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Bleeding-Edge
code/modules/scripting/Parser/Expressions.dm
371 строка
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Fixes all problems detected by SpacemanDMM (#35291)
01 ноя 2023, 04:39
Не верифицирован
01 ноя 2023, 04:39
2ba3079
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/* File: Expressions Procedures for parsing expressions. */ /* Macros: Expression Macros OPERATOR - A value indicating the parser currently expects a binary operator. VALUE - A value indicating the parser currently expects a value. SHIFT - Tells the parser to push the current operator onto the stack. REDUCE - Tells the parser to reduce the stack. */ #define OPERATOR 1 #define VALUE 2 #define SHIFT 0 #define REDUCE 1 /* Class: nS_Parser */ /datum/n_Parser/nS_Parser /* Var: expecting A variable which keeps track of whether an operator or value is expected. It should be either <OPERATOR> or <VALUE>. See <ParseExpression()> for more information. */ var/expecting = VALUE /* Proc: Precedence Compares two operators, decides which is higher in the order of operations, and returns <SHIFT> or <REDUCE>. */ /datum/n_Parser/nS_Parser/proc/Precedence(var/datum/node/expression/operation/top, var/datum/node/expression/operation/input) if(istype(top)) top = top.precedence if(istype(input)) input = input:precedence if(top >= input) return REDUCE return SHIFT /* Proc: GetExpression Takes a token expected to represent a value and returns an <expression> node. */ /datum/n_Parser/nS_Parser/proc/GetExpression(var/datum/token/T) if(!T) return if(istype(T, /datum/node/expression)) return T switch(T.type) if(/datum/token/word) return new/datum/node/expression/value/variable(T.value) if(/datum/token/accessor) var/datum/token/accessor/A = T var/datum/node/expression/value/variable/E// = new(A.member) var/datum/stack/S = new() while(istype(A.object, /datum/token/accessor)) S.Push(A) A = A.object ASSERT(istext(A.object)) while(A) var/datum/node/expression/value/variable/V = new() V.id = new(A.member) if(E) V.object = E else V.object = new/datum/node/identifier(A.object) E = V A = S.Pop() return E if(/datum/token/number, /datum/token/string) return new/datum/node/expression/value/literal(T.value) /* Proc: GetOperator Gets a path related to a token or string and returns an instance of the given type. This is used to get an instance of either a binary or unary operator from a token. Parameters: O - The input value. If this is a token, O is reset to the token's value. When O is a string and is in L, its associated value is used as the path to instantiate. type - The desired type of the returned object. L - The list in which to search for O. See Also: - <GetBinaryOperator()> - <GetUnaryOperator()> */ /datum/n_Parser/nS_Parser/proc/GetOperator(O, type = /datum/node/expression/operation, L[]) if(istype(O, type)) return O //O is already the desired type if(istype(O, /datum/token)) O = O:value //sets O to text if(istext(O)) //sets O to path if(L.Find(O)) O = L[O] else return null if(ispath(O)) O = new O //catches path from last check else return null //Unknown type return O /* Proc: GetBinaryOperator Uses <GetOperator()> to search for an instance of a binary operator type with which the given string is associated. For example, if O is set to "+", an <Add> node is returned. See Also: - <GetOperator()> - <GetUnaryOperator()> */ /datum/n_Parser/nS_Parser/proc/GetBinaryOperator(O) return GetOperator(O, /datum/node/expression/operation/binary, options.binary_operators) /* Proc: GetUnaryOperator Uses <GetOperator()> to search for an instance of a unary operator type with which the given string is associated. For example, if O is set to "!", a <LogicalNot> node is returned. See Also: - <GetOperator()> - <GetBinaryOperator()> */ /datum/n_Parser/nS_Parser/proc/GetUnaryOperator(O) return GetOperator(O, /datum/node/expression/operation/unary, options.unary_operators) /* Proc: Reduce Takes the operator on top of the opr stack and assigns its operand(s). Then this proc pushes the value of that operation to the top of the val stack. */ /datum/n_Parser/nS_Parser/proc/Reduce(var/datum/stack/opr, var/datum/stack/val) var/datum/node/expression/operation/O = opr.Pop() if(!O) return if(!istype(O)) errors += new/datum/scriptError("Error reducing expression - invalid operator.") return //Take O and assign its operands, popping one or two values from the val stack //depending on whether O is a binary or unary operator. if(istype(O, /datum/node/expression/operation/binary)) var/datum/node/expression/operation/binary/B=O B.exp2 = val.Pop() B.exp = val.Pop() val.Push(B) else O.exp=val.Pop() val.Push(O) /* Proc: EndOfExpression Returns true if the current token represents the end of an expression. Parameters: end - A list of values to compare the current token to. */ /datum/n_Parser/nS_Parser/proc/EndOfExpression(end[]) if(!curToken) return 1 if(istype(curToken, /datum/token/symbol) && end.Find(curToken.value)) return 1 if(istype(curToken, /datum/token/end) && end.Find(/datum/token/end)) return 1 return 0 /* Proc: ParseExpression Uses the Shunting-yard algorithm to parse expressions. Notes: - When an opening parenthesis is found, then <ParseParenExpression()> is called to handle it. - The <expecting> variable helps distinguish unary operators from binary operators (for cases like the - operator, which can be either). Articles: - <http://epaperpress.com/oper/> - <http://en.wikipedia.org/wiki/Shunting-yard_algorithm> See Also: - <ParseFunctionExpression()> - <ParseParenExpression()> - <ParseParamExpression()> */ /datum/n_Parser/nS_Parser/proc/ParseExpression(var/list/end = list(/datum/token/end), list/ErrChars = list("{", "}"), check_functions = 0) var/datum/stack/opr = new var/datum/stack/val = new src.expecting = VALUE var/loop = 0 while(TRUE) loop++ if(loop > 800) errors += new/datum/scriptError("Too many nested tokens.") return if(EndOfExpression(end)) break if(istype(curToken, /datum/token/symbol) && ErrChars.Find(curToken.value)) errors += new/datum/scriptError/BadToken(curToken) break if(index > tokens.len) //End of File errors += new/datum/scriptError/EndOfFile() break var/datum/token/ntok if(index + 1 <= tokens.len) ntok = tokens[index + 1] if(istype(curToken, /datum/token/symbol) && curToken.value == "(") //Parse parentheses expression if(expecting != VALUE) errors += new/datum/scriptError/ExpectedToken("operator", curToken) NextToken() continue val.Push(ParseParenExpression()) else if(istype(curToken, /datum/token/symbol)) //Operator found. var/datum/node/expression/operation/curOperator //Figure out whether it is unary or binary and get a new instance. if(src.expecting == OPERATOR) curOperator = GetBinaryOperator(curToken) if(!curOperator) errors += new/datum/scriptError/ExpectedToken("operator", curToken) NextToken() continue else curOperator = GetUnaryOperator(curToken) if(!curOperator) //given symbol isn't a unary operator errors += new/datum/scriptError/ExpectedToken("expression", curToken) NextToken() continue if(opr.Top() && Precedence(opr.Top(), curOperator) == REDUCE) //Check order of operations and reduce if necessary Reduce(opr, val) continue opr.Push(curOperator) src.expecting = VALUE else if(ntok && ntok.value == "(" && istype(ntok, /datum/token/symbol)\ && istype(curToken, /datum/token/word)) //Parse function call if(!check_functions) var/datum/token/preToken = curToken var/old_expect = src.expecting var/fex = ParseFunctionExpression() if(old_expect != VALUE) errors += new/datum/scriptError/ExpectedToken("operator", preToken) NextToken() continue val.Push(fex) else errors += new/datum/scriptError/ParameterFunction(curToken) break else if(istype(curToken, /datum/token/keyword)) //inline keywords var/datum/n_Keyword/kw = options.keywords[curToken.value] kw = new kw(inline=1) if(kw) if(!kw.Parse(src)) return else errors += new/datum/scriptError/BadToken(curToken) else if(istype(curToken, /datum/token/end)) //semicolon found where it wasn't expected errors += new/datum/scriptError/BadToken(curToken) NextToken() continue else if(expecting != VALUE) errors += new/datum/scriptError/ExpectedToken("operator", curToken) NextToken() continue val.Push(GetExpression(curToken)) src.expecting = OPERATOR NextToken() while(opr.Top()) Reduce(opr, val) //Reduce the value stack completely . = val.Pop() //Return what should be the last value on the stack if(val.Top()) // var/datum/node/N = val.Pop() errors += new/datum/scriptError("Error parsing expression. Unexpected value left on stack: [N.ToString()].") return null /* Proc: ParseFunctionExpression Parses a function call inside of an expression. See Also: - <ParseExpression()> */ /datum/n_Parser/nS_Parser/proc/ParseFunctionExpression() var/datum/node/expression/FunctionCall/exp = new exp.func_name = curToken.value NextToken() //skip function name NextToken() //skip open parenthesis, already found var/loops = 0 while(TRUE) loops++ if(loops >= 800) errors += new/datum/scriptError("Too many nested expressions.") break //CRASH("Something TERRIBLE has gone wrong in ParseFunctionExpression ;__;") if(istype(curToken, /datum/token/symbol) && curToken.value == ")") return exp exp.parameters += ParseParamExpression() if(errors.len) return exp if(curToken.value == "," && istype(curToken, /datum/token/symbol)) NextToken() //skip comma if(istype(curToken, /datum/token/end)) //Prevents infinite loop... errors += new/datum/scriptError/ExpectedToken(")") return exp /* Proc: ParseParenExpression Parses an expression that ends with a close parenthesis. This is used for parsing expressions inside of parentheses. See Also: - <ParseExpression()> */ /datum/n_Parser/nS_Parser/proc/ParseParenExpression() if(!CheckToken("(", /datum/token/symbol)) return return new/datum/node/expression/operation/unary/group(ParseExpression(list(")"))) /* Proc: ParseParamExpression Parses an expression that ends with either a comma or close parenthesis. This is used for parsing the parameters passed to a function call. See Also: - <ParseExpression()> */ /datum/n_Parser/nS_Parser/proc/ParseParamExpression(var/check_functions = 0) var/cf = check_functions return ParseExpression(list(",", ")"), check_functions = cf)