Found-by: m0viefreak
(in #298)

Consider indexing long buffers (say 300 chars). E.g. following line:
      integer offset=${${buf[start_pos+1,len]}[(i)$needle]}
will gradually go into large indices for first index [a,] and be kept
at large index for second index [,b]. Instead, we can remove already
processed characters from buf:
    proc_buf="${proc_buf[offset + $#arg + 1,-1]}"
$offset and $#arg are small, first index will not be large. $proc_buf
will be smaller and smaller and the second index [,-1] will run shorter
and shorter.

Inspired by #312.

_zsh_highlight_add_highlight appends to region_highlight $1 $2 and the
next non-null parameter. If there is no non-null parameter, do nothing,
This is so that highlighters can add a style with fallbacks if the most
specific style is not defined. If none of the applicable styles are
defined, do the right thing and don't add an invalid entry to
region_highlight.

The pattern highlighter doesn't use this function as it'd need too large
of an API change.

zsh older than workers/28418 (zsh revision 23bdfc7fd2)
doesn't support the «${name:offset:length}» syntax.  Therefore, use the older
«$name[start,end]» syntax instead.

Followup to 3cb58fd7d7b9e42067ffcf24892114dc2c9b26e4, "Optimization: -1 is
extra computation of string length internally".

Fixes zsh-users/zsh-syntax-highlighting#279.

While here, also add a test for the '!' reserved word (which is highlighted
since c216242b).

This is a continuation of 451665cb2a which did
the same for the $PS3 prompt.

Reported-by: Sebastian Gniazdowski

./parse.zsh "zplugin.zsh" > out_norm.txt 106,17s user 7,84s system 98% cpu 1:55,85 total

./parse.zsh "zplugin.zsh" > out_opt.txt 51,91s user 7,44s system 99% cpu 59,912 total

% wc -l zplugin.zsh
3188 zplugin.zsh

The input to the $PS3 prompt is not commands, so the 'main' highlighter is
not applicable to it.

Fixes zsh-users/zsh-syntax-highlighting#268.

This fixes fd's specified by a (single) digit.  The named fd syntax remains an XFail.

The default for [redirection] is 'none', so it wasn't actually being tested.

The important part of this change is removing the second conjunct from the
condition; the remainder of the change gives one example of when that matters.

At this time, no user-visible consequences are known.

Done in c30301d474 and
c687bddea3 for other tests.

Fixes zsh-users/zsh-syntax-highlighting#101.

This builds upon the test harness auto-cleaned-up directories work (c01533920).

There's simply no reason to use such names, now that the filename is no longer
itself test data.

Fixes zsh-users/zsh-syntax-highlighting#182.
Prerequisite for testing issue #228.

* tests/test-highlighting.zsh
  (run_test): Move functionality to run_test_internal; make run_test be a wrapper
    that handles creating and cleaning up the tempdir.

* tests/README.md: Document the new feature.

* "highlighters/main/test-data/path-space- .zsh"
* highlighters/main/test-data/path-tilde-named.zsh
* highlighters/main/test-data/path.zsh
    Change test data to not depend on being run from the source directory.

Followup to c0dafd1d850e582291b41d693369794d1ea31343, which changed the highlight of
those ')'s from <nothing> to [reserved-word].