Fix nested braces in mathtext \text arguments - #32147
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pyparsing has the builtin nested_expr; could that not be used instead of building our own machinery? |
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@anntzer Good suggestion. I looked at this. nested_expr works well for \substack, where the body is recursively parsed tokens and a nested list is the natural result. For \text, the argument is a brace-balanced literal string: nested braces are TeX groups (not rendered), {/} are literal braces, and interior whitespace must be preserved. nested_expr returns nested lists and, by default, skips whitespace between chunks, so we’d still need custom content, escape handling, and a flatten/unescape parse action. That ends up about as much machinery as _BracedText, with more risk around spaces next to escapes. Happy to switch if you’d still prefer the nested_expr shape for consistency. Please lmk! |
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Friendly bump. Circling back on the nested_expr question from Aug 2. Happy to refactor if you’d still prefer that for consistency; otherwise I think the current _BracedText approach is ready for another look. Thanks! |
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I am a bit confused why only |
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PR summary
Closes #32105.
\textused pyparsing'sQuotedString, which ends at the first}, so that made\text{{example}}failed with a cryptic ParseException.I replaced that with a small brace-balanced token that tracks nesting depth.
Nested unescaped braces are treated as TeX groups (not rendered), matching real LaTeX, so
\text{{example}}renders the same as\text{example}. Literal braces continue to use\{and\}.AI Disclosure
I used Cursor (generative AI) to explore the mathtext parser, draft the regression tests, and help write this PR description (to make sure I am following standards). I reviewed the change, verified the behavior against TeX grouping semantics, and ran a local smoke test covering nested braces, escaped braces, the existing
\texttest string, and malformed input.PR quality check
N/A for example/release notes/docs: this is a bug fix restoring expected LaTeX-like behavior of an existing command.