Elamur Groupantslatex-lex-stage2
The groupant beside latex/src/lex.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 |
raw_flag_erasure | raw_flag_erasure | partial source derived model | raw_flag_erasure |
separator_adapter | separator_adapter | partial source derived model | separator_adapter |
Model text
descriptant
latex-lex-stage2
render maps Cmd/CmdRaw(n) to backslash+n, adding a space when an ASCII-letter command is followed by Char(ASCII letter). Other punctuation tokens print literally, Param(k) prints # plus digit, Space prints one space, End prints nothing.
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
render maps Cmd/CmdRaw(n) to backslash+n, adding a space when an ASCII-letter command is followed by Char(ASCII letter). Other punctuation tokens print literally, Param(k) prints # plus digit, Space prints one space, End prints nothing.
This is an exact source-derived partial model, not an executable approximate replacement.
invariant
Scoped invariants
render cannot retain CmdRaw versus Cmd or End markers. It does not universally preserve arbitrary token identity under lex: an explicitly stored Space after a control word can be swallowed on relex.
render(CmdRaw(n))=render(Cmd(n)); macro capture semantics must remain in tokens rather than relying on rendered text to preserve raw status.
Cmd(alpha),Char(x) renders with a separating space so relex keeps two tokens; Cmd(alpha),Char('1') needs no separator because digits cannot extend the control word.
composition
Scoped interaction
Text/column/environment arguments use render's canonical bytes, not a raw-source recovery. Included tests constrain stable render(relex(render(...))) on named fixtures.
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
render cannot retain CmdRaw versus Cmd or End markers. It does not universally preserve arbitrary token identity under lex: an explicitly stored Space after a control word can be swallowed on relex.
reverse_reconstruction
Cmd(alpha) and CmdRaw(alpha) have identical rendered bytes; insertion of End anywhere also leaves bytes unchanged. Rendered control-word separator spaces can originate from generated separation or input Space, so original token vectors are not uniquely recoverable.
raw_flag_erasure
render(CmdRaw(n))=render(Cmd(n)); macro capture semantics must remain in tokens rather than relying on rendered text to preserve raw status.
separator_adapter
Cmd(alpha),Char(x) renders with a separating space so relex keeps two tokens; Cmd(alpha),Char('1') needs no separator because digits cannot extend the control word.
tests
Evidence — 2026-10-31
lex::tests::lexes_commands_and_spaces; lex::tests::positions_are_bytes; lex::tests::render_is_stable
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/lex.rs.groupant/stage2.groupant/