feat: implement brace expansion

[reubeno]

This covers one of the last big remaining holes in expansion (the other is history expansion), albeit with complexity.

Resolves #42

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Files not reviewed (1)

• brush-parser/src/error.rs: Evaluated as low risk

Comments suppressed due to low confidence (4)

brush-core/src/expansion.rs:474

• The function brace_expand_if_needed lacks test coverage for cases where brace expansion parsing fails. Consider adding tests to ensure proper error handling and logging.

fn brace_expand_if_needed(&self, word: &'a str) -> Result<Vec<Cow<'a, str>>, error::Error> {

brush-core/src/expansion.rs:484

• The parse_brace_expansions function call does not handle the case where the parse result is an error. This could lead to unexpected behavior. Consider handling the error case explicitly.

let parse_result = brush_parser::word::parse_brace_expansions(word, &self.parser_options);

brush-core/src/expansion.rs:498

• The map operation on the result variable should handle empty strings properly. Consider adding a check to ensure that empty strings are handled as intended.

let result = result.map(|s| s.into()).collect();

brush-core/src/expansion.rs:1638

• The generate_and_combine_brace_expansions function lacks test coverage for edge cases such as empty brace expressions and nested brace expressions. Consider adding tests for these cases.

.map(|piece| piece.generate().collect())

[github-actions]

Test Results

    2 files      9 suites   1m 22s ⏱️
  555 tests   555 ✅ 0 💤 0 ❌
1 096 runs  1 096 ✅ 0 💤 0 ❌

Results for commit 9f8e8e6.

♻️ This comment has been updated with latest results.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
expand_one_string	3.49 μs	3.50 μs	0.00 μs	⚪ Unchanged
instantiate_shell	62.43 μs	62.24 μs	-0.19 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	31964.62 μs	31718.78 μs	-245.83 μs	⚪ Unchanged
parse_bash_completion	2901.66 μs	2807.54 μs	-94.12 μs	🟢 -3.24%
parse_sample_script	4.31 μs	4.20 μs	-0.11 μs	🟢 -2.60%
run_echo_builtin_command	93.75 μs	95.69 μs	1.94 μs	🟠 +2.07%
run_one_builtin_command	111.40 μs	113.59 μs	2.19 μs	⚪ Unchanged
run_one_external_command	2107.98 μs	1952.50 μs	-155.49 μs	🟢 -7.38%
run_one_external_command_directly	1016.63 μs	1022.97 μs	6.35 μs	⚪ Unchanged

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
brush-core/src/expansion.rs	🟢 96.21%	🟢 96.1%	🔴 -0.11%
brush-core/src/shell.rs	🟢 77.86%	🟢 77.99%	🟢 0.13%
Overall Coverage	🟢 74.28%	🟢 74.56%	🟢 0.28%

Minimum allowed coverage is 70%, this run produced 74.56%