Syntax: Fasten highlighting, from 200ms to 20ms for first screen update

Problem:

The loading of a .md file was slow due to multiple nested lookback.
It is advised in vim help to prefer \zs, see :h /\@<
Anyway, it is useless to nest them.

089.080  000.085  000.085: sourcing /home/mtourneb/.vim/after/syntax/vimwiki.vim
089.264  005.184: opening buffers
089.322  000.058: BufEnter autocommands
089.323  000.001: editing files in windows
089.414  000.091: VimEnter autocommands
089.415  000.001: before starting main loop
303.698  214.283: first screen update
303.700  000.002: --- VIM STARTED ---

Solution:

Remove the function s:expand_delimiter in vars.vim.
It was doing a duplicate job with vimwiki#u#hi_expand_regex
And ... well avoid lookback as much as possible

091.784  000.087  000.087: sourcing /home/mtourneb/.vim/after/syntax/vimwiki.vim
091.991  006.034: opening buffers
092.050  000.059: BufEnter autocommands
092.052  000.002: editing files in windows
092.172  000.120: VimEnter autocommands
092.173  000.001: before starting main loop
112.574  020.401: first screen update
112.578  000.004: --- VIM STARTED ---

autoload/vimwiki/u.vim

@@ -295,13 +295,19 @@ endfunction
 function! vimwiki#u#get_punctuation_string() abort
   " Faster
   " See: https://github.github.com/gfm/#ascii-punctuation-character
-  return '!"#$%&''()*+,-./:;<=>?@\[\\\]^`{}|~'
+  " res = '!"#$%&''()*+,-./:;<=>?@\[\\\]^`{}|~'
+  " But I removed the * as it is treated as a special case
+  return '!"#$%&''()+,-./:;<=>?@\[\\\]^`{}|~'
 endfunction
 
 
 function! vimwiki#u#hi_expand_regex(lst) abort
   " Helper: Expand regex from reduced typeface delimiters
   " :param: list<list,delimiters>> with reduced regex
+  "   1: Left delimiter
+  "   2: right delimiter
+  "   3: possible characters to ignore (default '$^' => never match)
+  "   4: can multiply delimiter (boolean) (default 0 => do not repeat)
   " Return: list with extended regex delimiters (not inside a word)
   "   -- [['\*_', '_\*']] -> [['\*_\S\@=', '\S\@<=_\*\%(\s\|$\)\@=']]
   " Note: For purposes of this definition, the beginning and the end of the line count as Unicode whitespace.
@@ -313,42 +319,46 @@ function! vimwiki#u#hi_expand_regex(lst) abort
   for a_delimiter in a:lst
     let r_left_del = a_delimiter[0]
     let r_right_del = a_delimiter[1]
+    let r_repeat_del = len(a_delimiter) >= 3 ? a_delimiter[2] : '$^'
+    let b_can_mult = len(a_delimiter) >= 4 ? a_delimiter[3] : 0
+
+    " Craft the repeatable middle
+    let r_mult = b_can_mult ? '\+' : ''
+    let r_left_repeat = '\%(\%(' . r_left_del . '\)' . r_mult . '\)'
+    let r_right_repeat = '\%(\%(' . r_right_del . '\)' . r_mult . '\)'
+    let r_unescaped_repeat = '\%(\\\|\\\@<!' . r_repeat_del . '\)'
 
     " Regex Start:
     " Left-Flanking is not followed by space (or need of line)
-    let r_left_prefix = '\%(^\|[[:space:]]\@<=\)'
-    let r_left_prefix = '\\\@<!'
-    " -- not followed by Unicode whitespace,
-    let r_left_suffix = '\%([[:space:]\n]\@!\)'
 
-    " Left Case1: not followed by punctuation
+    " Left Case1: not followed by punctuation, start with blacklist
-    let r_left_suffix1 = '\%(\%([[:space:]\n' . punctuation . ']\)\@!\)'
     " -- Can escape the leftflank
-    let r_left_prefix1 = '\%(^\|\\\@<!\)'
+    let r_left_prefix1 = '\%(^\|' . r_unescaped_repeat . '\@<!\)'
+    let r_left_suffix1 = '\%(\%([[:space:]\n' . punctuation . ']\|' . r_unescaped_repeat . '\)\@!\)'
 
-    " Left Case2: followed by punctuation so must be preceded by Unicode whitespace or start of line or a punctuation character.
+    " Left Case2: followed by punctuation so must be preceded by whitelisted Unicode whitespace or start of line or a punctuation character.
-    let r_left_suffix2 = '\%([' . punctuation . ']\@=\)'
     let r_left_prefix2 = '\%(\%(^\|[[:space:]\n' . punctuation . ']\)\@<=\)'
+    let r_left_suffix2 = '\%([' . punctuation . ']\@=\)'
 
     " Left Concatenate
-    let r_start = '\%(' . r_left_prefix1 . r_left_del . r_left_suffix1
+    let r_start = '\%(' . r_left_prefix1 . '\zs' . r_left_repeat . '\ze' . r_left_suffix1
-    let r_start .= '\|' . r_left_prefix2 . r_left_del . r_left_suffix2 . '\)'
+    let r_start .= '\|' . r_left_prefix2 . '\zs' . r_left_repeat . '\ze' . r_left_suffix2 . '\)'
 
     " Regex End:
     " not preceded by Unicode whitespace
     let r_right_prefix = '\(^\|[^[:space:]]\@<=\)'
 
     " Right Case1: not preceded by a punctuation character (or start of line)
-    let r_right_prefix1 = '\%(\%(^\|[^[:space:]' . punctuation . ']\)\@<=\)'
+    let r_right_prefix1 = '\%(^\|\%([[:space:]\n' . punctuation . ']\|' . r_unescaped_repeat . '\)\@<!\)'
-    let r_right_suffix1 = ''
+    let r_right_suffix1 = '\%($\|' . r_unescaped_repeat . '\@!\)'
 
-    " Right Case2: preceded by a punctuation character and followed by Unicode whitespace or end of line  or a punctuation character
+    " Right Case2: preceded by a punctuation character and followed by Unicode whitespace or end of line or a punctuation character
     let r_right_prefix2 = '\%([' . punctuation . ']\@<=\)'
     let r_right_suffix2 = '\%(\%($\|[[:space:]' . punctuation . ']\)\@<=\)'
 
     " Right Concatenate
-    let r_end = '\%(' . r_right_prefix1 . r_right_del . r_right_suffix1
+    let r_end = '\%(' . r_right_prefix1 . r_right_repeat . r_right_suffix1
-    let r_end .= '\|' . r_right_prefix2 . r_right_del . r_right_suffix2 . '\)'
+    let r_end .= '\|' . r_right_prefix2 . r_right_repeat . r_right_suffix2 . '\)'
 
     call add(res, [r_start, r_end])
   endfor

autoload/vimwiki/vars.vim

@@ -753,19 +753,19 @@ function! s:get_markdown_syntaxlocal() abort
         \ 'symH': {'type': type(0), 'default': 0},
         \ 'typeface': {'type': type({}), 'default': {
         \   'bold': vimwiki#u#hi_expand_regex([
-        \     [s:expand_delimiter('__', 1), s:expand_delimiter('__', 1)],
+        \     ['__', '__', '[_*]', 1],
-        \     [s:expand_delimiter('\*\*', 1), s:expand_delimiter('\*\*', 1)],
+        \     ['\*\*', '\*\*', '[_*]', 1],
         \     ]),
         \   'italic': vimwiki#u#hi_expand_regex([
-        \     [s:expand_delimiter('_', 0), s:expand_delimiter('_', 0)],
+        \     ['_', '_', '[_*]', 0],
-        \     [s:expand_delimiter('\*', 0), s:expand_delimiter('\*', 0)],
+        \     ['\*', '\*', '[_*]', 0],
-        \     [s:expand_delimiter('\*_', 1), s:expand_delimiter('_\*', 1)],
+        \     ['\*_', '_\*', '[_*]', 1],
-        \     [s:expand_delimiter('_\*', 1), s:expand_delimiter('\*_', 1)],
+        \     ['_\*', '\*_', '[_*]', 1],
         \     ]),
         \   'underline': vimwiki#u#hi_expand_regex([]),
         \   'bold_italic': vimwiki#u#hi_expand_regex([
-        \     [s:expand_delimiter('\*\*\*', 1), s:expand_delimiter('\*\*\*', 1)],
+        \     ['___', '___', '[_*]', 1],
-        \     [s:expand_delimiter('___', 1), s:expand_delimiter('___', 1)],
+        \     ['\*\*\*', '\*\*\*', '[_*]', 1],
         \     ]),
         \   'code': [
         \       ['\%(^\|[^`\\]\)\@<=`\%($\|[^`]\)\@=',
@@ -1344,33 +1344,6 @@ function! s:normalize_syntax_settings(syntax) abort
 endfunction
 
 
-function! s:expand_delimiter(delim, b_can_mult) abort
-  " Helper: From a delimiter to the lookhead defensive version
-  " See: also vimwiki#u#hi_expand_regex
-  " TODO: get some cache to avoid recrafting the same prefix always
-  
-  " Clause: if nothing, return nothing
-  if len(a:delim) == 0
-    return '\%(\)'
-  endif
-
-  " let c_start = a:delim[0] ==# '\' ? a:delim[0:1] : a:delim[0]
-  " let c_end = (len(a:delim) > 1 && a:delim[-2:-2] ==# '\') ? a:delim[-2:-1] : a:delim[-1:]
-  " Hardcode for markdown
-  let c_start = '[_*]'
-  let c_end = '[_*]'
-
-  let rx_mult = a:b_can_mult ? '\+' : ''
-
-  let rx_start = '\%(^\|\%(\\\@<!' . c_start . '\)\@<!\)'
-  let rx_middle = '\%(\%(' . a:delim . '\)' . rx_mult . '\)'
-  let rx_end = '\%($\|\%(\\\@<!' . c_end . '\)\@!\)'
-
-  let res = '\%(' . rx_start . rx_middle . rx_end . '\)'
-  return res
-endfunction
-
-
 " ----------------------------------------------------------
 " 4. Command (exported) {{{1
 " ----------------------------------------------------------

test/search.vader

@@ -7,10 +7,16 @@ Execute (Setup search testing wrapper):
       Log 'Cheating for old vim version, do not want to reverse bug'
       return
     endif
+
+    " Execute command and grab output
     redir => output
     silent execute a:search_command
     redir END
+
+    " The location list should not be empty
     Assert !empty(getloclist(0)), a:test_name.": no location list result"
+
+    " The location list should contains entries
     Assert match(output, '\d of \d') > -1, a:test_name.": no result message"
 
     " Tests that VimwikiSearch is quoting the pattern correctly.
@@ -30,7 +36,6 @@ Execute (Search test wiki):
   AssertEqual "= Test Wiki =", getline(1)
   AssertEqual "vimwiki", &filetype
 
-
   call TestSearch('VimwikiSearch foo',        'pattern with no spaces')
   call TestSearch('VimwikiSearch foo bar',    'pattern with spaces')
   call TestSearch('VimwikiSearch foo\bar',    'pattern with ''\''')

test/syntax.vader

@@ -37,6 +37,7 @@ Given vimwiki (Markdown typeface with escape sequence #1044: _ __ * ** {{{2):
   a ~~staaill deleted~~ Del 9
   $$Eq\$$ uation follows$ Math 10
   `code \` not finished inline` Code 11
+  012345678901234567890
 
 Execute (Set syntax markdown):
   call SetSyntax('markdown')
@@ -48,7 +49,8 @@ Execute (Assert Syntax of escape typeface):
   AssertEqual 'VimwikiBold4'       , SyntaxAt(4, 14) . 4
   AssertEqual 'VimwikiItalic5'     , SyntaxAt(5, 14) . 5
   " See: #1303 where an escape start can close the region
-  AssertEqual '6'                  , SyntaxAt(6, 14) . 6
+  " Fixed removing vars.vim::expand_delimiter
+  AssertEqual 'VimwikiItalic6'     , SyntaxAt(6, 14) . 6
   AssertEqual 'VimwikiSuperScript7', SyntaxAt(7, 14) . 7
   AssertEqual 'VimwikiSubScript8'  , SyntaxAt(8, 14) . 8
   AssertEqual 'VimwikiDelText9'    , SyntaxAt(9, 14) . 9

test/syntax_markdown_gfm_typeface.vader

@@ -623,8 +623,8 @@ Execute (Set Markdown):
 
 Execute (Assert Syntax):
   CommentLine 'Empty emphasis'
-  AssertEqual '', SyntaxAt(1, 1)
+  AssertEqual '1', SyntaxAt(1, 1) . 1
-  AssertEqual '', SyntaxAt(2, 1)
+  AssertEqual '2', SyntaxAt(2, 1) . 2
 
 
 Given vimwiki (Typeface: https://github.github.com/gfm/#example-446):