Replace `:>` with `::` in `Class` definitions for coq/coq#18590

adjust-class-compat.py

#!/usr/bin/env python
import subprocess
import re

def get_git_grep_files(pattern):
    """Run git grep to find files matching a pattern."""
    result = subprocess.run(['git', 'grep', '--name-only', pattern], capture_output=True, text=True)
    if result.returncode != 0:
        raise Exception("git grep command failed")
    files = result.stdout.strip().split('\n')
    return files

def process_files(files, search_pattern, replace_pattern):
    """Process each file, searching for patterns and replacing them."""
    fs = {}
    for fname in files:
        with open(fname, "r") as f:
            fs[fname] = f.read()
    fs2 = {
        f: [m for m in re.findall(search_pattern, c, flags=re.MULTILINE|re.DOTALL) 
            if not m.startswith("Existing") and ":>" in m and re.search(replace_pattern, m, flags=re.MULTILINE|re.DOTALL)]
        for f, c in fs.items()
    }
    fs3 = {f: m for f, m in fs2.items() if m}

    for f, matches in fs3.items():
        original_content = fs[f]
        modified_content = original_content
        for val in matches:
            modified_content = modified_content.replace(val, val.replace(":>", "::"))
        with open(f, "w") as file:
            file.write(modified_content)

if __name__ == "__main__":
    class_pattern = 'Class '
    search_pattern = r'(?:Existing\s+)?Class\s.*?\.\s'
    replace_pattern = r':=\s*'

    files = get_git_grep_files(class_pattern)

    process_files(files, search_pattern, replace_pattern)