" Vim plugin for showing matching parens
" Maintainer: Bram Moolenaar <Bram@vim.org>
" Last Change: 2016 Feb 16

" Exit quickly when:
" - this plugin was already loaded (or disabled)
" - when 'compatible' is set
" - the "CursorMoved" autocmd event is not available.
if exists("g:loaded_matchparen") || &cp || !exists("##CursorMoved")
 finish
endif
let g:loaded_matchparen = 1

if !exists("g:matchparen_timeout")
 let g:matchparen_timeout = 300
endif
if !exists("g:matchparen_insert_timeout")
 let g:matchparen_insert_timeout = 60
endif

augroup matchparen
 " Replace all matchparen autocommands
 autocmd! CursorMoved,CursorMovedI,WinEnter * call s:Highlight_Matching_Pair()
 if exists('##TextChanged')
 autocmd! TextChanged,TextChangedI * call s:Highlight_Matching_Pair()
 endif
augroup END

" Skip the rest if it was already done.
if exists("*s:Highlight_Matching_Pair")
 finish
endif

let s:cpo_save = &cpo
set cpo-=C

" The function that is invoked (very often) to define a ":match" highlighting
" for any matching paren.
function! s:Highlight_Matching_Pair()
 " Remove any previous match.
 if exists('w:paren_hl_on') && w:paren_hl_on
 silent! call matchdelete(3)
 let w:paren_hl_on = 0
 endif

 " Avoid that we remove the popup menu.
 " Return when there are no colors (looks like the cursor jumps).
 if pumvisible() || (&t_Co < 8 && !has("gui_running"))
 return
 endif

 " Get the character under the cursor and check if it's in 'matchpairs'.
 let c_lnum = line('.')
 let c_col = col('.')
 let before = 0

 let text = getline(c_lnum)
 let matches = matchlist(text, '\(.\)\=\%'.c_col.'c\(.\=\)')
 if empty(matches)
 let [c_before, c] = ['', '']
 else
 let [c_before, c] = matches[1:2]
 endif
 let plist = split(&matchpairs, '.\zs[:,]')
 let i = index(plist, c)
 if i < 0
 " not found, in Insert mode try character before the cursor
 if c_col > 1 && (mode() == 'i' || mode() == 'R')
 let before = strlen(c_before)
 let c = c_before
 let i = index(plist, c)
 endif
 if i < 0
 " not found, nothing to do
 return
 endif
 endif

 " Figure out the arguments for searchpairpos().
 if i % 2 == 0
 let s_flags = 'nW'
 let c2 = plist[i + 1]
 else
 let s_flags = 'nbW'
 let c2 = c
 let c = plist[i - 1]
 endif
 if c == '['
 let c = '\['
 let c2 = '\]'
 endif

 " Find the match. When it was just before the cursor move it there for a
 " moment.
 if before > 0
 let has_getcurpos = exists("*getcurpos")
 if has_getcurpos
 " getcurpos() is more efficient but doesn't exist before 7.4.313.
 let save_cursor = getcurpos()
 else
 let save_cursor = winsaveview()
 endif
 call cursor(c_lnum, c_col - before)
 endif

 " Build an expression that detects whether the current cursor position is in
 " certain syntax types (string, comment, etc.), for use as searchpairpos()'s
 " skip argument.
 " We match "escape" for special items, such as lispEscapeSpecial.
 let s_skip = '!empty(filter(map(synstack(line("."), col(".")), ''synIDattr(v:val, "name")''), ' .
	\ '''v:val =~? "string\\|character\\|singlequote\\|escape\\|comment"''))'
 " If executing the expression determines that the cursor is currently in
 " one of the syntax types, then we want searchpairpos() to find the pair
 " within those syntax types (i.e., not skip). Otherwise, the cursor is
 " outside of the syntax types and s_skip should keep its value so we skip any
 " matching pair inside the syntax types.
 execute 'if' s_skip '| let s_skip = 0 | endif'

 " Limit the search to lines visible in the window.
 let stoplinebottom = line('w$')
 let stoplinetop = line('w0')
 if i % 2 == 0
 let stopline = stoplinebottom
 else
 let stopline = stoplinetop
 endif

 " Limit the search time to 300 msec to avoid a hang on very long lines.
 " This fails when a timeout is not supported.
 if mode() == 'i' || mode() == 'R'
 let timeout = exists("b:matchparen_insert_timeout") ? b:matchparen_insert_timeout : g:matchparen_insert_timeout
 else
 let timeout = exists("b:matchparen_timeout") ? b:matchparen_timeout : g:matchparen_timeout
 endif
 try
 let [m_lnum, m_col] = searchpairpos(c, '', c2, s_flags, s_skip, stopline, timeout)
 catch /E118/
 " Can't use the timeout, restrict the stopline a bit more to avoid taking
 " a long time on closed folds and long lines.
 " The "viewable" variables give a range in which we can scroll while
 " keeping the cursor at the same position.
 " adjustedScrolloff accounts for very large numbers of scrolloff.
 let adjustedScrolloff = min([&scrolloff, (line('w$') - line('w0')) / 2])
 let bottom_viewable = min([line('$'), c_lnum + &lines - adjustedScrolloff - 2])
 let top_viewable = max([1, c_lnum-&lines+adjustedScrolloff + 2])
 " one of these stoplines will be adjusted below, but the current values are
 " minimal boundaries within the current window
 if i % 2 == 0
 if has("byte_offset") && has("syntax_items") && &smc > 0
	let stopbyte = min([line2byte("$"), line2byte(".") + col(".") + &smc * 2])
	let stopline = min([bottom_viewable, byte2line(stopbyte)])
 else
	let stopline = min([bottom_viewable, c_lnum + 100])
 endif
 let stoplinebottom = stopline
 else
 if has("byte_offset") && has("syntax_items") && &smc > 0
	let stopbyte = max([1, line2byte(".") + col(".") - &smc * 2])
	let stopline = max([top_viewable, byte2line(stopbyte)])
 else
	let stopline = max([top_viewable, c_lnum - 100])
 endif
 let stoplinetop = stopline
 endif
 let [m_lnum, m_col] = searchpairpos(c, '', c2, s_flags, s_skip, stopline)
 endtry

 if before > 0
 if has_getcurpos
 call setpos('.', save_cursor)
 else
 call winrestview(save_cursor)
 endif
 endif

 " If a match is found setup match highlighting.
 if m_lnum > 0 && m_lnum >= stoplinetop && m_lnum <= stoplinebottom 
 if exists('*matchaddpos')
 call matchaddpos('MatchParen', [[c_lnum, c_col - before], [m_lnum, m_col]], 10, 3)
 else
 exe '3match MatchParen /\(\%' . c_lnum . 'l\%' . (c_col - before) .
	 \ 'c\)\|\(\%' . m_lnum . 'l\%' . m_col . 'c\)/'
 endif
 let w:paren_hl_on = 1
 endif
endfunction

" Define commands that will disable and enable the plugin.
command! NoMatchParen windo silent! call matchdelete(3) | unlet! g:loaded_matchparen |
	 \ au! matchparen
command! DoMatchParen runtime plugin/matchparen.vim | windo doau CursorMoved

let &cpo = s:cpo_save
unlet s:cpo_save