GNU grep's PCRE backend supports only a single pattern. Supplying
multiple patterns via repeated -e flags, or a pattern string that
contains a literal newline, must exit 2 with the message:
the -P option only supports a single pattern
Add the validation immediately after patterns are collected, before
regex-mode selection. Add a test covering:
- two separate -e flags with -P
- a newline-embedded pattern string with -P
- single -e with -P still works normally
Closes#34
The buffer-at-a-time fast path now serves the literal patterns that the
existing -l/-L/-q and binary tests used, leaving the line-at-a-time
engine's equivalents uncovered. Add bracket-class (non-literal) tests
for -l/-L/-q and binary handling (notice, -a text, without-match bail,
and the finalize-time notice), plus a fast-path test for a NUL that is
only discovered after a line was already printed.
No dead code was found: the remaining uncovered lines are writer I/O
error-propagation arms and pre-existing filesystem error handlers.
Literal searches were ~50-70x slower than GNU grep because every line
paid per-line costs (terminator scan, NUL scan, dispatch) even when a
buffer held no match. Add a buffer-at-a-time driver that scans whole
chunks with a substring searcher and only locates line boundaries
around the matches it finds; a chunk with no match costs a single
vectorized sweep and no per-line work.
The driver activates only for plain ASCII literal patterns (case
sensitive, no metacharacters) in the simpler output modes: -c, -l, -L,
-q, and plain line printing with -n/-b/filename/-m. Anything needing
match positions, context, inversion, color, or special binary handling
falls back to the unchanged line-at-a-time path. Output stays
byte-identical to that path, including binary/invalid-UTF-8 behavior.
- line_buffer: read_chunk() yields the largest span of complete lines.
- matcher: expose per-pattern memmem searchers when every pattern is a
plain literal (plain_literal()).
- searcher: eligible_for_fast_path(), fast_locate(), fast_print().
All scanning rides on the memchr crate (SIMD memchr/memrchr/memmem).
Unit tests for read_chunk and plain_literal; integration tests for
prefixes, -m, and multi-chunk line-number correctness.
Benchmarks (31 MB corpus) vs prior release:
-F (no match): 232ms -> 15ms (15.9x; now faster than GNU)
-c literal: 229ms -> 15ms (15.2x)
plain print: 248ms -> 18ms (13.5x)
Regex and -i paths are unchanged (still the line-at-a-time engine).
With -T, grep pads the prefix with a tab so line content lands on a tab
stop. GNU omits that tab when the line has no content: an empty line
prints just its prefix (a whitespace-only line still gets the tab).
uu_grep always wrote the tab, so empty matched lines gained a spurious
trailing tab. Gate the tab on non-empty content. Fixes the GNU testsuite
'initial-tab' test.
GNU grep tolerates options given more than once (boolean flags are
idempotent, value options take the last occurrence), but clap rejected
them with "cannot be used multiple times" (exit 2). Set
args_override_self(true) so clap replaces rather than errors; args with
ArgAction::Append (-e/-f/--include/--exclude) still accumulate.
Found by the differential fuzzer (e.g. `grep -e .* -E -n -o -n -x`).
Add a regression test covering repeated booleans, repeated value options
(last wins), and that -e still accumulates patterns.
Wondr
Leonard Hecker
Sylvestre Ledru
Kanishk Sachan
rifatx