idlize

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/*
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 * Copyright (c) 2022-2024 Huawei Device Co., Ltd.
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 * http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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const SKIP_FRAMES = 10
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/** This interface represents an unique observer that can be notified that some changes. */
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export interface Dependency {
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    /** Returns `true` if the dependency is no longer actual. */
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    readonly obsolete: boolean
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    /** Notifies the dependency that it should be invalidated. */
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    invalidate(): void
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}
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/** This class allows to store and update all dependencies. */
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export class Dependencies {
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    private frame = 0
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    private dependencies: Set<Dependency> | undefined = undefined
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    private latest: Dependency | undefined = undefined
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    /** Returns `true` if there are no dependencies to invalidate. */
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    get empty(): boolean {
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        return this.dependencies !== undefined
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            ? this.dependencies!.size == 0
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            : this.latest === undefined
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    }
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    /** @param dependency - a dependency to invalidate */
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    register(dependency?: Dependency): void {
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        if (dependency === undefined || dependency == this.latest || dependency.obsolete) return
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        if (this.dependencies !== undefined) {
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            this.dependencies!.add(dependency)
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        } else if (this.latest !== undefined) {
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            this.dependencies = new Set<Dependency>()
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            this.dependencies!.add(this.latest!)
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            this.dependencies!.add(dependency)
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        }
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        this.latest = dependency
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    }
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    /** Invalidates all dependencies and removes obsolete ones. */
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    updateDependencies(invalidate: boolean): void {
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        if (++this.frame < SKIP_FRAMES && !invalidate) return
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        this.frame = 0
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        if (this.dependencies !== undefined) {
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            let disposed: Array<Dependency> | undefined = undefined
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            const it = this.dependencies!.keys()
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            while (true) {
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                const result = it.next()
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                if (result.done) break
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                const dependency = result.value as Dependency
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                if (!updateDependency(invalidate, dependency)) {
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                    if (disposed) {
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                        disposed.push(dependency)
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                    } else {
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                        disposed = Array.of<Dependency>(dependency)
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                    }
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                }
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            }
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            if (disposed) {
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                let index = disposed.length
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                while (0 < index--) this.dependencies!.delete(disposed[index])
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            }
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        } else if (this.latest !== undefined && !updateDependency(invalidate, this.latest!)) {
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            this.latest = undefined
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        }
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    }
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}
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function updateDependency(invalidate: boolean, dependency: Dependency): boolean {
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    if (dependency.obsolete) return false
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    if (invalidate) dependency.invalidate()
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    return true
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}
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