mathjax.cr

Русская версия

A Crystal port of the MathJax (v3) core: TeX / AsciiMath / MathML → internal MML tree → MathML / HTML / SVG.

Ported after the ts/ sources of mathjax-src and the MathJax v2 font data:

Inputs

• TeX parser (input/tex): tokenizer, {...} groups, ^/_ scripts, primes, the \frac family, generalized fractions (a \over b, \atop, \choose, \above, \genfrac), \sqrt/\root, \left...\right with \middle, environments (matrix/pmatrix/bmatrix/vmatrix/Vmatrix/cases/ array/aligned/...), fonts (\mathrm, \mathbf, \mathbb, ...), accents (\vec, \hat, \overline, \overrightarrow, ...), spacing, \text, \stackrel, \overbrace/\underbrace, \phantom, \boxed, big operators with limits (munderover, \limits/\nolimits), \def/ \newcommand macros (with #1..#9).
• Extensions: color (\color, \textcolor, \definecolor with rgb/RGB/gray/HTML/cmyk models, \colorbox, \fcolorbox), cancel (\cancel, \bcancel, \xcancel, \sout), a physics subset (\abs, \norm, \dv, \pdv, \dd, \bra, \ket, \braket, \mel, \comm, ... — enabled via physics: true / --physics).
• AsciiMath (an input/asciimath subset): a/b fractions, ^/_, greek names, sum/prod/int with limits, relations and arrows (<= >= != -> => <=>), sqrt, hat/bar/vec/ul(...), |x|, floor/ceil, [[a,b],[c,d]] matrices, "..." text.
• MathML input (input/mml): XML → tree (round-trips with the serializer).

Outputs

• MathML — tree serialization.
• HTML — a simplified CommonHTML analogue: spans + CSS (MathJax.css).
• SVG — typeset with real TeX font metrics: the glyph table (width/height/depth in em) is ported from MathJax font data (MathJax::Fonts, Main/Math/Size1–4, ~900 glyphs).

Not ported

a11y (SRE — a separate large system), CHTML/SVG with font glyph paths (the SVG output uses <text> and system fonts), the action, autobold, bbox, bussproofs, cancel color options, centernot, colortbl, empheq, extpfeil, gensymb, html, mathtools, mhchem, newcommand conditionals, noerrors configurations, upgreek, verb extensions and the full AMS table (~180 base commands covered).

Installation

dependencies:
  mathjax:
    git: https://github.com/OrelSokolov/mathjax.cr

Usage

require "mathjax"

MathJax.to_mathml("\\frac{1}{2}")                   # MathML
MathJax.to_mathml("x^2", display: true)
MathJax.to_html("\\sqrt{2}")                        # HTML + mjx-* classes
MathJax.to_svg("\\frac{a+b}{c}")                    # SVG with TeX metrics
MathJax.css                                         # CSS for the HTML output
MathJax.parse("\\sum_{i=1}^n i")                    # => MathJax::Mml::Node
MathJax.to_mathml("\\abs{x}", physics: true)        # physics extension
MathJax::Mml::Serializer.call(
  MathJax.parse_asciimath("sum_(i=1)^n i"))         # AsciiMath input
MathJax.from_mathml("<math>...</math>")             # MathML input
MathJax::Fonts.width('a', "math_italic")            # 0.529 (TeX metrics)

Parse errors: MathJax::TeX::TexError, MathJax::AsciiMath::AsciiMathError, MathJax::Mml::MathmlError.

CLI

crystal run src/cli.cr -- --html --display < formula.tex
crystal run src/cli.cr -- --svg < formula.tex
crystal run src/cli.cr -- --physics --mml <<< '\dv{f}{x}'
crystal run src/cli.cr -- --ascii --mml <<< 'sum_(i=1)^n i'
echo '\frac{-b\pm\sqrt{b^2-4ac}}{2a}' | crystal run src/cli.cr

Tests

crystal spec   # 83 examples, including dataset thresholds

Integration testing (1-to-1 against MathJax)

1000 TeX formulas from English Wikipedia are run through mathjax.cr and through real MathJax (mathjax-full); the MathML trees are compared after normalization (see test/datasets/REPORT.md):

• 99.3% of formulas parsed (993/1000);
• 99.1% structurally identical trees (990/999 comparable).

crystal run tools/compare.cr        # full report + diffs.txt
crystal run tools/dump_one.cr -- 91 # ours vs ref trees for formula #91

The dataset and the reference are rebuildable: tools/fetch_formulas.cr (Wikipedia API) and tools/make_reference.js (node + mathjax-full).

A golden SVG dataset (1000 formulas with expected output from the original MathJax v3) lives in dataset/ — see dataset/README.md.

Layout

src/mathjax.cr                 public API
src/mathjax/tex/{parser,symbols}.cr     TeX input (input/tex port)
src/mathjax/asciimath/parser.cr         AsciiMath input
src/mathjax/mml/                         MML tree, serializer, MathML input
src/mathjax/html/renderer.cr            HTML output
src/mathjax/svg/renderer.cr             SVG output (metrics-based)
src/mathjax/fonts/tex_metrics.cr        TeX font glyph table (generated)
vendor/                                  MathJax sources (reference only)

License

Apache-2.0 (as is MathJax itself). mathjax.cr is an independent Crystal implementation; the font metrics are taken from MathJax data (Apache-2.0).