" Vim global plugin for folding text around search results
 " Last change:  Wed Aug 10 10:06:31 BST 2011
 " Maintainer:	Damian Conway
 " License:	This file is placed in the public domain.
 
 " If already loaded, we're done...
 if exists("loaded_foldsearch")
     finish
 endif
 let loaded_foldsearch = 1
 
 " Preserve external compatibility options, then enable full vim compatibility...
 let s:save_cpo = &cpo
 set cpo&vim
 
 " Remember default behaviours...
 let s:DEFFOLDMETHOD = &foldmethod
 let s:DEFFOLDEXPR   = &foldexpr
 let s:DEFFOLDTEXT   = &foldtext
 let s:DEFFOLDLEVEL  = 1000
 
 " This is what the options are changed to...
 let s:FOLDEXPR = 'FS_FoldSearchLevel()'
 let s:FOLDTEXT = {
 \   'visible'   : "'___/ line ' . (v:foldend+1) . ' \\' . repeat('_',200) ",
 \   'invisible' : "repeat(' ',200)",
 \}
 
 
 
 " Turn the mechanism on and off...
 function! FS_ToggleFoldAroundSearch (opts)
     " How much context to show...
     let b:FOLDCONTEXT = get(a:opts, 'context', 1)
     let &foldminlines = b:FOLDCONTEXT
 
     " Show folds???
     let folds_visible = get(a:opts, 'folds', 'visible')
 
     " Make sure we can remember the previous setup...
     if !exists('b:foldsearch')
         let b:foldsearch = { 'active' : 0 }
     endif
 
     " Turn off, if it's on...
     if b:foldsearch.active
         let &foldmethod = get(b:foldsearch, 'prevfoldmethod', s:DEFFOLDMETHOD)
         let &foldtext   = get(b:foldsearch, 'prevfoldtext',   s:DEFFOLDTEXT)
         let &foldlevel  = get(b:foldsearch, 'prevfoldlevel',  s:DEFFOLDLEVEL)
         let &foldexpr   = get(b:foldsearch, 'prevfoldexpr',   s:DEFFOLDEXPR)
 
         " Remove autocommands for refolding for each new search...
         augroup FoldSearch
             autocmd!
         augroup END
 
         " Remember that it's off...
         let b:foldsearch.active = 0
 
         " Disable special <CR> behaviour...
         nunmap <buffer> <CR>
 
         return 'zE'
 
     " Turn on, if it's off...
     else
 
         " Save old settings...
         let b:foldsearch.prevfoldmethod = &foldmethod
         let b:foldsearch.prevfoldexpr   = &foldexpr
         let b:foldsearch.prevfoldtext   = &foldtext
         let b:foldsearch.prevfoldlevel  = &foldlevel
 
         " Set up new behaviour...
         let &foldtext   = s:FOLDTEXT[folds_visible]
         let &foldexpr   = s:FOLDEXPR
         let &foldmethod = 'expr'
         let &foldlevel  = 0
 
         " Recalculate folding for each new search...
         augroup FoldSearch
             autocmd!
             autocmd CursorMoved  *  let b:inopenfold = foldlevel('.') && foldclosed('.') == -1
             autocmd CursorMoved  *  let &foldexpr  = &foldexpr
             autocmd CursorMoved  *  let &foldlevel = 0
             autocmd CursorMoved  *  call ReopenFold()
             function! ReopenFold ()
                 if b:inopenfold
                     normal zo
                 endif
             endfunction
         augroup END
 
         " Enable special <CR> behaviour...
         nnoremap <buffer> <expr> <CR> foldlevel('.') ? 'zA' : ''
 
         " Remember that it's on...
         let b:foldsearch.active = 1
 
         return ":redraw!\<CR>"
     endif
 endfunction
 
 " Search for a particular target and turn search folding on (if not already on)...
 function! FS_FoldAroundTarget (target, opts)
     let context       = get(a:opts, 'context', 1        )
     let folds_visible = get(a:opts, 'folds',   'visible')
 
     " If already in a foldsearch...
     if exists('b:foldsearch')
         if b:foldsearch.active
             " If already folding this pattern...
             if @/ == a:target
                 " Toggle off...
                 return ":nohlsearch\<CR>:exec 'normal ' . FS_ToggleFoldAroundSearch({'context':1})\<CR>"
 
             " Otherwise stay in foldsearch and switch to target...
             else
                 let b:FOLDCONTEXT = get(a:opts, 'context', 1)
                 let &foldtext     = s:FOLDTEXT[folds_visible]
                 let &foldminlines = 1
                 return '/' . a:target . "\<CR>"
             endif
         endif
     endif
 
     " If not already in a foldsearch, search for target then toggle on...
     return '/' . a:target . "\<CR>:exec 'normal ' . FS_ToggleFoldAroundSearch(".string(a:opts).")\<CR>"
 endfunction
 
 " Utility function implements folding expression...
 function! FS_FoldSearchLevel ()
     " Allow one line of context before and after...
     let startline = v:lnum > 1         ? v:lnum - b:FOLDCONTEXT : v:lnum
     let endline   = v:lnum < line('$') ? v:lnum + b:FOLDCONTEXT : v:lnum
     let context = getline(startline, endline)
 
     " Simulate smartcase matching...
     let matchpattern = @/
     if &smartcase && matchpattern =~ '\u'
         let matchpattern = '\C'.matchpattern
     endif
 
     " Line is folded if surrounding context doesn't match last search pattern...
     return match(context, matchpattern) == -1
 
 endfunction
 
 " Restore previous external compatibility options
 let &cpo = s:save_cpo