dom (3)

NAME

dom - Create an in-memory DOM tree from XML

SYNOPSIS

package require tdom

dom method ?arg arg ...?

DESCRIPTION

This command provides the creation of complete DOM trees in memory. In the usual case a string containing a XML information is parsed and converted into a DOM tree. method indicates a specific subcommand.

The valid methods are:

dom parse ?options? ?data?

Parses the XML information and builds up the DOM tree in memory providing a Tcl object command to this DOM document object. Example:

      

dom parse $xml doc
$doc documentElement root

parses the XML in the variable xml, creates the DOM tree in memory, make a reference to the document object, visible in Tcl as a document object command, and assigns this new object name to the variable doc. When doc gets freed, the DOM tree and the associated Tcl command object (document and all node objects) are freed automatically.

      
      

set document [dom parse $xml]
set root     [$document documentElement]

parses the XML in the variable xml, creates the DOM tree in memory, make a reference to the document object, visible in Tcl as a document object command, and returns this new object name, which is then stored in document. To free the underlying DOM tree and the associative Tcl object commands (document + nodes + fragment nodes) the document object command has to be explicitly deleted by:


      

$document delete

or

rename $document ""

The valid options are:

-simple

If -simple is specified, a simple but fast parser is used (conforms not fully to XML recommendation). That should double parsing and DOM generation speed. The encoding of the data is not transformed inside the parser. The simple parser does not respect any encoding information in the XML declaration. It skips over the internal DTD subset and ignores any information in it. Therefor it doesn't include defaulted attribute values into the tree, even if the according attribute declaration is in the internal subset. It also doesn't expand internal or external entity references other than the predefined entities and character references.

-html

If -html is specified, a fast HTML parser is used, which tries to even parse badly formed HTML into a DOM tree.

-keepEmpties

If -keepEmpties is specified, text nodes, which contain only whitespaces, will be part of the resulting DOM tree. In default case (-keepEmpties not given) those empty text nodes are removed at parsing time.

-channel <channel-ID>

If -channel <channel-ID> is specified, the input to be parsed is read from the specified channel. The encoding setting of the channel (via fconfigure -encoding) is respected, ie the data read from the channel are converted to UTF-8 according to the encoding settings, befor the data is parsed.

-baseurl <baseURI>

If -baseurl <baseURI> is specified, the baseURI is used as the base URI of the document. External entities referenced in the document are resolved relative to this base URI. This base URI is also stored within the DOM tree.

-feedbackAfter <#bytes>

If -feedbackAfter <#bytes> is specified, the tcl command ::dom::domParseFeedback is evaluated after parsing every #bytes. If you use this option, you have to create a tcl proc named ::dom::domParseFeedback, otherwise you will get an error. Please notice, that the calls of ::dom::domParseFeedback are not done exactly every #bytes, but always at the first element start after every #bytes.

-externalentitycommand <script>

If -externalentitycommand <script> is specified, the specified tcl script is called to resolve any external entities of the document. The actual evaluated command consists of this option followed by three arguments: the base uri, the system identifier of the entity and the public identifier of the entity. The base uri and the public identifier may be the empty list. The script has to return a tcl list consisting of three elements. The first element of this list signals, how the external entity is returned to the processor. At the moment, the two allowed types are "string" and "channel". The second element of the list has to be the (absolute) base URI of the external entity to be parsed. The third element of the list are data, either the already read data out of the external entity as string in the case of type "string", or the name of a tcl channel, in the case of type "channel". Note that if the script returns a tcl channel, it will not be closed by the processor. It must be closed separately if it is no longer required.

-useForeignDTD <boolean>

If <boolean> is true and the document does not have an external subset, the parser will call the -externalentitycommand script with empty values for the systemId and publicID arguments. Pleace notice, that, if the document also doesn't have an internal subset, the -startdoctypedeclcommand and -enddoctypedeclcommand scripts, if set, are not called. The -useForeignDTD respects

-paramentityparsing <always|never|notstandalone>

The -paramentityparsing option controls, if the parser tries to resolve the external entities (including the external DTD subset) of the document, while building the DOM tree. -paramentityparsing requires an argument, which must be either "always", "never", or "notstandalone". The value "always" means, that the parser tries to resolves (recursively) all external entities of the XML source. This is the default, in case -paramentityparsing is omitted. The value "never" means, that only the given XML source is parsed and no external entity (including the external subset) will be resolved and parsed. The value "notstandalone" means, that all external entities will be resolved and parsed, with the execption of documents, which explicitly states standalone="yes" in their XML declaration.

dom createDocument docElemName ?objVar?

Creates a new DOM document object with one element node with node name docElemName. The objVar controls the memory handling as explained above.

dom createDocumentNS uri docElemName ?objVar?

Creates a new DOM document object with one element node with node name docElemName. Uri gives the namespace of the document element to create. The objVar controls the memory handling as explained above.

dom createDocumentNode ?objVar?

Creates a new, 'empty' DOM document object without any element node. objVar controls the memory handling as explained above.

dom setResultEncoding ?encodingName?

If encodingName is not given the current global result encoding is returned. Otherwise the global result encoding is set to encodingName. All character data, attribute values, etc. will then be converted from UTF-8, which is delivered from the Expat XML parser, to the given 8 bit encoding at XML/DOM parse time. Valid values for encodingName are: utf-8, ascii, cp1250, cp1251, cp1252, cp1253, cp1254, cp1255, cp1256, cp437, cp850, en, iso8859-1, iso8859-2, iso8859-3, iso8859-4, iso8859-5, iso8859-6, iso8859-7, iso8859-8, iso8859-9, koi8-r.

dom createNodeCmd ?-returnNodeCmd? (element|comment|text|cdata|pi)Node commandName

This method creates Tcl commands, which in turn create tDOM nodes. Tcl commands created by this command are only avaliable inside a script given to the domNode method appendFromScript. If a command created with createNodeCmd is invoked in any other context, it will return error. The created command commandName replaces any existing command or procedure with that name. If the commandName includes any namespace qualifiers, it is created in the specified namespace.

If such command is invoked inside a script given as argument to the domNode method appendFromScript, it creates a new node and appends this node at the end of the child list of the invoking element node. If the option -returnNodeCmd was given, the command returns the created node as Tcl command. If this option was omitted, the command returns nothing. Each command creates always the same type of node. Which type of node is created by the command is determined by the first argument to the createNodeCmd. The syntax of the created command depends on the type of the node it creates.

If the first argument of the method is elementNode, the created command will create an element node. The tag name of the created node is commandName without namespace qualifiers. The syntax of the created command is:

elementNodeCmd ?attributeName attributeValue ...? ?script?
elementNodeCmd ?-attributeName attributeValue ...? ?script?
elementNodeCmd name_value_list script

The command syntax allows three different ways to specify the attributes of the resulting element. These could be specified with attributeName attributeValue argument pairs, in an "option style" way with -attriubteName attributeValue argument pairs (the '-' character is only syntactical sugar and will be stripped off) or as a Tcl list with elements interpreted as attribute name and the corresponding attribute value. The attribute name elements in the list may have a leading '-' character, which will be stripped off.

Every elementNodeCmd accepts an optional Tcl script as last argument. This script is evaluated as recursive appendFromScript script with the node created by the elementNodeCmd as parent of all nodes created by the script.

If the first argument of the method is textNode, the command will create a text node. The syntax of the created command is:

textNodeCmd ?-disableOutputEscaping? data

If the optional flag -disableOutputEscaping is given, the escaping of the ampersand character (&) and the left angle bracket (<) inside the data is disabled. You should use this flag carefully.

If the first argument of the method is commentNode, or cdataNode, the command will create an comment node or CDATA section node. The syntax of the created command is:

nodeCmd data

If the first argument of the method is piNode, the command will create a processing instruction node. The syntax of the created command is:

piNodeCmd target data

dom setStoreLineColumn ?boolean?

If switched on, the DOM nodes will contain line and column position information for the original XML document after parsing. The default is, not to store line and column position information.

dom setNameCheck ?boolean?

If NameCheck is true, every method which expects an XML Name, a full qualified name or a processing instructing target will check, if the given string is valid according to his production rule. For commands created with the createNodeCmd method to be used in the context of appendFromScript the status of the flag at creation time decides. If NameCheck is true at creation time, the command will check his arguments, otherwise not. The setNameCheck set this flag. It returns the current NameCheck flag state. The default state for NameCheck is true.

dom setTextCheck ?boolean?

If TextCheck is true, every command which expects XML Chars, a comment, a CDATA section value or a processing instructing value will check, if the given string is valid according to his production rule. For commands created with the createNodeCmd method to be used in the context of appendFromScript the status of the flag at creation time decides. If TextCheck is true at creation time, the command will check his arguments, otherwise not.The setTextCheck method set this flag. It returns the current TextCheck flag state. The default state for TextCheck is true.

dom setObjectCommands ?(automatic|token|command)?

Controls, if documents and nodes are created as tcl commands or as token to be used with the domNode and domDoc commands. If the mode is 'automatic', then methods used at tcl commands will create tcl commands and methods used at doc or node tokes will create tokens. If the mode is 'command' then always tcl commands will be created. If the mode is 'token', then always token will be created. The method returns the current mode. This method is an experimental interface.

dom isName name

Returns 1, if name is a valid XML Name according to production 5 of the XML 1.0 recommendation. This means, that name is a valid XML element or attribute name. Otherwise it returns 0.

dom isPIName name

Returns 1, if name is a valid XML processing instruction target according to production 17 of the XML 1.0 recommendation. Otherwise it returns 0.

dom isNCName name

Returns 1, if name is a valid NCName according to production 4 of the of the Namespaces in XML recommendation. Otherwise it returns 0.

dom isQName name

Returns 1, if name is a valid QName according to production 6 of the of the Namespaces in XML recommendation. Otherwise it returns 0.

dom isCharData string

Returns 1, if every character in string is a valid XML Char according to production 2 of the XML 1.0 recommendation. Otherwise it returns 0.

dom isComment string

Returns 1, if string is a valid comment according to production 15 of the XML 1.0 recommendation. Otherwise it returns 0.

dom isCDATA string

Returns 1, if string is valid according to production 20 of the XML 1.0 recommendation. Otherwise it returns 0.

dom isPIValue string

Returns 1, if string is valid according to production 16 of the XML 1.0 recommendation. Otherwise it returns 0.

KEYWORDS

XML, DOM, document, node, parsing