web2js

This is a Pascal compiler that targets WebAssembly, designed specifically to compile TeX.

Getting started

The following assumes you have TeX running on your machine (e.g., that tangle is available), and that you have the necessary TeX files installed on your system.

A quick path to generate the tex.wasm and core.dump files is

npm install
npm run build

Note that this is known to work with TeXLive 2023. A Dockerfile is included that provides a compatible Ubuntu 24.04 system to work with. To build and run the docker container execute the following.

docker build -t web2js .
docker run -it --rm -v `pwd`:/opt/web2js web2js

Inside the container execute npm run build to generate the tex.wasm and core.dump files.

More details on the build process are below.

Install node modules.

npm install

Generate the Pascal parser.

npm run build:parser

The contents of the texk and etexdir subdirectories were simply copied from tug.org via

mkdir texk
rsync -a --delete --exclude=.svn tug.org::tldevsrc/Build/source/texk/web2c/tex.web texk
rsync -a --delete --exclude=.svn tug.org::tldevsrc/Build/source/texk/web2c/etexdir .

Tie the TeX WEB source and e-TeX change file.

tie -m tex.web texk/tex.web etexdir/etex.ch date.ch tex-final-end.ch

Produce the Pascal source by tangling.

tangle -underline tex.web etex.sys

You will now have the Pascal source tex.p along with tex.pool which contains the strings.

Compile the tex.p sources to get the WebAssembly binary out.wasm.

node compile.js tex.p out.wasm

The above three commands can all be run with

npm run build:wasm

Then optimize and asyncify the wasm binary by running

wasm-opt --asyncify --pass-arg=asyncify-ignore-indirect \
  [email protected],library.getfilesize -O4 out.wasm -o tex.wasm

Note that if you want to unwind/rewind other imports in the library, add the imports to the asyncify-imports part in the above command.

Produce the memory dump corresponding to the WebAssembly binary.

node initex.js

To test the assembly and core dump run

node tex.js tex_packages/pgfplots.tex

Remove \\def\\pgfsysdriver{pgfsys-ximera.def} from initex.js, re-run node initex.js, and compile tex_packages/pgfplots.tex by running

node tex.js tex_packages/pgfplots.tex

This will output tex_packages/pgfplots.dvi. Convert to pdf to view using dvipdf (or dvips and ps2pdf).

Alternately change

library.setInput("\n&latex\n\\documentclass...\n\n",

in initex.js to

library.setInput("\n&latex\n\n",

to generate a general latex compiler. To use it uncomment the first two lines of tex_packages/pgfplots.tex.tex, and run

node tex.js tex_packages/pgfplots.tex