unexpand: accept a blank as a tab-list separator like GNU

[AlejandroCoronadoN]

GNU unexpand accepts both a comma and a blank between tab stops in -t/--tabs, so unexpand -t '2 3' behaves like unexpand -t '2,3'. uutils only splits on a comma, so the space form is rejected:

$ printf '  a   b\n' | unexpand -t '2 3' -a
unexpand: tab size contains invalid character(s): ' 3'

uutils' own expand already accepts both separators via an is_space_or_comma helper; only unexpand was inconsistent. This splits the tab list on a space or a comma too, mirroring expand. Verified byte for byte against GNU unexpand in the C locale for '2 3', ' 2 3', '2 3', '2, 3' and '1 4 7'; invalid values like -t x still error as before.

[codspeed-hq]

Merging this PR will improve performance by 3.44%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 177 untouched benchmarks
⏩ 229 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	du_wide_tree[(5000, 500)]	20.2 ms	19.6 ms	+3.44%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing AlejandroCoronadoN:unexpand-space-tab-separator (148fd58) with main (a9b64fc)²}

Footnotes

1. 229 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (71ebb92) during the generation of this report, so a9b64fc was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/tail/truncate. tests/tail/truncate is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/pr/bounded-memory (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/tail-n0f (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/dd/misc is no longer failing!
Note: The gnu test tests/seq/seq-epipe is now being skipped but was previously passing.
Congrats! The gnu test tests/tail/pipe-f is now passing!

[oech3]

Not a useful function. Please remove it and write code directly.

[AlejandroCoronadoN]

Good point, removed the helper and inlined it as s.split([' ', ',']). Thanks for the review!

[sylvestre]

GNU splits on blank, so a literal TAB is a valid separator too - s.split([' ', '\t', ',']). expand's is_space_or_comma has the same gap; worth fixing both here.

[AlejandroCoronadoN]

Good catch, added the tab so the split is now s.split([' ', '\t', ',']). Verified against GNU unexpand with a tab separator. Thanks!

[codspeed-hq]

Unable to generate the performance report

There was an internal error while processing the run's data. We're working on fixing the issue. Feel free to contact us on Discord or at support@codspeed.io if the issue persists.