Module java.desktop

Class Parser

  • All Implemented Interfaces:
    DTDConstants
    Direct Known Subclasses:
    DocumentParser

    public class Parser
    extends Object
    implements DTDConstants
    A simple DTD-driven HTML parser. The parser reads an HTML file from an InputStream and calls various methods (which should be overridden in a subclass) when tags and data are encountered.

    Unfortunately there are many badly implemented HTML parsers out there, and as a result there are many badly formatted HTML files. This parser attempts to parse most HTML files. This means that the implementation sometimes deviates from the SGML specification in favor of HTML.

    The parser treats \r and \r\n as \n. Newlines after starttags and before end tags are ignored just as specified in the SGML/HTML specification.

    The html spec does not specify how spaces are to be coalesced very well. Specifically, the following scenarios are not discussed (note that a space should be used here, but I am using &nbsp to force the space to be displayed):

    '<b>blah <i> <strike> foo' which can be treated as: '<b>blah <i><strike>foo'

    as well as: '<p><a href="xx"> <em>Using</em></a></p>' which appears to be treated as: '<p><a href="xx"><em>Using</em></a></p>'

    If strict is false, when a tag that breaks flow, (TagElement.breaksFlows) or trailing whitespace is encountered, all whitespace will be ignored until a non whitespace character is encountered. This appears to give behavior closer to the popular browsers.

    See Also:
    DTD, TagElement, SimpleAttributeSet
    • Field Detail

      • dtd

        protected DTD dtd
        The dtd.
      • strict

        protected boolean strict
        This flag determines whether or not the Parser will be strict in enforcing SGML compatibility. If false, it will be lenient with certain common classes of erroneous HTML constructs. Strict or not, in either case an error will be recorded.
    • Constructor Detail

      • Parser

        public Parser​(DTD dtd)
        Creates parser with the specified dtd.
        Parameters:
        dtd - the dtd.
    • Method Detail

      • getCurrentLine

        protected int getCurrentLine()
        Returns:
        the line number of the line currently being parsed
      • makeTag

        protected TagElement makeTag​(Element elem,
                                     boolean fictional)
        Makes a TagElement.
        Parameters:
        elem - the element storing the tag definition
        fictional - the value of the flag "fictional" to be set for the tag
        Returns:
        the created TagElement
      • makeTag

        protected TagElement makeTag​(Element elem)
        Makes a TagElement.
        Parameters:
        elem - the element storing the tag definition
        Returns:
        the created TagElement
      • getAttributes

        protected SimpleAttributeSet getAttributes()
        Returns attributes for the current tag.
        Returns:
        SimpleAttributeSet containing the attributes
      • flushAttributes

        protected void flushAttributes()
        Removes the current attributes.
      • handleText

        protected void handleText​(char[] text)
        Called when PCDATA is encountered.
        Parameters:
        text - the section text
      • handleTitle

        protected void handleTitle​(char[] text)
        Called when an HTML title tag is encountered.
        Parameters:
        text - the title text
      • handleComment

        protected void handleComment​(char[] text)
        Called when an HTML comment is encountered.
        Parameters:
        text - the comment being handled
      • handleEOFInComment

        protected void handleEOFInComment()
        Called when the content terminates without closing the HTML comment.
      • handleStartTag

        protected void handleStartTag​(TagElement tag)
        Called when a start tag is encountered.
        Parameters:
        tag - the tag being handled
      • handleEndTag

        protected void handleEndTag​(TagElement tag)
        Called when an end tag is encountered.
        Parameters:
        tag - the tag being handled
      • handleError

        protected void handleError​(int ln,
                                   String msg)
        An error has occurred.
        Parameters:
        ln - the number of line containing the error
        msg - the error message
      • error

        protected void error​(String err,
                             String arg1,
                             String arg2,
                             String arg3)
        Invokes the error handler.
        Parameters:
        err - the error type
        arg1 - the 1st error message argument
        arg2 - the 2nd error message argument
        arg3 - the 3rd error message argument
      • error

        protected void error​(String err,
                             String arg1,
                             String arg2)
        Invokes the error handler with the 3rd error message argument "?".
        Parameters:
        err - the error type
        arg1 - the 1st error message argument
        arg2 - the 2nd error message argument
      • error

        protected void error​(String err,
                             String arg1)
        Invokes the error handler with the 2nd and 3rd error message argument "?".
        Parameters:
        err - the error type
        arg1 - the 1st error message argument
      • error

        protected void error​(String err)
        Invokes the error handler with the 1st, 2nd and 3rd error message argument "?".
        Parameters:
        err - the error type
      • startTag

        protected void startTag​(TagElement tag)
                         throws ChangedCharSetException
        Handle a start tag. The new tag is pushed onto the tag stack. The attribute list is checked for required attributes.
        Parameters:
        tag - the tag
        Throws:
        ChangedCharSetException - if the document charset was changed
      • endTag

        protected void endTag​(boolean omitted)
        Handle an end tag. The end tag is popped from the tag stack.
        Parameters:
        omitted - true if the tag is no actually present in the document, but is supposed by the parser
      • markFirstTime

        protected void markFirstTime​(Element elem)
        Marks the first time a tag has been seen in a document
        Parameters:
        elem - the element represented by the tag
      • parseDTDMarkup

        public String parseDTDMarkup()
                              throws IOException
        Parses the Document Type Declaration markup declaration. Currently ignores it.
        Returns:
        the string representation of the markup declaration
        Throws:
        IOException - if an I/O error occurs
      • parseMarkupDeclarations

        protected boolean parseMarkupDeclarations​(StringBuffer strBuff)
                                           throws IOException
        Parse markup declarations. Currently only handles the Document Type Declaration markup. Returns true if it is a markup declaration false otherwise.
        Parameters:
        strBuff - the markup declaration
        Returns:
        true if this is a valid markup declaration; otherwise false
        Throws:
        IOException - if an I/O error occurs
      • parse

        public void parse​(Reader in)
                   throws IOException
        Parse an HTML stream, given a DTD.
        Parameters:
        in - the reader to read the source from
        Throws:
        IOException - if an I/O error occurs
      • getCurrentPos

        protected int getCurrentPos()
        Returns the current position.
        Returns:
        the current position