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Dylan M. Taylor
d56a2a1cb3
The corpus equations go through OMML, MathML and LaTeX and back; the OMML samples are written back as kept and from the tree. GridCraft's OMML to LaTeX test cases (crates/xlsx/src/omml.rs) give LaTeX that reads back the same through the tree. omml::parse and read_str are tested against other prefixes, the strict namespace, kept OMML, junk, the element cap and deep nesting.
56 lines
2.8 KiB
Markdown
56 lines
2.8 KiB
Markdown
# craft-math
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Equations as one tree, and the syntaxes it is read from and written to:
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| Module | Syntax | Read | Write |
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| --- | --- | --- | --- |
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| `math` | the tree: `MNode`, `MRun`, `Math` (an equation with its kept source OMML), modelled on the Office Math object model (ECMA-376 Part 1 §22.1) | | |
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| `math_linear` | UnicodeMath, the linear format Word shows (`x=(-b±√(b^2-4ac))/2a`) | `math::parse_linear` | `math::to_linear` |
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| `math_latex` | LaTeX math, including MathLive's spellings | `parse_latex` | `to_latex` |
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| `omml` | Office Math Markup (`m:oMath`, DOCX/PPTX/XLSX) | `read_omath`, `read_str` | `write_equation`, `write_str` |
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| `mathml` | presentation MathML (HTML, ODF formulas, the clipboard) | `parse`, `read`, `to_tree` | `to_mathml`, `linear_to_mathml` |
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Beside them: `math_symbols` (LaTeX names of symbols), `math_tree` (the arguments of a node, a walk
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over every run), `symbol_fonts` (Symbol, Wingdings and the other symbol fonts as Unicode) and
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`Rgb` (a run's colour).
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```rust
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use craft_math::{Math, math, math_latex, mathml, omml};
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let tree = math_latex::parse_latex(r"\frac{a}{b}+\sqrt{x}");
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assert_eq!(math::to_linear(&tree), "a/b+√x");
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// OMML out and back.
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let eq = Math { nodes: tree.clone(), ..Default::default() };
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let xml = omml::write_str("", false, &eq, None);
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let read = omml::read_str(&xml).unwrap();
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assert_eq!(read.nodes, tree);
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// MathML carries the linear format in an annotation, so it reads back exactly.
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let ml = mathml::linear_to_mathml("a/b+√x", true);
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assert_eq!(mathml::parse(&ml).and_then(|m| mathml::read(&m)), Some(("a/b+√x".to_string(), true)));
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```
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## Reading OMML
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`omml::read_omath` takes an `m:oMath` element of a `craft_xml` tree read with the canonical
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prefixes of `omml::NAMESPACES` (`m`, `w` and `mc`, transitional and strict URIs), so a document
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reader passes the element it already has. `omml::read_str` and `omml::parse` read a string. The
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source XML is kept in `Math::omml`; `write_equation` writes it back unchanged while the
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equation's colour is the same and the XML is well formed, so a saved document carries the
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equation as Word wrote it.
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## Limits
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Nesting is bounded by `math::MAX_DEPTH` in every reader and writer; `omml::parse` reads at most
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`omml::MAX_ELEMENTS` elements and `mathml::parse` keeps at most `mathml::MAX_NODES`; the LaTeX
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reader looks at 20,000 characters. Nothing panics on any input.
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## Provenance
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The tree, the linear format, LaTeX, the symbol names, the tree walk, the symbol fonts and `Rgb`
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are WordCraft's (`crates/doc`), as moved into craft-wordmodel; OMML is WordCraft's DOCX reader
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and writer (`crates/docx/src/read/math.rs`, `write/math.rs`) and MathML its formats crate's
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(`crates/formats/src/mathml.rs`), moved onto craft-xml. The MathLive command spellings and the
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round-trip corpus in `tests/corpus/` come from equaSHion (storytold/craft-libs#29).
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