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57 lines
1.8 KiB
57 lines
1.8 KiB
/* |
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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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