NAME
    LaTeX::TOM - A module for parsing, analyzing, and manipulating LaTeX
    documents.

SYNOPSIS
      use LaTeX::TOM;

      my $parser = new Parser;

      my $document = $parser->parseFile('mypaper.tex');

      my $latex = $document->toLaTeX;
        
      my $specialnodes = $document->getNodesByCondition(
        '$node->getNodeType eq \'TEXT\' && 
         $node->getNodeText =~ /magic string/');

      my $sections = $document->getNodesByCondition(
        '$node->getNodeType eq \'COMMAND\' &&
         $node->getCommandName =~ /section$/');

      my $indexme = $document->getIndexableText;

      $document->print;
        
DESCRIPTION
    This module provides a parser which parses and interprets (though not
    fully) LaTeX documents and returns a tree-based representation of what
    it finds. This tree is a LaTeX::TOM::Tree. The tree contains
    LaTeX::TOM:Node nodes.

    This module should be especially useful to anyone who wants to do
    processing of LaTeX documents that requires extraction of plain-text
    information, or altering of the plain-text components (or alternatively,
    the math-text components).

COMPONENTS
  LaTeX::TOM::Parser
    The parser recognizes 3 parameters upon creation. The parameters, in
    order, are

    parse error handling (= 0 || 1 || 2)
        Determines what happens when a parse error is encountered. 0 results
        in a warning. 1 results in a die. 2 results in silence. Note that
        particular groupings in LaTeX (i.e. newcommands and the like)
        contain invalid TeX or LaTeX, so you nearly always need this
        parameter to be 0 or 2 to completely parse the document.

    read inputs flag (= 0 || 1)
        This flag determines whether a scan for \input and \input-like
        commands is performed, and the resulting called files parsed and
        added to the parent parse tree. 0 means no, 1 means do it. Note that
        this will happen recursively if it is turned on. Also,
        bibliographies (.bbl files) are detected and included.

    apply mappings flag (= 0 || 1)
        This flag determines whether (most) user-defined mappings are
        applied. This means \defs, \newcommands, and \newenvironments. This
        is critical for properly analyzing the content of the document, as
        this must be phrased in terms of the semantics of the original TeX
        and LaTeX commands, not ad hoc user macros. So, for instance, do not
        expect plain-text extraction to work properly with this option off.

    The parser returns a LaTeX::TOM:Tree ($document in the SYNOPSIS).

  LaTeX::TOM::Node
    Nodes may be of the following types:

    TEXT
        TEXT nodes can be thought of as representing the plain-text portions
        of the LaTeX document. This includes math and anything else that is
        not a recognized TeX or LaTeX command, or user-defined command. In
        reality, TEXT nodes contain commands that this parser does not yet
        recognize the semantics of.

    COMMAND
        A COMMAND node represents a TeX command. It always has child nodes
        in a tree, though the tree might be empty if the command operates on
        zero parameters. An example of a command is

          \textbf{blah}

        This would parse into a COMMAND node for *textbf*, which would have
        a subtree containing the TEXT node with text ``blah.''

    ENVIRONMENT
        Similarly, TeX environments parse into ENVIRONMENT nodes, which have
        metadata about the environment, along with a subtree representing
        what is contained in the environment. For example,

          \begin{equation}
            r = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} 
          \end{equation}

        Would parse into an ENVIRONMENT node of the class ``equation'' with
        a child tree containing the result of parsing ``r = \frac{-b \pm
        \sqrt{b^2 - 4ac}}{2a}.''

    GROUP
        A GROUP is like an anonymous COMMAND. Since you can put whatever you
        want in curly-braces ({}) in TeX in order to make semantically
        isolated regions, this separation is preserved by the parser. A
        GROUP is just the subtree of the parsed contents of plain
        curly-braces.

        It is important to note that currently only the first GROUP in a
        series of GROUPs following a LaTeX command will actually be parsed
        into a COMMAND node. The reason is that, for the initial purposes of
        this module, it was not necessary to recognize additional GROUPs as
        additional parameters to the COMMAND. However, this is something
        that this module really should do eventually. Currently if you want
        all the parameters to a multi-parametered command, you'll need to
        pick out all the following GROUP nodes yourself.

        Eventually this will become something like a list which is stored in
        the COMMAND node, much like XML::DOM's treatment of attributes.
        These are, in a sense, apart from the rest of the document tree.
        Then GROUP nodes will become much more rare.

    COMMENT
        A COMMENT node is very similar to a TEXT node, except it is
        specifically for lines beginning with ``%'' (the TeX comment
        delimeter) or the right-hand portion of a line that has ``%'' at
        some internal point.

  LaTeX::TOM::Trees
    As mentioned before, the Tree is the return result of a parse.

    The tree is nothing more than an arrayref of Nodes, some of which may
    contain their own trees. This is useful knowledge at this point, since
    the user isn't provided with a full suite of convenient
    tree-modification methods. However, Trees do already have some very
    convenient methods, described in the next section.

METHODS
    In this section all of the methods for each of the components are listed
    and described.

  LaTeX::TOM::Parser
    The methods for the parser (aside from the constructor, discussed above)
    are :

    parseFile (filename)
        Read in the contents of *filename* and parse them, returning a
        LaTeX::TOM:Tree.

    parse (string)
        Parse the string *string* and return a LaTeX::TOM::Tree.

  LaTeX::TOM::Tree
    This section contains methods for the Trees returned by the parser.

    copy
        Duplicate a tree into new memory.

    print
        A debug print of the structure of the tree.

    plainText
        Returns an arrayref which is a list of strings representing the text
        of all getNodePlainTextFlag = 1 TEXT nodes, in an inorder traversal.

    indexableText
        A method like the above but which goes one step further; it cleans
        all of the returned text and concatenates it into a single string
        which one could consider having all of the standard information
        retrieval value for the document, making it useful for indexing.

    toLaTeX
        Return a string representing the LaTeX encoded by the tree. This is
        especially useful to get a normal document again, after modifying
        nodes of the tree.

    getTopLevelNodes
        Return an arrayref which is a list of LaTeX::TOM::Nodes at the top
        level of the Tree.

    getAllNodes
        Return an arrayref with all nodes of the tree. This "flattens" the
        tree.

    getCommandNodesByName (name)
        Return an arrayref with all COMMAND nodes in the tree which have a
        name matching *name*.

    getEnvironmentsByName (name)
        Return an arrayref with all ENVIRONMENT nodes in the tree which have
        a class matching *name*.

    getNodesByCondition (expression)
        This is a catch-all search method which can be used to pull out
        nodes that match pretty much any perl expression, without manually
        having to traverse the tree. *expression* is a valid perl expression
        which makes reference to the perl variable $node when testing
        something about the currently scrutinized node of the tree. See the
        SYNOPSIS for examples.

  LaTeX::TOM::Node
    This section contains the methods for nodes of the parsed Trees.

    getNodeType
        Returns the type, one of 'TEXT', 'COMMAND', 'ENVIRONMENT', 'GROUP',
        or 'COMMENT', as described above.

    getNodeText
        Applicable for TEXT or COMMENT nodes; this returns the document text
        they contain. This is undef for other node types.

    setNodeText
        Set the node text, also for TEXT and COMMENT nodes.

    getNodeStartingPosition
        Get the starting character position in the document of this node.
        For TEXT and COMMENT nodes, this will be where the text begins. For
        ENVIRONMENT, COMMAND, or GROUP nodes, this will be the position of
        the *last* character of the opening identifier.

    getNodeEndingPosition
        Same as above, but for last character. For GROUP, ENVIRONMENT, or
        COMMAND nodes, this will be the *first* character of the closing
        identifier.

    getNodeOuterStartingPosition
        Same as getNodeStartingPosition, but for GROUP, ENVIRONMENT, or
        COMMAND nodes, this returns the *first* character of the opening
        identifier.

    getNodeOuterEndingPosition
        Same as getNodeEndingPosition, but for GROUP, ENVIRONMENT, or
        COMMAND nodes, this returns the *last* character of the closing
        identifier.

    getNodeMathFlag
        This applies to any node type. It is 1 if the node sets, or is
        contained within, a math mode region. 0 otherwise. TEXT nodes which
        have this flag as 1 can be assumed to be the actual mathematics
        contained in the document.

    getNodePlainTextFlag
        This applies only to TEXT nodes. It is 1 if the node is non-math and
        is visible (in other words, will end up being a part of the output
        document). One would only want to index TEXT nodes with this
        property, for information retrieval purposes.

    getEnvironmentClass
        This applies only to ENVIRONMENT nodes. Returns what class of
        environment the node represents (the X in \begin{X} and \end{X}).

    getCommandName
        This applies only to COMMAND nodes. Returns the name of the command
        (the X in \X{...}).

    getChildTree
        This applies only to COMMAND, ENVIRONMENT, and GROUP nodes: it
        returns the LaTeX::TOM::Tree which is ``under'' the calling node.

    getFirstChild
        This applies only to COMMAND, ENVIRONMENT, and GROUP nodes: it
        returns the first node from the first level of the child subtree.

    getLastChild
        Same as above, but for the last node of the first level.

    getPreviousSibling
        Return the prior node on the same level of the tree.

    getNextSibling
        Same as above, but for following node.

    getParent
        Get the parent node of this node in the tree.

    getNextGroupNode
        This is an interesting function, and kind of a hack because of the
        way the parser makes the current tree. Basically it will give you
        the next sibling that is a GROUP node, until it either hits the end
        of the tree level, a TEXT node which doesn't match /^\s*$/, or a
        COMMAND node.

        This is useful for finding all GROUPed parameters after a COMMAND
        node (see comments for 'GROUP' in the 'COMPONENTS' /
        'LaTeX::TOM::Node' section). You can just have a while loop that
        calls this method until it gets 'undef', and you'll know you've
        found all the parameters to a command.

        Note: this may be bad, but TEXT Nodes matching /^\s*\[[0-9]+\]$/
        (optional parameter groups) are treated as if they were 'blank'.

CAVEATS
    Due to the lack of tree-modification methods, currently this module is
    mostly useful for minor modifications to the parsed document, for
    instance, altering the text of TEXT nodes but not deleting the nodes. Of
    course, the user can still do this by breaking abstraction and directly
    modifying the Tree.

    Also note that the parsing is not complete. This module was not written
    with the intention of being able to produce output documents the way
    ``latex'' does. The intent was instead to be able to analyze and modify
    the document on a logical level with regards to the content; it doesn't
    care about the document formatting and outputting side of TeX/LaTeX.

    There is much work still to be done. See the TODO list in the TOM.pm
    source.

BUGS
    Probably plenty. However, this module has performed fairly well on a set
    of ~1000 research publications from the Computing Research Repository,
    so I deemed it ``good enough'' to use for purposes similar to mine.

    Please let me know of parser errors if you discover any.

AUTHOR
    Written by Aaron Krowne <akrowne@vt.edu>

    Maintained by Steven Schubiger <schubiger@cpan.org>

WEB SITE
    Please see http://br.endernet.org/~akrowne/elaine/latex_tom/ for this
    module's home on the WWW.

HISTORY
    .02c
      Bug fixes: Handling of newlines and whitespace between commands and
      parameters and groups, handling of \w+\d+ commands (thanks Leo
      Tenenblat for both of these), documentation bugfix: "parseFile", not
      "parsefile".

    .02b
      License included (BSD), some minor code indenting cleanups.

    .02
      This is the first release version.

    .01
      Non-OOP version of the current functionality. Not released.

