1 files changed, 131 insertions, 0 deletions
diff --git a/ftplugin/svelte/fold.vim b/ftplugin/svelte/fold.vim
new file mode 100644
index 00000000..2732660a
--- /dev/null
+++ b/ftplugin/svelte/fold.vim
@@ -0,0 +1,131 @@
+if polyglot#init#is_disabled(expand('<sfile>:p'), 'svelte', 'ftplugin/svelte/fold.vim')
+  finish
+endif
+
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+"
+" Config {{{
+"
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+let s:use_foldexpr = exists("g:vim_svelte_plugin_use_foldexpr") 
+      \ && g:vim_svelte_plugin_use_foldexpr == 1
+"}}}
+
+if !s:use_foldexpr | finish | endif
+
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+"
+" Settings {{{
+"
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+setlocal foldmethod=expr
+setlocal foldexpr=GetSvelteFold(v:lnum)
+"}}}
+
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+"
+" Variables {{{
+"
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+let s:empty_line = '\v^\s*$'
+let s:block_end = '\v^\s*}|]|\)'
+let s:svelte_tag_start = '\v^\<\w+' 
+let s:svelte_tag_end = '\v^\<\/\w+' 
+let s:svelte_internal_blocks = '\v:(else|then|catch)'
+"}}}
+
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+"
+" Functions {{{
+"
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+"  see :h fold-expr
+"  value			    meaning
+"  0			        the line is not in a fold
+"  1, 2, ..		    the line is in a fold with this level
+"  -1			        the fold level is undefined, use the fold level of a
+"			            line before or after this line, whichever is the
+"			            lowest.
+"  "="			      use fold level from the previous line
+"  "a1", "a2", ..	add one, two, .. to the fold level of the previous
+"			            line, use the result for the current line
+"  "s1", "s2", ..	subtract one, two, .. from the fold level of the
+"                 previous line, use the result for the next line
+"  ">1", ">2", ..	a fold with this level starts at this line
+"  "<1", "<2", ..	a fold with this level ends at this line
+function! GetSvelteFold(lnum)
+  let this_line = getline(a:lnum)
+  let next_line = getline(a:lnum + 1)
+
+  " Handle empty lines
+  if this_line =~ s:empty_line
+    return -1
+  endif
+
+  " Handle start/end tags
+  if this_line =~ s:svelte_tag_start
+    return '>1'
+  endif
+  if this_line =~ s:svelte_tag_end
+    " If return '<1', fold will get incorrect with prev line
+    return 1
+  endif
+
+  " Fold by indent
+  if a:lnum > 1
+    let prev_indent = s:IndentLevel(a:lnum - 1)
+  else
+    let prev_indent = 0
+  endif
+  let this_indent = s:IndentLevel(a:lnum)
+  let next_indent = s:IndentLevel(s:NextNonBlankLine(a:lnum))
+
+  " Fold separately on blocks
+  if this_line =~ s:svelte_internal_blocks
+    return '>'.next_indent
+  endif
+
+  if GetSvelteTag(a:lnum) == 'script'
+    " Handle closing '}'
+    if this_line =~ '\v^\s*},?\s*$'
+      return '<'.prev_indent
+    endif
+
+    " --this
+    " ----next
+    if this_indent < next_indent
+      return '>'.next_indent
+    endif
+
+    " ----this
+    " --next
+    if this_indent >= next_indent 
+      return this_indent
+    endif
+  else
+    " Template or style
+    return this_indent
+  endif
+endfunction
+
+function! s:IndentLevel(lnum)
+  " Add 1 to indentLevel, so start/end tags can fold properly
+  return indent(a:lnum) / &shiftwidth + 1
+endfunction
+
+function! s:NextNonBlankLine(lnum)
+  let next_line = a:lnum + 1
+  let last_line = line('$')
+
+  while next_line <= last_line
+    if getline(next_line) =~ '\v\S'
+      return next_line
+    endif
+
+    let next_line += 1
+  endwhile
+
+  return 0
+endfunction
+"}}}
+" vim: fdm=marker