if (tokens.matchToken("empty")) {
							operator = "not empty";
							hasRightValue = false;
						} else {
							operator = "!=";
						}
					} else if (tokens.matchToken("in")) {
						operator = "in";
					} else if (tokens.matchToken("a")) {
						operator = "a";
						typeCheck = true;
					} else if (tokens.matchToken("empty")) {
						operator = "empty";
						hasRightValue = false;
					} else {
						operator = "==";
					}
				} else if (tokens.matchToken("matches") || tokens.matchToken("match")) {
					operator = "match";
				} else if (tokens.matchToken("contains") || tokens.matchToken("contain")) {
					operator = "contain";
				} else if (tokens.matchToken("do") || tokens.matchToken("does")) {
					tokens.requireToken("not");
					if (tokens.matchToken("matches") || tokens.matchToken("match")) {
						operator = "not match";
					} else if (tokens.matchToken("contains") || tokens.matchToken("contain")) {
						operator = "not contain";
					} else {
						parser.raiseParseError(tokens, "Expected matches or contains");
					}
				}
			}

			if (operator) {
				// Do not allow chained comparisons, which is dumb
				if (typeCheck) {
					var typeName = tokens.requireTokenType("IDENTIFIER");
					var nullOk = !tokens.matchOpToken("!");
				} else if (hasRightValue) {
					var rhs = parser.requireElement("mathExpression", tokens);
					if (operator === "match" || operator === "not match") {
						rhs = rhs.css ? rhs.css : rhs;
					}
				}
				expr = {
					type: "comparisonOperator",
					operator: operator,
					typeName: typeName,
					nullOk: nullOk,
					lhs: expr,
					rhs: rhs,
					args: [expr, rhs],
					op: function (context, lhsVal, rhsVal) {
						if (operator === "==") {
							return lhsVal == rhsVal;
						} else if (operator === "!=") {
							return lhsVal != rhsVal;
						}
						if (operator === "in") {
							return rhsVal != null && Array.from(rhsVal).indexOf(lhsVal) >= 0;
						}
						if (operator === "not in") {
							return rhsVal == null || Array.from(rhsVal).indexOf(lhsVal) < 0;
						}
						if (operator === "match") {
							return lhsVal != null && lhsVal.matches(rhsVal);
						}
						if (operator === "not match") {
							return lhsVal == null || !lhsVal.matches(rhsVal);
						}
						if (operator === "contain") {
							return lhsVal != null && lhsVal.contains(rhsVal);
						}
						if (operator === "not contain") {
							return lhsVal == null || !lhsVal.contains(rhsVal);
						}
						if (operator === "===") {
							return lhsVal === rhsVal;
						} else if (operator === "!==") {
							return lhsVal !== rhsVal;
						} else if (operator === "<") {
							return lhsVal < rhsVal;
						} else if (operator === ">") {
							return lhsVal > rhsVal;
						} else if (operator === "<=") {
							return lhsVal <= rhsVal;
						} else if (operator === ">=") {
							return lhsVal >= rhsVal;
						} else if (operator === "empty") {
							return runtime.isEmpty(lhsVal);
						} else if (operator === "not empty") {
							return !runtime.isEmpty(lhsVal);
						} else if (operator === "a") {
							return runtime.typeCheck(lhsVal, typeName.value, nullOk);
						} else if (operator === "not a") {
							return !runtime.typeCheck(lhsVal, typeName.value, nullOk);
						} else {
							throw "Unknown comparison : " + operator;
						}
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
			}
			return expr;
		});

		_parser.addGrammarElement("comparisonExpression", function (parser, runtime, tokens) {
			return parser.parseAnyOf(["comparisonOperator", "mathExpression"], tokens);
		});

		_parser.addGrammarElement("logicalOperator", function (parser, runtime, tokens) {
			var expr = parser.parseElement("comparisonExpression", tokens);
			var logicalOp,
				initialLogicalOp = null;
			logicalOp = tokens.matchToken("and") || tokens.matchToken("or");
			while (logicalOp) {
				initialLogicalOp = initialLogicalOp || logicalOp;
				if (initialLogicalOp.value !== logicalOp.value) {
					parser.raiseParseError(tokens, "You must parenthesize logical operations with different operators");
				}
				var rhs = parser.requireElement("comparisonExpression", tokens);
				const operator = logicalOp.value;
				expr = {
					type: "logicalOperator",
					operator: operator,
					lhs: expr,
					rhs: rhs,
					args: [expr, rhs],
					op: function (context, lhsVal, rhsVal) {
						if (operator === "and") {
							return lhsVal && rhsVal;
						} else {
							return lhsVal || rhsVal;
						}
					},
					evaluate: function (context) {
						return runtime.unifiedEval(this, context);
					},
				};
				logicalOp = tokens.matchToken("and") || tokens.matchToken("or");
			}
			return expr;
		});

		_parser.addGrammarElement("logicalExpression", function (parser, runtime, tokens) {
			return parser.parseAnyOf(["logicalOperator", "mathExpression"], tokens);
		});

		_parser.addGrammarElement("asyncExpression", function (parser, runtime, tokens) {
			if (tokens.matchToken("async")) {
				var value = parser.requireElement("logicalExpression", tokens);
				var expr = {
					type: "asyncExpression",
					value: value,
					evaluate: function (context) {
						return {
							asyncWrapper: true,
							value: this.value.evaluate(context), //OK
						};
					},
				};
				return expr;
			} else {
				return parser.parseElement("logicalExpression", tokens);
			}
		});

		_parser.addGrammarElement("expression", function (parser, runtime, tokens) {
			tokens.matchToken("the"); // optional the
			return parser.parseElement("asyncExpression", tokens);
		});

		_parser.addGrammarElement("assignableExpression", function (parser, runtime, tokens) {
			tokens.matchToken("the"); // optional the

			// TODO obviously we need to generalize this as a left hand side / targetable concept
			var expr = parser.parseElement("primaryExpression", tokens);
			if (expr && (
				expr.type === "symbol" ||
				expr.type === "ofExpression" ||
				expr.type === "propertyAccess" ||
				expr.type === "attributeRefAccess" ||
				expr.type === "attributeRef" ||
				expr.type === "possessive")
			) {
				return expr;
			} else {
				_parser.raiseParseError(
					tokens,
					"A target expression must be writable.  The expression type '" + (expr && expr.type) + "' is not."
				);
			}
			return expr;
		});

		_parser.addGrammarElement("hyperscript", function (parser, runtime, tokens) {
			var features = [];

			if (tokens.hasMore()) {
				while (parser.featureStart(tokens.currentToken()) || tokens.currentToken().value === "(") {
					var feature = parser.requireElement("feature", tokens);
					features.push(feature);
					tokens.matchToken("end"); // optional end
				}
			}
			return {
				type: "hyperscript",
				features: features,
				apply: function (target, source, args) {
					// no op
					for (const feature of features) {
						feature.install(target, source, args);
					}
				},
			};
		});

		var parseEventArgs = function (tokens) {
			var args = [];
			// handle argument list (look ahead 3)
			if (
				tokens.token(0).value === "(" &&
				(tokens.token(1).value === ")" || tokens.token(2).value === "," || tokens.token(2).value === ")")
			) {
				tokens.matchOpToken("(");
				do {
					args.push(tokens.requireTokenType("IDENTIFIER"));
				} while (tokens.matchOpToken(","));
				tokens.requireOpToken(")");
			}
			return args;
		};

		_parser.addFeature("on", function (parser, runtime, tokens) {
			if (!tokens.matchToken("on")) return;
			var every = false;
			if (tokens.matchToken("every")) {
				every = true;
			}
			var events = [];
			var displayName = null;
			do {
				var on = parser.requireElement("eventName", tokens, "Expected event name");

				var eventName = on.evaluate(); // OK No Promise

				if (displayName) {
					displayName = displayName + " or " + eventName;
				} else {
					displayName = "on " + eventName;
				}
				var args = parseEventArgs(tokens);

				var filter = null;
				if (tokens.matchOpToken("[")) {
					filter = parser.requireElement("expression", tokens);
					tokens.requireOpToken("]");
				}

				if (tokens.currentToken().type === "NUMBER") {
					var startCountToken = tokens.consumeToken();
					var startCount = parseInt(startCountToken.value);
					if (tokens.matchToken("to")) {
						var endCountToken = tokens.consumeToken();
						var endCount = parseInt(endCountToken.value);
					} else if (tokens.matchToken("and")) {
						var unbounded = true;
						tokens.requireToken("on");
					}
				}

				if (eventName === "intersection") {
					var intersectionSpec = {};
					if (tokens.matchToken("with")) {
						intersectionSpec["with"] = parser.requireElement("expression", tokens).evaluate();
					}
					if (tokens.matchToken("having")) {
						do {
							if (tokens.matchToken("margin")) {
								intersectionSpec["rootMargin"] = parser.requireElement("stringLike", tokens).evaluate();
							} else if (tokens.matchToken("threshold")) {
								intersectionSpec["threshold"] = parser.requireElement("expression", tokens).evaluate();
							} else {
								parser.raiseParseError(tokens, "Unknown intersection config specification");
							}
						} while (tokens.matchToken("and"));
					}
				} else if (eventName === "mutation") {
					var mutationSpec = {};
					if (tokens.matchToken("of")) {
						do {
							if (tokens.matchToken("anything")) {
								mutationSpec["attributes"] = true;
								mutationSpec["subtree"] = true;
								mutationSpec["characterData"] = true;
								mutationSpec["childList"] = true;
							} else if (tokens.matchToken("childList")) {
								mutationSpec["childList"] = true;
							} else if (tokens.matchToken("attributes")) {
								mutationSpec["attributes"] = true;
								mutationSpec["attributeOldValue"] = true;
							} else if (tokens.matchToken("subtree")) {
								mutationSpec["subtree"] = true;
							} else if (tokens.matchToken("characterData")) {
								mutationSpec["characterData"] = true;
								mutationSpec["characterDataOldValue"] = true;
							} else if (tokens.currentToken().type === "ATTRIBUTE_REF") {
								var attribute = tokens.consumeToken();
								if (mutationSpec["attributeFilter"] == null) {
									mutationSpec["attributeFilter"] = [];
								}
								if (attribute.value.indexOf("@") == 0) {
									mutationSpec["attributeFilter"].push(attribute.value.substring(1));
								} else {
									parser.raiseParseError(
										tokens,
										"Only shorthand attribute references are allowed here"
									);
								}
							} else {
								parser.raiseParseError(tokens, "Unknown mutation config specification");
							}
						} while (tokens.matchToken("or"));
					} else {
						mutationSpec["attributes"] = true;
						mutationSpec["characterData"] = true;
						mutationSpec["childList"] = true;
					}
				}

				var from = null;
				var elsewhere = false;
				if (tokens.matchToken("from")) {
					if (tokens.matchToken("elsewhere")) {
						elsewhere = true;
					} else {
						from = parser.parseElement("expression", tokens);
						if (!from) {
							parser.raiseParseError(tokens, 'Expected either target value or "elsewhere".');
						}
					}
				}
				// support both "elsewhere" and "from elsewhere"
				if (from === null && elsewhere === false && tokens.matchToken("elsewhere")) {
					elsewhere = true;
				}

				if (tokens.matchToken("in")) {
					var inExpr = parser.parseAnyOf(["idRef", "queryRef", "classRef"], tokens);
				}

				if (tokens.matchToken("debounced")) {
					tokens.requireToken("at");
					var timeExpr = parser.requireElement("timeExpression", tokens);
					// @ts-ignore
					var debounceTime = timeExpr.evaluate({}); // OK No promise TODO make a literal time expr
				} else if (tokens.matchToken("throttled")) {
					tokens.requireToken("at");
					var timeExpr = parser.requireElement("timeExpression", tokens);
					// @ts-ignore
					var throttleTime = timeExpr.evaluate({}); // OK No promise TODO make a literal time expr
				}

				events.push({
					execCount: 0,
					every: every,
					on: eventName,
					args: args,
					filter: filter,
					from: from,
					inExpr: inExpr,
					elsewhere: elsewhere,
					startCount: startCount,
					endCount: endCount,
					unbounded: unbounded,
					debounceTime: debounceTime,
					throttleTime: throttleTime,
					mutationSpec: mutationSpec,
					intersectionSpec: intersectionSpec,
				});
			} while (tokens.matchToken("or"));

			var queue = [];
			var queueLast = true;
			if (!every) {
				if (tokens.matchToken("queue")) {
					if (tokens.matchToken("all")) {
						var queueAll = true;
						var queueLast = false;
					} else if (tokens.matchToken("first")) {
						var queueFirst = true;
					} else if (tokens.matchToken("none")) {
						var queueNone = true;
					} else {
						tokens.requireToken("last");
					}
				}
			}

			var commandList = parser.parseElement("commandList", tokens);

			var implicitReturn = {
				type: "implicitReturn",
				op: function (context) {
					// automatically resolve at the end of an event handler if nothing else does
					context.meta.resolve();
					return runtime.HALT;
				},
				execute: function (ctx) {
					// do nothing
				},
			};

			if (commandList) {
				/** @type {GrammarElement} */
				var start = commandList;

				var end = start;
				while (end.next) {
					end = end.next;
				}
				end.next = implicitReturn;
			} else {
				start = implicitReturn;
			}

			var onFeature = {
				displayName: displayName,
				events: events,
				start: start,
				every: every,
				executing: false,
				execCount: 0,
				queue: queue,
				execute: function (/** @type {Context} */ ctx) {
					if (this.executing && every === false) {
						if (queueNone || (queueFirst && queue.length > 0)) {
							return;
						}
						if (queueLast) {
							onFeature.queue.length = 0;
						}
						onFeature.queue.push(ctx);
						return;
					}
					onFeature.execCount++;
					this.executing = true;
					ctx.meta.resolve = function () {
						onFeature.executing = false;
						var queued = onFeature.queue.shift();
						if (queued) {
							setTimeout(function () {
								onFeature.execute(queued);
							}, 1);
						}
					};
					ctx.meta.reject = function (err) {
						console.error(err.message ? err.message : err);
						var hypertrace = runtime.getHyperTrace(ctx, err);
						if (hypertrace) {
							hypertrace.print();
						}
						runtime.triggerEvent(ctx.me, "exception", {
							error: err,
						});
						onFeature.executing = false;
						var queued = onFeature.queue.shift();
						if (queued) {
							setTimeout(function () {
								onFeature.execute(queued);
							}, 1);
						}
					};
					start.execute(ctx);
				},
				install: function (elt, source) {
					for (const eventSpec of onFeature.events) {
						var targets;
						if (eventSpec.elsewhere) {
							targets = [document];
						} else if (eventSpec.from) {
							targets = eventSpec.from.evaluate(runtime.makeContext(elt, onFeature, elt, null));
						} else {
							targets = [elt];
						}
						runtime.forEach(targets, function (target) {
							// OK NO PROMISE

							var eventName = eventSpec.on;
							if (eventSpec.mutationSpec) {
								eventName = "hyperscript:mutation";
								const observer = new MutationObserver(function (mutationList, observer) {
									console.log(target, mutationList);
									if (!onFeature.executing) {
										_runtime.triggerEvent(target, eventName, {
											mutationList: mutationList,
											observer: observer,
										});
									}
								});
								observer.observe(target, eventSpec.mutationSpec);
							}

							if (eventSpec.intersectionSpec) {
								eventName = "hyperscript:insersection";
								const observer = new IntersectionObserver(function (entries) {
									for (const entry of entries) {
										var detail = {
											observer: observer,
										};
										detail = mergeObjects(detail, entry);
										detail["intersecting"] = entry.isIntersecting;
										_runtime.triggerEvent(target, eventName, detail);
									}
								}, eventSpec.intersectionSpec);
								observer.observe(target);
							}

							target.addEventListener(eventName, function listener(evt) {
								// OK NO PROMISE
								if (elt instanceof Node && target !== elt && !elt.isConnected) {
									target.removeEventListener(eventName, listener);
									return;
								}

								var ctx = runtime.makeContext(elt, onFeature, elt, evt);
								if (eventSpec.elsewhere && elt.contains(evt.target)) {
									return;
								}
								if (eventSpec.from) {
									ctx.result = target;
								}

								// establish context
								for (const arg of eventSpec.args) {
									ctx[arg.value] =
										ctx.event[arg.value] || ('detail' in ctx.event ? ctx.event['detail'][arg.value] : null);
								}

								// apply filter
								if (eventSpec.filter) {
									var initialCtx = ctx.meta.context;
									ctx.meta.context = ctx.event;
									try {
										var value = eventSpec.filter.evaluate(ctx); //OK NO PROMISE
										if (value) {
											// match the javascript semantics for if statements
										} else {
											return;
										}
									} finally {
										ctx.meta.context = initialCtx;
									}
								}

								if (eventSpec.inExpr) {
									var inElement = evt.target;
									while (true) {
										if (inElement.matches && inElement.matches(eventSpec.inExpr.css)) {
											ctx.result = inElement;
											break;
										} else {
											inElement = inElement.parentElement;
											if (inElement == null) {
												return; // no match found
											}
										}
									}
								}

								// verify counts
								eventSpec.execCount++;
								if (eventSpec.startCount) {
									if (eventSpec.endCount) {
										if (
											eventSpec.execCount < eventSpec.startCount ||
											eventSpec.execCount > eventSpec.endCount
										) {
											return;
										}
									} else if (eventSpec.unbounded) {
										if (eventSpec.execCount < eventSpec.startCount) {
											return;
										}
									} else if (eventSpec.execCount !== eventSpec.startCount) {
										return;
									}
								}

								//debounce
								if (eventSpec.debounceTime) {
									if (eventSpec.debounced) {
										clearTimeout(eventSpec.debounced);
									}
									eventSpec.debounced = setTimeout(function () {
										onFeature.execute(ctx);
									}, eventSpec.debounceTime);
									return;
								}

								// throttle
								if (eventSpec.throttleTime) {
									if (
										eventSpec.lastExec &&
										Date.now() < eventSpec.lastExec + eventSpec.throttleTime
									) {
										return;
									} else {
										eventSpec.lastExec = Date.now();
									}
								}

								// apply execute
								onFeature.execute(ctx);
							});
						});
					}
				},
			};
			parser.setParent(start, onFeature);
			return onFeature;
		});

		_parser.addFeature("def", function (parser, runtime, tokens) {
			if (!tokens.matchToken("def")) return;
			var functionName = parser.requireElement("dotOrColonPath", tokens);
			var nameVal = functionName.evaluate(); // OK
			var nameSpace = nameVal.split(".");
			var funcName = nameSpace.pop();

			var args = [];
			if (tokens.matchOpToken("(")) {
				if (tokens.matchOpToken(")")) {
					// emtpy args list
				} else {
					do {
						args.push(tokens.requireTokenType("IDENTIFIER"));
					} while (tokens.matchOpToken(","));
					tokens.requireOpToken(")");
				}
			}

			var start = parser.requireElement("commandList", tokens);
			if (tokens.matchToken("catch")) {
				var errorSymbol = tokens.requireTokenType("IDENTIFIER").value;
				var errorHandler = parser.parseElement("commandList", tokens);
			}
			var functionFeature = {
				displayName:
					funcName +
					"(" +
					args
						.map(function (arg) {
							return arg.value;
						})
						.join(", ") +
					")",
				name: funcName,
				args: args,
				start: start,
				errorHandler: errorHandler,
				errorSymbol: errorSymbol,
				install: function (target, source) {
					var func = function () {
						// null, worker
						var ctx = runtime.makeContext(source, functionFeature, target, null);

						// install error handler if any
						ctx.meta.errorHandler = errorHandler;
						ctx.meta.errorSymmbol = errorSymbol;

						for (var i = 0; i < args.length; i++) {
							var name = args[i];
							var argumentVal = arguments[i];
							if (name) {
								ctx[name.value] = argumentVal;
							}
						}
						ctx.meta.caller = arguments[args.length];
						if (ctx.meta.caller) {
							ctx.meta.callingCommand = ctx.meta.caller.meta.command;
						}
						var resolve,
							reject = null;
						var promise = new Promise(function (theResolve, theReject) {
							resolve = theResolve;
							reject = theReject;
						});
						start.execute(ctx);
						if (ctx.meta.returned) {
							return ctx.meta.returnValue;
						} else {
							ctx.meta.resolve = resolve;
							ctx.meta.reject = reject;
							return promise;
						}
					};
					func.hyperfunc = true;
					func.hypername = nameVal;
					runtime.assignToNamespace(target, nameSpace, funcName, func);
				},
			};

			var implicitReturn = {
				type: "implicitReturn",
				op: function (context) {
					// automatically return at the end of the function if nothing else does
					context.meta.returned = true;
					if (context.meta.resolve) {
						context.meta.resolve();
					}
					return runtime.HALT;
				},
				execute: function (context) {
					// do nothing
				},
			};
			// terminate body
			if (start) {
				var end = start;
				while (end.next) {
					end = end.next;
				}
				end.next = implicitReturn;
			} else {
				functionFeature.start = implicitReturn;
			}

			// terminate error handler
			if (errorHandler) {
				var end = errorHandler;
				while (end.next) {
					end = end.next;
				}
				end.next = implicitReturn;
			}

			parser.setParent(start, functionFeature);
			return functionFeature;
		});

		_parser.addFeature("init", function (parser, runtime, tokens) {
			if (!tokens.matchToken("init")) return;

			var start = parser.parseElement("commandList", tokens);
			var initFeature = {
				start: start,
				install: function (target, source) {
					setTimeout(function () {
						start && start.execute(runtime.makeContext(target, initFeature, target, null));
					}, 0);
				},
			};

			var implicitReturn = {
				type: "implicitReturn",
				op: function (context) {
					return runtime.HALT;
				},
				execute: function (context) {
					// do nothing
				},
			};
			// terminate body
			if (start) {
				var end = start;
				while (end.next) {
					end = end.next;
				}
				end.next = implicitReturn;
			} else {
				initFeature.start = implicitReturn;
			}
			parser.setParent(start, initFeature);
			return initFeature;
		});

		_parser.addFeature("worker", function (parser, runtime, tokens) {
			if (tokens.matchToken("worker")) {
				parser.raiseParseError(
					tokens,
					"In order to use the 'worker' feature, include " +
						"the _hyperscript worker plugin. See " +
						"https://hyperscript.org/features/worker/ for " +
						"more info."
				);
			}
		});

		_parser.addFeature("behavior", function (parser, runtime, tokens) {
			if (!tokens.matchToken("behavior")) return;
			var path = parser.requireElement("dotOrColonPath", tokens).evaluate();
			var nameSpace = path.split(".");
			var name = nameSpace.pop();

			var formalParams = [];
			if (tokens.matchOpToken("(") && !tokens.matchOpToken(")")) {
				do {
					formalParams.push(tokens.requireTokenType("IDENTIFIER").value);
				} while (tokens.matchOpToken(","));
				tokens.requireOpToken(")");
			}
			var hs = parser.requireElement("hyperscript", tokens);
			for (var i = 0; i < hs.features.length; i++) {
				var feature = hs.features[i];
				feature.behavior = path;
			}

			return {
				install: function (target, source) {
					runtime.assignToNamespace(
						globalScope.document && globalScope.document.body,
						nameSpace,
						name,
						function (target, source, innerArgs) {
							var internalData = runtime.getInternalData(target);
							var elementScope = getOrInitObject(internalData, path + "Scope");
							for (var i = 0; i < formalParams.length; i++) {
								elementScope[formalParams[i]] = innerArgs[formalParams[i]];
							}
							hs.apply(target, source);
						}
					);
				},
			};
		});

		_parser.addFeature("install", function (parser, runtime, tokens) {
			if (!tokens.matchToken("install")) return;
			var behaviorPath = parser.requireElement("dotOrColonPath", tokens).evaluate();
			var behaviorNamespace = behaviorPath.split(".");
			var args = parser.parseElement("namedArgumentList", tokens);

			var installFeature;
			return (installFeature = {
				install: function (target, source) {
					runtime.unifiedEval(
						{
							args: [args],
							op: function (ctx, args) {
								var behavior = globalScope;
								for (var i = 0; i < behaviorNamespace.length; i++) {
									behavior = behavior[behaviorNamespace[i]];
									if (typeof behavior !== "object" && typeof behavior !== "function")
										throw new Error("No such behavior defined as " + behaviorPath);
								}

								if (!(behavior instanceof Function))
									throw new Error(behaviorPath + " is not a behavior");

								behavior(target, source, args);
							},
						},
						runtime.makeContext(target, installFeature, target)
					);
				},
			});
		});

		_parser.addGrammarElement("jsBody", function (parser, runtime, tokens) {
			var jsSourceStart = tokens.currentToken().start;
			var jsLastToken = tokens.currentToken();

			var funcNames = [];
			var funcName = "";
			var expectFunctionDeclaration = false;
			while (tokens.hasMore()) {
				jsLastToken = tokens.consumeToken();
				var peek = tokens.token(0, true);
				if (peek.type === "IDENTIFIER" && peek.value === "end") {
					break;
				}
				if (expectFunctionDeclaration) {
					if (jsLastToken.type === "IDENTIFIER" || jsLastToken.type === "NUMBER") {
						funcName += jsLastToken.value;
					} else {
						if (funcName !== "") funcNames.push(funcName);
						funcName = "";
						expectFunctionDeclaration = false;
					}
				} else if (jsLastToken.type === "IDENTIFIER" && jsLastToken.value === "function") {
					expectFunctionDeclaration = true;
				}
			}
			var jsSourceEnd = jsLastToken.end + 1;

			return {
				type: "jsBody",
				exposedFunctionNames: funcNames,
				jsSource: tokens.source.substring(jsSourceStart, jsSourceEnd),
			};
		});

		_parser.addFeature("js", function (parser, runtime, tokens) {
			if (!tokens.matchToken("js")) return;
			var jsBody = parser.requireElement("jsBody", tokens);

			var jsSource =
				jsBody.jsSource +
				"\nreturn { " +
				jsBody.exposedFunctionNames
					.map(function (name) {
						return name + ":" + name;
					})
					.join(",") +
				" } ";
			var func = new Function(jsSource);

			return {
				jsSource: jsSource,
				function: func,
				exposedFunctionNames: jsBody.exposedFunctionNames,
				install: function () {
					mergeObjects(globalScope, func());
				},
			};
		});

		_parser.addCommand("js", function (parser, runtime, tokens) {
			if (!tokens.matchToken("js")) return;
			// Parse inputs
			var inputs = [];
			if (tokens.matchOpToken("(")) {
				if (tokens.matchOpToken(")")) {
					// empty input list
				} else {
					do {
						var inp = tokens.requireTokenType("IDENTIFIER");
						inputs.push(inp.value);
					} while (tokens.matchOpToken(","));
					tokens.requireOpToken(")");
				}
			}

			var jsBody = parser.requireElement("jsBody", tokens);
			tokens.matchToken("end");

			var func = varargConstructor(Function, inputs.concat([jsBody.jsSource]));

			var command = {
				jsSource: jsBody.jsSource,
				function: func,
				inputs: inputs,
				op: function (context) {
					var args = [];
					inputs.forEach(function (input) {
						args.push(runtime.resolveSymbol(input, context, 'default'));
					});
					var result = func.apply(globalScope, args);
					if (result && typeof result.then === "function") {
						return new Promise(function (resolve) {
							result.then(function (actualResult) {
								context.result = actualResult;
								resolve(runtime.findNext(this, context));
							});
						});
					} else {
						context.result = result;
						return runtime.findNext(this, context);
					}
				},
			};
			return command;
		});

		_parser.addCommand("async", function (parser, runtime, tokens) {
			if (!tokens.matchToken("async")) return;
			if (tokens.matchToken("do")) {
				var body = parser.requireElement("commandList", tokens);

				// Append halt
				var end = body;
				while (end.next) end = end.next;
				end.next = runtime.HALT;

				tokens.requireToken("end");
			} else {
				var body = parser.requireElement("command", tokens);
			}
			var command = {
				body: body,
				op: function (context) {
					setTimeout(function () {
						body.execute(context);
					});
					return runtime.findNext(this, context);
				},
			};
			return command;
		});

		_parser.addCommand("tell", function (parser, runtime, tokens) {
			var startToken = tokens.currentToken();
			if (!tokens.matchToken("tell")) return;
			var value = parser.requireElement("expression", tokens);
			var body = parser.requireElement("commandList", tokens);
			if (tokens.hasMore()) {
				tokens.requireToken("end");
			}
			var slot = "tell_" + startToken.start;
			var tellCmd = {
				value: value,
				body: body,
				args: [value],
				resolveNext: function (context) {
					var iterator = context.meta.iterators[slot];
					if (iterator.index < iterator.value.length) {
						context.beingTold = iterator.value[iterator.index++];
						return body;
					} else {
						// restore original me
						context.beingTold = iterator.originalBeingTold;
						if (this.next) {
							return this.next;
						} else {
							return runtime.findNext(this.parent, context);
						}
					}
				},
				op: function (context, value) {
					if (value == null) {
						value = [];
					} else if (!(Array.isArray(value) || value instanceof NodeList)) {
						value = [value];
					}
					context.meta.iterators[slot] = {
						originalBeingTold: context.beingTold,
						index: 0,
						value: value,
					};
					return this.resolveNext(context);
				},
			};
			parser.setParent(body, tellCmd);
			return tellCmd;
		});

		_parser.addCommand("wait", function (parser, runtime, tokens) {
			if (!tokens.matchToken("wait")) return;
			var command;

			// wait on event
			if (tokens.matchToken("for")) {
				tokens.matchToken("a"); // optional "a"
				var events = [];
				do {
					var lookahead = tokens.token(0);
					if (lookahead.type === 'NUMBER' || lookahead.type === 'L_PAREN') {
						events.push({
							time: parser.requireElement('timeExpression', tokens).evaluate() // TODO: do we want to allow async here?
						})
					} else {
						events.push({
							name: _parser.requireElement("dotOrColonPath", tokens, "Expected event name").evaluate(),
							args: parseEventArgs(tokens),
						});
					}
				} while (tokens.matchToken("or"));

				if (tokens.matchToken("from")) {
					var on = parser.requireElement("expression", tokens);
				}

				// wait on event
				command = {
					event: events,
					on: on,
					args: [on],
					op: function (context, on) {
						var target = on ? on : context.me;
						if (!(target instanceof EventTarget))
							throw new Error("Not a valid event target: " + this.on.sourceFor());
						return new Promise((resolve) => {
							var resolved = false;
							for (const eventInfo of events) {
								var listener = (event) => {
									context.result = event;
									for (const arg of eventInfo.args) {
										context[arg.value] =
											event[arg.value] || (event.detail ? event.detail[arg.value] : null);
									}
									if (!resolved) {
										resolved = true;
										resolve(runtime.findNext(this, context));
									}
								};
								if (eventInfo.name) target.addEventListener(eventInfo.name, listener, { once: true });
								else if (eventInfo.time) setTimeout(listener, eventInfo.time, eventInfo.time)
							}
						});
					},
				};
				return command;
			} else {
				var time;
				if (tokens.matchToken("a")) {
					tokens.requireToken("tick");
					time = 0;
				} else {
					time = _parser.requireElement("timeExpression", tokens);
				}

				command = {
					type: "waitCmd",
					time: time,
					args: [time],
					op: function (context, timeValue) {
						return new Promise((resolve) => {
							setTimeout(() => {
								resolve(runtime.findNext(this, context));
							}, timeValue);
						});
					},
					execute: function (context) {
						return runtime.unifiedExec(this, context);
					},
				};
				return command;
			}
		});

		// TODO  - colon path needs to eventually become part of ruby-style symbols
		_parser.addGrammarElement("dotOrColonPath", function (parser, runtime, tokens) {
			var root = tokens.matchTokenType("IDENTIFIER");
			if (root) {
				var path = [root.value];

				var separator = tokens.matchOpToken(".") || tokens.matchOpToken(":");
				if (separator) {
					do {
						path.push(tokens.requireTokenType("IDENTIFIER").value);
					} while (tokens.matchOpToken(separator.value));
				}

				return {
					type: "dotOrColonPath",
					path: path,
					evaluate: function () {
						return path.join(separator ? separator.value : "");
					},
				};
			}
		});

		_parser.addGrammarElement("eventName", function (parser, runtime, tokens) {
			var token;
			if ((token = tokens.matchTokenType("STRING"))) {
				return {
					evaluate: function() {
						return token.value;
					},
				};
			}

			return parser.parseElement("dotOrColonPath", tokens);
		});

		_parser.addCommand("send", function (parser, runtime, tokens) {
			if (!tokens.matchToken("send")) return;
			var eventName = parser.requireElement("eventName", tokens);

			var details = parser.parseElement("namedArgumentList", tokens);
			if (tokens.matchToken("to")) {
				var to = parser.requireElement("expression", tokens);
			} else {
				var to = parser.requireElement("implicitMeTarget", tokens);
			}

			var sendCmd = {
				eventName: eventName,
				details: details,
				to: to,
				args: [to, eventName, details],
				op: function (context, to, eventName, details) {
					runtime.forEach(to, function (target) {
						runtime.triggerEvent(target, eventName, details ? details : {});
					});
					return runtime.findNext(sendCmd, context);
				},
			};
			return sendCmd;
		});

		var parseReturnFunction = function (parser, runtime, tokens, returnAValue) {
			if (returnAValue) {
				var value = parser.requireElement("expression", tokens);
			}

			var returnCmd = {
				value: value,
				args: [value],
				op: function (context, value) {
					var resolve = context.meta.resolve;
					context.meta.returned = true;
					if (resolve) {
						if (value) {
							resolve(value);
						} else {
							resolve();
						}
					} else {
						context.meta.returned = true;
						context.meta.returnValue = value;
					}
					return runtime.HALT;
				},
			};
			return returnCmd;
		};

		_parser.addCommand("return", function (parser, runtime, tokens) {
			if (tokens.matchToken("return")) {
				return parseReturnFunction(parser, runtime, tokens, true);
			}
		});

		_parser.addCommand("exit", function (parser, runtime, tokens) {
			if (tokens.matchToken("exit")) {
				return parseReturnFunction(parser, runtime, tokens, false);
			}
		});

		_parser.addCommand("halt", function (parser, runtime, tokens) {
			if (tokens.matchToken("halt")) {
				if (tokens.matchToken("the")) {
					tokens.requireToken("event");
					// optional possessive
					if (tokens.matchOpToken("'")) {
						tokens.requireToken("s");
					}
					var keepExecuting = true;
				}
				if (tokens.matchToken("bubbling")) {
					var bubbling = true;
				} else if (tokens.matchToken("default")) {
					var haltDefault = true;
				}
				var exit = parseReturnFunction(parser, runtime, tokens, false);

				var haltCmd = {
					keepExecuting: true,
					bubbling: bubbling,
					haltDefault: haltDefault,
					exit: exit,
					op: function (ctx) {
						if (ctx.event) {
							if (bubbling) {
								ctx.event.stopPropagation();
							} else if (haltDefault) {
								ctx.event.preventDefault();
							} else {
								ctx.event.stopPropagation();
								ctx.event.preventDefault();
							}
							if (keepExecuting) {
								return runtime.findNext(this, ctx);
							} else {
								return exit;
							}
						}
					},
				};
				return haltCmd;
			}
		});

		_parser.addCommand("log", function (parser, runtime, tokens) {
			if (!tokens.matchToken("log")) return;
			var exprs = [parser.parseElement("expression", tokens)];
			while (tokens.matchOpToken(",")) {
				exprs.push(parser.requireElement("expression", tokens));
			}
			if (tokens.matchToken("with")) {
				var withExpr = parser.requireElement("expression", tokens);
			}
			var logCmd = {
				exprs: exprs,
				withExpr: withExpr,
				args: [withExpr, exprs],
				op: function (ctx, withExpr, values) {
					if (withExpr) {
						withExpr.apply(null, values);
					} else {
						console.log.apply(null, values);
					}
					return runtime.findNext(this, ctx);
				},
			};
			return logCmd;
		});

		_parser.addCommand("throw", function (parser, runtime, tokens) {
			if (!tokens.matchToken("throw")) return;
			var expr = parser.requireElement("expression", tokens);
			var throwCmd = {
				expr: expr,
				args: [expr],
				op: function (ctx, expr) {
					runtime.registerHyperTrace(ctx, expr);
					var reject = ctx.meta && ctx.meta.reject;
					if (reject) {
						reject(expr);
						return runtime.HALT;
					} else {
						throw expr;
					}
				},
			};
			return throwCmd;
		});

		var parseCallOrGet = function (parser, runtime, tokens) {
			var expr = parser.requireElement("expression", tokens);
			var callCmd = {
				expr: expr,
				args: [expr],
				op: function (context, result) {
					context.result = result;
					return runtime.findNext(callCmd, context);
				},
			};
			return callCmd;
		};
		_parser.addCommand("call", function (parser, runtime, tokens) {
			if (!tokens.matchToken("call")) return;
			var call = parseCallOrGet(parser, runtime, tokens);
			if (call.expr && call.expr.type !== "functionCall") {
				parser.raiseParseError(tokens, "Must be a function invocation");
			}
			return call;
		});
		_parser.addCommand("get", function (parser, runtime, tokens) {
			if (tokens.matchToken("get")) {
				return parseCallOrGet(parser, runtime, tokens);
			}
		});

		_parser.addCommand("make", function (parser, runtime, tokens) {
			if (!tokens.matchToken("make")) return;
			tokens.matchToken("a") || tokens.matchToken("an");

			var expr = parser.requireElement("expression", tokens);

			var args = [];
			if (expr.type !== "queryRef" && tokens.matchToken("from")) {
				do {
					args.push(parser.requireElement("expression", tokens));
				} while (tokens.matchOpToken(","));
			}

			if (tokens.matchToken("called")) {
				var name = tokens.requireTokenType("IDENTIFIER").value;
			}

			var command;
			if (expr.type === "queryRef") {
				command = {
					op: function (ctx) {
						var match,
							tagname = "div",
							id,
							classes = [];
						var re = /(?:(^|#|\.)([^#\. ]+))/g;
						while ((match = re.exec(expr.css))) {
							if (match[1] === "") tagname = match[2].trim();
							else if (match[1] === "#") id = match[2].trim();
							else classes.push(match[2].trim());
						}

						var result = document.createElement(tagname);
						if (id !== undefined) result.id = id;
						for (var i = 0; i < classes.length; i++) {
							var cls = classes[i];
							result.classList.add(cls)
						}

						ctx.result = result;
						if (name) ctx[name] = result;

						return runtime.findNext(this, ctx);
					},
				};
				return command;
			} else {
				command = {
					args: [expr, args],
					op: function (ctx, expr, args) {
						ctx.result = varargConstructor(expr, args);
						if (name) ctx[name] = ctx.result;

						return runtime.findNext(this, ctx);
					},
				};
				return command;
			}
		});

		_parser.addGrammarElement("pseudoCommand", function (parser, runtime, tokens) {

			try {
				var expr = parser.requireElement("primaryExpression", tokens);
			} finally {
				tokens.popFollow();
			}
			if (expr.type !== "functionCall" && expr.root.type !== "symbol" && expr.root.root != null) {
				parser.raiseParseError(tokens, "Implicit function calls must start with a simple function");
			}

			var functionName = expr.root.name;

			if (tokens.matchAnyToken("the", "to", "on", "with", "into", "from", "at")) {
				var target = parser.requireElement("expression", tokens);
			} else if (tokens.matchToken("me")) {
				var target = parser.requireElement("implicitMeTarget", tokens);
			}
			var functionArgs = expr.argExressions;

			/** @type {GrammarElement} */
			var pseudoCommand = {
				type: "pseudoCommand",
				expr: expr,
				args: [target, functionArgs],
				op: function (context, target, args) {
					if (target) {
						var func = target[functionName];
					} else {
						var func = runtime.resolveSymbol(functionName, context);
					}
					if (func.hyperfunc) {
						args.push(context);
					}
					var result = func.apply(target, args);
					context.result = result;
					return runtime.findNext(pseudoCommand, context);
				},
				execute: function (context) {
					return runtime.unifiedExec(this, context);
				},
			};

			return pseudoCommand;
		});

		/**
		 * @param {ParserObject} parser
		 * @param {RuntimeObject} runtime
		 * @param {TokensObject} tokens
		 * @param {*} target
		 * @param {*} value
		 * @returns
		 */
		var makeSetter = function (parser, runtime, tokens, target, value) {
			var symbolWrite = target.type === "symbol";
			var attributeWrite = target.type === "attributeRef";
			if (!attributeWrite && !symbolWrite && target.root == null) {
				parser.raiseParseError(tokens, "Can only put directly into symbols, not references");
			}

			var root = null;
			var prop = null;
			if (symbolWrite) {
				// root is null
			} else if (attributeWrite) {
				root = parser.requireElement("implicitMeTarget", tokens);
				var attribute = target;
			} else {
				prop = target.prop ? target.prop.value : null;
				var attribute = target.attribute;
				root = target.root;
			}

			/** @type {GrammarElement} */
			var setCmd = {
				target: target,
				symbolWrite: symbolWrite,
				value: value,
				args: [root, value],
				op: function (context, root, valueToSet) {
					if (symbolWrite) {
						runtime.setSymbol(target.name, context, target.symbolType, valueToSet);
					} else {
						runtime.implicitLoop(root, function (elt) {
							if (attribute) {
								if (valueToSet == null) {
									elt.removeAttribute(attribute.name);
								} else {
									elt.setAttribute(attribute.name, valueToSet);
								}
							} else {
								elt[prop] = valueToSet;
							}
						});
					}
					return runtime.findNext(this, context);
				},
			};
			return setCmd;
		};

		_parser.addCommand("default", function (parser, runtime, tokens) {
			if (!tokens.matchToken("default")) return;
			var target = parser.requireElement("assignableExpression", tokens);
			tokens.requireToken("to");

			var value = parser.requireElement("expression", tokens);

			/** @type {GrammarElement} */
			var setter = makeSetter(parser, runtime, tokens, target, value);
			var defaultCmd = {
				target: target,
				value: value,
				setter: setter,
				args: [target],
				op: function (context, target) {
					if (target) {
						return runtime.findNext(this, context);
					} else {
						return setter;
					}
				},
			};
			setter.parent = defaultCmd;
			return defaultCmd;
		});

		_parser.addCommand("set", function (parser, runtime, tokens) {
			if (!tokens.matchToken("set")) return;
			if (tokens.currentToken().type === "L_BRACE") {
				var obj = parser.requireElement("objectLiteral", tokens);
				tokens.requireToken("on");
				var target = parser.requireElement("expression", tokens);

				var command = {
					objectLiteral: obj,
					target: target,
					args: [obj, target],
					op: function (ctx, obj, target) {
						mergeObjects(target, obj);
						return runtime.findNext(this, ctx);
					},
				};
				return command;
			}

			try {
				tokens.pushFollow("to");
				var target = parser.requireElement("assignableExpression", tokens);
			} finally {
				tokens.popFollow();
			}
			tokens.requireToken("to");
			var value = parser.requireElement("expression", tokens);
			return makeSetter(parser, runtime, tokens, target, value);
		});

		_parser.addCommand("if", function (parser, runtime, tokens) {
			if (!tokens.matchToken("if")) return;
			var expr = parser.requireElement("expression", tokens);
			tokens.matchToken("then"); // optional 'then'
			var trueBranch = parser.parseElement("commandList", tokens);
			if (tokens.matchToken("else")) {
				var falseBranch = parser.parseElement("commandList", tokens);
			}
			if (tokens.hasMore()) {
				tokens.requireToken("end");
			}

			/** @type {GrammarElement} */
			var ifCmd = {
				expr: expr,
				trueBranch: trueBranch,
				falseBranch: falseBranch,
				args: [expr],
				op: function (context, exprValue) {
					if (exprValue) {
						return trueBranch;
					} else if (falseBranch) {
						return falseBranch;
					} else {
						return runtime.findNext(this, context);
					}
				},
			};
			parser.setParent(trueBranch, ifCmd);
			parser.setParent(falseBranch, ifCmd);
			return ifCmd;
		});

		var parseRepeatExpression = function (parser, tokens, runtime, startedWithForToken) {
			var innerStartToken = tokens.currentToken();
			var identifier;
			if (tokens.matchToken("for") || startedWithForToken) {
				var identifierToken = tokens.requireTokenType("IDENTIFIER");
				identifier = identifierToken.value;
				tokens.requireToken("in");
				var expression = parser.requireElement("expression", tokens);
			} else if (tokens.matchToken("in")) {
				identifier = "it";
				var expression = parser.requireElement("expression", tokens);
			} else if (tokens.matchToken("while")) {
				var whileExpr = parser.requireElement("expression", tokens);
			} else if (tokens.matchToken("until")) {
				var isUntil = true;
				if (tokens.matchToken("event")) {
					var evt = _parser.requireElement("dotOrColonPath", tokens, "Expected event name");
					if (tokens.matchToken("from")) {
						var on = parser.requireElement("expression", tokens);
					}
				} else {
					var whileExpr = parser.requireElement("expression", tokens);
				}
			} else if (tokens.matchTokenType("NUMBER")) {
				var times = parseFloat(innerStartToken.value);
				tokens.requireToken("times");
			} else {
				tokens.matchToken("forever"); // consume optional forever
				var forever = true;
			}

			if (tokens.matchToken("index")) {
				var identifierToken = tokens.requireTokenType("IDENTIFIER");
				var indexIdentifier = identifierToken.value;
			}

			var loop = parser.parseElement("commandList", tokens);
			if (loop && evt) {
				// if this is an event based loop, wait a tick at the end of the loop so that
				// events have a chance to trigger in the loop condition o_O)))
				var last = loop;
				while (last.next) {
					last = last.next;
				}
				var waitATick = {
					type: "waitATick",
					op: function () {
						return new Promise(function (resolve) {
							setTimeout(function () {
								resolve(runtime.findNext(waitATick));
							}, 0);
						});
					},
				};
				last.next = waitATick;
			}
			if (tokens.hasMore()) {
				tokens.requireToken("end");
			}

			if (identifier == null) {
				identifier = "_implicit_repeat_" + innerStartToken.start;
				var slot = identifier;
			} else {
				var slot = identifier + "_" + innerStartToken.start;
			}

			var repeatCmd = {
				identifier: identifier,
				indexIdentifier: indexIdentifier,
				slot: slot,
				expression: expression,
				forever: forever,
				times: times,
				until: isUntil,
				event: evt,
				on: on,
				whileExpr: whileExpr,
				resolveNext: function () {
					return this;
				},
				loop: loop,
				args: [whileExpr],
				op: function (context, whileValue) {
					var iteratorInfo = context.meta.iterators[slot];
					var keepLooping = false;
					var loopVal = null;
					if (this.forever) {
						keepLooping = true;
					} else if (this.until) {
						if (evt) {
							keepLooping = context.meta.iterators[slot].eventFired === false;
						} else {
							keepLooping = whileValue !== true;
						}
					} else if (whileExpr) {
						keepLooping = whileValue;
					} else if (times) {
						keepLooping = iteratorInfo.index < this.times;
					} else {
						var nextValFromIterator = iteratorInfo.iterator.next();
						keepLooping = !nextValFromIterator.done;
						loopVal = nextValFromIterator.value;
					}

					if (keepLooping) {
						if (iteratorInfo.value) {
							context.result = context[identifier] = loopVal;
						} else {
							context.result = iteratorInfo.index;
						}
						if (indexIdentifier) {
							context[indexIdentifier] = iteratorInfo.index;
						}
						iteratorInfo.index++;
						return loop;
					} else {
						context.meta.iterators[slot] = null;
						return runtime.findNext(this.parent, context);
					}
				},
			};
			parser.setParent(loop, repeatCmd);
			var repeatInit = {
				name: "repeatInit",
				args: [expression, evt, on],
				op: function (context, value, event, on) {
					var iteratorInfo = {
						index: 0,
						value: value,
						eventFired: false,
					};
					context.meta.iterators[slot] = iteratorInfo;
					if (value && value[Symbol.iterator]) {
						iteratorInfo.iterator = value[Symbol.iterator]();
					}
					if (evt) {
						var target = on || context.me;
						target.addEventListener(
							event,
							function (e) {
								context.meta.iterators[slot].eventFired = true;
							},
							{ once: true }
						);
					}
					return repeatCmd; // continue to loop
				},
				execute: function (context) {
					return runtime.unifiedExec(this, context);
				},
			};
			parser.setParent(repeatCmd, repeatInit);
			return repeatInit;
		};

		_parser.addCommand("repeat", function (parser, runtime, tokens) {
			if (tokens.matchToken("repeat")) {
				return parseRepeatExpression(parser, tokens, runtime, false);
			}
		});

		_parser.addCommand("for", function (parser, runtime, tokens) {
			if (tokens.matchToken("for")) {
				return parseRepeatExpression(parser, tokens, runtime, true);
			}
		});

		_parser.addGrammarElement("stringLike", function (parser, runtime, tokens) {
			return _parser.parseAnyOf(["string", "nakedString"], tokens);
		});

		_parser.addCommand("append", function (parser, runtime, tokens) {
			if (!tokens.matchToken("append")) return;
			var target = null;
			var prop = null;

			var value = parser.requireElement("expression", tokens);

			if (tokens.matchToken("to")) {
				target = parser.requireElement("expression", tokens);
			}

			if (target == null) {
				prop = "result";
			} else if (target.type === "symbol") {
				prop = target.name;
			} else if (target.type === "propertyAccess") {
				prop = target.prop.value;
			} else {
				throw "Unable to append to " + target.type;
			}

			var command = {
				value: value,
				target: target,
				args: [value],
				op: function (context, value) {
					if (Array.isArray(context[prop])) {
						context[prop].push(value);
					} else if (context[prop] instanceof Element) {
						if (typeof value == "string") {
							context[prop].innerHTML += value;
						} else {
							throw "Don't know how to append non-strings to an HTML Element yet.";
						}
					} else {
						context[prop] += value;
					}

					return runtime.findNext(this, context);
				},
				execute: function (context) {
					return runtime.unifiedExec(this, context/*, value, target*/);
				},
			};
			return command;
		});

		_parser.addCommand("increment", function (parser, runtime, tokens) {
			if (!tokens.matchToken("increment")) return;
			var amount;

			// This is optional.  Defaults to "result"
			var target = parser.parseElement("assignableExpression", tokens);

			// This is optional. Defaults to 1.
			if (tokens.matchToken("by")) {
				amount = parser.requireElement("expression", tokens);
			}

			var command = {
				target: target,
				args: [target, amount],
				op: function (context, targetValue, amount) {
					targetValue = targetValue ? parseFloat(targetValue) : 0;
					amount = amount ? parseFloat(amount) : 1;
					var newValue = targetValue + amount;
					var setter = makeSetter(parser, runtime, tokens, target, newValue);
					context.result = newValue;
					setter.parent = this;
					return setter;
				},
				execute: function (context) {
					return runtime.unifiedExec(this, context/* , target, amount */);
				},
			};
			return command;
		});

		_parser.addCommand("decrement", function (parser, runtime, tokens) {
			if (!tokens.matchToken("decrement")) return;
			var amount;

			// This is optional.  Defaults to "result"
			var target = parser.parseElement("assignableExpression", tokens);

			// This is optional. Defaults to 1.
			if (tokens.matchToken("by")) {
				amount = parser.requireElement("expression", tokens);
			}

			var command = {
				target: target,
				args: [target, amount],
				op: function (context, targetValue, amount) {
					targetValue = targetValue ? parseFloat(targetValue) : 0;
					amount = amount ? parseFloat(amount) : 1;
					var newValue = targetValue - amount;
					var setter = makeSetter(parser, runtime, tokens, target, newValue);
					context.result = newValue;
					setter.parent = this;
					return setter;
				},
				execute: function (context) {
					return runtime.unifiedExec(this, context/*, target, amount*/);
				},
			};
			return command;
		});

		_parser.addCommand("fetch", function (parser, runtime, tokens) {
			if (!tokens.matchToken("fetch")) return;
			var url = parser.requireElement("stringLike", tokens);
			var args = parser.parseElement("objectLiteral", tokens);

			var type = "text";
			var conversion;
			if (tokens.matchToken("as")) {
				tokens.matchToken("a") || tokens.matchToken("an");
				if (tokens.matchToken("json") || tokens.matchToken("Object")) {
					type = "json";
				} else if (tokens.matchToken("response")) {
					type = "response";
				} else if (tokens.matchToken("html")) {
					type = "html";
				} else if (tokens.matchToken("text")) {
					// default, ignore
				} else {
					conversion = parser.requireElement("dotOrColonPath", tokens).evaluate();
				}
			}

			/** @type {GrammarElement} */
			var fetchCmd = {
				url: url,
				argExpressions: args,
				args: [url, args],
				op: function (context, url, args) {
					var detail = args || {};
					detail["sentBy"] = context.me;
					runtime.triggerEvent(context.me, "hyperscript:beforeFetch", detail);
					args = detail;
					return fetch(url, args)
						.then(function (resp) {
							if (type === "response") {
								context.result = resp;
								return runtime.findNext(fetchCmd, context);
							}
							if (type === "json") {
								return resp.json().then(function (result) {
									context.result = result;
									return runtime.findNext(fetchCmd, context);
								});
							}
							return resp.text().then(function (result) {
								if (conversion) result = runtime.convertValue(result, conversion);

								if (type === "html") result = runtime.convertValue(result, "Fragment");

								context.result = result;
								return runtime.findNext(fetchCmd, context);
							});
						})
						.catch(function (reason) {
							runtime.triggerEvent(context.me, "fetch:error", {
								reason: reason,
							});
							throw reason;
						});
				},
			};
			return fetchCmd;
		});
	}

	//====================================================================
	// Initialization
	//====================================================================
	function ready(fn) {
		if (document.readyState !== "loading") {
			setTimeout(fn);
		} else {
			document.addEventListener("DOMContentLoaded", fn);
		}
	}

	function getMetaConfig() {
		/** @type {HTMLMetaElement} */
		var element = document.querySelector('meta[name="htmx-config"]');
		if (element) {
			return parseJSON(element.content);
		} else {
			return null;
		}
	}

	function mergeMetaConfig() {
		var metaConfig = getMetaConfig();
		if (metaConfig) {
			_hyperscript.config = mergeObjects(_hyperscript.config, metaConfig);
		}
	}

	if ("document" in globalScope) {
		/** @type {HTMLScriptElement[]} */
		var scripts = Array.from(document.querySelectorAll("script[type='text/hyperscript'][src]"))
		Promise.all(
			scripts.map(function (script) {
				return fetch(script.src)
					.then(function (res) {
						return res.text();
					})
					.then(function (code) {
						return _runtime.evaluate(code);
					});
			})
		).then(function () {
			ready(function () {
				mergeMetaConfig();
				_runtime.processNode(document.documentElement);
				document.addEventListener("htmx:load", function (/** @type {CustomEvent} */ evt) {
					_runtime.processNode(evt.detail.elt);
				});
			});
		});
	}

	//====================================================================
	// API
	//====================================================================
	return mergeObjects(
		function (str, ctx) {
			return _runtime.evaluate(str, ctx); //OK
		},
		{
			internals: {
				lexer: _lexer,
				parser: _parser,
				runtime: _runtime,
			},
			ElementCollection: ElementCollection,
			addFeature: function (keyword, definition) {
				_parser.addFeature(keyword, definition);
			},
			addCommand: function (keyword, definition) {
				_parser.addCommand(keyword, definition);
			},
			addLeafExpression: function (name, definition) {
				_parser.addLeafExpression(name, definition);
			},
			addIndirectExpression: function (name, definition) {
				_parser.addIndirectExpression(name, definition);
			},
			evaluate: function (str, ctx) {
				//OK
				return _runtime.evaluate(str, ctx); //OK
			},
			parse: function (str) {
				//OK
				return _runtime.parse(str); //OK
			},
			processNode: function (elt) {
				_runtime.processNode(elt);
			},
			config: {
				attributes: "_, script, data-script",
				defaultTransition: "all 500ms ease-in",
				disableSelector: "[disable-scripting], [data-disable-scripting]",
				conversions: CONVERSIONS,
			},
		}
	);
});