| 1 | 1 | def grep(pattern: str, flags: str, files: list[str]) -> str: |
| 2 | | pass |
| 2 | """ |
| 3 | Search files for lines matching a search string and return all matching lines. |
| 4 | |
| 5 | Args: |
| 6 | pattern (str): The string to search for. |
| 7 | flags (str): Space-separated flags for customizing behavior. |
| 8 | files (list[str]): List of file paths to search in. |
| 9 | |
| 10 | Returns: |
| 11 | str: Matching lines, possibly with file names and line numbers. |
| 12 | |
| 13 | Flags: |
| 14 | -n: Prepend line numbers. |
| 15 | -l: Output only file names. |
| 16 | -i: Case-insensitive matching. |
| 17 | -v: Invert matching. |
| 18 | -x: Match entire line only. |
| 19 | """ |
| 20 | # Parse flags |
| 21 | flag_list = flags.split() if flags else [] |
| 22 | line_numbers = '-n' in flag_list |
| 23 | files_only = '-l' in flag_list |
| 24 | case_insensitive = '-i' in flag_list |
| 25 | invert_match = '-v' in flag_list |
| 26 | exact_match = '-x' in flag_list |
| 27 | |
| 28 | # Prepare pattern for comparison |
| 29 | search_pattern = pattern.lower() if case_insensitive else pattern |
| 30 | |
| 31 | # Edge Case: No files provided |
| 32 | if not files: |
| 33 | return "" |
| 34 | |
| 35 | results = [] |
| 36 | matching_files = set() |
| 37 | |
| 38 | # Edge Case: Pattern is empty |
| 39 | if not pattern: |
| 40 | # An empty pattern would match all lines, but we follow standard behavior |
| 41 | pass |
| 42 | |
| 43 | multiple_files = len(files) > 1 |
| 44 | |
| 45 | for file_path in files: |
| 46 | try: |
| 47 | with open(file_path, 'r', encoding='utf-8') as file: |
| 48 | for line_num, line in enumerate(file, 1): |
| 49 | # Prepare line for comparison |
| 50 | compare_line = line.lower() if case_insensitive else line |
| 51 | |
| 52 | # Determine if line matches |
| 53 | if exact_match: |
| 54 | match = (search_pattern == compare_line.rstrip('\n')) |
| 55 | else: |
| 56 | match = (search_pattern in compare_line) |
| 57 | |
| 58 | # Apply invert flag |
| 59 | if invert_match: |
| 60 | match = not match |
| 61 | |
| 62 | if match: |
| 63 | matching_files.add(file_path) |
| 64 | |
| 65 | # Edge Case: Only file names requested |
| 66 | if files_only: |
| 67 | continue |
| 68 | |
| 69 | output_line = line.rstrip('\n') |
| 70 | |
| 71 | # Edge Case: Multiple files, prepend file name |
| 72 | if multiple_files: |
| 73 | output_line = f"{file_path}:{output_line}" |
| 74 | |
| 75 | # Edge Case: Line numbers requested |
| 76 | if line_numbers: |
| 77 | # Insert line number after file name if present |
| 78 | if multiple_files: |
| 79 | parts = output_line.split(':', 1) |
| 80 | output_line = f"{parts[0]}:{line_num}:{parts[1] if len(parts) > 1 else ''}" |
| 81 | else: |
| 82 | output_line = f"{line_num}:{output_line}" |
| 83 | |
| 84 | results.append(output_line) |
| 85 | except FileNotFoundError: |
| 86 | # Edge Case: File not found - continue with other files |
| 87 | continue |
| 88 | except PermissionError: |
| 89 | # Edge Case: Permission denied - continue with other files |
| 90 | continue |
| 91 | except Exception: |
| 92 | # Edge Case: Other file reading errors - continue with other files |
| 93 | continue |
| 94 | |
| 95 | # Edge Case: Only file names requested |
| 96 | if files_only: |
| 97 | # Return file names in the order they were encountered |
| 98 | ordered_matching_files = [f for f in files if f in matching_files] |
| 99 | return "\n".join(ordered_matching_files) + ("\n" if ordered_matching_files else "") |
| 100 | |
| 101 | return "\n".join(results) + ("\n" if results else "") |
| 102 | |
| 103 | # Handled Edge Cases: No files provided, pattern is empty, multiple files, line numbers requested, only file names requested, file not found, permission denied, other file reading errors |