tex-fast-recompile 0.4.0

A Python module to speed up TeX compilation.

tex-fast-recompile

A Python module to speed up TeX compilation.

This is similar to the mylatexformat TeX package that it works by "speed up" some "preamble", but unlike using "precompiled preamble" i.e. custom TeX format, this package works with every package including package that executes some Lua code, or load OpenType font.

Installation

It can be installed from PyPI or GitHub:

• https://pypi.org/project/tex-fast-recompile/
• https://github.com/user202729/tex-fast-recompile

You also need to install the helper TeX package fastrecompile.sty, which can be found in the tex/ directory. Refer to https://tex.stackexchange.com/q/1137/250119 for installation instruction.

(currently the TeX package is not available on CTAN)

Usage

Normal mode

If installed properly, an executable tex_fast_recompile should be available on your command-line.

Run tex_fast_recompile --help to view the available options.

For example you can use it as follows:

tex_fast_recompile pdflatex a.tex

to compile a.tex to a.pdf and automatically watch it on changes.

Usually prepending it to your LaTeX compilation command suffices.

LaTeXmk emulation mode

For compatibility with e.g. vimtex plugin, an executable tex_fast_recompile_latexmk is provided, which takes arguments similar to that of latexmk. (but it does not do multiple compilation passes or invoke bibliography/indexing commands etc., and the simulation might not be complete)

Run tex_fast_recompile_latexmk --help to view the available options. (should be similar to latexmk's accepted options)

For VimTeX usage, putting the following configuration in .vimrc usually suffices:

let g:vimtex_compiler_method='latexmk'
let g:vimtex_compiler_latexmk = { 'executable' : 'tex_fast_recompile_latexmk' }

Limitations

• Any file \input in the preamble must not be changed. (when the preamble changes, the program will automatically detect that)
• You must not read from the terminal anywhere in the preamble, such as with functions \read -1 to ... or \ior_get_term:nN .... (if you're not sure what this mean, you should be safe)

Advanced notes

Extra note

If you want to read the log file, refer to the help of --copy-log option.

It's possible to print out some content in the "preamble" part, but if you do so...

\documentclass{article}
\usepackage{fastrecompile}  % add the package here
% other preamble lines...
\begin{document}

123
\clearpage
\fastrecompileendpreamble
456

\end{document}

you must also use the --copy-output option if you want to view the resulting PDF.

--no-add-package mode

Behind the scene, some magic is done on your TeX file.

If you want to do that manually, you need to modify your TeX file as follows:

\documentclass{article}
\usepackage{fastrecompile}  % manually add the package here
% other preamble lines...
\begin{document}

% put the line below where the preamble ends:
\fastrecompileendpreamble

...

\end{document}

then compile your document with --no-add-package flag added.

Note that:

• \fastrecompileendpreamble must appear exactly once in the main file.
• There must be nothing else on the line that contains \fastrecompileendpreamble.
• SyncTeX features of the text part in the "preamble" may not be correct.

How does it work?

The principle is very simple. Notice that while the user want fast refresh, the file does not change very frequently.

As such, we start the compiler before the file has changed to process the "preamble", then when the file changed we continue processing the rest of the file.

A graph for illustration:

Before:

(each * represents a file change, |--.--| represents a compilation where the . marks where the preamble processing is done)

+----------------------------------------------------> Time
     *          *                *           *
     |--.--|    |--.--|          |--.--|     |--.--|

After:

+----------------------------------------------------> Time
     *          *                *           *
     |--.--|--. --|--.           --|--.      --|

It can be easily seen that after the change, it only takes 2 instead of 5 time units from when the file is saved to when the change is reflected in the PDF.