mslex

Warnings

• gotcha mslex specifically targets the non-POSIX, often inconsistent, command-line parsing and quoting rules of Windows (`cmd.exe`, `CommandLineToArgvW`, `msvcrt.dll`). Directly replacing the standard library `shlex` with `mslex` on non-Windows (POSIX) systems will result in incorrect behavior.
  Fix: Use the `oslex` or `oslex2` library if you need cross-platform `shlex`-like behavior that automatically adapts to the operating system. Alternatively, explicitly gate `mslex` usage with `if sys.platform == 'win32':` checks.
• gotcha Windows command-line parsing has historical ambiguities (e.g., differences between older `msvcrt.dll` and modern UCRT). By default, `mslex.split()` attempts to parse a string using both common Windows C runtime behaviors and raises a `ValueError` if they disagree, indicating an ambiguous input. This strictness ensures correctness but might require explicit `ucrt=True` or `ucrt=False` arguments for specific scenarios.
  Fix: If `mslex.split()` raises a `ValueError` due to ambiguity, consult the Windows command-line parsing rules and specify `ucrt=True` for modern C runtime behavior or `ucrt=False` for older `msvcrt.dll` emulation, based on the target program's compilation. Also, consider the `like_cmd=True` parameter for `cmd.exe` specific parsing behavior.
• gotcha The `mslex.quote()` function provides a `for_cmd` parameter (default `True`) that dictates whether the output string should be correctly parsed by `cmd.exe` *and* `CommandLineToArgvW` (when `True`), or just `CommandLineToArgvW` directly (when `False`). Incorrectly setting this can lead to misinterpretation of quoted arguments by the target process.
  Fix: Ensure the `for_cmd` argument in `mslex.quote()` is set appropriately for your use case. If the quoted string will be passed directly to a program that uses `CommandLineToArgvW` (e.g., via `subprocess.Popen` without `shell=True`), `for_cmd=False` might be more suitable. If it's intended for a `cmd.exe` command, `for_cmd=True` is typically correct.

Install

• pip install mslex Install stable version

Imports

• mslex

  import mslex

  The library exports its functions directly under the 'mslex' module name.
• split

  from mslex import split

• quote

  from mslex import quote

• join

  from mslex import join

Quickstart

This quickstart demonstrates the core `mslex.quote` and `mslex.split` functions. It shows how to quote a path with spaces for Windows command lines and how to parse a command string into arguments. A note on complex Windows quoting behavior is included, highlighting mslex's ability to handle nuances and potential ambiguities.

import mslex
import sys

# Example 1: Quoting a string for Windows command line
path_with_spaces = r'C:\Program Files\My App\app.exe'
quoted_path = mslex.quote(path_with_spaces)
print(f"Original path: {path_with_spaces}")
print(f"Quoted path: {quoted_path}")
# Expected: C:\\Program\ Files\\My\ App\\app.exe (or similar depending on for_cmd)

# Example 2: Splitting a Windows command line string
command_string = 'dir "C:\\Program Files" /s'
args = mslex.split(command_string)
print(f"Command string: {command_string}")
print(f"Split arguments: {args}")
# Expected: ['dir', 'C:\\Program Files', '/s']

# Example 3: Handling complex Windows quoting nuances
# mslex attempts to parse both UCRT and msvcrt.dll ways by default and can raise an error if they disagree.
# You can specify ucrt=True/False or like_cmd=True/False for specific behaviors.
# This example demonstrates a basic split without specific runtime flags.
complex_command = 'program.exe arg1 "arg 2 with spaces" ^"escaped arg^"'
if sys.platform == 'win32':
    try:
        parsed_complex_args = mslex.split(complex_command)
        print(f"Complex command (Windows): {complex_command}")
        print(f"Parsed complex arguments: {parsed_complex_args}")
    except ValueError as e:
        print(f"Could not parse complex command due to ambiguity: {e}")
else:
    print(f"mslex is primarily for Windows; skipping complex example on {sys.platform}")