mirror of https://github.com/jkjoy/sunpeiwen.git
58 lines
1.8 KiB
JavaScript
58 lines
1.8 KiB
JavaScript
/*
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Copyright 2018 Google LLC
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Use of this source code is governed by an MIT-style
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license that can be found in the LICENSE file or at
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https://opensource.org/licenses/MIT.
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*/
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import { WorkboxError } from 'workbox-core/_private/WorkboxError.js';
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import { assert } from 'workbox-core/_private/assert.js';
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import '../_version.js';
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/**
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* @param {Blob} blob A source blob.
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* @param {number} [start] The offset to use as the start of the
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* slice.
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* @param {number} [end] The offset to use as the end of the slice.
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* @return {Object} An object with `start` and `end` properties, reflecting
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* the effective boundaries to use given the size of the blob.
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*
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* @private
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*/
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function calculateEffectiveBoundaries(blob, start, end) {
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if (process.env.NODE_ENV !== 'production') {
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assert.isInstance(blob, Blob, {
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moduleName: 'workbox-range-requests',
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funcName: 'calculateEffectiveBoundaries',
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paramName: 'blob',
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});
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}
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const blobSize = blob.size;
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if ((end && end > blobSize) || (start && start < 0)) {
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throw new WorkboxError('range-not-satisfiable', {
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size: blobSize,
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end,
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start,
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});
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}
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let effectiveStart;
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let effectiveEnd;
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if (start !== undefined && end !== undefined) {
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effectiveStart = start;
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// Range values are inclusive, so add 1 to the value.
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effectiveEnd = end + 1;
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}
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else if (start !== undefined && end === undefined) {
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effectiveStart = start;
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effectiveEnd = blobSize;
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}
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else if (end !== undefined && start === undefined) {
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effectiveStart = blobSize - end;
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effectiveEnd = blobSize;
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}
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return {
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start: effectiveStart,
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end: effectiveEnd,
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};
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}
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export { calculateEffectiveBoundaries };
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