100 lines
3.7 KiB
JavaScript
100 lines
3.7 KiB
JavaScript
'use strict';
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var GetIntrinsic = require('get-intrinsic');
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var min = GetIntrinsic('%Math.min%');
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var $TypeError = require('es-errors/type');
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var $ArrayBuffer = GetIntrinsic('%ArrayBuffer%', true);
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var $Uint8Array = GetIntrinsic('%Uint8Array%', true);
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var callBound = require('call-bind/callBound');
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var byteLength = require('array-buffer-byte-length');
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var $maxByteLength = callBound('%ArrayBuffer.prototype.maxByteLength%', true);
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var copy = function copyAB(src, start, end) {
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var that = new $Uint8Array(src);
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if (typeof end === 'undefined') {
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end = that.length; // eslint-disable-line no-param-reassign
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}
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var result = new $ArrayBuffer(end - start);
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var resultArray = new $Uint8Array(result);
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for (var i = 0; i < resultArray.length; i++) {
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resultArray[i] = that[i + start];
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}
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return result;
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};
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var $abSlice = callBound('%ArrayBuffer.prototype.slice%', true)
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|| function slice(ab, a, b) { // in node < 0.11, slice is an own nonconfigurable property
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return ab.slice ? ab.slice(a, b) : copy(ab, a, b); // node 0.8 lacks `slice`
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};
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var DetachArrayBuffer = require('./DetachArrayBuffer');
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var IsDetachedBuffer = require('./IsDetachedBuffer');
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var IsFixedLengthArrayBuffer = require('./IsFixedLengthArrayBuffer');
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var ToIndex = require('./ToIndex');
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var isArrayBuffer = require('is-array-buffer');
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var isSharedArrayBuffer = require('is-shared-array-buffer');
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module.exports = function ArrayBufferCopyAndDetach(arrayBuffer, newLength, preserveResizability) {
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if (preserveResizability !== 'PRESERVE-RESIZABILITY' && preserveResizability !== 'FIXED-LENGTH') {
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throw new $TypeError('`preserveResizability` must be ~PRESERVE-RESIZABILITY~ or ~FIXED-LENGTH~');
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}
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if (!isArrayBuffer(arrayBuffer) || isSharedArrayBuffer(arrayBuffer)) {
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throw new $TypeError('`arrayBuffer` must be an ArrayBuffer'); // steps 1 - 2
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}
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var abByteLength;
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var newByteLength;
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if (typeof newLength === 'undefined') { // step 3
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newByteLength = byteLength(arrayBuffer); // step 3.a
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abByteLength = newByteLength;
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} else { // step 4
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newByteLength = ToIndex(newLength); // step 4.a
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}
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if (IsDetachedBuffer(arrayBuffer)) {
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throw new $TypeError('`arrayBuffer` must not be detached'); // step 5
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}
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var newMaxByteLength;
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if (preserveResizability === 'PRESERVE-RESIZABILITY' && !IsFixedLengthArrayBuffer(arrayBuffer)) { // step 6
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newMaxByteLength = $maxByteLength(arrayBuffer); // step 6.a
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} else { // step 7
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newMaxByteLength = 'EMPTY'; // step 7.a
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}
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// commented out since there's no way to set or access this key
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// 8. If arrayBuffer.[[ArrayBufferDetachKey]] is not undefined, throw a TypeError exception.
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// 9. Let newBuffer be ? AllocateArrayBuffer(%ArrayBuffer%, newByteLength, newMaxByteLength).
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var newBuffer = newMaxByteLength === 'EMPTY' ? new $ArrayBuffer(newByteLength) : new $ArrayBuffer(newByteLength, { maxByteLength: newMaxByteLength });
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if (typeof abByteLength !== 'number') {
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abByteLength = byteLength(arrayBuffer);
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}
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var copyLength = min(newByteLength, abByteLength); // step 10
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if (newByteLength > copyLength) {
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var taNew = new $Uint8Array(newBuffer);
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var taOld = new $Uint8Array(arrayBuffer);
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for (var i = 0; i < copyLength; i++) {
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taNew[i] = taOld[i];
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}
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} else {
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newBuffer = $abSlice(arrayBuffer, 0, copyLength); // ? optimization for when the new buffer will not be larger than the old one
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}
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/*
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11. Let fromBlock be arrayBuffer.[[ArrayBufferData]].
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12. Let toBlock be newBuffer.[[ArrayBufferData]].
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13. Perform CopyDataBlockBytes(toBlock, 0, fromBlock, 0, copyLength).
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14. NOTE: Neither creation of the new Data Block nor copying from the old Data Block are observable. Implementations may implement this method as a zero-copy move or a realloc.
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*/
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DetachArrayBuffer(arrayBuffer); // step 15
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return newBuffer; // step 16
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};
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