dwml-ts

Convert MS Office OMML (Office Math Markup Language, the <m:oMath> markup used in .docx / .pptx / .xlsx) to LaTeX — in TypeScript.

A faithful port of the Python dwml library with 100% output fidelity on its reference fixtures, hardened for real-world OOXML import pipelines (PowerPoint, Word).

• Pure, synchronous, deterministic — no async, no config singletons.
• DOM-free — runs identically in the browser bundle and in Node. No DOMParser / XMLSerializer / xmldom.
• One tiny runtime dep: txml for parsing (which PPTist already ships — zero new bytes).
• Never throws on unknown constructs — degrades per-node to concatenated text content, so one odd <m:oMath> can't kill a whole paragraph import.

Install

npm install dwml-ts

API

All output is bare LaTeX — no $/$$ delimiters, no trailing whitespace. The caller decides inline vs. display math (e.g. PPTist wraps it in its own span.pptist-math[data-latex] element).

ommlToLatex(xml, options?): string

Convert one OMML fragment to bare LaTeX. Accepts <m:oMath>, <m:oMathPara> or the <a14:m> wrapper as an XML string, and tolerates missing xmlns declarations (fragments sliced out of slide XML where the namespace lives on a root you don't have).

import { ommlToLatex } from 'dwml-ts';

ommlToLatex('<m:oMath><m:r><m:t>x+1</m:t></m:r></m:oMath>');
// => 'x+1'

ommlToLatex('<m:oMath><m:rad><m:radPr><m:degHide m:val="1"/></m:radPr><m:deg/><m:e><m:r><m:t>5</m:t></m:r></m:e></m:rad></m:oMath>');
// => '\\sqrt{5}'

ommlNodeToLatex(node, options?): string

Node-level entry: convert an already-parsed txml TNode. This is the important one for import pipelines — walk each <a:p> of the slide XML yourself to preserve run order (text run → math → text run), and pass math nodes straight in. One parse per slide, no re-parsing fragments.

import { parse } from 'txml';
import { ommlNodeToLatex } from 'dwml-ts';

const nodes = parse(slideXml);
// ... find the <m:oMath> node(s) you care about, then:
const latex = ommlNodeToLatex(omathNode);

extractOmmlLatex(xml, options?): string[]

Batch: find and convert every <m:oMath> in any OOXML document/fragment, returning one bare LaTeX string per formula, in document order.

import { extractOmmlLatex } from 'dwml-ts';

const [first, second] = extractOmmlLatex(documentXml);

OmmlToLatexOptions

export interface OmmlToLatexOptions {
  /** Called once per element local-name the converter had to degrade. */
  onUnsupported?: (localName: string) => void;
}

Behavior guarantees

| Guarantee | Notes | | --- | --- | | Bare LaTeX out | No delimiters, no trailing whitespace. | | Never throws | Unknown constructs degrade per-node to concatenated text (m:borderBox, m:phant, unknown m:fName, unknown m:limLow base, …). A dropped \frac bar is recoverable; an exception is not. | | Namespace by local name | Matches oMath / f / r / … regardless of prefix (m:, none, or re-prefixed). Real-world producers vary. | | Namespace-agnostic attributes | m:val / val / re-prefixed attributes resolve by local name. |

Supported OMML constructs

m:oMath / m:oMathPara / <a14:m> wrappers, and:

• Runs — m:r / m:t with Unicode→LaTeX symbol mapping (see below)
• Fractions — m:f with m:fPr types bar (default, \frac), skw (^{n}/_{d}), noBar (\genfrac, binomial), lin ({n}/{d})
• Scripts — m:sSub, m:sSup, m:sSubSup (and m:sPre, degraded)
• Radicals — m:rad with m:deg and degHide (\sqrt, \sqrt[n])
• N-ary — m:nary (\sum, \int, \prod, … via CHR_BO)
• Delimiters — m:d with begChr / endChr / sepChr (\left…\right)
• Functions — m:func / m:fName (\sin, \cos, \log, \ln, …)
• Accents — m:acc (\hat, \tilde, \vec, … via CHR)
• Bars — m:bar (\overline / \underline)
• Limits — m:limLow (\lim_{…}), m:limUpp (\overset)
• Matrix — m:m / m:mr (\begin{matrix}…\end{matrix})
• Equation array — m:eqArr (\begin{array}{c}…\end{array})
• Group char — m:groupChr (\overbrace, \underbrace, …)
• Box — m:box (passthrough)

Unicode → LaTeX mapping

Run text is mapped to LaTeX with a two-tier lookup (per Unicode code point, so astral-plane Mathematical Alphanumeric Symbols are handled correctly):

1. dwml's symbol table (src/latex-dict.ts) — Mathematical Alphanumeric Symbols U+1D400–U+1D7FF → ASCII (𝐴→A, 𝑥→x), Greek (π→\pi, both plain U+03B1.. and math-italic U+1D6FC..), relation/operator symbols (≤→\leq, ≥→\geq, ≠→\ne, ·→\cdot, ×→\times, ∞→\infty, →→\rightarrow, …).
2. Verbatim Unicode — everything else is kept as-is (světlo → světlo, € → €). OMML is Unicode-native and math renderers (MathLive, KaTeX, unicode-math) accept Unicode identifiers/symbols in math mode, whereas text-mode escapes (\v{e}, \ss, \textendash, \ensuremath{…}) are invalid inside an equation and lossy on the way back to OMML. A literal \ becomes {\backslash}.

LaTeX-special characters in runs (%, &, _, {, }, #, $, ~, ^) are escaped via dwml's escape_latex (a% → a\%).

unicodeToLatex() (the pylatexenc-derived text-mode encoder, src/uni2latex.generated.ts) is still exported for consumers that need it, but is no longer used for run text.

Examples

| OMML input | LaTeX output | | --- | --- | | \sin(\sqrt[3]{x})^{x^{11}}/_{b}x_{m}^{n} fixture | \sin(\sqrt[3]{x})^{x^{11}}/_{b}x_{m}^{n} | | group fixture | A\overbrace{123}\underbrace{456}=\left\{a+b\right) | | matrix fixture | A=\left(\begin{matrix}1&2&3\\4&5&6\end{matrix}\right)\sum_{1}^{20}x | | no-bar fraction (binomial) | \left(x+a\right)^{n}=\sum_{k=0}^{n}\left(\genfrac{}{}{0pt}{}{n}{k}\right)x^{k}a^{n-k} |

Project layout

src/
  index.ts                 public API (ommlToLatex / ommlNodeToLatex / extractOmmlLatex)
  omml.ts                  the converter (never-throw, namespace-agnostic)
  latex-dict.ts            dwml symbol dictionaries
  latex-encode.ts          pylatexenc-derived unicode->latex encoder
  uni2latex.generated.ts   generated pylatexenc map (do not edit by hand)
tests/
  api.test.ts              consumer contract + dwml reference fidelity
  constructs.test.ts       per-construct coverage
  ground-truth.json        Python dwml reference outputs
reference/                 original Python sources (base + two forks + canonical merge)
scripts/
  gen_uni2latex.py         regenerate the unicode map from pylatexenc
  gen_ground_truth.py      regenerate tests/ground-truth.json from Python dwml

Development

npm install
npm test          # rstest
npm run build     # rslib -> dist/{index.js,index.d.ts} (ESM only)

# regenerate the unicode map / ground truth (requires Python + pylatexenc)
npm run gen:unicode
npm run gen:groundtruth

Attribution

• Port of dwml (Apache-2.0), incorporating fixes from the xavier-bw/dwml fork (log/ln functions) and bazingarj/OMML-to-Latex-py fork (whitespace-tolerant function names). Test fixtures under reference/tests-base/ are Apache-2.0, from the original project.
• The Unicode→LaTeX map is derived from pylatexenc (MIT, © Philippe Faist).

License

Apache-2.0