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330 lines
13 KiB
JavaScript
330 lines
13 KiB
JavaScript
![]()
15 years ago
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dojo.provide("dojox.json.ref");
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dojo.require("dojo.date.stamp");
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// summary:
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// Adds advanced JSON {de}serialization capabilities to the base json library.
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// This enhances the capabilities of dojo.toJson and dojo.fromJson,
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// adding referencing support, date handling, and other extra format handling.
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// On parsing, references are resolved. When references are made to
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// ids/objects that have been loaded yet, the loader function will be set to
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// _loadObject to denote a lazy loading (not loaded yet) object.
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dojox.json.ref = {
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resolveJson: function(/*Object*/ root,/*Object?*/ args){
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// summary:
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// Indexes and resolves references in the JSON object.
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// description:
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// A JSON Schema object that can be used to advise the handling of the JSON (defining ids, date properties, urls, etc)
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//
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// root:
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// The root object of the object graph to be processed
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// args:
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// Object with additional arguments:
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//
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// The *index* parameter.
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// This is the index object (map) to use to store an index of all the objects.
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// If you are using inter-message referencing, you must provide the same object for each call.
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// The *defaultId* parameter.
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// This is the default id to use for the root object (if it doesn't define it's own id)
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// The *idPrefix* parameter.
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// This the prefix to use for the ids as they enter the index. This allows multiple tables
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// to use ids (that might otherwise collide) that enter the same global index.
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// idPrefix should be in the form "/Service/". For example,
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// if the idPrefix is "/Table/", and object is encountered {id:"4",...}, this would go in the
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// index as "/Table/4".
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// The *idAttribute* parameter.
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// This indicates what property is the identity property. This defaults to "id"
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// The *assignAbsoluteIds* parameter.
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// This indicates that the resolveJson should assign absolute ids (__id) as the objects are being parsed.
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//
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// The *schemas* parameter
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// This provides a map of schemas, from which prototypes can be retrieved
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// The *loader* parameter
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// This is a function that is called added to the reference objects that can't be resolved (lazy objects)
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// return:
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// An object, the result of the processing
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args = args || {};
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var idAttribute = args.idAttribute || 'id';
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var prefix = args.idPrefix || '';
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var assignAbsoluteIds = args.assignAbsoluteIds;
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var index = args.index || {}; // create an index if one doesn't exist
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var timeStamps = args.timeStamps;
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var ref,reWalk=[];
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var pathResolveRegex = /^(.*\/)?(\w+:\/\/)|[^\/\.]+\/\.\.\/|^.*\/(\/)/;
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var addProp = this._addProp;
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var F = function(){};
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function walk(it, stop, defaultId, schema, defaultObject){
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// this walks the new graph, resolving references and making other changes
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var update, val, id = idAttribute in it ? it[idAttribute] : defaultId;
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if(id !== undefined){
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id = (prefix + id).replace(pathResolveRegex,'$2$3');
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}
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var target = defaultObject || it;
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if(id !== undefined){ // if there is an id available...
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if(assignAbsoluteIds){
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it.__id = id;
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}
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if(args.schemas && (!(it instanceof Array)) && // won't try on arrays to do prototypes, plus it messes with queries
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(val = id.match(/^(.+\/)[^\.\[]*$/))){ // if it has a direct table id (no paths)
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schema = args.schemas[val[1]];
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}
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// if the id already exists in the system, we should use the existing object, and just
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// update it... as long as the object is compatible
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if(index[id] && ((it instanceof Array) == (index[id] instanceof Array))){
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target = index[id];
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delete target.$ref; // remove this artifact
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update = true;
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}else{
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var proto = schema && schema.prototype; // and if has a prototype
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if(proto){
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// if the schema defines a prototype, that needs to be the prototype of the object
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F.prototype = proto;
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target = new F();
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}
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}
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index[id] = target; // add the prefix, set _id, and index it
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if(timeStamps){
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timeStamps[id] = args.time;
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}
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}
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var properties = schema && schema.properties;
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var length = it.length;
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for(var i in it){
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if(i==length){
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break;
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}
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if(it.hasOwnProperty(i)){
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val=it[i];
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var propertyDefinition = properties && properties[i];
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if(propertyDefinition && propertyDefinition.format == 'date-time' && typeof val == 'string'){
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val = dojo.date.stamp.fromISOString(val);
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}else if((typeof val =='object') && val && !(val instanceof Date)){
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ref=val.$ref;
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if(ref){ // a reference was found
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// make sure it is a safe reference
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delete it[i];// remove the property so it doesn't resolve to itself in the case of id.propertyName lazy values
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var path = ref.replace(/(#)([^\.\[])/,'$1.$2').match(/(^([^\[]*\/)?[^#\.\[]*)#?([\.\[].*)?/); // divide along the path
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if((ref = (path[1]=='$' || path[1]=='this' || path[1]=='') ? root : index[(prefix + path[1]).replace(pathResolveRegex,'$2$3')])){ // a $ indicates to start with the root, otherwise start with an id
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// if there is a path, we will iterate through the path references
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if(path[3]){
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path[3].replace(/(\[([^\]]+)\])|(\.?([^\.\[]+))/g,function(t,a,b,c,d){
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ref = ref && ref[b ? b.replace(/[\"\'\\]/,'') : d];
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});
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}
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}
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if(ref){
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// otherwise, no starting point was found (id not found), if stop is set, it does not exist, we have
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// unloaded reference, if stop is not set, it may be in a part of the graph not walked yet,
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// we will wait for the second loop
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val = ref;
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}else{
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if(!stop){
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var rewalking;
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if(!rewalking){
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reWalk.push(target); // we need to rewalk it to resolve references
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}
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rewalking = true; // we only want to add it once
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}else{
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val = walk(val, false, val.$ref, propertyDefinition);
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// create a lazy loaded object
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val._loadObject = args.loader;
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}
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}
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}else{
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if(!stop){ // if we are in stop, that means we are in the second loop, and we only need to check this current one,
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// further walking may lead down circular loops
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val = walk(
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val,
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reWalk==it,
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id && addProp(id, i), // the default id to use
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propertyDefinition,
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// if we have an existing object child, we want to
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// maintain it's identity, so we pass it as the default object
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target != it && typeof target[i] == 'object' && target[i]
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);
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}
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}
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}
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it[i] = val;
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if(target!=it && !target.__isDirty){// do updates if we are updating an existing object and it's not dirty
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var old = target[i];
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target[i] = val; // only update if it changed
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if(update && val !== old && // see if it is different
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!target._loadObject && // no updates if we are just lazy loading
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!(val instanceof Date && old instanceof Date && val.getTime() == old.getTime()) && // make sure it isn't an identical date
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!(typeof val == 'function' && typeof old == 'function' && val.toString() == old.toString()) && // make sure it isn't an indentical function
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index.onUpdate){
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index.onUpdate(target,i,old,val); // call the listener for each update
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}
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}
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}
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}
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if(update){
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// this means we are updating, we need to remove deleted
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for(i in target){
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if(!target.__isDirty && target.hasOwnProperty(i) && !it.hasOwnProperty(i) && i != '__id' && i != '__clientId' && !(target instanceof Array && isNaN(i))){
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if(index.onUpdate && i != "_loadObject" && i != "_idAttr"){
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index.onUpdate(target,i,target[i],undefined); // call the listener for each update
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}
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delete target[i];
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while(target instanceof Array && target.length && target[target.length-1] === undefined){
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// shorten the target if necessary
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target.length--;
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}
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}
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}
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}else{
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if(index.onLoad){
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index.onLoad(target);
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}
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}
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return target;
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}
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if(root && typeof root == 'object'){
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root = walk(root,false,args.defaultId); // do the main walk through
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walk(reWalk,false); // re walk any parts that were not able to resolve references on the first round
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}
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return root;
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},
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fromJson: function(/*String*/ str,/*Object?*/ args){
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// summary:
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// evaluates the passed string-form of a JSON object.
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//
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// str:
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// a string literal of a JSON item, for instance:
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// '{ "foo": [ "bar", 1, { "baz": "thud" } ] }'
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// args: See resolveJson
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//
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// return:
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// An object, the result of the evaluation
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function ref(target){ // support call styles references as well
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return {$ref:target};
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}
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try{
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var root = eval('(' + str + ')'); // do the eval
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}catch(e){
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throw new SyntaxError("Invalid JSON string: " + e.message + " parsing: "+ str);
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}
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if(root){
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return this.resolveJson(root, args);
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}
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return root;
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},
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toJson: function(/*Object*/ it, /*Boolean?*/ prettyPrint, /*Object?*/ idPrefix, /*Object?*/ indexSubObjects){
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// summary:
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// Create a JSON serialization of an object.
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// This has support for referencing, including circular references, duplicate references, and out-of-message references
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// id and path-based referencing is supported as well and is based on http://www.json.com/2007/10/19/json-referencing-proposal-and-library/.
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//
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// it:
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// an object to be serialized.
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//
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// prettyPrint:
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// if true, we indent objects and arrays to make the output prettier.
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// The variable dojo.toJsonIndentStr is used as the indent string
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// -- to use something other than the default (tab),
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// change that variable before calling dojo.toJson().
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//
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// idPrefix: The prefix that has been used for the absolute ids
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//
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// return:
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// a String representing the serialized version of the passed object.
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var useRefs = this._useRefs;
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var addProp = this._addProp;
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idPrefix = idPrefix || ''; // the id prefix for this context
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var paths={};
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var generated = {};
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function serialize(it,path,_indentStr){
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if(typeof it == 'object' && it){
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var value;
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if(it instanceof Date){ // properly serialize dates
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return '"' + dojo.date.stamp.toISOString(it,{zulu:true}) + '"';
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}
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var id = it.__id;
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if(id){ // we found an identifiable object, we will just serialize a reference to it... unless it is the root
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if(path != '#' && ((useRefs && !id.match(/#/)) || paths[id])){
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var ref = id;
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if(id.charAt(0)!='#'){
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if(it.__clientId == id){
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ref = "cid:" + id;
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}else if(id.substring(0, idPrefix.length) == idPrefix){ // see if the reference is in the current context
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// a reference with a prefix matching the current context, the prefix should be removed
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ref = id.substring(idPrefix.length);
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}else{
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// a reference to a different context, assume relative url based referencing
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ref = id;
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}
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}
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return serialize({
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$ref: ref
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},'#');
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}
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path = id;
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}else{
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it.__id = path; // we will create path ids for other objects in case they are circular
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generated[path] = it;
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}
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paths[path] = it;// save it here so they can be deleted at the end
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_indentStr = _indentStr || "";
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var nextIndent = prettyPrint ? _indentStr + dojo.toJsonIndentStr : "";
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var newLine = prettyPrint ? "\n" : "";
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var sep = prettyPrint ? " " : "";
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if(it instanceof Array){
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var res = dojo.map(it, function(obj,i){
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var val = serialize(obj, addProp(path, i), nextIndent);
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if(typeof val != "string"){
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val = "undefined";
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}
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return newLine + nextIndent + val;
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});
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return "[" + res.join("," + sep) + newLine + _indentStr + "]";
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}
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var output = [];
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for(var i in it){
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if(it.hasOwnProperty(i)){
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var keyStr;
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if(typeof i == "number"){
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keyStr = '"' + i + '"';
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}else if(typeof i == "string" && (i.charAt(0) != '_' || i.charAt(1) != '_')){
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// we don't serialize our internal properties __id and __clientId
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keyStr = dojo._escapeString(i);
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}else{
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// skip non-string or number keys
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continue;
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}
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var val = serialize(it[i],addProp(path, i),nextIndent);
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if(typeof val != "string"){
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// skip non-serializable values
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continue;
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}
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output.push(newLine + nextIndent + keyStr + ":" + sep + val);
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}
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}
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return "{" + output.join("," + sep) + newLine + _indentStr + "}";
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}else if(typeof it == "function" && dojox.json.ref.serializeFunctions){
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return it.toString();
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}
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return dojo.toJson(it); // use the default serializer for primitives
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}
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var json = serialize(it,'#','');
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if(!indexSubObjects){
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for(var i in generated) {// cleanup the temporary path-generated ids
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delete generated[i].__id;
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}
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}
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return json;
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},
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_addProp: function(id, prop){
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return id + (id.match(/#/) ? id.length == 1 ? '' : '.' : '#') + prop;
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},
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_useRefs: false,
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serializeFunctions: false
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}
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