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denoland-deno/runtime/js/01_web_util.js

161 lines
4.7 KiB
JavaScript

// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
"use strict";
((window) => {
const illegalConstructorKey = Symbol("illegalConstructorKey");
function requiredArguments(
name,
length,
required,
) {
if (length < required) {
const errMsg = `${name} requires at least ${required} argument${
required === 1 ? "" : "s"
}, but only ${length} present`;
throw new TypeError(errMsg);
}
}
const objectCloneMemo = new WeakMap();
function cloneArrayBuffer(
srcBuffer,
srcByteOffset,
srcLength,
_cloneConstructor,
) {
// this function fudges the return type but SharedArrayBuffer is disabled for a while anyway
return srcBuffer.slice(
srcByteOffset,
srcByteOffset + srcLength,
);
}
/** Clone a value in a similar way to structured cloning. It is similar to a
* StructureDeserialize(StructuredSerialize(...)). */
function cloneValue(value) {
switch (typeof value) {
case "number":
case "string":
case "boolean":
case "undefined":
case "bigint":
return value;
case "object": {
if (objectCloneMemo.has(value)) {
return objectCloneMemo.get(value);
}
if (value === null) {
return value;
}
if (value instanceof Date) {
return new Date(value.valueOf());
}
if (value instanceof RegExp) {
return new RegExp(value);
}
if (value instanceof SharedArrayBuffer) {
return value;
}
if (value instanceof ArrayBuffer) {
const cloned = cloneArrayBuffer(
value,
0,
value.byteLength,
ArrayBuffer,
);
objectCloneMemo.set(value, cloned);
return cloned;
}
if (ArrayBuffer.isView(value)) {
const clonedBuffer = cloneValue(value.buffer);
// Use DataViewConstructor type purely for type-checking, can be a
// DataView or TypedArray. They use the same constructor signature,
// only DataView has a length in bytes and TypedArrays use a length in
// terms of elements, so we adjust for that.
let length;
if (value instanceof DataView) {
length = value.byteLength;
} else {
length = value.length;
}
return new (value.constructor)(
clonedBuffer,
value.byteOffset,
length,
);
}
if (value instanceof Map) {
const clonedMap = new Map();
objectCloneMemo.set(value, clonedMap);
value.forEach((v, k) => {
clonedMap.set(cloneValue(k), cloneValue(v));
});
return clonedMap;
}
if (value instanceof Set) {
// assumes that cloneValue still takes only one argument
const clonedSet = new Set([...value].map(cloneValue));
objectCloneMemo.set(value, clonedSet);
return clonedSet;
}
// default for objects
const clonedObj = {};
objectCloneMemo.set(value, clonedObj);
const sourceKeys = Object.getOwnPropertyNames(value);
for (const key of sourceKeys) {
clonedObj[key] = cloneValue(value[key]);
}
Reflect.setPrototypeOf(clonedObj, Reflect.getPrototypeOf(value));
return clonedObj;
}
case "symbol":
case "function":
default:
throw new DOMException("Uncloneable value in stream", "DataCloneError");
}
}
const handlerSymbol = Symbol("eventHandlers");
function makeWrappedHandler(handler) {
function wrappedHandler(...args) {
if (typeof wrappedHandler.handler !== "function") {
return;
}
return wrappedHandler.handler.call(this, ...args);
}
wrappedHandler.handler = handler;
return wrappedHandler;
}
function defineEventHandler(emitter, name, defaultValue = undefined) {
// HTML specification section 8.1.5.1
Object.defineProperty(emitter, `on${name}`, {
get() {
return this[handlerSymbol]?.get(name)?.handler ?? defaultValue;
},
set(value) {
if (!this[handlerSymbol]) {
this[handlerSymbol] = new Map();
}
let handlerWrapper = this[handlerSymbol]?.get(name);
if (handlerWrapper) {
handlerWrapper.handler = value;
} else {
handlerWrapper = makeWrappedHandler(value);
this.addEventListener(name, handlerWrapper);
}
this[handlerSymbol].set(name, handlerWrapper);
},
configurable: true,
enumerable: true,
});
}
window.__bootstrap.webUtil = {
illegalConstructorKey,
requiredArguments,
defineEventHandler,
cloneValue,
};
})(this);