katex-parser

A Rust port of the KaTeX parser: lexes and parses LaTeX math expressions with full macro expansion into a typed ParseNode AST, and renders that AST to Unicode text.

Usage

use katex_parser::{parse, render, RenderConfig, Settings};

// Parse LaTeX into a typed AST.
let nodes = parse(r"\frac{1}{2} + \sqrt[3]{x}", &mut Settings::new())?;

// Render the AST as Unicode text.
let text = render(&nodes, RenderConfig::new());
assert_eq!(text, "1∕2 + ³√x");

# Ok::<(), katex_parser::ParseError>(())

Settings configures display mode, user macros, strictness, trust policy, and a persistent macro store shared across parses:

use katex_parser::{parse, render, Macros, Settings};
use std::collections::HashMap;

let mut settings = Settings::new();
settings.display_mode = true; // display-style fractions/matrices
settings.macro_store = Some(Macros::new(HashMap::new()));
settings.global_group = true; // persist \newcommand across parses

parse(r"\newcommand{\R}{\mathbb{R}}", &mut settings)?;
let nodes = parse(r"\R", &mut settings)?; // \R is still defined

Features

• Typed AST — every construct becomes a ParseNode variant (GenFrac, Sqrt, Array, Op, SupSub, …), mirroring KaTeX.
• Macro expansion — \def/\gdef/\edef/\xdef, \newcommand, argument substitution, delimiter arguments, \@ifnextchar, \noexpand.
• Environments — array, matrix, cases, aligned/align, gather, equation, subarray, and commutative-diagram CD.
• Unicode rendering backend — block fractions, matrices, boxes, and commutative diagrams with baseline alignment, plus font mapping (\mathbb, \mathbf, \mathcal, …) and Unicode script sub/superscripts.
• Zero dependencies.

License

AGPL-3.0. See LICENSE.