Grammar and parser contract - Design model

Platform spec article

Grammar and parser contract - Design model

Back to Grammar and parser contract ◎ Open feature in platform map

Spec standingStandard

Owner

Piotr Mikstacki pmikstacki@cybernomad.it

Submitter

Piotr Mikstacki pmikstacki@cybernomad.it

Current document

ADRs (3)

1. 0001-feature-hub-authority Feature hub authority Accepted

   This feature hub owns normative MUST/SHOULD contract text for Grammar and parser contract.

   Context

   Sibling articles under this feature previously restated requirements in inconsistent forms.

   Decision

   This feature hub owns normative MUST/SHOULD contract text. Sibling articles must not redefine hub requirements and should link here for authority.

   Consequences

   Contract changes start on the hub or in linked ADRs, then propagate to articles and implementation anchors.

   Verification anchors

   • site/website/src/content/docs/platform-spec/compiler/front-end/grammar-and-parser-contract/index.mdx
   • article bundle under the same feature directory.

   Open full ADR page

2. 0002-spec-over-implementation-notes Specification over implementation notes Accepted

   Platform-spec text supersedes informal crate comments for Grammar and parser contract.

   Context

   Implementation crates accumulated informal notes that diverged from published contracts.

   Decision

   Normative platform-spec prose and ADRs under this feature supersede informal comments in implementation crates until explicitly migrated into spec text.

   Consequences

   Engineers file spec/ADR updates when behavior changes; crate comments are non-authoritative for conformance arguments.

   Verification anchors

   • compiler/crates/beskid_analysis/src/beskid.pest
   • compiler/crates/beskid_analysis/src/syntax/
   • compiler/crates/beskid_analysis/src/syntax/items/parse_helpers.rs

   Open full ADR page

3. 0003-primary-contract-choice Primary contract for Grammar and parser contract Accepted

   This feature hub defines the normative contract for **grammar and parser contract** and links newcomer-oriented referenc

   Context

   This feature hub defines the normative contract for grammar and parser contract and links newcomer-oriented reference articles.

   Decision

   The reference compiler must implement Grammar and parser contract as documented in this feature hub and its article bundle.

   Consequences

   Changes require hub/ADR updates and verification anchor extensions.

   Verification anchors

   • compiler/crates/beskid_analysis/src/beskid.pest
   • compiler/crates/beskid_analysis/src/syntax/
   • compiler/crates/beskid_analysis/src/syntax/items/parse_helpers.rs

   Open full ADR page

Articles

• Grammar and parser contract - Contracts and edge cases States the normative guarantees and what happens at boundaries or failure edges. article Standard
• Grammar and parser contract - Design model Explains the persistent concepts, entities, and boundaries this feature relies on. article Standard Reviewed Wed May 20
• Grammar and parser contract - Examples Gives concrete newcomer-friendly scenarios mapped to real compiler paths. article Standard
• Grammar and parser contract - FAQ and troubleshooting Answers common operator and contributor questions with practical next checks. article Standard
• Grammar and parser contract - Flow and algorithm Walks through runtime/order-of-operations behavior in the implementation. article Standard
• Grammar and parser contract - Verification and traceability Shows how the team proves this feature works and where evidence lives. article Standard

History

0 revisions (git unavailable at build; counts may be empty)

Open full history on GitHub

No commits recorded for this path.

Completeness

OKfeature · 0 SpecSection(s) · 2 H2 heading(s)

Full tree: run pnpm verify:platform-spec-layout (writes src/generated/platform-spec-layout-report.json).

Related spec docs

• Feature
  Grammar and parser contract

  Parent feature hub

• Feature
  extend type

  Type extension syntax for generated members

• Feature
  Language macros

  MacroDefinition, MacroInvocation, MacroMetavariableExpr

• Feature
  Parser and AST contracts

  AST mapping for grammar productions

This article documents design model for grammar and parser contract in the reference compiler.

Anchored code paths

• compiler/crates/beskid_analysis/src/beskid.pest defines grammar tokens and precedence.
• compiler/crates/beskid_analysis/src/syntax/ builds syntax items from parser output.
• compiler/crates/beskid_analysis/src/syntax/items/parse_helpers.rs contains shared parse helpers.

Metaprogramming grammar (removed)

The reference compiler must not define a language-level meta item grammar. Compiler mods use ordinary Beskid source plus SDK contracts (Collector, Generator, Analyzer, Rewriter).

Legacy MetaDefinition productions must be removed from beskid.pest and AST/HIR surfaces.

extend type production (v0.2 target)

The grammar must define extend type as the normative type-extension syntax (see extend type). Generators emit extend type blocks as typed AST contributions.

Implementation must pair pest rules with item parsers under compiler/crates/beskid_analysis/src/syntax/items/ and snapshot tests under compiler/crates/beskid_tests.

Language macro productions (v0.2 target)

The grammar must define:

Production	Role
MacroDefinition	Visibility? macro Identifier ( MacroParameterList ) Block — module InnerItem.
MacroParameter	MacroFragmentKind Identifier (closed kind keywords).
MacroInvocation	Identifier ! optional ( MacroArgumentList ) optional braced Block — expression position.
MacroMetavariableExpr	$ Identifier — legal only inside MacroDefinition bodies.

See Language macros. Expansion is host-driven in macro.expand; the parser only materializes definitions and invocation sites.

Practical notes

• Treat diagnostics and tests as part of the contract, not optional implementation details.
• When grammar changes, update this article and conformance tests in the same change.