mxgraph/javascript/src/js/io/mxObjectCodec.js

mxGraph is a fully client side JavaScript diagramming library that uses SVG and HTML for rendering.

/**
 * Copyright (c) 2006-2015, JGraph Ltd
 * Copyright (c) 2006-2015, Gaudenz Alder
 */
/**
 * Class: mxObjectCodec
 *
 * Generic codec for JavaScript objects that implements a mapping between
 * JavaScript objects and XML nodes that maps each field or element to an
 * attribute or child node, and vice versa.
 * 
 * Atomic Values:
 * 
 * Consider the following example.
 * 
 * (code)
 * var obj = new Object();
 * obj.foo = "Foo";
 * obj.bar = "Bar";
 * (end)
 * 
 * This object is encoded into an XML node using the following.
 * 
 * (code)
 * var enc = new mxCodec();
 * var node = enc.encode(obj);
 * (end)
 * 
 * The output of the encoding may be viewed using <mxLog> as follows.
 * 
 * (code)
 * mxLog.show();
 * mxLog.debug(mxUtils.getPrettyXml(node));
 * (end)
 * 
 * Finally, the result of the encoding looks as follows.
 * 
 * (code)
 * <Object foo="Foo" bar="Bar"/>
 * (end)
 * 
 * In the above output, the foo and bar fields have been mapped to attributes
 * with the same names, and the name of the constructor was used for the
 * nodename.
 * 
 * Booleans:
 *
 * Since booleans are numbers in JavaScript, all boolean values are encoded
 * into 1 for true and 0 for false. The decoder also accepts the string true
 * and false for boolean values.
 * 
 * Objects:
 * 
 * The above scheme is applied to all atomic fields, that is, to all non-object
 * fields of an object. For object fields, a child node is created with a
 * special attribute that contains the fieldname. This special attribute is
 * called "as" and hence, as is a reserved word that should not be used for a
 * fieldname.
 * 
 * Consider the following example where foo is an object and bar is an atomic
 * property of foo.
 * 
 * (code)
 * var obj = {foo: {bar: "Bar"}};
 * (end)
 * 
 * This will be mapped to the following XML structure by mxObjectCodec.
 * 
 * (code)
 * <Object>
 *   <Object bar="Bar" as="foo"/>
 * </Object>
 * (end)
 * 
 * In the above output, the inner Object node contains the as-attribute that
 * specifies the fieldname in the enclosing object. That is, the field foo was
 * mapped to a child node with an as-attribute that has the value foo.
 * 
 * Arrays:
 * 
 * Arrays are special objects that are either associative, in which case each
 * key, value pair is treated like a field where the key is the fieldname, or
 * they are a sequence of atomic values and objects, which is mapped to a
 * sequence of child nodes. For object elements, the above scheme is applied
 * without the use of the special as-attribute for creating each child. For
 * atomic elements, a special add-node is created with the value stored in the
 * value-attribute.
 * 
 * For example, the following array contains one atomic value and one object
 * with a field called bar. Furthermore it contains two associative entries
 * called bar with an atomic value, and foo with an object value.
 * 
 * (code)
 * var obj = ["Bar", {bar: "Bar"}];
 * obj["bar"] = "Bar";
 * obj["foo"] = {bar: "Bar"};
 * (end)
 * 
 * This array is represented by the following XML nodes.
 * 
 * (code)
 * <Array bar="Bar">
 *   <add value="Bar"/>
 *   <Object bar="Bar"/>
 *   <Object bar="Bar" as="foo"/>
 * </Array>
 * (end)
 * 
 * The Array node name is the name of the constructor. The additional
 * as-attribute in the last child contains the key of the associative entry,
 * whereas the second last child is part of the array sequence and does not
 * have an as-attribute.
 * 
 * References:
 * 
 * Objects may be represented as child nodes or attributes with ID values,
 * which are used to lookup the object in a table within <mxCodec>. The
 * <isReference> function is in charge of deciding if a specific field should
 * be encoded as a reference or not. Its default implementation returns true if
 * the fieldname is in <idrefs>, an array of strings that is used to configure
 * the <mxObjectCodec>.
 * 
 * Using this approach, the mapping does not guarantee that the referenced
 * object itself exists in the document. The fields that are encoded as
 * references must be carefully chosen to make sure all referenced objects
 * exist in the document, or may be resolved by some other means if necessary.
 * 
 * For example, in the case of the graph model all cells are stored in a tree
 * whose root is referenced by the model's root field. A tree is a structure
 * that is well suited for an XML representation, however, the additional edges
 * in the graph model have a reference to a source and target cell, which are
 * also contained in the tree. To handle this case, the source and target cell
 * of an edge are treated as references, whereas the children are treated as
 * objects. Since all cells are contained in the tree and no edge references a
 * source or target outside the tree, this setup makes sure all referenced
 * objects are contained in the document.
 * 
 * In the case of a tree structure we must further avoid infinite recursion by
 * ignoring the parent reference of each child. This is done by returning true
 * in <isExcluded>, whose default implementation uses the array of excluded
 * fieldnames passed to the mxObjectCodec constructor.
 * 
 * References are only used for cells in mxGraph. For defining other
 * referencable object types, the codec must be able to work out the ID of an
 * object. This is done by implementing <mxCodec.reference>. For decoding a
 * reference, the XML node with the respective id-attribute is fetched from the
 * document, decoded, and stored in a lookup table for later reference. For
 * looking up external objects, <mxCodec.lookup> may be implemented.
 * 
 * Expressions:
 * 
 * For decoding JavaScript expressions, the add-node may be used with a text
 * content that contains the JavaScript expression. For example, the following
 * creates a field called foo in the enclosing object and assigns it the value
 * of <mxConstants.ALIGN_LEFT>.
 * 
 * (code)
 * <Object>
 *   <add as="foo">mxConstants.ALIGN_LEFT</add>
 * </Object>
 * (end)
 * 
 * The resulting object has a field called foo with the value "left". Its XML
 * representation looks as follows.
 * 
 * (code)
 * <Object foo="left"/>
 * (end)
 * 
 * This means the expression is evaluated at decoding time and the result of
 * the evaluation is stored in the respective field. Valid expressions are all
 * JavaScript expressions, including function definitions, which are mapped to
 * functions on the resulting object.
 * 
 * Expressions are only evaluated if <allowEval> is true.
 * 
 * Constructor: mxObjectCodec
 *
 * Constructs a new codec for the specified template object.
 * The variables in the optional exclude array are ignored by
 * the codec. Variables in the optional idrefs array are
 * turned into references in the XML. The optional mapping
 * may be used to map from variable names to XML attributes.
 * The argument is created as follows:
 *
 * (code)
 * var mapping = new Object();
 * mapping['variableName'] = 'attribute-name';
 * (end)
 *
 * Parameters:
 *
 * template - Prototypical instance of the object to be
 * encoded/decoded.
 * exclude - Optional array of fieldnames to be ignored.
 * idrefs - Optional array of fieldnames to be converted to/from
 * references.
 * mapping - Optional mapping from field- to attributenames.
 */
function mxObjectCodec(template, exclude, idrefs, mapping)
{
	this.template = template;
	
	this.exclude = (exclude != null) ? exclude : [];
	this.idrefs = (idrefs != null) ? idrefs : [];
	this.mapping = (mapping != null) ? mapping : [];
	
	this.reverse = new Object();
	
	for (var i in this.mapping)
	{
		this.reverse[this.mapping[i]] = i;
	}
};

/**
 * Variable: allowEval
 *
 * Static global switch that specifies if expressions in arrays are allowed.
 * Default is false. NOTE: Enabling this carries a possible security risk.
 */
mxObjectCodec.allowEval = false;

/**
 * Variable: template
 *
 * Holds the template object associated with this codec.
 */
mxObjectCodec.prototype.template = null;

/**
 * Variable: exclude
 *
 * Array containing the variable names that should be
 * ignored by the codec.
 */
mxObjectCodec.prototype.exclude = null;

/**
 * Variable: idrefs
 *
 * Array containing the variable names that should be
 * turned into or converted from references. See
 * <mxCodec.getId> and <mxCodec.getObject>.
 */
mxObjectCodec.prototype.idrefs = null;

/**
 * Variable: mapping
 *
 * Maps from from fieldnames to XML attribute names.
 */
mxObjectCodec.prototype.mapping = null;

/**
 * Variable: reverse
 *
 * Maps from from XML attribute names to fieldnames.
 */
mxObjectCodec.prototype.reverse = null;

/**
 * Function: getName
 * 
 * Returns the name used for the nodenames and lookup of the codec when
 * classes are encoded and nodes are decoded. For classes to work with
 * this the codec registry automatically adds an alias for the classname
 * if that is different than what this returns. The default implementation
 * returns the classname of the template class.
 */
mxObjectCodec.prototype.getName = function()
{
	return mxUtils.getFunctionName(this.template.constructor);
};

/**
 * Function: cloneTemplate
 * 
 * Returns a new instance of the template for this codec.
 */
mxObjectCodec.prototype.cloneTemplate = function()
{
	return new this.template.constructor();
};

/**
 * Function: getFieldName
 * 
 * Returns the fieldname for the given attributename.
 * Looks up the value in the <reverse> mapping or returns
 * the input if there is no reverse mapping for the
 * given name.
 */
mxObjectCodec.prototype.getFieldName = function(attributename)
{
	if (attributename != null)
	{
		var mapped = this.reverse[attributename];
		
		if (mapped != null)
		{
			attributename = mapped;
		}
	}
	
	return attributename;
};

/**
 * Function: getAttributeName
 * 
 * Returns the attributename for the given fieldname.
 * Looks up the value in the <mapping> or returns
 * the input if there is no mapping for the
 * given name.
 */
mxObjectCodec.prototype.getAttributeName = function(fieldname)
{
	if (fieldname != null)
	{
		var mapped = this.mapping[fieldname];
		
		if (mapped != null)
		{
			fieldname = mapped;
		}
	}
	
	return fieldname;
};

/**
 * Function: isExcluded
 *
 * Returns true if the given attribute is to be ignored by the codec. This
 * implementation returns true if the given fieldname is in <exclude> or
 * if the fieldname equals <mxObjectIdentity.FIELD_NAME>.
 *
 * Parameters:
 *
 * obj - Object instance that contains the field.
 * attr - Fieldname of the field.
 * value - Value of the field.
 * write - Boolean indicating if the field is being encoded or decoded.
 * Write is true if the field is being encoded, else it is being decoded.
 */
mxObjectCodec.prototype.isExcluded = function(obj, attr, value, write)
{
	return attr == mxObjectIdentity.FIELD_NAME ||
		mxUtils.indexOf(this.exclude, attr) >= 0;
};

/**
 * Function: isReference
 *
 * Returns true if the given fieldname is to be treated
 * as a textual reference (ID). This implementation returns
 * true if the given fieldname is in <idrefs>.
 *
 * Parameters:
 *
 * obj - Object instance that contains the field.
 * attr - Fieldname of the field.
 * value - Value of the field. 
 * write - Boolean indicating if the field is being encoded or decoded.
 * Write is true if the field is being encoded, else it is being decoded.
 */
mxObjectCodec.prototype.isReference = function(obj, attr, value, write)
{
	return mxUtils.indexOf(this.idrefs, attr) >= 0;
};

/**
 * Function: encode
 *
 * Encodes the specified object and returns a node
 * representing then given object. Calls <beforeEncode>
 * after creating the node and <afterEncode> with the 
 * resulting node after processing.
 *
 * Enc is a reference to the calling encoder. It is used
 * to encode complex objects and create references.
 *
 * This implementation encodes all variables of an
 * object according to the following rules:
 *
 * - If the variable name is in <exclude> then it is ignored.
 * - If the variable name is in <idrefs> then <mxCodec.getId>
 * is used to replace the object with its ID.
 * - The variable name is mapped using <mapping>.
 * - If obj is an array and the variable name is numeric
 * (ie. an index) then it is not encoded.
 * - If the value is an object, then the codec is used to
 * create a child node with the variable name encoded into
 * the "as" attribute.
 * - Else, if <encodeDefaults> is true or the value differs
 * from the template value, then ...
 * - ... if obj is not an array, then the value is mapped to
 * an attribute.
 * - ... else if obj is an array, the value is mapped to an
 * add child with a value attribute or a text child node,
 * if the value is a function.
 *
 * If no ID exists for a variable in <idrefs> or if an object
 * cannot be encoded, a warning is issued using <mxLog.warn>.
 *
 * Returns the resulting XML node that represents the given
 * object.
 *
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * obj - Object to be encoded.
 */
mxObjectCodec.prototype.encode = function(enc, obj)
{
	var node = enc.document.createElement(this.getName());
	
	obj = this.beforeEncode(enc, obj, node);
	this.encodeObject(enc, obj, node);
	
	return this.afterEncode(enc, obj, node);
};
	
/**
 * Function: encodeObject
 *
 * Encodes the value of each member in then given obj into the given node using
 * <encodeValue>.
 * 
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * obj - Object to be encoded.
 * node - XML node that contains the encoded object.
 */
mxObjectCodec.prototype.encodeObject = function(enc, obj, node)
{
	enc.setAttribute(node, 'id', enc.getId(obj));
	
    for (var i in obj)
    {
		var name = i;
		var value = obj[name];
		
    	if (value != null && !this.isExcluded(obj, name, value, true))
    	{
    		if (mxUtils.isInteger(name))
    		{
    			name = null;
    		}
    		
    		this.encodeValue(enc, obj, name, value, node);
    	}
    }
};

/**
 * Function: encodeValue
 * 
 * Converts the given value according to the mappings
 * and id-refs in this codec and uses <writeAttribute>
 * to write the attribute into the given node.
 * 
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * obj - Object whose property is going to be encoded.
 * name - XML node that contains the encoded object.
 * value - Value of the property to be encoded.
 * node - XML node that contains the encoded object.
 */
mxObjectCodec.prototype.encodeValue = function(enc, obj, name, value, node)
{
	if (value != null)
	{
		if (this.isReference(obj, name, value, true))
		{
			var tmp = enc.getId(value);
			
			if (tmp == null)
			{
		    	mxLog.warn('mxObjectCodec.encode: No ID for ' +
		    		this.getName() + '.' + name + '=' + value);
		    	return; // exit
		    }
		    
		    value = tmp;
		}

		var defaultValue = this.template[name];
		
		// Checks if the value is a default value and
		// the name is correct
		if (name == null || enc.encodeDefaults || defaultValue != value)
		{
			name = this.getAttributeName(name);
			this.writeAttribute(enc, obj, name, value, node);	
		}
	}
};

/**
 * Function: writeAttribute
 * 
 * Writes the given value into node using <writePrimitiveAttribute>
 * or <writeComplexAttribute> depending on the type of the value.
 */
mxObjectCodec.prototype.writeAttribute = function(enc, obj, name, value, node)
{
	if (typeof(value) != 'object' /* primitive type */)
	{
		this.writePrimitiveAttribute(enc, obj, name, value, node);
	}
	else /* complex type */
	{
		this.writeComplexAttribute(enc, obj, name, value, node);
	}
};

/**
 * Function: writePrimitiveAttribute
 * 
 * Writes the given value as an attribute of the given node.
 */
mxObjectCodec.prototype.writePrimitiveAttribute = function(enc, obj, name, value, node)
{
	value = this.convertAttributeToXml(enc, obj, name, value, node);
	
	if (name == null)
	{
		var child = enc.document.createElement('add');
		
		if (typeof(value) == 'function')
		{
    		child.appendChild(enc.document.createTextNode(value));
    	}
    	else
    	{
    		enc.setAttribute(child, 'value', value);
    	}
    	
		node.appendChild(child);
	}
	else if (typeof(value) != 'function')
	{
    	enc.setAttribute(node, name, value);
	}		
};
	
/**
 * Function: writeComplexAttribute
 * 
 * Writes the given value as a child node of the given node.
 */
mxObjectCodec.prototype.writeComplexAttribute = function(enc, obj, name, value, node)
{
	var child = enc.encode(value);
	
	if (child != null)
	{
		if (name != null)
		{
    		child.setAttribute('as', name);
    	}
    	
    	node.appendChild(child);
	}
	else
	{
		mxLog.warn('mxObjectCodec.encode: No node for ' + this.getName() + '.' + name + ': ' + value);
	}
};

/**
 * Function: convertAttributeToXml
 * 
 * Converts true to "1" and false to "0" is <isBooleanAttribute> returns true.
 * All other values are not converted.
 * 
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * obj - Objec to convert the attribute for.
 * name - Name of the attribute to be converted.
 * value - Value to be converted.
 */
mxObjectCodec.prototype.convertAttributeToXml = function(enc, obj, name, value)
{
	// Makes sure to encode boolean values as numeric values
	if (this.isBooleanAttribute(enc, obj, name, value))
	{	
		// Checks if the value is true (do not use the value as is, because
		// this would check if the value is not null, so 0 would be true)
		value = (value == true) ? '1' : '0';
	}
	
	return value;
};

/**
 * Function: isBooleanAttribute
 * 
 * Returns true if the given object attribute is a boolean value.
 * 
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * obj - Objec to convert the attribute for.
 * name - Name of the attribute to be converted.
 * value - Value of the attribute to be converted.
 */
mxObjectCodec.prototype.isBooleanAttribute = function(enc, obj, name, value)
{
	return (typeof(value.length) == 'undefined' && (value == true || value == false));
};

/**
 * Function: convertAttributeFromXml
 * 
 * Converts booleans and numeric values to the respective types. Values are
 * numeric if <isNumericAttribute> returns true.
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * attr - XML attribute to be converted.
 * obj - Objec to convert the attribute for.
 */
mxObjectCodec.prototype.convertAttributeFromXml = function(dec, attr, obj)
{
	var value = attr.value;
	
	if (this.isNumericAttribute(dec, attr, obj))
	{
		value = parseFloat(value);
		
		if (isNaN(value) || !isFinite(value))
		{
			value = 0;
		}
	}
	
	return value;
};

/**
 * Function: isNumericAttribute
 * 
 * Returns true if the given XML attribute is or should be a numeric value.
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * attr - XML attribute to be converted.
 * obj - Objec to convert the attribute for.
 */
mxObjectCodec.prototype.isNumericAttribute = function(dec, attr, obj)
{
	// Handles known numeric attributes for generic objects
	var result = (obj.constructor == mxGeometry &&
		(attr.name == 'x' || attr.name == 'y' ||
		attr.name == 'width' || attr.name == 'height')) ||
		(obj.constructor == mxPoint &&
		(attr.name == 'x' || attr.name == 'y')) ||
		mxUtils.isNumeric(attr.value);
	
	return result;
};

/**
 * Function: beforeEncode
 *
 * Hook for subclassers to pre-process the object before
 * encoding. This returns the input object. The return
 * value of this function is used in <encode> to perform
 * the default encoding into the given node.
 *
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * obj - Object to be encoded.
 * node - XML node to encode the object into.
 */
mxObjectCodec.prototype.beforeEncode = function(enc, obj, node)
{
	return obj;
};

/**
 * Function: afterEncode
 *
 * Hook for subclassers to post-process the node
 * for the given object after encoding and return the
 * post-processed node. This implementation returns 
 * the input node. The return value of this method
 * is returned to the encoder from <encode>.
 *
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * obj - Object to be encoded.
 * node - XML node that represents the default encoding.
 */
mxObjectCodec.prototype.afterEncode = function(enc, obj, node)
{
	return node;
};

/**
 * Function: decode
 *
 * Parses the given node into the object or returns a new object
 * representing the given node.
 *
 * Dec is a reference to the calling decoder. It is used to decode
 * complex objects and resolve references.
 *
 * If a node has an id attribute then the object cache is checked for the
 * object. If the object is not yet in the cache then it is constructed
 * using the constructor of <template> and cached in <mxCodec.objects>.
 *
 * This implementation decodes all attributes and childs of a node
 * according to the following rules:
 *
 * - If the variable name is in <exclude> or if the attribute name is "id"
 * or "as" then it is ignored.
 * - If the variable name is in <idrefs> then <mxCodec.getObject> is used
 * to replace the reference with an object.
 * - The variable name is mapped using a reverse <mapping>.
 * - If the value has a child node, then the codec is used to create a
 * child object with the variable name taken from the "as" attribute.
 * - If the object is an array and the variable name is empty then the
 * value or child object is appended to the array.
 * - If an add child has no value or the object is not an array then
 * the child text content is evaluated using <mxUtils.eval>.
 *
 * For add nodes where the object is not an array and the variable name
 * is defined, the default mechanism is used, allowing to override/add
 * methods as follows:
 *
 * (code)
 * <Object>
 *   <add as="hello"><![CDATA[
 *     function(arg1) {
 *       mxUtils.alert('Hello '+arg1);
 *     }
 *   ]]></add>
 * </Object>
 * (end) 
 *
 * If no object exists for an ID in <idrefs> a warning is issued
 * using <mxLog.warn>.
 *
 * Returns the resulting object that represents the given XML node
 * or the object given to the method as the into parameter.
 *
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * node - XML node to be decoded.
 * into - Optional objec to encode the node into.
 */
mxObjectCodec.prototype.decode = function(dec, node, into)
{
	var id = node.getAttribute('id');
	var obj = dec.objects[id];
	
	if (obj == null)
	{
		obj = into || this.cloneTemplate();
		
		if (id != null)
		{
			dec.putObject(id, obj);
		}
	}
	
	node = this.beforeDecode(dec, node, obj);
	this.decodeNode(dec, node, obj);
	
    return this.afterDecode(dec, node, obj);
};	

/**
 * Function: decodeNode
 * 
 * Calls <decodeAttributes> and <decodeChildren> for the given node.
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * node - XML node to be decoded.
 * obj - Objec to encode the node into.
 */	
mxObjectCodec.prototype.decodeNode = function(dec, node, obj)
{
	if (node != null)
	{
		this.decodeAttributes(dec, node, obj);
		this.decodeChildren(dec, node, obj);
	}
};

/**
 * Function: decodeAttributes
 * 
 * Decodes all attributes of the given node using <decodeAttribute>.
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * node - XML node to be decoded.
 * obj - Objec to encode the node into.
 */	
mxObjectCodec.prototype.decodeAttributes = function(dec, node, obj)
{
	var attrs = node.attributes;
	
	if (attrs != null)
	{
		for (var i = 0; i < attrs.length; i++)
		{
			this.decodeAttribute(dec, attrs[i], obj);
		}
	}
};

/**
 * Function: isIgnoredAttribute
 * 
 * Returns true if the given attribute should be ignored. This implementation
 * returns true if the attribute name is "as" or "id".
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * attr - XML attribute to be decoded.
 * obj - Objec to encode the attribute into.
 */	
mxObjectCodec.prototype.isIgnoredAttribute = function(dec, attr, obj)
{
	return attr.nodeName == 'as' || attr.nodeName == 'id';
};

/**
 * Function: decodeAttribute
 * 
 * Reads the given attribute into the specified object.
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * attr - XML attribute to be decoded.
 * obj - Objec to encode the attribute into.
 */	
mxObjectCodec.prototype.decodeAttribute = function(dec, attr, obj)
{
	if (!this.isIgnoredAttribute(dec, attr, obj))
	{
		var name = attr.nodeName;
		
		// Converts the string true and false to their boolean values.
		// This may require an additional check on the obj to see if
		// the existing field is a boolean value or uninitialized, in
		// which case we may want to convert true and false to a string.
		var value = this.convertAttributeFromXml(dec, attr, obj);
		var fieldname = this.getFieldName(name);
		
		if (this.isReference(obj, fieldname, value, false))
		{
			var tmp = dec.getObject(value);
			
			if (tmp == null)
			{
		    	mxLog.warn('mxObjectCodec.decode: No object for ' +
		    		this.getName() + '.' + name + '=' + value);
		    	return; // exit
		    }
		    
		    value = tmp;
		}

		if (!this.isExcluded(obj, name, value, false))
		{
			//mxLog.debug(mxUtils.getFunctionName(obj.constructor)+'.'+name+'='+value);
			obj[name] = value;
		}
	}
};

/**
 * Function: decodeChildren
 * 
 * Decodes all children of the given node using <decodeChild>.
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * node - XML node to be decoded.
 * obj - Objec to encode the node into.
 */	
mxObjectCodec.prototype.decodeChildren = function(dec, node, obj)
{
	var child = node.firstChild;
	
	while (child != null)
	{
		var tmp = child.nextSibling;
		
		if (child.nodeType == mxConstants.NODETYPE_ELEMENT &&
			!this.processInclude(dec, child, obj))
		{
			this.decodeChild(dec, child, obj);
		}
		
		child = tmp;
	}
};

/**
 * Function: decodeChild
 * 
 * Reads the specified child into the given object.
 * 
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * child - XML child element to be decoded.
 * obj - Objec to encode the node into.
 */	
mxObjectCodec.prototype.decodeChild = function(dec, child, obj)
{
	var fieldname = this.getFieldName(child.getAttribute('as'));
	
	if (fieldname == null || !this.isExcluded(obj, fieldname, child, false))
	{
		var template = this.getFieldTemplate(obj, fieldname, child);
		var value = null;
		
		if (child.nodeName == 'add')
		{
			value = child.getAttribute('value');
			
			if (value == null && mxObjectCodec.allowEval)
			{
				value = mxUtils.eval(mxUtils.getTextContent(child));
			}
		}
		else
		{
			value = dec.decode(child, template);
		}

		try
		{
			this.addObjectValue(obj, fieldname, value, template);
		}
		catch (e)
		{
			throw new Error(e.message + ' for ' + child.nodeName);
		}
	}
};

/**
 * Function: getFieldTemplate
 * 
 * Returns the template instance for the given field. This returns the
 * value of the field, null if the value is an array or an empty collection
 * if the value is a collection. The value is then used to populate the
 * field for a new instance. For strongly typed languages it may be
 * required to override this to return the correct collection instance
 * based on the encoded child.
 */	
mxObjectCodec.prototype.getFieldTemplate = function(obj, fieldname, child)
{
	var template = obj[fieldname];
	
	// Non-empty arrays are replaced completely
    if (template instanceof Array && template.length > 0)
    {
        template = null;
    }
    
    return template;
};

/**
 * Function: addObjectValue
 * 
 * Sets the decoded child node as a value of the given object. If the
 * object is a map, then the value is added with the given fieldname as a
 * key. If the fieldname is not empty, then setFieldValue is called or
 * else, if the object is a collection, the value is added to the
 * collection. For strongly typed languages it may be required to
 * override this with the correct code to add an entry to an object.
 */	
mxObjectCodec.prototype.addObjectValue = function(obj, fieldname, value, template)
{
	if (value != null && value != template)
	{
		if (fieldname != null && fieldname.length > 0)
		{
			obj[fieldname] = value;
		}
		else
		{
			obj.push(value);
		}
		//mxLog.debug('Decoded '+mxUtils.getFunctionName(obj.constructor)+'.'+fieldname+': '+value);
	}
};

/**
 * Function: processInclude
 *
 * Returns true if the given node is an include directive and
 * executes the include by decoding the XML document. Returns
 * false if the given node is not an include directive.
 *
 * Parameters:
 *
 * dec - <mxCodec> that controls the encoding/decoding process.
 * node - XML node to be checked.
 * into - Optional object to pass-thru to the codec.
 */
mxObjectCodec.prototype.processInclude = function(dec, node, into)
{
	if (node.nodeName == 'include')
	{
		var name = node.getAttribute('name');
		
		if (name != null)
		{
			try
			{
				var xml = mxUtils.load(name).getDocumentElement();
				
				if (xml != null)
				{
					dec.decode(xml, into);
				}
			}
			catch (e)
			{
				// ignore
			}
		}
		
		return true;
	}
	
	return false;
};

/**
 * Function: beforeDecode
 *
 * Hook for subclassers to pre-process the node for
 * the specified object and return the node to be
 * used for further processing by <decode>.
 * The object is created based on the template in the 
 * calling method and is never null. This implementation
 * returns the input node. The return value of this
 * function is used in <decode> to perform
 * the default decoding into the given object.
 *
 * Parameters:
 *
 * dec - <mxCodec> that controls the decoding process.
 * node - XML node to be decoded.
 * obj - Object to encode the node into.
 */
mxObjectCodec.prototype.beforeDecode = function(dec, node, obj)
{
	return node;
};

/**
 * Function: afterDecode
 *
 * Hook for subclassers to post-process the object after
 * decoding. This implementation returns the given object
 * without any changes. The return value of this method
 * is returned to the decoder from <decode>.
 *
 * Parameters:
 *
 * enc - <mxCodec> that controls the encoding process.
 * node - XML node to be decoded.
 * obj - Object that represents the default decoding.
 */
mxObjectCodec.prototype.afterDecode = function(dec, node, obj)
{
	return obj;
};