Architecture

ROUP has one semantic parser implementation and two delivery layers.

Safe Rust parser

The workspace root package is the complete parser. It accepts an explicit dialect version policy, host-language profile, and source form, and returns a typed OpenMP or OpenACC AST. Every expression and structured clause payload is parsed before the result is returned. Unknown syntax, invalid combinations, unsupported host syntax, and trailing input are hard errors.

The root crate builds only an rlib and has #![forbid(unsafe_code)]. Its semantic enums have Rust-native layouts and no ABI discriminants. Syntax that was standardized by an older specification remains accepted by later exact version modes. Standard aliases are recognized at the parser boundary and map to one canonical semantic node.

Parsing is organized into four boundaries:

1. The source-form lexer validates the pragma or Fortran sentinel and line continuation rules.
2. The grammar recognizes directive and clause syntax without inventing defaults for malformed input.
3. Semantic construction creates the typed AST and host-expression trees.
4. Availability and context validation intersect every used feature with the configured specification and reject invalid clause, nesting, and association combinations.

Diagnostics carry stable codes and checked UTF-8 byte, line, and column spans.

Optional C ABI

crates/roup-capi is a separate workspace package. It depends on the safe Rust parser, but the parser never depends on it. The ABI uses opaque generational handles, by-value options, explicit byte buffers, and structured error handles. All foreign-pointer access is confined to one audited boundary module; every other ABI module denies unsafe code.

Directive parameters and clause payloads are exposed as typed fields. A missing typed conversion is a hard error. The repository document docs/C_ABI_ARCHITECTURE.md defines the detailed ownership and layout rules.

Compatibility adapters

compat/ompparser and compat/accparser build against the optional C ABI and construct the corresponding upstream C++ IR directly from typed queries. They do not link to Rust enum layouts and do not reinterpret canonical strings. Unsupported conversions are hard errors.

The upstream projects are pinned git submodules. A repository test requires both worktrees to match their recorded gitlinks, builds each adapter from a clean CMake directory, and registers both upstream ctest directories unchanged. At the current pins this runs all 1,534 ompparser and 918 accparser upstream tests, plus five local ABI/adapter checks. No upstream fixture or reference is rewritten and no test is filtered, disabled, or allowed to fail.