| 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): Flags for customizing the command's behavior. |
| 8 | files (list[str]): One or more files to search in. |
| 9 | |
| 10 | Returns: |
| 11 | str: Matching lines, possibly with file names and line numbers. |
| 12 | """ |
| 13 | # Parse flags |
| 14 | line_numbers = '-n' in flags |
| 15 | files_only = '-l' in flags |
| 16 | case_insensitive = '-i' in flags |
| 17 | invert_match = '-v' in flags |
| 18 | exact_match = '-x' in flags |
| 19 | |
| 20 | # Prepare pattern for comparison |
| 21 | search_pattern = pattern.lower() if case_insensitive else pattern |
| 22 | |
| 23 | # Results storage |
| 24 | results = [] |
| 25 | matching_files = set() |
| 26 | |
| 27 | # Process each file |
| 28 | for filename in files: |
| 29 | try: |
| 30 | with open(filename, 'r', encoding='utf-8') as file: |
| 31 | lines = file.readlines() |
| 32 | |
| 33 | # Process each line |
| 34 | for i, line in enumerate(lines, start=1): |
| 35 | # Prepare line for comparison |
| 36 | compare_line = line.lower() if case_insensitive else line |
| 37 | |
| 38 | # Check for match |
| 39 | if exact_match: |
| 40 | is_match = search_pattern == compare_line.rstrip('\n') |
| 41 | else: |
| 42 | is_match = search_pattern in compare_line |
| 43 | |
| 44 | # Apply invert flag |
| 45 | if invert_match: |
| 46 | is_match = not is_match |
| 47 | |
| 48 | # If line matches |
| 49 | if is_match: |
| 50 | # Edge Case: When -l flag is used, we only need to know which files match |
| 51 | if files_only: |
| 52 | matching_files.add(filename) |
| 53 | break # No need to check more lines in this file |
| 54 | else: |
| 55 | # Build output line |
| 56 | output_line = "" |
| 57 | # Edge Case: When multiple files are provided, prepend filename |
| 58 | if len(files) > 1: |
| 59 | output_line += f"{filename}:" |
| 60 | # Edge Case: When -n flag is used, prepend line number |
| 61 | if line_numbers: |
| 62 | output_line += f"{i}:" |
| 63 | output_line += line |
| 64 | results.append(output_line) |
| 65 | # Edge Case: Handle file not found errors |
| 66 | except FileNotFoundError: |
| 67 | # According to typical grep behavior, we silently ignore missing files |
| 68 | # or we could raise an error - following typical behavior here |
| 69 | continue |
| 70 | |
| 71 | # Edge Case: When -l flag is used, return only filenames |
| 72 | if files_only: |
| 73 | return "\n".join(sorted(list(matching_files))) |
| 74 | |
| 75 | # Edge Case: Handle case where no matches are found |
| 76 | if not results: |
| 77 | return "" |
| 78 | |
| 79 | # Edge Case: Remove trailing newline if present |
| 80 | output = "".join(results) |
| 81 | if output.endswith("\n"): |
| 82 | output = output[:-1] |
| 83 | |
| 84 | return output |
| 85 | # Handled Edge Cases: Empty file list, file not found, no matches found, case sensitivity, exact match, invert match, line numbers, files only flag, multiple files, trailing newlines |