README.md

OpenQASM 3 Parser

A lexer, parser, and semantic analyzer for OpenQASM 3 programs.

Overview

This crate provides a complete front-end for processing OpenQASM 3 source code. It operates entirely in the OpenQASM domain and produces a typed semantic AST suitable for further compilation or analysis.

The processing pipeline has two stages:

1. Lexing & Parsing — Tokenizes and parses OpenQASM 3 source into a syntax tree (QasmParseResult)
2. Semantic Analysis — Lowers the syntax tree into a semantic AST with type checking, symbol resolution, and const evaluation (QasmSemanticParseResult)

Source Resolution

OpenQASM programs can include other files via include statements. This crate abstracts filesystem access behind the SourceResolver trait, enabling:

• In-memory source resolution for editors and notebooks
• Custom filesystem backends
• Include cycle detection

OpenQASM Standard Library Types

The crate includes implementations of OpenQASM-native types:

• Angle — Fixed-point angle representation
• Complex — Complex number type
• Duration — Timing duration type

Usage

Parse and semantically analyze an OpenQASM 3 program:

use qsc_openqasm_parser::semantic;

let source = r#"
    OPENQASM 3.0;
    include "stdgates.inc";
    qubit[2] q;
    h q[0];
    cx q[0], q[1];
    bit[2] c;
    c = measure q;
"#;

let result = semantic::parse(source, "bell.qasm");
if result.has_errors() {
    for error in result.all_errors() {
        eprintln!("{error}");
    }
} else {
    println!("parsed {} statements", result.program.statements.len());
}

License

MIT