Improve performance of folding

Folding is very slow for large files.
Drop `s:effective_line()` to reduce call of `s:is_mkdCode()`.

diff --git a/after/ftplugin/markdown.vim b/after/ftplugin/markdown.vim
index 1d0572c969cc3629560840dbb3979c53e83f069c..d965a71f2e3990246cd41fa563a9d11444a9c45a 100644 (file)
--- a/after/ftplugin/markdown.vim
+++ b/after/ftplugin/markdown.vim
@@ -10,24 +10,19 @@ function! s:is_mkdCode(lnum)
     return synIDattr(synID(a:lnum, 1, 0), 'name') == 'mkdCode'
 endfunction
 
     return synIDattr(synID(a:lnum, 1, 0), 'name') == 'mkdCode'
 endfunction
 

-function! s:effective_line(lnum)
-    let line = getline(a:lnum)
-    return (line !~ '^[=-#]' || s:is_mkdCode(a:lnum)) ? '' : line
-endfunction
-

 if get(g:, "vim_markdown_folding_style_pythonic", 0)
     function! Foldexpr_markdown(lnum)
 if get(g:, "vim_markdown_folding_style_pythonic", 0)
     function! Foldexpr_markdown(lnum)

-        let l2 = s:effective_line(a:lnum+1)
-        if  l2 =~ '^==\+\s*'
+        let l2 = getline(a:lnum+1)
+        if  l2 =~ '^==\+\s*' && !s:is_mkdCode(a:lnum+1)

             " next line is underlined (level 1)
             return '>0'
             " next line is underlined (level 1)
             return '>0'

-        elseif l2 =~ '^--\+\s*'
+        elseif l2 =~ '^--\+\s*' && !s:is_mkdCode(a:lnum+1)

             " next line is underlined (level 2)
             return '>1'
         endif
 
             " next line is underlined (level 2)
             return '>1'
         endif
 

-        let l1 = s:effective_line(a:lnum)
-        if l1 =~ '^#'
+        let l1 = getline(a:lnum)
+        if l1 =~ '^#' && !s:is_mkdCode(a:lnum)

             " current line starts with hashes
             return '>'.(matchend(l1, '^#\+') - 1)
         elseif a:lnum == 1
             " current line starts with hashes
             return '>'.(matchend(l1, '^#\+') - 1)
         elseif a:lnum == 1


@@ -52,17 +47,17 @@ if get(g:, "vim_markdown_folding_style_pythonic", 0)
     endfunction
 else
     function! Foldexpr_markdown(lnum)
     endfunction
 else
     function! Foldexpr_markdown(lnum)

-        let l2 = s:effective_line(a:lnum+1)
-        if  l2 =~ '^==\+\s*'
+        let l2 = getline(a:lnum+1)
+        if  l2 =~ '^==\+\s*' && !s:is_mkdCode(a:lnum+1)

             " next line is underlined (level 1)
             return '>1'
             " next line is underlined (level 1)
             return '>1'

-        elseif l2 =~ '^--\+\s*'
+        elseif l2 =~ '^--\+\s*' && !s:is_mkdCode(a:lnum+1)

             " next line is underlined (level 2)
             return '>2'
         endif
 
             " next line is underlined (level 2)
             return '>2'
         endif
 

-        let l1 = s:effective_line(a:lnum)
-        if l1 =~ '^#'
+        let l1 = getline(a:lnum)
+        if l1 =~ '^#' && !s:is_mkdCode(a:lnum)

             " don't include the section title in the fold
             return '-1'
         endif
             " don't include the section title in the fold
             return '-1'
         endif


@@ -70,9 +65,9 @@ else
         if (a:lnum == 1)
             let l0 = ''
         else
         if (a:lnum == 1)
             let l0 = ''
         else

-            let l0 = s:effective_line(a:lnum-1)
+            let l0 = getline(a:lnum-1)

         endif
         endif

-        if l0 =~ '^#'
+        if l0 =~ '^#' && !s:is_mkdCode(a:lnum-1)

             " current line starts with hashes
             return '>'.matchend(l0, '^#\+')
         else
             " current line starts with hashes
             return '>'.matchend(l0, '^#\+')
         else