kbknapp / clap-rs / 3326

94%

Pull #845

travis-ci

feature: use textwrap crate for wrapping help texts

The textwrap crate uses a simpler linear-time algorithm for wrapping
the text. The current algorithm in wrap_help uses several O(n) calls
to String::insert and String::remove, which makes it potentially
quadratic in complexity.

... benchcmp

Notice how the wrapping_newline_chars test was updated -- the old
algorithm had a subtle bug where it would break lines too early. That
is, it wrapped the text like

    ARGS:
        <mode>    x, max, maximum   20 characters, contains
                  symbols.
                  l, long           Copy-friendly,
                  14 characters, contains symbols.
                  m, med, medium    Copy-friendly, 8
                  characters, contains symbols.";

when it should really have wrapped it like

    ARGS:
        <mode>    x, max, maximum   20 characters, contains
                  symbols.
                  l, long           Copy-friendly, 14
                  characters, contains symbols.
                  m, med, medium    Copy-friendly, 8
                  characters, contains symbols.";

Notice how the word "14" was incorrectly moved to the next line. There
is clearly room for the word on the line with the "l, long" option
since there is room for "contains" just above it.

The algorithm in textwrap handles this case correctly.

9 of 9 new or added lines in 2 files covered. (100.0%)

7974 of 8656 relevant lines covered (92.12%)

0.92 hits per line