brace-expansion 0.1.1

Bash-style brace expansion: a{b,c}d -> [abd, acd], {1..3} -> [1,2,3]. A faithful port of the brace-expansion npm package. Zero dependencies.
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brace-expansion

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Bash-style brace expansion — a{b,c}d → ["abd", "acd"], {1..3} → ["1", "2", "3"]. A faithful Rust port of the brace-expansion npm package (the expander behind minimatch/glob), which implements bash's rules. Zero dependencies and #![no_std].

use brace_expansion::expand;

assert_eq!(expand("a{b,c}d"), ["abd", "acd"]);
assert_eq!(expand("{1..3}"), ["1", "2", "3"]);
assert_eq!(expand("{a..c}"), ["a", "b", "c"]);
assert_eq!(expand("{01..03}"), ["01", "02", "03"]);   // zero-padded
assert_eq!(expand("{1..10..2}"), ["1", "3", "5", "7", "9"]); // step
assert_eq!(expand("a{b,c{d,e}}f"), ["abf", "acdf", "acef"]); // nested

Why brace-expansion?

Brace expansion is the first thing a shell does to a glob, and the JS module that implements it is one of the most-depended-on packages in existence. Its rules are deceptively subtle — numeric and alphabetic sequences, optional steps and zero-padding, nested sets, backslash escaping, and a handful of bash compatibility quirks. This is that algorithm, ported faithfully: output is identical to the npm package (verified over thousands of patterns), which in turn matches bash for ordinary patterns.

[dependencies]
brace-expansion = "0.1"

API

Item Purpose
expand(pattern) Expand a pattern into a Vec<String>
expand_with_max(pattern, max) Same, with a custom result cap
EXPANSION_MAX The default cap (100_000)

Behavior

  • Comma sets ({a,b,c}) expand to each member; sets combine as a cross product.
  • {x..y} is a sequence: numeric ({1..5}, {-3..3}) or alphabetic ({a..e}), with an optional step ({0..10..2}) and zero-padding ({01..05}).
  • Sets and sequences nest arbitrarily.
  • \{, \}, \,, \., and \\ are escaped and emitted literally.
  • Patterns with no valid expansion (foo, {a}, a{}b) are returned unchanged, including bash's leading-{} quirk.

Output is identical to the npm package for ordinary patterns (verified over many thousands of cases). A few deliberate edge differences: sequence endpoints use exact i64 arithmetic rather than JavaScript's lossy f64 (so they stay exact past 2^53), nesting beyond a few hundred levels degrades gracefully instead of recursing without bound, and the literal NUL-delimited markers used internally are not expected in real patterns.

Contributors ✨

This project follows the all-contributors specification. Contributions of any kind are welcome — code, docs, bug reports, ideas, reviews! See the emoji key for how each contribution is recognized, and open a PR or issue to get involved.

Thanks goes to these wonderful people:

License

Licensed under either of Apache-2.0 or MIT at your option.