Elamur Groupantslatex-ast-stage0
The groupant beside latex/src/ast.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 |
singleton_quotient | singleton_quotient | partial source derived model | singleton_quotient |
empty_identity | empty_identity | partial source derived model | empty_identity |
Model text
descriptant
latex-ast-stage0
empty()=Row([]). norm(v)=v[0] when len(v)=1, otherwise Row(v); singleton extraction consumes the vector by pop.
Epoch 2026-10-31: replaced stage topic lists with concrete transitions, exclusions and compatible antecedents. Four meaningful typed views replace the previous six-view bookkeeping catalog. Shared syntax and source byte bounds are unchanged.
approximant
Scoped forward relation
empty()=Row([]). norm(v)=v[0] when len(v)=1, otherwise Row(v); singleton extraction consumes the vector by pop.
This is an exact source-derived partial model, not an executable approximate replacement.
invariant
Scoped invariants
norm([Char(x)]) cannot yield Row([Char(x)]); norm([]) cannot invent an atom. Existing nested Row nodes are not recursively flattened.
norm([Row([a,b])]) and norm([a,b]) both produce Row([a,b]); this is an outer-list quotient, not recursive semantic simplification.
empty and norm([]) are structurally identical, but norm([Group(empty())]) preserves Group(empty()) rather than equating explicit braces to an empty row.
composition
Scoped interaction
Parser list/table routines use norm after collecting atoms. These constructors do not enforce invariants on manually constructed Node::Row values.
The manifest binds this stage to the unchanged parent syntax projection and exact source byte range. Parent cost remains an upper accounting context; no independent whole-file invocation or execution count is assigned to this fragment.
models
behavior_complement
norm([Char(x)]) cannot yield Row([Char(x)]); norm([]) cannot invent an atom. Existing nested Row nodes are not recursively flattened.
reverse_reconstruction
For non-Row atom a, norm inverse is exactly {[a]}. For Row(v), compatible lists include v when len(v)!=1 and [Row(v)] always. Thus Row([]) can come from [] or [Row([])]; normalization loses that outer-list provenance.
singleton_quotient
norm([Row([a,b])]) and norm([a,b]) both produce Row([a,b]); this is an outer-list quotient, not recursive semantic simplification.
empty_identity
empty and norm([]) are structurally identical, but norm([Group(empty())]) preserves Group(empty()) rather than equating explicit braces to an empty row.
tests
Evidence — 2026-10-31
ast::wave28_tests::normalization_and_span_quotient; ast::wave28_tests::traversal_preserves_script_and_unknown_order
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/ast.rs.groupant/stage0.groupant/