IsViewOutOfBounds.js 1.7 KB

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  1. 'use strict';
  2. var $TypeError = require('es-errors/type');
  3. var IsDetachedBuffer = require('./IsDetachedBuffer');
  4. var IsFixedLengthArrayBuffer = require('./IsFixedLengthArrayBuffer');
  5. var isDataViewWithBufferWitnessRecord = require('../helpers/records/data-view-with-buffer-witness-record');
  6. var dataViewBuffer = require('data-view-buffer');
  7. var dataViewByteLength = require('data-view-byte-length');
  8. var dataViewByteOffset = require('data-view-byte-offset');
  9. // https://262.ecma-international.org/15.0/#sec-isviewoutofbounds
  10. module.exports = function IsViewOutOfBounds(viewRecord) {
  11. if (!isDataViewWithBufferWitnessRecord(viewRecord)) {
  12. throw new $TypeError('Assertion failed: `viewRecord` must be a DataView With Buffer Witness Record');
  13. }
  14. var view = viewRecord['[[Object]]']; // step 1
  15. var bufferByteLength = viewRecord['[[CachedBufferByteLength]]']; // step 2
  16. if (IsDetachedBuffer(dataViewBuffer(view)) !== (bufferByteLength === 'DETACHED')) {
  17. // step 3
  18. throw new $TypeError('Assertion failed: `IsDetachedBuffer(dataViewBuffer(view))` must be true if and only if `bufferByteLength === ~DETACHED~');
  19. }
  20. if (bufferByteLength === 'DETACHED') {
  21. return true; // step 4
  22. }
  23. var byteOffsetStart = dataViewByteOffset(view); // step 5
  24. var isFixed = IsFixedLengthArrayBuffer(dataViewBuffer(view));
  25. var viewByteLength = isFixed ? dataViewByteLength(view) : 'AUTO'; // view.[[ByteLength]]
  26. var byteOffsetEnd = viewByteLength === 'AUTO' ? bufferByteLength : byteOffsetStart + viewByteLength; // steps 6 - 7
  27. if (byteOffsetStart > bufferByteLength || byteOffsetEnd > bufferByteLength) {
  28. return true; // step 8
  29. }
  30. // 9. NOTE: 0-length DataViews are not considered out-of-bounds.
  31. return false; // step 10
  32. };