import hashlib
from typing import Dict, Set

class IncrementalIndexerCache:
    """Tracks file content hashes to prevent redundant AST parsing."""
    
    def __init__(self):
        self._hashes: Dict[str, str] = {}
        
    def _compute_hash(self, content: str) -> str:
        return hashlib.sha256(content.encode('utf-8')).hexdigest()
        
    def should_reindex(self, filepath: str, content: str) -> bool:
        content_hash = self._compute_hash(content)
        if self._hashes.get(filepath) == content_hash:
            return False
        self._hashes[filepath] = content_hash
        return True
        
    def invalidate(self, filepath: str):
        self._hashes.pop(filepath, None)