wcwidth - Simplified wcwidth for MicroPython

This is a simplified version of wcwidth optimized for MicroPython and embedded systems.

Size Comparison

Version	Lines of Code	Disk Size	Unicode Versions
MicroPython wcwidth	746	88 KB	1 version (17.0.0 only)
Original wcwidth	7,888	672 KB	21 versions (4.1.0 - 17.0.0)

Size reduction: ~90% (from 672 KB to 88 KB)

What's Removed

• Multi-version support (only Unicode 17.0.0 is included)
• Version selection logic and environment variable handling
• Standard library functools.lru_cache (replaced with simple dict-based cache)
• VS15 table (not commonly used)
• Warnings and detailed error messages
• lru_cache replace by simplistic cache implementation

What's Kept

• Full Unicode 17.0.0 character width tables
• wcwidth() - character width measurement
• wcswidth() - string width measurement
• Support for:
  • Wide characters (CJK, emoji, etc.)
  • Zero-width characters (combining marks, ZWJ, etc.)
  • VS16 (Variation Selector 16) for emoji modifiers
  • Control character detection

Installation

Simplest way to install the module on your MicroPython board is via mpremote mip:

mpremote mip install github:josverl/mp_wcwidth

Usage

from wcwidth import wcwidth, wcswidth

# Get width of a single character
print(wcwidth('A'))      # 1 (normal ASCII)
print(wcwidth('你'))     # 2 (wide CJK character)
print(wcwidth('🪲'))     # 2 (wide emoji)
print(wcwidth('\u0301')) # 0 (combining accent)
print(wcwidth('\n'))     # -1 (control character)

# Get width of a string
print(wcswidth('Hello'))         # 5
print(wcswidth('你好'))           # 4
print(wcswidth('print("🪲")'))   # 11

Demo

A simple demo script demo.py is included to showcase the functionality:

# Install the module and demo script to your MicroPython device
mpremote mip install github:josverl/mp_wcwidth
mpremote mip install --target . github:josverl/mp_wcwidth/demo.py

# Run the demo on the device 
mpremote exec "exec(open('demo.py').read())"

Caching

The simplified version includes a minimal cache implementation (simple_cache.py) that replaces Python's functools.lru_cache:

• Fixed size: Uses a simple dict with size limit (no reallocation)
• FIFO eviction: When full, clears entire cache (ultra-simple)
• No external dependencies: Pure Python, MicroPython compatible
• Minimal overhead: ~90 lines of code
• Default cache size: 128 entries for wcwidth()

The cache significantly improves performance for repeated character width lookups.

Testing

All basic functionality works identically to the original:

python -c "import wcwidth; print(wcwidth.wcwidth('🪲'))"  # 2

mpremote exec "import wcwidth; print(wcwidth.wcwidth('🪲'))"  # 2

License

Same as original wcwidth (MIT License)

Credits

Based on wcwidth by Jeff Quast, which is based on Markus Kuhn's wcwidth.c implementation.