| 1 | 1 | def grep(pattern: str, flags: str, files: list[str]) -> str: |
| 2 | | pass |
| 2 | # Parse flags - handle both individual flags and combined flags |
| 3 | line_numbers = '-n' in flags or 'n' in flags |
| 4 | files_only = '-l' in flags or 'l' in flags |
| 5 | case_insensitive = '-i' in flags or 'i' in flags |
| 6 | invert_match = '-v' in flags or 'v' in flags |
| 7 | exact_match = '-x' in flags or 'x' in flags |
| 8 | |
| 9 | # Prepare pattern for comparison |
| 10 | search_pattern = pattern.lower() if case_insensitive else pattern |
| 11 | |
| 12 | # Results storage |
| 13 | results = [] |
| 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 (remove trailing newline for comparison) |
| 28 | line_content = line.rstrip('\n') |
| 29 | compare_line = line_content.lower() if case_insensitive else line_content |
| 30 | |
| 31 | # Check for match based on exact_match flag |
| 32 | if exact_match: |
| 33 | is_match = (search_pattern == compare_line) |
| 34 | else: |
| 35 | is_match = (search_pattern in compare_line) |
| 36 | |
| 37 | # Apply invert flag |
| 38 | if invert_match: |
| 39 | is_match = not is_match |
| 40 | |
| 41 | # If line matches criteria |
| 42 | if is_match: |
| 43 | matched_files.add(filename) |
| 44 | |
| 45 | # If we only need file names, we can break early |
| 46 | if files_only: |
| 47 | break |
| 48 | |
| 49 | # Format output line |
| 50 | output_line = "" |
| 51 | |
| 52 | # Add filename prefix if multiple files |
| 53 | if len(files) > 1: |
| 54 | output_line += f"{filename}:" |
| 55 | |
| 56 | # Add line number if requested |
| 57 | if line_numbers: |
| 58 | output_line += f"{line_num}:" |
| 59 | |
| 60 | # Add the actual line content (with its original newline) |
| 61 | output_line += line |
| 62 | |
| 63 | results.append(output_line) |
| 64 | |
| 65 | # If we only need file names and we found a match, we can stop processing this file |
| 66 | if files_only and filename in matched_files: |
| 67 | continue |
| 68 | |
| 69 | # If files_only flag is set, return only the file names |
| 70 | if files_only: |
| 71 | # Edge Case: No files matched the pattern - return empty string |
| 72 | if not matched_files: |
| 73 | return "" |
| 74 | return "\n".join(sorted(list(matched_files))) |
| 75 | |
| 76 | # Edge Case: No lines matched the pattern - return empty string |
| 77 | # Edge Case: Empty file list - return empty string |
| 78 | if not results: |
| 79 | return "" |
| 80 | |
| 81 | # Join results with newlines but don't add a trailing newline |
| 82 | return "".join(results[:-1]) + results[-1].rstrip('\n') if results else "" |
| 83 | |
| 84 | # Handled Edge Cases: File not found, No files matched the pattern, No lines matched the pattern, Empty file list |