Package org.htmlparser

Class PrototypicalNodeFactory

  • All Implemented Interfaces:
    java.io.Serializable, NodeFactory
    public class PrototypicalNodeFactory
extends java.lang.Object
implements java.io.Serializable, NodeFactory
    A node factory based on the prototype pattern. This factory uses the prototype pattern to generate new nodes. These are cloned as needed to form new Text, Remark and Tag nodes.

    Text and remark nodes are generated from prototypes accessed via the textPrototype and remarkPrototype properties respectively. Tag nodes are generated as follows:

    Prototype tags, in the form of undifferentiated tags, are held in a hash table. On a request for a tag, the attributes are examined for the name of the tag to be created. If a prototype of that name has been registered (exists in the hash table), it is cloned and the clone is given the characteristics (Attributes, start and end position) of the requested tag.

    In the case that no tag has been registered under that name, a generic tag is created from the prototype acessed via the tagPrototype property.

    The hash table of registered tags can be automatically populated with all the known tags from the org.htmlparser.tags package when the factory is constructed, or it can start out empty and be populated explicitly.

    Here is an example of how to override all text issued from Text.toPlainTextString(), in this case decoding (converting character references), which illustrates the use of setting the text prototype: 

     PrototypicalNodeFactory factory = new PrototypicalNodeFactory ();
 factory.setTextPrototype (
     // create a inner class that is a subclass of TextNode
     new TextNode () {
         public String toPlainTextString()
         {
             String original = super.toPlainTextString ();
             return (org.htmlparser.util.Translate.decode (original));
         }
     });
 Parser parser = new Parser ();
 parser.setNodeFactory (factory);

    Here is an example of using a custom link tag, in this case just printing the URL, which illustrates registering a tag: 

    
 class PrintingLinkTag extends LinkTag
 {
     public void doSemanticAction ()
         throws
             ParserException
     {
         System.out.println (getLink ());
     }
 }
 PrototypicalNodeFactory factory = new PrototypicalNodeFactory ();
 factory.registerTag (new PrintingLinkTag ());
 Parser parser = new Parser ();
 parser.setNodeFactory (factory);

    See Also:
    Serialized Form

    • Field Detail

      • mText

        protected Text mText
        The prototypical text node.

      • mRemark

        protected Remark mRemark
        The prototypical remark node.

      • mTag

        protected Tag mTag
        The prototypical tag node.

      • mBlastocyst

        protected java.util.Map mBlastocyst
        The list of tags to return. The list is keyed by tag name.

    • Constructor Detail

      • PrototypicalNodeFactory

        public PrototypicalNodeFactory()
        Create a new factory with all tags registered. Equivalent to PrototypicalNodeFactory(false).

      • PrototypicalNodeFactory

        public PrototypicalNodeFactory​(boolean empty)
        Create a new factory.
        Parameters:
        empty - If true, creates an empty factory, otherwise create a new factory with all tags registered.

      • PrototypicalNodeFactory

        public PrototypicalNodeFactory​(Tag tag)
        Create a new factory with the given tag as the only registered tag.
        Parameters:
        tag - The single tag to register in the otherwise empty factory.

      • PrototypicalNodeFactory

        public PrototypicalNodeFactory​(Tag[] tags)
        Create a new factory with the given tags registered.
        Parameters:
        tags - The tags to register in the otherwise empty factory.

    • Method Detail

      • put

        public Tag put​(java.lang.String id,
               Tag tag)
        Adds a tag to the registry.
        Parameters:
        id - The name under which to register the tag. For proper operation, the id should be uppercase so it will be matched by a Map lookup.
        tag - The tag to be returned from a createTagNode(org.htmlparser.lexer.Page, int, int, java.util.Vector) call.
        Returns:
        The tag previously registered with that id if any, or null if none.

      • get

        public Tag get​(java.lang.String id)
        Gets a tag from the registry.
        Parameters:
        id - The name of the tag to return.
        Returns:
        The tag registered under the id name, or null if none.

      • remove

        public Tag remove​(java.lang.String id)
        Remove a tag from the registry.
        Parameters:
        id - The name of the tag to remove.
        Returns:
        The tag that was registered with that id, or null if none.

      • clear

        public void clear()
        Clean out the registry.

      • getTagNames

        public java.util.Set getTagNames()
        Get the list of tag names.
        Returns:
        The names of the tags currently registered.

      • registerTag

        public void registerTag​(Tag tag)
        Register a tag. Registers the given tag under every id that the tag has (i.e. all names returned by tag.getIds().

        For proper operation, the ids are converted to uppercase so they will be matched by a Map lookup.

        Parameters:
        tag - The tag to register.

      • unregisterTag

        public void unregisterTag​(Tag tag)
        Unregister a tag. Unregisters the given tag from every id the tag has.

        The ids are converted to uppercase to undo the operation of registerTag.

        Parameters:
        tag - The tag to unregister.

      • setTextPrototype

        public void setTextPrototype​(Text text)
        Set the object to be used to generate text nodes.
        Parameters:
        text - The prototype for Text nodes. If null the prototype is set to the default (TextNode).
        See Also:
        getTextPrototype()

      • setRemarkPrototype

        public void setRemarkPrototype​(Remark remark)
        Set the object to be used to generate remark nodes.
        Parameters:
        remark - The prototype for Remark nodes. If null the prototype is set to the default (RemarkNode).
        See Also:
        getRemarkPrototype()

      • createStringNode

        public Text createStringNode​(Page page,
                             int start,
                             int end)
        Create a new string node.
        Specified by:
        createStringNode in interface NodeFactory
        Parameters:
        page - The page the node is on.
        start - The beginning position of the string.
        end - The ending position of the string.
        Returns:
        A text node comprising the indicated characters from the page.

      • createRemarkNode

        public Remark createRemarkNode​(Page page,
                               int start,
                               int end)
        Create a new remark node.
        Specified by:
        createRemarkNode in interface NodeFactory
        Parameters:
        page - The page the node is on.
        start - The beginning position of the remark.
        end - The ending positiong of the remark.
        Returns:
        A remark node comprising the indicated characters from the page.

      • createTagNode

        public Tag createTagNode​(Page page,
                         int start,
                         int end,
                         java.util.Vector attributes)
        Create a new tag node. Note that the attributes vector contains at least one element, which is the tag name (standalone attribute) at position zero. This can be used to decide which type of node to create, or gate other processing that may be appropriate.
        Specified by:
        createTagNode in interface NodeFactory
        Parameters:
        page - The page the node is on.
        start - The beginning position of the tag.
        end - The ending positiong of the tag.
        attributes - The attributes contained in this tag.
        Returns:
        A tag node comprising the indicated characters from the page.