Locale::Po4a::TeX(3) convert TeX documents and derivates from/to PO files

## DESCRIPTION

The po4a (PO for anything) project goal is to ease translations (and more interestingly, the maintenance of translations) using gettext tools on areas where they were not expected like documentation.

Locale::Po4a::TeX is a module to help the translation of TeX documents into other [human] languages. It can also be used as a base to build modules for TeX-based documents.

Users should probably use the LaTeX module, which inherite from the TeX module and contains the definitions of common LaTeX commands.

## TRANSLATING WITH PO4A::TEX

This module can be used directly to handle generic TeX documents. This will split your document in smaller blocks (paragraphs, verbatim blocks, or even smaller like titles or indexes).

There are some options (described in the next section) that can customize this behavior. If this doesn't fit to your document format you're encouraged to write your own module derived from this, to describe your format's details. See the section WRITING DERIVATE MODULES below, for the process description.

This module can also be customized by lines starting with % po4a:'' in the TeX file. These customizations are described in the INLINE CUSTOMIZATION section.

## OPTIONS ACCEPTED BY THIS MODULE

These are this module's particular options:
debug
Activate debugging for some internal mechanisms of this module. Use the source to see which parts can be debugged.
no_wrap
Comma-separated list of environments which should not be re-wrapped.

Note that there is a difference between verbatim and no_wrap environments. There is no command and comments analysis in verbatim blocks.

If this environment was not already registered, po4a will consider that this environment does not take any parameters.

exclude_include
Colon-separated list of files that should not be included by \input and \include.
definitions
The name of a file containing definitions for po4a, as defined in the INLINE CUSTOMIZATION section. You can use this option if it is not possible to put the definitions in the document being translated.
verbatim
Comma-separated list of environments which should be taken as verbatim.

If this environment was not already registered, po4a will consider that this environment does not take any parameters.

Using these options permits to override the behaviour of the commands defined in the default lists.

## INLINE CUSTOMIZATION

The TeX module can be customized with lines starting by % po4a:. These lines are interpreted as commands to the parser. The following commands are recognized:
% po4a: command command1 alias command2
Indicates that the arguments of the command1 command should be treated as the arguments of the command2 command.
% po4a: command command1 parameters
This permit to describe in detail the parameters of the command1 command. This information will be used to check the number of arguments and their types.

You can precede the command1 command by

an asterisk (*)
po4a will extract this command from paragraphs (if it is located at the beginning or the end of a paragraph). The translators will then have to translate the parameters that are marked as translatable.
a plus (+)
As for an asterisk, the command will be extracted if it appear at an extremity of a block, but the parameters won't be translated separately. The translator will have to translate the command concatenated to all its parameters. This permits to keep more context, and is useful for commands with small words in parameter, which can have multiple meanings (and translations).

Note: In this case you don't have to specify which parameters are translatable, but po4a must know the type and number of parameters.

a minus (-)
In this case, the command won't be extracted from any block. But if it appears alone on a block, then only the parameters marked as translatable will be presented to the translator. This is useful for font commands. These commands should generally not be separated from their paragraph (to keep the context), but there is no reason to annoy the translator with them if a whole string is enclosed in such a command.

The parameters argument is a set of [] (to indicate an optional argument) or {} (to indicate a mandatory argument). You can place an underscore (_) between these brackets to indicate that the parameter must be translated. For example:
% po4a: command *chapter [_]{_}

This indicates that the chapter command has two parameters: an optional (short title) and a mandatory one, which must both be translated. If you want to specify that the href command has two mandatory parameters, that you don't want to translate the URL (first parameter), and that you don't want this command to be separated from its paragraph (which allow the translator to move the link in the sentence), you can use:
% po4a: command -href {}{_}

In this case, the information indicating which arguments must be translated is only used if a paragraph is only composed of this href command.

% po4a: environment env parameters
This permits to define the parameters accepted by the env environment. This information is latter used to check the number of arguments of the \begin command, and permit to specify which one must be translated. The syntax of the parameters argument is the same as described for the ??? commands. The first parameter of the \begin command is the name of the environment. This parameter must not be specified in the list of parameters. Here are some examples:
% po4a: environment multicols {}
% po4a: environment equation

As for the commands, env can be preceded by a plus (+) to indicate that the \begin command must be translated with all its arguments.

% po4a: separator env "regex"
Indicates that an environment should be split according to the given regular expression.

The regular expression is delimited by quotes. It should not create any backreference. You should use (?:) if you need a group. It may also need some escapes.

For example, the LaTeX module uses the (?:&|\\\\)'' regular expression to translate separately each cell of a table (lines are separated by '\\' and cells by '&').

The notion of environment is expended to the type displayed in the PO file. This can be used to split on \\\\'' in the first mandatory argument of the title command. In this case, the environment is title{#1}.

% po4a: verbatim environment env
Indicate that env is a verbatim environment. Comments and commands will be ignored in this environment.

If this environment was not already registered, po4a will consider that this environment does not take any parameters.

## WRITING DERIVATE MODULES

pre_trans
post_trans
translate
Wrapper around Transtractor's translate, with pre- and post-processing filters.

Comments of a paragraph are inserted as a PO comment for the first translated string of this paragraph.

get_leading_command($buffer) This function returns: A command name If no command is found at the beginning of the given buffer, this string will be empty. Only commands that can be separated are considered. The %separated_command hash contains the list of these commands. A variant This indicates if a variant is used. For example, an asterisk (*) can be added at the end of sections command to specify that they should not be numbered. In this case, this field will contain *''. If there is no variant, the field is an empty string. An array of tuples (type of argument, argument) The type of argument can be either '{' (for mandatory arguments) or '[' (for optional arguments). The remaining buffer The rest of the buffer after the removal of this leading command and its arguments. If no command is found, the original buffer is not touched and returned in this field. get_trailing_command($buffer)
The same as get_leading_command, but for commands at the end of a buffer.
translate_buffer
Recursively translate a buffer by separating leading and trailing commands (those which should be translated separately) from the buffer.

If a function is defined in %translate_buffer_env for the current environment, this function will be used to translate the buffer instead of translate_buffer().

Recursively read a file, appending included files which are not listed in the @exclude_include array. Included files are searched using the kpsewhich command from the Kpathsea library.

Except from the file inclusion part, it is a cut and paste from Transtractor's read.

parse_definition_file
Subroutine for parsing a file with po4a directives (definitions for new commands).
parse_definition_line
Parse a definition line of the form % po4a: ''.

See the INLINE CUSTOMIZATION section for more details.

is_closed
parse

## INTERNAL FUNCTIONS used to write derivated parsers

Command and environment functions take the following arguments (in addition to the \$self object):
A command name
A variant
An array of (type, argument) tuples
The current environment

The first 3 arguments are extracted by get_leading_command or get_trailing_command.

Command and environment functions return the translation of the command with its arguments and a new environment.

Environment functions are called when a \begin command is found. They are called with the \begin command and its arguments.

The TeX module only proposes one command function and one environment function: generic_command and generic_environment.

generic_command uses the information specified by register_generic_command or by adding definition to the TeX file:
% po4a: command command1 parameters

generic_environment uses the information specified by register_generic_environment or by adding definition to the TeX file:
% po4a: environment env parameters

Both functions will only translate the parameters that were specified as translatable (with a '_'). generic_environment will append the name of the environment to the environment stack and generic_command will append the name of the command followed by an identifier of the parameter (like {#7} or [#2]).

## STATUS OF THIS MODULE

This module needs more tests.

It was tested on a book and with the Python documentation.

## TODO LIST

Automatic detection of new commands
The TeX module could parse the newcommand arguments and try to guess the number of arguments, their type and whether or not they should be translated.
Translation of the environment separator
When \item is used as an environment separator, the item argument is attached to the following string.
Some commands should be added to the environment stack
These commands should be specified by couples. This could allow to specify commands beginning or ending a verbatim environment.
Others
Various other points are tagged TODO in the source.

## KNOWN BUGS

Various points are tagged FIXME in the source.

## AUTHORS

Nicolas François <[email protected]>