246 lines
8.6 KiB
Plaintext
246 lines
8.6 KiB
Plaintext
/* eslint-disable no-bitwise */
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import createBlob from './createBlob';
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// Sadly, the best way to save binary data in WebSQL/localStorage is serializing
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// it to Base64, so this is how we store it to prevent very strange errors with less
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// verbose ways of binary <-> string data storage.
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var BASE_CHARS =
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'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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var BLOB_TYPE_PREFIX = '~~local_forage_type~';
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var BLOB_TYPE_PREFIX_REGEX = /^~~local_forage_type~([^~]+)~/;
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var SERIALIZED_MARKER = '__lfsc__:';
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var SERIALIZED_MARKER_LENGTH = SERIALIZED_MARKER.length;
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// OMG the serializations!
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var TYPE_ARRAYBUFFER = 'arbf';
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var TYPE_BLOB = 'blob';
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var TYPE_INT8ARRAY = 'si08';
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var TYPE_UINT8ARRAY = 'ui08';
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var TYPE_UINT8CLAMPEDARRAY = 'uic8';
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var TYPE_INT16ARRAY = 'si16';
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var TYPE_INT32ARRAY = 'si32';
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var TYPE_UINT16ARRAY = 'ur16';
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var TYPE_UINT32ARRAY = 'ui32';
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var TYPE_FLOAT32ARRAY = 'fl32';
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var TYPE_FLOAT64ARRAY = 'fl64';
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var TYPE_SERIALIZED_MARKER_LENGTH =
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SERIALIZED_MARKER_LENGTH + TYPE_ARRAYBUFFER.length;
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var toString = Object.prototype.toString;
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function stringToBuffer(serializedString) {
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// Fill the string into a ArrayBuffer.
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var bufferLength = serializedString.length * 0.75;
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var len = serializedString.length;
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var i;
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var p = 0;
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var encoded1, encoded2, encoded3, encoded4;
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if (serializedString[serializedString.length - 1] === '=') {
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bufferLength--;
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if (serializedString[serializedString.length - 2] === '=') {
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bufferLength--;
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}
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}
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var buffer = new ArrayBuffer(bufferLength);
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var bytes = new Uint8Array(buffer);
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for (i = 0; i < len; i += 4) {
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encoded1 = BASE_CHARS.indexOf(serializedString[i]);
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encoded2 = BASE_CHARS.indexOf(serializedString[i + 1]);
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encoded3 = BASE_CHARS.indexOf(serializedString[i + 2]);
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encoded4 = BASE_CHARS.indexOf(serializedString[i + 3]);
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/*jslint bitwise: true */
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bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
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bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
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bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
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}
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return buffer;
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}
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// Converts a buffer to a string to store, serialized, in the backend
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// storage library.
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function bufferToString(buffer) {
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// base64-arraybuffer
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var bytes = new Uint8Array(buffer);
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var base64String = '';
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var i;
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for (i = 0; i < bytes.length; i += 3) {
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/*jslint bitwise: true */
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base64String += BASE_CHARS[bytes[i] >> 2];
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base64String += BASE_CHARS[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
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base64String +=
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BASE_CHARS[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
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base64String += BASE_CHARS[bytes[i + 2] & 63];
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}
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if (bytes.length % 3 === 2) {
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base64String = base64String.substring(0, base64String.length - 1) + '=';
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} else if (bytes.length % 3 === 1) {
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base64String =
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base64String.substring(0, base64String.length - 2) + '==';
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}
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return base64String;
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}
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// Serialize a value, afterwards executing a callback (which usually
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// instructs the `setItem()` callback/promise to be executed). This is how
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// we store binary data with localStorage.
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function serialize(value, callback) {
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var valueType = '';
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if (value) {
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valueType = toString.call(value);
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}
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// Cannot use `value instanceof ArrayBuffer` or such here, as these
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// checks fail when running the tests using casper.js...
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//
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// TODO: See why those tests fail and use a better solution.
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if (
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value &&
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(valueType === '[object ArrayBuffer]' ||
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(value.buffer &&
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toString.call(value.buffer) === '[object ArrayBuffer]'))
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) {
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// Convert binary arrays to a string and prefix the string with
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// a special marker.
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var buffer;
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var marker = SERIALIZED_MARKER;
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if (value instanceof ArrayBuffer) {
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buffer = value;
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marker += TYPE_ARRAYBUFFER;
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} else {
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buffer = value.buffer;
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if (valueType === '[object Int8Array]') {
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marker += TYPE_INT8ARRAY;
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} else if (valueType === '[object Uint8Array]') {
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marker += TYPE_UINT8ARRAY;
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} else if (valueType === '[object Uint8ClampedArray]') {
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marker += TYPE_UINT8CLAMPEDARRAY;
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} else if (valueType === '[object Int16Array]') {
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marker += TYPE_INT16ARRAY;
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} else if (valueType === '[object Uint16Array]') {
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marker += TYPE_UINT16ARRAY;
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} else if (valueType === '[object Int32Array]') {
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marker += TYPE_INT32ARRAY;
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} else if (valueType === '[object Uint32Array]') {
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marker += TYPE_UINT32ARRAY;
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} else if (valueType === '[object Float32Array]') {
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marker += TYPE_FLOAT32ARRAY;
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} else if (valueType === '[object Float64Array]') {
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marker += TYPE_FLOAT64ARRAY;
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} else {
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callback(new Error('Failed to get type for BinaryArray'));
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}
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}
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callback(marker + bufferToString(buffer));
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} else if (valueType === '[object Blob]') {
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// Conver the blob to a binaryArray and then to a string.
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var fileReader = new FileReader();
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fileReader.onload = function() {
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// Backwards-compatible prefix for the blob type.
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var str =
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BLOB_TYPE_PREFIX +
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value.type +
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'~' +
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bufferToString(this.result);
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callback(SERIALIZED_MARKER + TYPE_BLOB + str);
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};
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fileReader.readAsArrayBuffer(value);
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} else {
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try {
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callback(JSON.stringify(value));
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} catch (e) {
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console.error("Couldn't convert value into a JSON string: ", value);
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callback(null, e);
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}
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}
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}
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// Deserialize data we've inserted into a value column/field. We place
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// special markers into our strings to mark them as encoded; this isn't
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// as nice as a meta field, but it's the only sane thing we can do whilst
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// keeping localStorage support intact.
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//
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// Oftentimes this will just deserialize JSON content, but if we have a
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// special marker (SERIALIZED_MARKER, defined above), we will extract
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// some kind of arraybuffer/binary data/typed array out of the string.
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function deserialize(value) {
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// If we haven't marked this string as being specially serialized (i.e.
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// something other than serialized JSON), we can just return it and be
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// done with it.
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if (value.substring(0, SERIALIZED_MARKER_LENGTH) !== SERIALIZED_MARKER) {
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return JSON.parse(value);
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}
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// The following code deals with deserializing some kind of Blob or
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// TypedArray. First we separate out the type of data we're dealing
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// with from the data itself.
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var serializedString = value.substring(TYPE_SERIALIZED_MARKER_LENGTH);
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var type = value.substring(
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SERIALIZED_MARKER_LENGTH,
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TYPE_SERIALIZED_MARKER_LENGTH
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);
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var blobType;
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// Backwards-compatible blob type serialization strategy.
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// DBs created with older versions of localForage will simply not have the blob type.
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if (type === TYPE_BLOB && BLOB_TYPE_PREFIX_REGEX.test(serializedString)) {
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var matcher = serializedString.match(BLOB_TYPE_PREFIX_REGEX);
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blobType = matcher[1];
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serializedString = serializedString.substring(matcher[0].length);
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}
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var buffer = stringToBuffer(serializedString);
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// Return the right type based on the code/type set during
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// serialization.
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switch (type) {
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case TYPE_ARRAYBUFFER:
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return buffer;
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case TYPE_BLOB:
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return createBlob([buffer], { type: blobType });
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case TYPE_INT8ARRAY:
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return new Int8Array(buffer);
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case TYPE_UINT8ARRAY:
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return new Uint8Array(buffer);
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case TYPE_UINT8CLAMPEDARRAY:
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return new Uint8ClampedArray(buffer);
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case TYPE_INT16ARRAY:
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return new Int16Array(buffer);
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case TYPE_UINT16ARRAY:
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return new Uint16Array(buffer);
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case TYPE_INT32ARRAY:
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return new Int32Array(buffer);
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case TYPE_UINT32ARRAY:
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return new Uint32Array(buffer);
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case TYPE_FLOAT32ARRAY:
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return new Float32Array(buffer);
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case TYPE_FLOAT64ARRAY:
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return new Float64Array(buffer);
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default:
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throw new Error('Unkown type: ' + type);
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}
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}
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var localforageSerializer = {
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serialize: serialize,
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deserialize: deserialize,
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stringToBuffer: stringToBuffer,
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bufferToString: bufferToString
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};
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export default localforageSerializer;
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