Inspired by #312.

Use correct indexing also for cursor-matchingbracket.

Fixup for 95d82568d8

Part of #306

ISEARCH_ACTIVE was renamed ISEARCHMATCH_ACTIVE in workers/38921
(commit f06be0ffcf2c to zsh itself).

Fixes #299.

Closes #297.

Use 'print -r --' instead, so literal backslashes in $BUFFER aren't expanded.

Found-by: Matthew Martin

The new output improves readability of the 'main' highlighter's test output.

Without this when bracket_color_size is 0,
    $(( (levelpos[$pos] - 1) % bracket_color_size + 1 ))
errors with division by zero.

Since the _zsh_highlight_add_highlight that the tests use ignores
ZSH_HIGHLIGHT_STYLES, we can test both an injective mapping and an empty
mapping at once.

Closes #287. Testing the keys directly removes the need for
unused_highlight which will be removed next.

This removes the need for the typepos array.

zsh arrays start at one, and this will make the next commit easier.

Review-by: Matthew Martin

'none' is a valid highlighting type. Since by convention styles are all
lowercase, 'NONE' shouldn't conflict with anything.

Closes #289.

_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.

No need to fork every time.

Compute «${#BUFFER}» just once.  I haven't measured the effect of this, but
it might just avoid a strlen() every time around the loop, which could add
up for large ${BUFFER}s.

See issue #295.

Fixes zsh-users/zsh-syntax-highlighting#292 (compatibility with zsh-5.1.1/msys2 on windows).

In basic regular expressions | is not a special character that spearates
branches, so use an extended regular expression.

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.

7e7e291b20 broke 'zle -C' completions, as reported in #278 just now.

Re-Fixes zsh-users/zsh-syntax-highlighting#278.

The last commit inadvertently broke interactive use, although the test suite passed.

See issue #278.

The 'eval' was never needed, and the lack of proper quoting of the interpolated
variables caused issues, such as #278.

Fixes zsh-users/zsh-syntax-highlighting#278.

- Extract duplicated code into a new function.
  This makes it easier to add support for other entries in the
  future, that cannot be accessed in the current version of zsh
  (isearch, suffix).
- Make decision logic more comprehensible.
- Respect deliberately empty entries in zle_highlight.
  Don't force the default value when the user deliberately sets
  an entry in zle_highlight to the empty string.
  For example
    zle_highligh(paste:)
  to disable paste highlighting completely.

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

Thanks to Andrew Janke.

Fixes zsh-users/zsh-syntax-highlighting#270.