1 files changed, 233 insertions, 0 deletions
diff --git a/www/lib/localforage/src/utils/serializer.js b/www/lib/localforage/src/utils/serializer.js
new file mode 100644
index 00000000..08e5fc8f
--- /dev/null
+++ b/www/lib/localforage/src/utils/serializer.js
@@ -0,0 +1,233 @@
+import createBlob from './createBlob';
+
+// Sadly, the best way to save binary data in WebSQL/localStorage is serializing
+// it to Base64, so this is how we store it to prevent very strange errors with less
+// verbose ways of binary <-> string data storage.
+var BASE_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
+
+var BLOB_TYPE_PREFIX = '~~local_forage_type~';
+var BLOB_TYPE_PREFIX_REGEX = /^~~local_forage_type~([^~]+)~/;
+
+var SERIALIZED_MARKER = '__lfsc__:';
+var SERIALIZED_MARKER_LENGTH = SERIALIZED_MARKER.length;
+
+// OMG the serializations!
+var TYPE_ARRAYBUFFER = 'arbf';
+var TYPE_BLOB = 'blob';
+var TYPE_INT8ARRAY = 'si08';
+var TYPE_UINT8ARRAY = 'ui08';
+var TYPE_UINT8CLAMPEDARRAY = 'uic8';
+var TYPE_INT16ARRAY = 'si16';
+var TYPE_INT32ARRAY = 'si32';
+var TYPE_UINT16ARRAY = 'ur16';
+var TYPE_UINT32ARRAY = 'ui32';
+var TYPE_FLOAT32ARRAY = 'fl32';
+var TYPE_FLOAT64ARRAY = 'fl64';
+var TYPE_SERIALIZED_MARKER_LENGTH = SERIALIZED_MARKER_LENGTH +
+    TYPE_ARRAYBUFFER.length;
+
+function stringToBuffer(serializedString) {
+    // Fill the string into a ArrayBuffer.
+    var bufferLength = serializedString.length * 0.75;
+    var len = serializedString.length;
+    var i;
+    var p = 0;
+    var encoded1, encoded2, encoded3, encoded4;
+
+    if (serializedString[serializedString.length - 1] === '=') {
+        bufferLength--;
+        if (serializedString[serializedString.length - 2] === '=') {
+            bufferLength--;
+        }
+    }
+
+    var buffer = new ArrayBuffer(bufferLength);
+    var bytes = new Uint8Array(buffer);
+
+    for (i = 0; i < len; i += 4) {
+        encoded1 = BASE_CHARS.indexOf(serializedString[i]);
+        encoded2 = BASE_CHARS.indexOf(serializedString[i + 1]);
+        encoded3 = BASE_CHARS.indexOf(serializedString[i + 2]);
+        encoded4 = BASE_CHARS.indexOf(serializedString[i + 3]);
+
+        /*jslint bitwise: true */
+        bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
+        bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
+        bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
+    }
+    return buffer;
+}
+
+// Converts a buffer to a string to store, serialized, in the backend
+// storage library.
+function bufferToString(buffer) {
+    // base64-arraybuffer
+    var bytes = new Uint8Array(buffer);
+    var base64String = '';
+    var i;
+
+    for (i = 0; i < bytes.length; i += 3) {
+        /*jslint bitwise: true */
+        base64String += BASE_CHARS[bytes[i] >> 2];
+        base64String += BASE_CHARS[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
+        base64String += BASE_CHARS[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
+        base64String += BASE_CHARS[bytes[i + 2] & 63];
+    }
+
+    if ((bytes.length % 3) === 2) {
+        base64String = base64String.substring(0, base64String.length - 1) + '=';
+    } else if (bytes.length % 3 === 1) {
+        base64String = base64String.substring(0, base64String.length - 2) + '==';
+    }
+
+    return base64String;
+}
+
+// Serialize a value, afterwards executing a callback (which usually
+// instructs the `setItem()` callback/promise to be executed). This is how
+// we store binary data with localStorage.
+function serialize(value, callback) {
+    var valueString = '';
+    if (value) {
+        valueString = value.toString();
+    }
+
+    // Cannot use `value instanceof ArrayBuffer` or such here, as these
+    // checks fail when running the tests using casper.js...
+    //
+    // TODO: See why those tests fail and use a better solution.
+    if (value && (value.toString() === '[object ArrayBuffer]' ||
+        value.buffer &&
+        value.buffer.toString() === '[object ArrayBuffer]')) {
+        // Convert binary arrays to a string and prefix the string with
+        // a special marker.
+        var buffer;
+        var marker = SERIALIZED_MARKER;
+
+        if (value instanceof ArrayBuffer) {
+            buffer = value;
+            marker += TYPE_ARRAYBUFFER;
+        } else {
+            buffer = value.buffer;
+
+            if (valueString === '[object Int8Array]') {
+                marker += TYPE_INT8ARRAY;
+            } else if (valueString === '[object Uint8Array]') {
+                marker += TYPE_UINT8ARRAY;
+            } else if (valueString === '[object Uint8ClampedArray]') {
+                marker += TYPE_UINT8CLAMPEDARRAY;
+            } else if (valueString === '[object Int16Array]') {
+                marker += TYPE_INT16ARRAY;
+            } else if (valueString === '[object Uint16Array]') {
+                marker += TYPE_UINT16ARRAY;
+            } else if (valueString === '[object Int32Array]') {
+                marker += TYPE_INT32ARRAY;
+            } else if (valueString === '[object Uint32Array]') {
+                marker += TYPE_UINT32ARRAY;
+            } else if (valueString === '[object Float32Array]') {
+                marker += TYPE_FLOAT32ARRAY;
+            } else if (valueString === '[object Float64Array]') {
+                marker += TYPE_FLOAT64ARRAY;
+            } else {
+                callback(new Error('Failed to get type for BinaryArray'));
+            }
+        }
+
+        callback(marker + bufferToString(buffer));
+    } else if (valueString === '[object Blob]') {
+        // Conver the blob to a binaryArray and then to a string.
+        var fileReader = new FileReader();
+
+        fileReader.onload = function() {
+            // Backwards-compatible prefix for the blob type.
+            var str = BLOB_TYPE_PREFIX + value.type + '~' +
+                bufferToString(this.result);
+
+            callback(SERIALIZED_MARKER + TYPE_BLOB + str);
+        };
+
+        fileReader.readAsArrayBuffer(value);
+    } else {
+        try {
+            callback(JSON.stringify(value));
+        } catch (e) {
+            console.error("Couldn't convert value into a JSON string: ",
+                value);
+
+            callback(null, e);
+        }
+    }
+}
+
+// Deserialize data we've inserted into a value column/field. We place
+// special markers into our strings to mark them as encoded; this isn't
+// as nice as a meta field, but it's the only sane thing we can do whilst
+// keeping localStorage support intact.
+//
+// Oftentimes this will just deserialize JSON content, but if we have a
+// special marker (SERIALIZED_MARKER, defined above), we will extract
+// some kind of arraybuffer/binary data/typed array out of the string.
+function deserialize(value) {
+    // If we haven't marked this string as being specially serialized (i.e.
+    // something other than serialized JSON), we can just return it and be
+    // done with it.
+    if (value.substring(0,
+            SERIALIZED_MARKER_LENGTH) !== SERIALIZED_MARKER) {
+        return JSON.parse(value);
+    }
+
+    // The following code deals with deserializing some kind of Blob or
+    // TypedArray. First we separate out the type of data we're dealing
+    // with from the data itself.
+    var serializedString = value.substring(TYPE_SERIALIZED_MARKER_LENGTH);
+    var type = value.substring(SERIALIZED_MARKER_LENGTH,
+        TYPE_SERIALIZED_MARKER_LENGTH);
+
+    var blobType;
+    // Backwards-compatible blob type serialization strategy.
+    // DBs created with older versions of localForage will simply not have the blob type.
+    if (type === TYPE_BLOB && BLOB_TYPE_PREFIX_REGEX.test(serializedString)) {
+        var matcher = serializedString.match(BLOB_TYPE_PREFIX_REGEX);
+        blobType = matcher[1];
+        serializedString = serializedString.substring(matcher[0].length);
+    }
+    var buffer = stringToBuffer(serializedString);
+
+    // Return the right type based on the code/type set during
+    // serialization.
+    switch (type) {
+        case TYPE_ARRAYBUFFER:
+            return buffer;
+        case TYPE_BLOB:
+            return createBlob([buffer], {type: blobType});
+        case TYPE_INT8ARRAY:
+            return new Int8Array(buffer);
+        case TYPE_UINT8ARRAY:
+            return new Uint8Array(buffer);
+        case TYPE_UINT8CLAMPEDARRAY:
+            return new Uint8ClampedArray(buffer);
+        case TYPE_INT16ARRAY:
+            return new Int16Array(buffer);
+        case TYPE_UINT16ARRAY:
+            return new Uint16Array(buffer);
+        case TYPE_INT32ARRAY:
+            return new Int32Array(buffer);
+        case TYPE_UINT32ARRAY:
+            return new Uint32Array(buffer);
+        case TYPE_FLOAT32ARRAY:
+            return new Float32Array(buffer);
+        case TYPE_FLOAT64ARRAY:
+            return new Float64Array(buffer);
+        default:
+            throw new Error('Unkown type: ' + type);
+    }
+}
+
+var localforageSerializer = {
+    serialize: serialize,
+    deserialize: deserialize,
+    stringToBuffer: stringToBuffer,
+    bufferToString: bufferToString
+};
+
+export default localforageSerializer;