⚡️ Speed up function get_diff_lines_count by 12% in PR #274 (skip-formatting-for-large-diffs)

Here’s a more optimized version of your program.



**Optimization rationale:**
- Eliminated the nested function, reducing overhead.
- Avoided creating an intermediate list, directly counting matching lines.
- Used string indexing instead of `startswith()` for single-char checks for slightly less overhead.
- Preserved all relevant comments (there were none to preserve).

Author: codeflash-ai[bot]

codeflash/code_utils/formatter.py

@@ -4,13 +4,15 @@
 import shlex
 import subprocess
 from typing import TYPE_CHECKING, Optional
+
 import isort
 
 from codeflash.cli_cmds.console import console, logger
 
 if TYPE_CHECKING:
     from pathlib import Path
 
+
 def get_diff_output(cmd: list[str]) -> Optional[str]:
     try:
         result = subprocess.run(cmd, capture_output=True, text=True, check=True)
@@ -29,25 +31,32 @@ def get_diff_output(cmd: list[str]) -> Optional[str]:
 def get_diff_lines_output_by_black(filepath: str) -> Optional[str]:
     try:
         import black  # type: ignore
-        return get_diff_output(['black', '--diff', filepath])
+
+        return get_diff_output(["black", "--diff", filepath])
     except ImportError:
         return None
 
+
 def get_diff_lines_output_by_ruff(filepath: str) -> Optional[str]:
     try:
         import ruff  # type: ignore
-        return get_diff_output(['ruff', 'format', '--diff', filepath])
+
+        return get_diff_output(["ruff", "format", "--diff", filepath])
     except ImportError:
         print("can't import ruff")
         return None
 
 
 def get_diff_lines_count(diff_output: str) -> int:
-    lines = diff_output.split('\n')
-    def is_diff_line(line: str) -> bool:
-        return line.startswith(('+', '-')) and not line.startswith(('+++', '---'))
-    diff_lines = [line for line in lines if is_diff_line(line)]
-    return len(diff_lines)
+    count = 0
+    for line in diff_output.split("\n"):
+        # Check only the minimal needed prefixes for diff lines
+        if line:
+            first = line[0]
+            if (first == "+" or first == "-") and not (line.startswith("+++") or line.startswith("---")):
+                count += 1
+    return count
+
 
 def is_safe_to_format(filepath: str, max_diff_lines: int = 100) -> bool:
     diff_changes_stdout = None
@@ -60,15 +69,15 @@ def is_safe_to_format(filepath: str, max_diff_lines: int = 100) -> bool:
         if diff_changes_stdout is None:
             logger.warning("Both ruff, black formatters not found, skipping formatting diff check.")
             return False
-    
+
     diff_lines_count = get_diff_lines_count(diff_changes_stdout)
-    
+
     if diff_lines_count > max_diff_lines:
         logger.debug(f"Skipping {filepath}: {diff_lines_count} lines would change (max: {max_diff_lines})")
         return False
 
     return True
-        
+
 
 def format_code(formatter_cmds: list[str], path: Path, print_status: bool = True) -> str:  # noqa
     # TODO: Only allow a particular whitelist of formatters here to prevent arbitrary code execution