accparser

accparser is a standalone OpenACC 3.4 directive parser for C, C++, and Fortran. It separates the directive envelope and OpenACC structure from opaque host-language expressions, then produces an owning, value-semantic typed AST. Invalid input produces diagnostics and never produces a partial AST.

Prerequisites

The build requires CMake 3.20 or later, ANTLR 4, and the ANTLR 4 C++ runtime. On Ubuntu or Debian:

sudo apt update
sudo apt install -y antlr4 libantlr4-runtime-dev build-essential cmake

Build and test

cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build
cd build
ctest --output-on-failure

The regression suite includes focused positive and negative parser tests, concurrent parsing, semantic parse-print-parse checks, and pragmas extracted from OpenACCV-V.

Optional hardening configurations are available:

cmake -S . -B build-asan -DCMAKE_BUILD_TYPE=Debug \
  -DACCPARSER_ENABLE_ASAN_UBSAN=ON
cmake -S . -B build-tsan -DCMAKE_BUILD_TYPE=Debug \
  -DACCPARSER_ENABLE_TSAN=ON

With Clang, -DACCPARSER_BUILD_FUZZER=ON also builds parser_fuzz. A seed corpus is provided in tests/fuzz_corpus.

Public API

Include OpenACCParser.h; public headers do not expose generated ANTLR types. The caller specifies the base language and source form explicitly:

#include "OpenACCParser.h"

openacc::ParseResult result = openacc::parseDirective(
    "#pragma acc parallel loop gang vector private(a)",
    {openacc::Language::Cxx, openacc::InputForm::CPragma});

if (!result.succeeded()) {
  for (const openacc::Diagnostic &diagnostic : result.diagnostics) {
    // diagnostic.code, diagnostic.message, and diagnostic.range are available.
  }
  return;
}

std::string canonical = openacc::formatDirective(*result.directive);

Supported input forms are a directive body, a C/C++ #pragma, a C/C++ _Pragma operator, and free- or fixed-form Fortran sentinels. The formatter can emit any selected envelope through openacc::PrintOptions; by default it emits #pragma for C/C++ and a free-form sentinel for Fortran.

The AST owns its data and uses clause-specific types. For example, copyin, copyout, and create have distinct modifier enums, device-specific clauses are partitioned into explicit groups, lists are nonempty by construction, and host fragments are distinguished as conditions, integer expressions, variable references, routine names, and other semantic categories.

parseOpenACC(std::string) remains as a deprecated transition wrapper. New code should use openacc::parseDirective, which is reentrant, has no global merge mode, and returns structured diagnostics.