55 lines
1.8 KiB
JavaScript
55 lines
1.8 KiB
JavaScript
'use strict';
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var $TypeError = require('es-errors/type');
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var IsDetachedBuffer = require('./IsDetachedBuffer');
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var TypedArrayElementSize = require('./TypedArrayElementSize');
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var isTypedArrayWithBufferWitnessRecord = require('../helpers/records/typed-array-with-buffer-witness-record');
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var typedArrayBuffer = require('typed-array-buffer');
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var typedArrayByteOffset = require('typed-array-byte-offset');
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var typedArrayLength = require('typed-array-length');
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// https://tc39.es/ecma262/#sec-istypedarrayoutofbounds
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module.exports = function IsTypedArrayOutOfBounds(taRecord) {
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if (!isTypedArrayWithBufferWitnessRecord(taRecord)) {
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throw new $TypeError('Assertion failed: `taRecord` must be a TypedArray With Buffer Witness Record');
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}
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var O = taRecord['[[Object]]']; // step 1
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var bufferByteLength = taRecord['[[CachedBufferByteLength]]']; // step 2
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if (IsDetachedBuffer(typedArrayBuffer(O)) && bufferByteLength !== 'DETACHED') {
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throw new $TypeError('Assertion failed: typed array is detached only if the byte length is ~DETACHED~'); // step 3
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}
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if (bufferByteLength === 'DETACHED') {
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return true; // step 4
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}
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var byteOffsetStart = typedArrayByteOffset(O); // step 5
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var byteOffsetEnd;
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var length = typedArrayLength(O);
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// TODO: probably use package for array length
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// seems to apply when TA is backed by a resizable/growable AB
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if (length === 'AUTO') { // step 6
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byteOffsetEnd = bufferByteLength; // step 6.a
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} else {
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var elementSize = TypedArrayElementSize(O); // step 7.a
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byteOffsetEnd = byteOffsetStart + (length * elementSize); // step 7.b
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}
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if (byteOffsetStart > bufferByteLength || byteOffsetEnd > bufferByteLength) {
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return true; // step 8
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}
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// 9. NOTE: 0-length TypedArrays are not considered out-of-bounds.
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return false; // step 10
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};
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