67 lines
1.8 KiB
Plaintext
67 lines
1.8 KiB
Plaintext
'use strict';
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var forEach = require('for-each');
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var callBind = require('call-bind');
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var typedArrays = require('available-typed-arrays')();
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var getters = {};
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var hasProto = require('has-proto')();
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var gOPD = Object.getOwnPropertyDescriptor;
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var oDP = Object.defineProperty;
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if (gOPD) {
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var getByteOffset = function (x) {
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return x.byteOffset;
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};
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forEach(typedArrays, function (typedArray) {
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// In Safari 7, Typed Array constructors are typeof object
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if (typeof global[typedArray] === 'function' || typeof global[typedArray] === 'object') {
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var Proto = global[typedArray].prototype;
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var descriptor = gOPD(Proto, 'byteOffset');
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if (!descriptor && hasProto) {
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var superProto = Proto.__proto__; // eslint-disable-line no-proto
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descriptor = gOPD(superProto, 'byteOffset');
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}
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// Opera 12.16 has a magic byteOffset data property on instances AND on Proto
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if (descriptor && descriptor.get) {
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getters[typedArray] = callBind(descriptor.get);
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} else if (oDP) {
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// this is likely an engine where instances have a magic byteOffset data property
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var arr = new global[typedArray](2);
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descriptor = gOPD(arr, 'byteOffset');
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if (descriptor && descriptor.configurable) {
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oDP(arr, 'length', { value: 3 });
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}
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if (arr.length === 2) {
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getters[typedArray] = getByteOffset;
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}
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}
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}
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});
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}
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var tryTypedArrays = function tryAllTypedArrays(value) {
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var foundOffset;
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forEach(getters, function (getter) {
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if (typeof foundOffset !== 'number') {
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try {
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var offset = getter(value);
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if (typeof offset === 'number') {
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foundOffset = offset;
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}
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} catch (e) {}
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}
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});
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return foundOffset;
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};
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var isTypedArray = require('is-typed-array');
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module.exports = function typedArrayByteOffset(value) {
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if (!isTypedArray(value)) {
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return false;
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}
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return tryTypedArrays(value);
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};
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