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<h1 class="page-title">Source: Serialiser.js</h1>
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<pre class="prettyprint source linenums"><code>"use strict";
/**
* Provides functionality to encode and decode JavaScript objects to strings
* and back again. This differs from JSON.stringify and JSON.parse in that
* special objects such as dates can be encoded to strings and back again
* so that the reconstituted version of the string still contains a JavaScript
* date object.
* @constructor
*/
var Serialiser = function () {
this.init.apply(this, arguments);
};
Serialiser.prototype.init = function () {
this._encoder = [];
this._decoder = {};
// Register our handlers
this.registerEncoder('$date', function (data) {
if (data instanceof Date) {
return data.toISOString();
}
});
this.registerDecoder('$date', function (data) {
return new Date(data);
});
};
/**
* Register an encoder that can handle encoding for a particular
* object type.
* @param {String} handles The name of the handler e.g. $date.
* @param {Function} method The encoder method.
*/
Serialiser.prototype.registerEncoder = function (handles, method) {
this._encoder.push(function (data) {
var methodVal = method(data),
returnObj;
if (methodVal !== undefined) {
returnObj = {};
returnObj[handles] = methodVal;
}
return returnObj;
});
};
/**
* Register a decoder that can handle decoding for a particular
* object type.
* @param {String} handles The name of the handler e.g. $date. When an object
* has a field matching this handler name then this decode will be invoked
* to provide a decoded version of the data that was previously encoded by
* it's counterpart encoder method.
* @param {Function} method The decoder method.
*/
Serialiser.prototype.registerDecoder = function (handles, method) {
this._decoder[handles] = method;
};
/**
* Loops the encoders and asks each one if it wants to handle encoding for
* the passed data object. If no value is returned (undefined) then the data
* will be passed to the next encoder and so on. If a value is returned the
* loop will break and the encoded data will be used.
* @param {Object} data The data object to handle.
* @returns {*} The encoded data.
* @private
*/
Serialiser.prototype._encode = function (data) {
// Loop the encoders and if a return value is given by an encoder
// the loop will exit and return that value.
var count = this._encoder.length,
retVal;
while (count-- && !retVal) {
retVal = this._encoder[count](data);
}
return retVal;
};
/**
* Converts a previously encoded string back into an object.
* @param {String} data The string to convert to an object.
* @returns {Object} The reconstituted object.
*/
Serialiser.prototype.parse = function (data) {
return this._parse(JSON.parse(data));
};
/**
* Handles restoring an object with special data markers back into
* it's original format.
* @param {Object} data The object to recurse.
* @param {Object=} target The target object to restore data to.
* @returns {Object} The final restored object.
* @private
*/
Serialiser.prototype._parse = function (data, target) {
var i;
if (typeof data === 'object') {
if (data instanceof Array) {
target = target || [];
} else {
target = target || {};
}
// Iterate through the object's keys and handle
// special object types and restore them
for (i in data) {
if (data.hasOwnProperty(i)) {
if (i.substr(0, 1) === '$' && this._decoder[i]) {
// This is a special object type and a handler
// exists, restore it
return this._decoder[i](data[i]);
}
// Not a special object or no handler, recurse as normal
target[i] = this._parse(data[i], target[i]);
}
}
} else {
target = data;
}
// The data is a basic type
return target;
};
/**
* Converts an object to a encoded string representation.
* @param {Object} data The object to encode.
*/
Serialiser.prototype.stringify = function (data) {
return JSON.stringify(this._stringify(data));
};
/**
* Recurse down an object and encode special objects so they can be
* stringified and later restored.
* @param {Object} data The object to parse.
* @param {Object=} target The target object to store converted data to.
* @returns {Object} The converted object.
* @private
*/
Serialiser.prototype._stringify = function (data, target) {
var handledData,
i;
if (typeof data === 'object') {
// Handle special object types so they can be encoded with
// a special marker and later restored by a decoder counterpart
handledData = this._encode(data);
if (handledData) {
// An encoder handled this object type so return it now
return handledData;
}
if (data instanceof Array) {
target = target || [];
} else {
target = target || {};
}
// Iterate through the object's keys and serialise
for (i in data) {
if (data.hasOwnProperty(i)) {
target[i] = this._stringify(data[i], target[i]);
}
}
} else {
target = data;
}
// The data is a basic type
return target;
};
module.exports = Serialiser;</code></pre>
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