viper.py

#!/usr/bin/env python3
"""
viper — Python-to-C++ transpiler CLI
Usage: python viper.py <file1.py> [file2.py ...] [-o output.cpp]
"""
import ast
import argparse
import os
import sys

from core import Transpiler, TranspileError
from resolver import ImportResolver


def main():
    parser = argparse.ArgumentParser(
        prog="viper",
        description="Viper: transpile typed Python to C++17",
    )
    parser.add_argument("files", nargs="+", help="Python source files")
    parser.add_argument("-o", "--output", help="Output file (default: stdout)")
    args = parser.parse_args()

    modules: list = []
    module_names: list = []
    for path in args.files:
        try:
            with open(path, encoding="utf-8") as f:
                src = f.read()
        except OSError as e:
            print(f"viper: cannot open '{path}': {e}", file=sys.stderr)
            sys.exit(1)
        try:
            tree = ast.parse(src, filename=path)
        except SyntaxError as e:
            print(f"viper: syntax error in '{path}': {e}", file=sys.stderr)
            sys.exit(1)
        modules.append(tree)
        module_names.append(os.path.splitext(os.path.basename(path))[0])

    # Recursively resolve all imports (stubs or Python source)
    resolver = ImportResolver(set(module_names))
    try:
        extra = resolver.collect(modules)
    except TranspileError as e:
        print(f"viper: {e}", file=sys.stderr)
        sys.exit(1)
    for tree, name in extra:
        modules.append(tree)
        module_names.append(name)

    transpiler = Transpiler(modules, module_names)
    try:
        result = transpiler.transpile()
    except TranspileError as e:
        print(f"viper: {e}", file=sys.stderr)
        sys.exit(1)

    if args.output:
        try:
            with open(args.output, "w", encoding="utf-8") as f:
                f.write(result)
        except OSError as e:
            print(f"viper: cannot write '{args.output}': {e}", file=sys.stderr)
            sys.exit(1)
        print(f"Written to {args.output}")
    else:
        print(result)


if __name__ == "__main__":
    main()