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

     use LaTeX::TOM;

     $parser = LaTeX::TOM->new;

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

     $latex = $document->toLaTeX;

     $specialnodes = $document->getNodesByCondition(sub {
         my $node = shift;
         return (
           $node->getNodeType eq 'TEXT'
             && $node->getNodeText =~ /magic string/

     $sections = $document->getNodesByCondition(sub {
         my $node = shift;
         return (
           $node->getNodeType eq 'COMMAND'
             && $node->getCommandName =~ /section$/

     $indexme = $document->getIndexableText;


    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).

    The parser recognizes 3 parameters upon creation by "LaTeX::TOM->new".
    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

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

    Nodes may be of the following types:

        "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.

        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


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

        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,

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

        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}.''

        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

        It is important to note that currently only the first "GROUP" in a
        series of "GROUP"s 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
        "GROUP"s 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.

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

    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.

    ""  Instantiate a new parser object.

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

    The methods for the parser are:

   parseFile (filename)
    ""  Read in the contents of *filename* and parse them, returning a

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

    This section contains methods for the Trees returned by the parser.

    ""  Duplicate a tree into new memory.

    ""  A debug print of the structure of the tree.

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

    ""  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.

    ""  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.

    ""  Return a list of "LaTeX::TOM::Nodes" at the top level of the Tree.

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

   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 (code reference)
    ""  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. *code reference* is a perl code
        reference which receives as its first argument the node of the tree
        that is currently scrutinized and is expected to return a boolean
        value. See the SYNOPSIS for examples.

    ""  Returns the first node of the tree. This is useful if you want to
        walk the tree yourself, starting with the first node.

    This section contains the methods for nodes of the parsed Trees.

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

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

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

    ""  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.

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

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

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

    ""  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.

    ""  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.

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

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

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

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

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

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

    ""  Same as above, but for following node.

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

    ""  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 "GROUP"ed 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'.

    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

    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 the maintainer know of parser errors if you discover any.

    Thanks to (in order of appearance) who have contributed valuable
    suggestions and patches:

     Otakar Smrz
     Moritz Lenz
     James Bowlin
     Jesse S. Bangs
     Cord Merrell
     Debian Perl Group
     Eli Billauer

    Written by Aaron Krowne <>

    Maintained by Steven Schubiger <>

    This program is free software; you may redistribute it and/or modify it
    under the same terms as Perl itself.

    See <>