| 1 | 1 | def grep(pattern: str, flags: str, files: list[str]) -> str: |
| 2 | | pass |
| 2 | # Parse flags |
| 3 | line_numbers = '-n' in flags |
| 4 | filenames_only = '-l' in flags |
| 5 | case_insensitive = '-i' in flags |
| 6 | invert_match = '-v' in flags |
| 7 | exact_match = '-x' in flags |
| 8 | |
| 9 | # Prepare pattern for comparison |
| 10 | search_pattern = pattern.lower() if case_insensitive else pattern |
| 11 | |
| 12 | # Initialize results |
| 13 | result_lines = [] |
| 14 | matched_files = set() |
| 15 | |
| 16 | # Process each file |
| 17 | for filename in files: |
| 18 | try: |
| 19 | with open(filename, 'r', encoding='utf-8') as file: |
| 20 | lines = file.readlines() |
| 21 | except FileNotFoundError: |
| 22 | # Edge Case: File not found - skip the file |
| 23 | continue |
| 24 | |
| 25 | # Process each line in the file |
| 26 | for line_num, line in enumerate(lines, start=1): |
| 27 | # Prepare line for comparison |
| 28 | compare_line = line.lower() if case_insensitive else line |
| 29 | |
| 30 | # Determine if line matches |
| 31 | if exact_match: |
| 32 | matches = (compare_line.rstrip('\n\r') == search_pattern) |
| 33 | else: |
| 34 | matches = (search_pattern in compare_line) |
| 35 | |
| 36 | # Apply invert flag |
| 37 | if invert_match: |
| 38 | matches = not matches |
| 39 | |
| 40 | # If line matches, process according to flags |
| 41 | if matches: |
| 42 | # Edge Case: Filenames only flag - just record the filename |
| 43 | if filenames_only: |
| 44 | matched_files.add(filename) |
| 45 | break # No need to check more lines in this file |
| 46 | else: |
| 47 | # Build output line |
| 48 | output_line = "" |
| 49 | # Edge Case: Multiple files - prepend filename |
| 50 | if len(files) > 1: |
| 51 | output_line += f"{filename}:" |
| 52 | # Edge Case: Line numbers flag - prepend line number |
| 53 | if line_numbers: |
| 54 | output_line += f"{line_num}:" |
| 55 | output_line += line |
| 56 | result_lines.append(output_line) |
| 57 | |
| 58 | # Edge Case: Filenames only flag - return only filenames |
| 59 | if filenames_only: |
| 60 | return "\n".join(sorted(matched_files)) + ("\n" if matched_files else "") |
| 61 | |
| 62 | # Edge Case: No matches - return empty string |
| 63 | return "".join(result_lines) |
| 64 | |
| 65 | # Handled Edge Cases: File not found, Filenames only flag, Multiple files, Line numbers flag, No matches |