Elamur Groupantstreebanks-render-decimal-grouping
The groupant beside tools/treebanks/src/render.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 | model.md |
| ast | partial | ../syntax.json |
| composition | partial | Composition |
| cost | partial | invariant-and-cost |
| descriptant | present | descriptant |
| invariant | partial | invariant-and-cost |
| tests | 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 |
zero_case | zero_case | partial source derived model | zero_case |
threshold_boundary | threshold_boundary | partial source derived model | threshold_boundary |
width_bound | width_bound | partial source derived model | width_bound |
right_alignment | right_alignment | partial source derived model | right_alignment |
Model text
descriptant
Descriptant
Convert u64 to decimal and insert a space before each nonfirst digit whose remaining suffix length is divisible by three.
Epoch 2026-10-31
Prospective source reading identified conditional input alignment, information loss and failure order before tests. Existing production code is retained; added tests use actual helpers. Finite results update this source-bound model, not all parser/corpus semantics.
No executable percentage surrogate has a justified observation metric for these categorical/effectful APIs. Future profiles require metric, domain and real-reference evidence at caps 1/2/5/10%; no higher cap. Syntax is partial lexical Rust projection without macro expansion or semantic resolution.
approximant
Forward approximant
Convert u64 to decimal and insert a space before each nonfirst digit whose remaining suffix length is divisible by three.
Composition
This fragment is the exact byte-scoped helper identified in the manifest; its relation is restricted to the operations above.
The containing source wires this scoped relation to its callers. Treeagree proposal→gate→commit and treebanks parse→match→collect→render are actual joins; parsecmp is an independent diagnostic path. The external group model distinguishes these tags.
catalog
Typed models for treebanks-render-decimal-grouping
Subject: source SHA-256 1d5101cda9ced92075a30cb2fd999239fc136ec6c5d315230f18c4c0fa15403a; manifest supplies exact source/byte scope. Domain: admitted states in forward model, nonoverflow arithmetic and successful allocations. Observation: one terminating invocation, except explicitly described file trace. Source-derived partial relations; named finite tests constrain selected cases only. Each entry holds arguments and environment fixed except its stated intervention.
behavior_complement
Output cannot contain leading/trailing spaces or nondecimal characters other than internal grouping spaces.
Operator: inner exclusion on admitted domain. Evidence: source branch derivation plus tests.md; unexercised branches remain hypotheses. Oracle: evaluate the scoped actual helper on admissible fixtures and compare this observation. No universal proof.
reverse_reconstruction
Removing spaces and parsing u64 uniquely recovers input within canonical num output language; arbitrary spaced decimal input is not an inverse domain.
Operator: compatible antecedent relation, retaining ambiguity. Evidence: source branch derivation plus tests.md; unexercised branches remain hypotheses. Oracle: evaluate the scoped actual helper on admissible fixtures and compare this observation. No universal proof.
zero_case
Zero maps to exactly 0 with no separator; values below 1000 retain ordinary decimal spelling.
Operator: specialized observation relation under the stated fixed inputs. Evidence: source branch derivation plus tests.md; unexercised branches remain hypotheses. Oracle: evaluate the scoped actual helper on admissible fixtures and compare this observation. No universal proof.
threshold_boundary
999 has no separator, 1000 becomes 1 000; every additional three digits adds one separator.
Operator: specialized observation relation under the stated fixed inputs. Evidence: source branch derivation plus tests.md; unexercised branches remain hypotheses. Oracle: evaluate the scoped actual helper on admissible fixtures and compare this observation. No universal proof.
width_bound
Largest u64 has 20 decimal digits and six separators, total 26 output bytes; no arithmetic on numeric magnitude beyond formatting.
Operator: specialized observation relation under the stated fixed inputs. Evidence: source branch derivation plus tests.md; unexercised branches remain hypotheses. Oracle: evaluate the scoped actual helper on admissible fixtures and compare this observation. No universal proof.
right_alignment
Group boundaries count remaining digits from right, independently of locale; all separators are ASCII space.
Operator: specialized observation relation under the stated fixed inputs. Evidence: source branch derivation plus tests.md; unexercised branches remain hypotheses. Oracle: evaluate the scoped actual helper on admissible fixtures and compare this observation. No universal proof.
tests
Scoped evidence
Parent native slice and exact names are in ../tests.md.
Only named finite assertions cover selected inputs; other branches and invalid-domain behavior remain source-derived.
This fragment has no independent full-coverage claim. Its byte range and source hash bind the source-derived relation; parent test success is evidence only where that helper is actually reached.
invariant-and-cost
Invariant and cost
O(decimal digits), at most 20 input digits and 6 separator spaces for u64; one output String.
Output cannot contain leading/trailing spaces or nondecimal characters other than internal grouping spaces.
The complement and specialized catalog constrain preserved coordinates and effect boundaries. Empty/malformed domains are only guaranteed where explicitly admitted. No whole-program cost bound follows from a helper bound.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/tools/treebanks/src/render.rs.groupant/decimal-grouping.groupant/