# `lgtdoc`

This is the default Logtalk documenting tool for generating API documentation for libraries and applications. It uses the structural reflection API to extract and output in XML format relevant documentation about a source file, a library or directory of source files, or all loaded source files. The tool predicates accept several options for generating the XML files, including the output directory.

The `lgtdoc/xml` directory contains several ready-to-use Bash and PowerShell scripts for converting the XML documenting files into final formats, including (X)HTML, PDF, Markdown, and reStructuredText (for use with Sphinx), and plain text files. The scripts are described in their `man` pages and made available in the system path by default.

## Requirements

This tool requirements for converting the XML files it generates to a final format are as follows:

1. Converting XML files to (X)HTML, reStructuredText, Markdown, or plain text files requires a XSLT processor. The supported XSLT processors for Bash conversion scripts are:

- xsltproc: https://gitlab.gnome.org/GNOME/libxslt/-/wikis/home

- Xalan: https://xml.apache.org/xalan-c/index.html

- Saxon: https://www.saxonica.com

On Windows, the PowerShell scripts use the .Net XSLT classes.

The reStructuredText files output is usually used as an intermediate step to generate Sphinx HTML, PDF, ePub, and Texinfo files. The additional requirements are:

- Sphinx: https://www.sphinx-doc.org/

- Pygments: https://pygments.org/

- Read the Docs theme: https://github.com/readthedocs/sphinx_rtd_theme

2. Converting XML files to PDF files require a XSL-FO processor. The supported XSL-FO processors for Bash and PowerShell conversion scripts are:

- Apache FOP processor: https://xmlgraphics.apache.org/fop/

- RenderX XEP processor: https://www.renderx.com/

For additional details, including compatible dependency versions and available conversion scripts, see the `xml/NOTES.md` file. See the `tools/NOTES.md` file for per operating-system installation instructions for the above dependencies.

## API documentation

This tool API documentation is available at:

../../apis/library_index.html#lgtdoc

## Loading

This tool can be loaded using the query:

    | ?- logtalk_load(lgtdoc(loader)).

## Testing

To test this tool, load the `tester.lgt` file:

    | ?- logtalk_load(lgtdoc(tester)).

## Documenting source code

For information on documenting your source code, notably on documenting directives, consult the documenting section of the User Manual:

../../handbook/userman/documenting.html

Extracting documenting information from your source code using this tool requires compiling the source files using the `source_data(on)` compiler flag. For example:

    | ?- logtalk_load(source_file, [source_data(on)]).

Usually, this flag is set for all application source files in the corresponding loader file. In alternative, you may also turn on the `source_data` flag globally by typing:

    | ?- set_logtalk_flag(source_data, on).

The tool API allows generating documentation for libraries, directories, and files, complemented with library, directory, entity, and predicate indexes. Note that the source files to be documented must be loaded prior to using this tool predicates to generate the documentation.

## Generating documentation

For a simple application, assuming a library alias is defined for it (e.g. `my_app`), and at the top-level interpreter, we can generate the application documentation by typing:

    | ?- {my_app(loader)}.
    ...

    | ?- {lgtdoc(loader)}.
    ...

    | ?- lgtdoc::library(my_app).
    ...

By default, the documenting XML files are created in a `xml_docs` directory in the current working directory. But usually all documenting files are collected for both the application and the libraries it uses in a common directory so that all documentation links resolved properly. The `lgtdoc` predicates can take a list of options to customize the generated XML documenting files. See the remarks section in the lgtdocp protocol documentation for details on the available options.

After generating the XML documenting files, these can be easily converted into final formats using the provided scripts. For example, assuming that we want to generate HTML documentation:

    $ cd xml_docs
    $ lgt2html -t "My app"

To generate the documentation in Sphinx format instead (as used by Logtalk itself for its APIs):

    $ cd xml_docs
    $ lgt2rst -s -- -q -p "Application name" -a "Author name" -v "Version X.YZ.P"
    $ make html

In this case, the generated documentation will be in the `xml_docs/_build/html/` directory. See the scripts man pages or call them using the `-h` option to learn more about their supported options.

For more complex applications, you can use the `doclet` tool to define a doclet to automate all the steps required to generate documentation. The doclet message that triggers the process can also be sent automatically when the `make` tool is used with the `documentation` target.

## Documentation linter checks

When the `lgtdoc_missing_directives` flag is set to `warning` (its usual default value), the `lgtdoc` tool prints warnings on missing entity `info/1` directives and missing predicate `info/2` and `mode/2` directives.

When the `lgtdoc_missing_info_key` flag is set to `warning` (its usual default value), the `lgtdoc` tool prints warnings on entity `info/1` directive and predicate `info/2` directive missing de facto required keys (e.g., `comment`, `parameters` or `parnames` for parametric entities, `arguments` or `argnames` for predicates/non-terminals with arguments).

When the `lgtdoc_invalid_dates` flag is set to `warning` (its usual default value), the `lgtdoc` tool prints warnings on invalid dates (including dates in the future) in `info/1` directives.

When the `lgtdoc_non_standard_exceptions` flag is set to `warning` (its usual default value), the `lgtdoc` tool prints warnings on non-standard exceptions. This linter check is particularly effective in detecting typos when specifying standard exceptions.

When the `lgtdoc_missing_punctuation` flag is set to `warning` (its usual default value), the `lgtdoc` tool prints warnings on missing ending periods (full stops), exclamation marks, or question marks in `info/1-2` directives (in comments, remarks, parameter descriptions, and argument descriptions).

Set a flag value to `silent` to turn off the corresponding linter warnings.