Elamur Groupantslatex-parse
The groupant beside latex/src/parse.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial | approximant |
| ast | partial | syntax.json |
| composition | partial | composition |
| descriptant | present | descriptant |
| invariant | partial | invariant |
| tests | executed bounded checks | tests |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
failure_precedence | failure_precedence | partial source derived model | failure_precedence |
macro_resources | macro_resources | partial source derived model | macro_resources |
row_normalization | row_normalization | partial source derived model | row_normalization |
unknown_fallback | unknown_fallback | partial source derived model | unknown_fallback |
Parts
Model text
descriptant
latex-parse
parse_with initializes local macro state and token stack. list consumes until stop kind, normalizes rows; top tables choose Aligned if any row has multiple cells else Gathered. Local macros shadow external before built-in dispatch, CmdRaw bypasses expansion. Unknown grouped arguments parse or become canonical Text on recoverable failure.
Epoch2026-10-31: full source reviewed before edits; prospective models retained externally. No optimization.
approximant
Forward relation
parse_with initializes local macro state and token stack. list consumes until stop kind, normalizes rows; top tables choose Aligned if any row has multiple cells else Gathered. Local macros shadow external before built-in dispatch, CmdRaw bypasses expansion. Unknown grouped arguments parse or become canonical Text on recoverable failure.
No useful approximate executable metric for exact categorical syntax; future caps1/2/5/10% only.
invariant
Domain, invariant and cost
parse_with initializes local macro state and token stack. list consumes until stop kind, normalizes rows; top tables choose Aligned if any row has multiple cells else Gathered. Local macros shadow external before built-in dispatch, CmdRaw bypasses expansion. Unknown grouped arguments parse or become canonical Text on recoverable failure.
Depth threshold400; expansions10000; token threshold1000000 checked pre-expansion. primes saturate255; offsets u32 require representable lengths. Argument errors occur before duplicate sup/sub check.
Cost in source bytes B, expanded tokens T, body/argument copies C and tree N: O(B+T+C) plus delimiter matching and repeated nested operations; storage includes tokens, macro clones and tree; recursion bounded only along list depth.
composition
Composition
parse_with initializes local macro state and token stack. list consumes until stop kind, normalizes rows; top tables choose Aligned if any row has multiple cells else Gathered. Local macros shadow external before built-in dispatch, CmdRaw bypasses expansion. Unknown grouped arguments parse or become canonical Text on recoverable failure.
Build generates table enums consumed by parser dispatch and printers. Lexer tokens feed macros and parser; parser returns AST whose equality ignores spans. Printers and gate compare that quotient, not original bytes. Shared parent syntax backs scoped stages; stages are byte-bound projections, not independent Rust modules.
models
behavior_complement
Accepted unmatched closers and duplicate scripts are excluded, but arbitrary TeX semantic validity is not established. MAX_TOKENS is a check before substitution, not a global peak allocation ceiling.
reverse_reconstruction
parse preimage includes comments, spacing, aliases, dropped presentation commands and macro programs with the same expanded normalized structure. Error preimage includes sources sharing first reached failure and byte offset; no unique original recoverability.
failure_precedence
script obtains argument before checking occupied slot; genfrac parses six args before delimiter validation.
macro_resources
Local definitions persist for formula; expansion increments before threshold check and substitution may exceed token threshold.
row_normalization
Only one trailing empty row removed; single top cell unwrapped; other tables explicit Env.
unknown_fallback
Failed unknown argument can become Text after stack truncation; local macro changes are not rolled back.
tests
Evidence — 2026-10-31
parse::tests (7 named tests); integration unbalanced_is_an_error_with_position and macros_newcommand_def_let_declareop
Selected library filters ast:: lex:: macros:: parse:: print:: table:: and integration gate excluding document_extraction_with_preamble_macros and random_token_soup_never_panics_and_roundtrips. Direct rustc --test latex/build.rs exercises private helpers. All selected tests twice debug/release with identical sorted names. Four compiled mutants at build/AST/parser/printer boundaries fail assertions then exact restoration passes. These do not individually cover every source. Build-main failure effects, allocation failures and universal roundtrip are unproved. Strict Clippy reports existing lints. No corpus/live VMM/API/GPU/full-school/held-out tests.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/latex/src/parse.rs.groupant/