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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* This is a simple set of functions for serializing and parsing JS objects
* to and from files.
*/
function JSONSerializer(file) {
if (typeof file == "string")
this._file = new nsLocalFile(file);
else
this._file = file;
this._open = false;
}
JSONSerializer.prototype = {
/*
* Opens the serializer on the file specified when created, in either the read
* ("<") or write (">") directions. When the file is open, only the
* appropriate direction of serialization/deserialization may be performed.
*
* Note: serialize and deserialize automatically open the file if it is not
* open.
*
* @param dir The string representing the direction of serialization.
* @returns Value indicating whether the file was opened successfully.
*/
open: function(dir) {
if (!ASSERT((dir == ">") || (dir == "<"), "Bad serialization direction!")) {
return false;
}
if (this._open) {
return false;
}
this._fileStream = new LocalFile(this._file, dir);
if ((typeof this._fileStream == "object") && this._fileStream) {
this._open = true;
}
return this._open;
},
/*
* Closes the file stream and ends reading or writing.
*
* @returns Value indicating whether the file was closed successfully.
*/
close: function() {
if (this._open) {
this._fileStream.close();
delete this._fileStream;
this._open = false;
}
return true;
},
/*
* Serializes a single object into the file stream. All properties of the
* object are stored in the stream, including properties that contain other
* objects.
*
* @param obj JS object to serialize to the file.
*/
serialize: function(obj) {
if (!this._open) {
this.open(">");
}
if (!ASSERT(this._open, "Unable to open the file for writing!")) {
return;
}
this._fileStream.write(JSON.stringify(obj, null, 2));
},
/*
* Reads in enough of the file to deserialize (realize) a single object. The
* object deserialized is returned; all sub-properties of the object are
* deserialized with it.
*
* @returns JS object parsed from the file.
*/
deserialize: function() {
if (!this._open) {
this.open("<");
}
if (!ASSERT(this._open, "Unable to open the file for reading!"))
return false;
let rv = null;
try {
rv = JSON.parse(this._fileStream.read());
}
catch(ex) {
dd("Syntax error while deserializing file!");
dd(ex.message);
dd(ex.stack);
}
return rv;
},
};
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