Braceexpand

0.1.7 · active · verified Fri Apr 10

Braceexpand is a Python library that implements Bash-style brace expansion, allowing for the generation of arbitrary strings based on patterns. It provides an iterator over expanded strings, supporting integer ranges, character ranges, sequences, and nested patterns. The current version is 0.1.7, and it is compatible with Python 2.7 and 3.6+. While it closely mimics Bash behavior, it has a slower release cadence, with the last major update to 0.1.7 being in May 2021.

Warnings

breaking Unlike Bash, a pattern containing unbalanced braces will raise an `UnbalancedBracesError` exception. Bash would typically partly expand or ignore such patterns.
Fix: Ensure all opening braces `{` have a corresponding closing brace `}`. Implement try-except blocks for `UnbalancedBracesError` if processing user-supplied patterns.
gotcha Mixed-case character ranges like `{Z..a}` or `{a..Z}` will not include the characters `[]^_`` between 'Z' and 'a' in ASCII order. This differs from some Bash environments.
Fix: Be explicit with character sets if needing to include non-alphanumeric characters, or use separate expansions for uppercase and lowercase ranges. E.g., `{a..z,A..Z}`.
gotcha The `braceexpand` function returns an iterator, not a list. If you need all expanded strings at once, you must explicitly convert the iterator to a list (e.g., `list(braceexpand(...))`).
Fix: Always wrap the call in `list()` if you require a complete list, or iterate directly over the returned object.
gotcha Performance may be an issue for very large datasets. The library is not designed for high-performance scenarios with extensive expansions.
Fix: For extremely large or performance-critical expansions, consider alternative methods or preprocess patterns to minimize expansion complexity.
gotcha The backslash (`\`) is the default escape character. If you want to expand patterns containing literal backslashes or disable escaping, you need to use raw strings and/or set `escape=False`.
Fix: Use raw strings (e.g., `r'...'`) for patterns with backslashes you want treated literally or set `braceexpand(pattern, escape=False)` to disable backslash escaping entirely.

Install

pip install braceexpand Install from PyPI

Imports

braceexpand
```
from braceexpand import braceexpand
```
UnbalancedBracesError
```
from braceexpand import UnbalancedBracesError
```
Import for handling errors related to malformed brace patterns.

Quickstart

This quickstart demonstrates basic brace expansion for integer and character ranges, sequence expansion, and nested patterns. It also shows how to catch the `UnbalancedBracesError` for malformed input strings, a key deviation from Bash behavior. The `braceexpand` function returns an iterator, so `list()` is often used to see all results immediately.

from braceexpand import braceexpand

# Example 1: Integer range
expanded_items = list(braceexpand('item{1..3}'))
print(f"Integer range: {expanded_items}")

# Example 2: Character range
expanded_chars = list(braceexpand('{a..c}'))
print(f"Character range: {expanded_chars}")

# Example 3: Sequence expansion
expanded_files = list(braceexpand('index.html{,.backup}'))
print(f"Sequence expansion: {expanded_files}")

# Example 4: Nested patterns
expanded_versions = list(braceexpand('python{2.{5..7},3.{2,3}}'))
print(f"Nested patterns: {expanded_versions}")

# Example 5: Handling unbalanced braces (raises an exception)
from braceexpand import UnbalancedBracesError
try:
    list(braceexpand('{1{2,3}'))
except UnbalancedBracesError as e:
    print(f"Caught expected error: {e}")

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