NAME¶

"LaTeXML::Package" - Support for package implementations and document customization.

SYNOPSIS¶

This package defines and exports most of the procedures users will need to customize or extend LaTeXML. The LaTeXML implementation of some package might look something like the following, but see the installed "LaTeXML/Package" directory for realistic examples.

  use LaTeXML::Package;
  use strict;
  #
  # Load "anotherpackage"
  RequirePackage('anotherpackage');
  #
  # A simple macro, just like in TeX
  DefMacro('\thesection', '\thechapter.\roman{section}');
  #
  # A constructor defines how a control sequence generates XML:
  DefConstructor('\thanks{}', "<ltx:thanks>#1</ltx:thanks>");
  #
  # And a simple environment ...
  DefEnvironment('{abstract}','<abstract>#body</abstract>');
  #
  # A math  symbol \Real to stand for the Reals:
  DefMath('\Real', "\x{211D}", role=>'ID');
  #
  # Or a semantic floor:
  DefMath('\floor{}','\left\lfloor#1\right\rfloor');
  #
  # More esoteric ...
  # Use a RelaxNG schema
  RelaxNGSchema("MySchema");
  # Or use a special DocType if you have to:
  # DocType("rootelement",
  #         "-//Your Site//Your DocType",'your.dtd',
  #          prefix=>"http://whatever/");
  #
  # Allow sometag elements to be automatically closed if needed
  Tag('prefix:sometag', autoClose=>1);
  #
  # Don't forget this, so perl knows the package loaded.
  1;

DESCRIPTION¶

To provide a LaTeXML-specific version of a LaTeX package "mypackage.sty" or class "myclass.cls" (so that eg. "\usepackage{mypackage}" works), you create the file "mypackage.sty.ltxml" or "myclass.cls.ltxml" and save it in the searchpath (current directory, or one of the directories given to the --path option, or possibly added to the variable SEARCHPATHS). Similarly, to provide document-specific customization for, say, "mydoc.tex", you would create the file "mydoc.latexml" (typically in the same directory). However, in the first cases, "mypackage.sty.ltxml" are loaded instead of "mypackage.sty", while a file like "mydoc.latexml" is loaded in addition to "mydoc.tex". In either case, you'll "use LaTeXML::Package;" to import the various declarations and defining forms that allow you to specify what should be done with various control sequences, whether there is special treatment of certain document elements, and so forth. Using "LaTeXML::Package" also imports the functions and variables defined in LaTeXML::Global, so see that documentation as well. Since LaTeXML attempts to mimic TeX, a familiarity with TeX's processing model is also helpful. Additionally, it is often useful, when implementing non-trivial behaviour, to think TeX-like. Many of the following forms take code references as arguments or options. That is, either a reference to a defined sub, "\&somesub", or an anonymous function sub { ... }. To document these cases, and the arguments that are passed in each case, we'll use a notation like CODE($token,..).

Control Sequences¶

Many of the following forms define the behaviour of control sequences. In TeX you'll typically only define macros. In LaTeXML, we're effectively redefining TeX itself, so we define macros as well as primitives, registers, constructors and environments. These define the behaviour of these commands when processed during the various phases of LaTeX's immitation of TeX's digestive tract. The first argument to each of these defining forms ("DefMacro", "DefPrimive", etc) is a prototype consisting of the control sequence being defined along with the specification of parameters required by the control sequence. Each parameter describes how to parse tokens following the control sequence into arguments or how to delimit them. To simplify coding and capture common idioms in TeX/LaTeX programming, latexml's parameter specifications are more expressive than TeX's "\def" or LaTeX's "\newcommand". Examples of the prototypes for familiar TeX or LaTeX control sequences are:

   DefConstructor('\usepackage[]{}',...
   DefPrimitive('\multiply Variable SkipKeyword:by Number',..
   DefPrimitive('\newcommand OptionalMatch:* {Token}[][]{}', ...

Control Sequence Parameters The general syntax for parameter for a control sequence is something like

  OpenDelim? Modifier? Type (: value (| value)* )? CloseDelim?

The enclosing delimiters, if any, are either {} or [], affect the way the argument is delimited. With {}, a regular TeX argument (token or sequence balanced by braces) is read before parsing according to the type (if needed). With [], a LaTeX optional argument is read, delimited by (non-nested) square brackets. The modifier can be either "Optional" or "Skip", allowing the argument to be optional. For "Skip", no argument is contributed to the argument list. The shorthands {} and [] default the type to "Plain" and reads a normal TeX argument or LaTeX default argument. The predefined argument types are as follows.

"Plain", "Semiverbatim"

Reads a standard TeX argument being either the next token, or if the next token is an {, the balanced token list. In the case of "Semiverbatim", many catcodes are disabled, which is handy for URL's, labels and similar.

"Token", "XToken"

Read a single TeX Token. For "XToken", if the next token is expandable, it is repeatedly expanded until an unexpandable token remains, which is returned.

"Number", "Dimension", "Glue" or "MuGlue"

Read an Object corresponding to Number, Dimension, Glue or MuGlue, using TeX's rules for parsing these objects.

"Until:"match

Reads tokens until a match to the tokens match is found, returning the tokens preceding the match. This corresponds to TeX delimited arguments.

"UntilBrace"

Reads tokens until the next open brace "{". This corresponds to the peculiar TeX construct "\def\foo#{...".

"Match:"match(|match)*, "Keyword:" match(|match)*

Reads tokens expecting a match to one of the token lists match, returning the one that matches, or undef. For "Keyword", case and catcode of the matches are ignored. Additionally, any leading spaces are skipped.

"Balanced"

Read tokens until a closing }, but respecting nested {} pairs.

"Variable"

Reads a token, expanding if necessary, and expects a control sequence naming a writable register. If such is found, it returns an array of the corresponding definition object, and any arguments required by that definition.

"SkipSpaces"

Skips any space tokens, but contributes nothing to the argument list.

Control of Scoping Most defining commands accept an option to control how the definition is stored, "scope=>$scope", where $scope can be c<'global'> for global definitions, 'local', to be stored in the current stack frame, or a string naming a scope. A scope saves a set of definitions and values that can be activated at a later time. Particularly interesting forms of scope are those that get automatically activated upon changes of counter and label. For example, definitions that have "scope=>'section:1.1'" will be activated when the section number is "1.1", and will be deactivated when the section ends. Macros

"DefMacro($prototype,$string | $tokens | $code,%options);"

Defines the macro expansion for $prototype. If a $string is supplied, it will be tokenized at definition time, and any macro arguments will be substituted for parameter indicators (eg #1) at expansion time; the result is used as the expansion of the control sequence. The only option, other than "scope", is "isConditional" which should be true, for conditional control sequences (TeX uses these to keep track of conditional nesting when skipping to \else or \fi).

 

If defined by $code, the form is "CODE($gullet,@args)" and it must return a list of LaTeXML::Token's.

"DefMacroI($cs,$paramlist,$string | $tokens | $code,%options);"

Internal form of "DefMacro" where the control sequence and parameter list have already been parsed; useful for definitions from within code. Also, slightly more efficient for macros with no arguments (use "undef" for $paramlist).

Primitives

"DefPrimitive($prototype,CODE($stomach,@args),%options);"

Define a primitive control sequence. These are usually done for side effect and so CODE should end with "return;", but can also return a list of digested items.

 

The only option is for the special case: "isPrefix=>1" is used for assignment prefixes (like \global).

"DefPrimitiveI($cs,$paramlist,CODE($stomach,@args),%options);"

Internal form of "DefPrimitive" where the control sequence and parameter list have already been parsed; useful for definitions from within code.

"DefRegister($prototype,$value,%options);"

Defines a register with the given initial value (a Number, Dimension, Glue, MuGlue or Tokens --- I haven't handled Box's yet). Usually, the $prototype is just the control sequence, but registers are also handled by prototypes like "\count{Number}". "DefRegister" arranges that the register value can be accessed when a numeric, dimension, ... value is being read, and also defines the control sequence for assignment.

 

Options are

"DefRegisterI($cs,$paramlist,$value,%options);"

Internal form of "DefRegister" where the control sequence and parameter list have already been parsed; useful for definitions from within code.

Constructors

"DefConstructor($prototype,$xmlpattern | $code,%options);"

The Constructor is where LaTeXML really starts getting interesting; invoking the control sequence will generate an arbitrary XML fragment in the document tree. More specifically: during digestion, the arguments will be read and digested, creating a LaTeXML::Whatsit to represent the object. During absorbtion by the LaTeXML::Document, the "Whatsit" will generate the XML fragment according to the replacement $xmlpattern, or by executing "CODE".

 

The $xmlpattern is simply a bit of XML as a string with certain substitutions to be made. The substitutions are of the following forms:

 

If code is supplied, the form is "CODE($document,@args,%properties)"

"DefConstructorI($cs,$paramlist,$xmlpattern | $code,%options);"

Internal form of "DefConstructor" where the control sequence and parameter list have already been parsed; useful for definitions from within code.

"DefMath($prototype,$tex,%options);"

A common shorthand constructor; it defines a control sequence that creates a mathematical object, such as a symbol, function or operator application. The options given can effectively create semantic macros that contribute to the eventual parsing of mathematical content. In particular, it generates an XMDual using the replacement $tex for the presentation. The content information is drawn from the name and options

 

These "DefConstructor" options also apply:

 

  reversion, alias, beforeDigest, afterDigest,
  beforeConstruct, afterConstruct and scope.
    

 

Additionally, it accepts

"DefMathI($cs,$paramlist,$tex,%options);"

Internal form of "DefMath" where the control sequence and parameter list have already been parsed; useful for definitions from within code.

"DefEnvironment($prototype,$replacement,%options);"

Defines an Environment that generates a specific XML fragment. The $replacement is of the same form as that for DefConstructor, but will generally include reference to the "#body" property. Upon encountering a "\begin{env}": the mode is switched, if needed, else a new group is opened; then the environment name is noted; the beforeDigest daemon is run. Then the Whatsit representing the begin command (but ultimately the whole environment) is created and the afterDigestBegin daemon is run. Next, the body will be digested and collected until the balancing "\end{env}". Then, any afterDigest daemon is run, the environment is ended, finally the mode is ended or the group is closed. The body and "\end{env}" whatsit are added to the "\begin{env}"'s whatsit as body and trailer, respectively.

 

It shares options with "DefConstructor":

 

 mode, requireMath, forbidMath, properties, nargs,
 font, beforeDigest, afterDigest, beforeConstruct, 
 afterConstruct and scope.
    

 

Additionally, "afterDigestBegin" is effectively an "afterDigest" for the "\begin{env}" control sequence.

"DefEnvironmentI($name,$paramlist,$replacement,%options);"

Internal form of "DefEnvironment" where the control sequence and parameter list have already been parsed; useful for definitions from within code.

Class and Packages¶

"RequirePackage($package,%options);"

Finds and loads a package implementation (usually "*.sty.ltxml", unless "raw" is specified) for the required $package. The options are:

"LoadClass($class,%options);"

Finds and loads a class definition (usually "*.cls.ltxml"). The only option is

"FindFile($name,%options);"

Find an appropriate file with the given $name in the current directories in "SEARCHPATHS". If a file ending with ".ltxml" is found, it will be preferred. The options are:

"DeclareOption($option,$code);"

Declares an option for the current package or class. The $code can be a string or Tokens (which will be macro expanded), or can be a code reference which is treated as a primitive.

 

If a package or class wants to accomodate options, it should start with one or more "DeclareOptions", followed by "ProcessOptions()".

"PassOptions($name,$ext,@options);"

Causes the given @options (strings) to be passed to the package (if $ext is "sty") or class (if $ext is "cls") named by $name.

"ProcessOptions();"

Processes the options that have been passed to the current package or class in a fashion similar to LaTeX. If the keyword "inorder=>1" is given, the options are processed in the order they were used, like "ProcessOptions*".

"ExecuteOptions(@options);"

Process the options given explicitly in @options.

Counters and IDs¶

"NewCounter($ctr,$within,%options);"

Defines a new counter, like LaTeX's \newcounter, but extended. It defines a counter that can be used to generate reference numbers, and defines \the$ctr, etc. It also defines an "uncounter" which can be used to generate ID's (xml:id) for unnumbered objects. $ctr is the name of the counter. If defined, $within is the name of another counter which, when incremented, will cause this counter to be reset. The options are

 

   idprefix  Specifies a prefix to be used to generate ID's
             when using this counter
   nested    Not sure that this is even sane.
    

"$num = CounterValue($ctr);"

Fetches the value associated with the counter $ctr.

"$tokens = StepCounter($ctr);"

Analog of "\stepcounter", steps the counter and returns the expansion of "\the$ctr". Usually you should use "RefStepCounter($ctr)" instead.

"$keys = RefStepCounter($ctr);"

Analog of "\refstepcounter", steps the counter and returns a hash containing the keys "refnum="$refnum, id=>$id>. This makes it suitable for use in a "properties" option to constructors. The "id" is generated in parallel with the reference number to assist debugging.

"$keys = RefStepID($ctr);"

Like to "RefStepCounter", but only steps the "uncounter", and returns only the id; This is useful for unnumbered cases of objects that normally get both a refnum and id.

"ResetCounter($ctr);"

Resets the counter $ctr to zero.

"GenerateID($document,$node,$whatsit,$prefix);"

Generates an ID for nodes during the construction phase, useful for cases where the counter based scheme is inappropriate. The calling pattern makes it appropriate for use in Tag, as in
Tag('ltx:para',sub { GenerateID(@_,'p'); })

 

If $node doesn't already have an xml:id set, it computes an appropriate id by concatenating the xml:id of the closest ancestor with an id (if any), the prefix and a unique counter.

Document Model¶

Constructors define how TeX markup will generate XML fragments, but the Document Model is used to control exactly how those fragments are assembled.

"Tag($tag,%properties);"

Declares properties of elements with the name $tag.

 

The recognized properties are:

"RelaxNGSchema($schemaname);"

Specifies the schema to use for determining document model. You can leave off the extension; it will look for ".rng", and maybe eventually, ".rnc" once that is implemented.

"RegisterNamespace($prefix,$URL);"

Declares the $prefix to be associated with the given $URL. These prefixes may be used in ltxml files, particularly for constructors, xpath expressions, etc. They are not necessarily the same as the prefixes that will be used in the generated document (See DocType).

"DocType($rootelement,$publicid,$systemid,%namespaces);"

Declares the expected rootelement, the public and system ID's of the document type to be used in the final document. The hash %namespaces specifies the namespaces prefixes that are expected to be found in the DTD, along with each associated namespace URI. Use the prefix "#default" for the default namespace (ie. the namespace of non-prefixed elements in the DTD).

 

The prefixes defined for the DTD may be different from the prefixes used in implementation CODE (eg. in ltxml files; see RegisterNamespace). The generated document will use the namespaces and prefixes defined for the DTD.

Document Rewriting¶

During document construction, as each node gets closed, the text content gets simplfied. We'll call it applying ligatures, for lack of a better name.

"DefLigature($regexp,%options);"

Apply the regular expression (given as a string: "/fa/fa/" since it will be converted internally to a true regexp), to the text content. The only option is "fontTest=CODE($font)"; if given, then the substitution is applied only when "fontTest" returns true.

 

Predefined Ligatures combine sequences of "." or single-quotes into appropriate Unicode characters.

"DefMathLigature(CODE($document,@nodes));"

CODE is called on each sequence of math nodes at a given level. If they should be replaced, return a list of "($n,$string,%attributes)" to replace the text content of the first node with $string content and add the given attributes. The next "$n-1" nodes are removed. If no replacement is called for, CODE should return undef.

 

Predefined Math Ligatures combine letter or digit Math Tokens (XMTok) into multicharacter symbols or numbers, depending on the font (non math italic).

After document construction, various rewriting and augmenting of the document can take place.

"DefRewrite(%specification);"

"DefMathRewrite(%specification);"

These two declarations define document rewrite rules that are applied to the document tree after it has been constructed, but before math parsing, or any other postprocessing, is done. The %specification consists of a seqeuence of key/value pairs with the initial specs successively narrowing the selection of document nodes, and the remaining specs indicating how to modify or replace the selected nodes.

 

The following select portions of the document:

Mid-Level support¶

"$tokens = Expand($tokens);"

Expands the given $tokens according to current definitions.

"$boxes = Digest($tokens);"

Processes and digestes the $tokens. Any arguments needed by control sequences in $tokens must be contained within the $tokens itself.

"@tokens = Invocation($cs,@args);"

Constructs a sequence of tokens that would invoke the token $cs on the arguments.

"RawTeX('... tex code ...');"

RawTeX is a convenience function for including chunks of raw TeX (or LaTeX) code in a Package implementation. It is useful for copying portions of the normal implementation that can be handled simply using macros and primitives.

"Let($token1,$token2);"

Gives $token1 the same `meaning' (definition) as $token2; like TeX's \let.

Argument Readers¶

"ReadParameters($gullet,$spec);"

Reads from $gullet the tokens corresponding to $spec (a Parameters object).

"DefParameterType($type,CODE($gullet,@values),%options);"

Defines a new Parameter type, $type, with CODE for its reader.

 

Options are:

"DefColumnType($proto,$expansion);"

Defines a new column type for tabular and arrays. $proto is the prototype for the pattern, analogous to the pattern used for other definitions, except that macro being defined is a single character. The $expansion is a string specifying what it should expand into, typically more verbose column specification.

Access to State¶

"$value = LookupValue($name);"

Lookup the current value associated with the the string $name.

"AssignValue($name,$value,$scope);"

Assign $value to be associated with the the string $name, according to the given scoping rule.

 

Values are also used to specify most configuration parameters (which can therefor also be scoped). The recognized configuration parameters are:

 

 VERBOSITY         : the level of verbosity for debugging
                     output, with 0 being default.
 STRICT            : whether errors (eg. undefined macros)
                     are fatal.
 INCLUDE_COMMENTS  : whether to preserve comments in the
                     source, and to add occasional line
                     number comments. (Default true).
 PRESERVE_NEWLINES : whether newlines in the source should
                     be preserved (not 100% TeX-like).
                     By default this is true.
 SEARCHPATHS       : a list of directories to search for
                     sources, implementations, etc.
    

"PushValue($type,$name,@values);"

This is like "AssignValue", but pushes values onto the end of the value, which should be a LIST reference. Scoping is not handled here (yet?), it simply pushes the value onto the last binding of $name.

"UnshiftValue($type,$name,@values);"

Similar to "PushValue", but pushes a value onto the front of the values, which should be a LIST reference.

"$value = LookupCatcode($char);"

Lookup the current catcode associated with the the character $char.

"AssignCatcode($char,$catcode,$scope);"

Set $char to have the given $catcode, with the assignment made according to the given scoping rule.

 

This method is also used to specify whether a given character is active in math mode, by using "math:$char" for the character, and using a value of 1 to specify that it is active.

"$meaning = LookupMeaning($token);"

Looks up the current meaning of the given $token which may be a Definition, another token, or the token itself if it has not otherwise been defined.

"$defn = LookupDefinition($token);"

Looks up the current definition, if any, of the $token.

"InstallDefinition($defn);"

Install the Definition $defn into $STATE under its control sequence.

Low-level Functions¶

"CleanLabel($label,$prefix);"

Cleans a $label of disallowed characters, prepending $prefix (or "LABEL", if none given).

"CleanIndexKey($key);"

Cleans an index key, so it can be used as an ID.

"CleanBibKey($key);"

Cleans a bibliographic citation key, so it can be used as an ID.

"CleanURL($url);"

Cleans a url.

"UTF($code);"

Generates a UTF character, handy for the the 8 bit characters. For example, "UTF(0xA0)" generates the non-breaking space.

"MergeFont(%style);"

Set the current font by merging the font style attributes with the current font. The attributes and likely values (the values aren't required to be in this set):

 

 family : serif, sansserif, typewriter, caligraphic,
          fraktur, script
 series : medium, bold
 shape  : upright, italic, slanted, smallcaps
 size   : tiny, footnote, small, normal, large,
          Large, LARGE, huge, Huge
 color  : any named color, default is black
    

 

Some families will only be used in math. This function returns nothing so it can be easily used in beforeDigest, afterDigest.

"@tokens = roman($number);"

Formats the $number in (lowercase) roman numerals, returning a list of the tokens.

"@tokens = Roman($number);"

Formats the $number in (uppercase) roman numerals, returning a list of the tokens.

AUTHOR¶

Bruce Miller <bruce.miller@nist.gov>

COPYRIGHT¶

Public domain software, produced as part of work done by the United States Government & not subject to copyright in the US.