carbon-lang/.agents/skills/summarize_testdata_changes/scripts/parse_diff.py

__copyright__ = """
Part of the Carbon Language project, under the Apache License v2.0 with LLVM
Exceptions. See /LICENSE for license information.
SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
"""

import sys
from collections import defaultdict
from typing import TextIO, Dict, List


def parse_diff(stream: TextIO) -> None:
    current_file: str = ""
    file_changes: Dict[str, Dict[str, List[str]]] = defaultdict(
        lambda: {"input": [], "stderr": [], "stdout": []}
    )

    for line in stream:
        if line.startswith("diff --git"):
            parts = line.split()
            if len(parts) >= 4:
                current_file = (
                    parts[3][2:] if parts[3].startswith("b/") else parts[3]
                )
        elif line.startswith("+") or line.startswith("-"):
            if not line.startswith("+++") and not line.startswith("---"):
                stripped = line[1:].strip()
                if stripped.startswith("// CHECK:STDERR"):
                    file_changes[current_file]["stderr"].append(
                        line.rstrip("\n")
                    )
                elif stripped.startswith("// CHECK:STDOUT"):
                    file_changes[current_file]["stdout"].append(
                        line.rstrip("\n")
                    )
                elif stripped.startswith("// CHECK"):
                    file_changes[current_file]["stdout"].append(
                        line.rstrip("\n")
                    )
                else:
                    file_changes[current_file]["input"].append(
                        line.rstrip("\n")
                    )

    for f, c in file_changes.items():
        if not c["input"] and not c["stderr"] and not c["stdout"]:
            continue
        print(f"File: {f}")
        if c["input"]:
            print("  --- Input Changes ---")
            for change in c["input"]:
                print(f"  {change}")
        if c["stderr"]:
            print("  --- STDERR Changes ---")
            for change in c["stderr"]:
                print(f"  {change}")
        if c["stdout"]:
            print("  --- STDOUT Changes ---")
            for change in c["stdout"]:
                print(f"  {change}")
        print("-" * 40)


if __name__ == "__main__":
    parse_diff(sys.stdin)