---
title: "latex-lex — Mova code model"
description: "Mova code model of latex/src/lex.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/latex/src/lex.rs.groupant/"
---
Elamur: [Mova](https://md.mova.elamur.ai/free/en/) · [Dictionary](https://md.dictionary.elamur.ai/free/en/) · [Research](https://md.research.elamur.ai/free/en/) · **Groupants**

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# latex-lex

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

- **kind:** groupant
- **status:** partial source bound model
- **source:** [`latex/src/lex.rs`](https://github.com/ElamurAI/mova-free/blob/main/latex/src/lex.rs)
- **source SHA-256:** `65c9e2c47772827a…`
- **repository folder:** [`latex/src/lex.rs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/latex/src/lex.rs.groupant)
- **repository commit:** `48f2e6f74146`

> **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](#approximant) |
| **ast** | partial | `syntax.json` |
| **composition** | partial | [composition](#composition) |
| **descriptant** | present | [descriptant](#descriptant) |
| **invariant** | partial | [invariant](#invariant) |
| **tests** | executed bounded checks | [tests](#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](#behavior-complement) |
| `reverse_reconstruction` | reverse_reconstruction | partial source derived model | [reverse_reconstruction](#reverse-reconstruction) |
| `byte_coordinates` | byte_coordinates | partial source derived model | [byte_coordinates](#byte-coordinates) |
| `substream_boundary` | substream_boundary | partial source derived model | [substream_boundary](#substream-boundary) |
| `stack_order` | stack_order | partial source derived model | [stack_order](#stack-order) |
| `render_loss` | render_loss | partial source derived model | [render_loss](#render-loss) |

## Parts

- [latex-lex-stage0](https://md.groupants.elamur.ai/free/en/mova/latex/src/lex.rs.groupant/stage0.groupant/)
- [latex-lex-stage1](https://md.groupants.elamur.ai/free/en/mova/latex/src/lex.rs.groupant/stage1.groupant/)
- [latex-lex-stage2](https://md.groupants.elamur.ai/free/en/mova/latex/src/lex.rs.groupant/stage2.groupant/)

## Model text


### descriptant

#### latex-lex

lex appends tokens, borrows command substrings and reports base+byte offset. ASCII command words eat following ASCII whitespace; comments consume until LF; spaces and tilde collapse. Stream reverses vectors, pushes front in reverse, and preserves End on failed substream scans. render serializes tokens with control-word separators.

Epoch2026-10-31: full source reviewed before edits; prospective models retained externally. No optimization.

### approximant

#### Forward relation

lex appends tokens, borrows command substrings and reports base+byte offset. ASCII command words eat following ASCII whitespace; comments consume until LF; spaces and tilde collapse. Stream reverses vectors, pushes front in reverse, and preserves End on failed substream scans. render serializes tokens with control-word separators.

No useful approximate executable metric for exact categorical syntax; future caps1/2/5/10% only.

### invariant

#### Domain, invariant and cost

lex appends tokens, borrows command substrings and reports base+byte offset. ASCII command words eat following ASCII whitespace; comments consume until LF; spaces and tilde collapse. Stream reverses vectors, pushes front in reverse, and preserves End on failed substream scans. render serializes tokens with control-word separators.

Empty appends nothing; existing trailing Space affects append coalescing. UTF-8 input valid; base+byte offset must fit u32 for nonwrapping semantics.

O(B+T) lex/storage, push O(k), group scanning O(k), render O(output); u32 addition overflow and oversized input cast excluded by representable-offset domain.

### composition

#### Composition

lex appends tokens, borrows command substrings and reports base+byte offset. ASCII command words eat following ASCII whitespace; comments consume until LF; spaces and tilde collapse. Stream reverses vectors, pushes front in reverse, and preserves End on failed substream scans. render serializes tokens with control-word separators.

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

No parser errors are returned by lex; trailing backslash and malformed parameter syntax remain characters. End may not disappear through group_tokens failure.

### reverse_reconstruction

Sources producing a token stream differ by comments and whitespace and command-word spacing. render removes End and maps CmdRaw to Cmd; exact reverse is a compatible-source set with those distinctions forgotten.

### byte_coordinates

Greek alpha occupies2 bytes so subsequent token offsets differ from scalar columns.

### substream_boundary

Group and optional collectors restore End, consume preceding tokens, and return failure.

### stack_order

next(push_front([a,b],s))=a then b then old s.

### render_loss

End absent and raw flag lost; separator required only control word before ASCII letter in render.

### 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.