Double (or better) indent performance!

By utilising some ugly mutable state, this change more than doubles the
performance of the indentation code.  You can expect even further
benefits in larger code blocks.  This should completely eliminate any
need for the `clojure_maxlines` configuration option.

Author: axvr

indent/clojure.vim

@@ -41,7 +41,7 @@ function! s:SyntaxMatch(pattern, line, col)
 endfunction
 
 function! s:IgnoredRegion()
-	return s:SyntaxMatch('\vstring|regex|comment|character', line('.'), col('.'))
+	return s:SyntaxMatch('\(string\|regex\|comment\|character\)', line('.'), col('.'))
 endfunction
 
 function! s:NotAStringDelimiter()
@@ -80,47 +80,59 @@ function! s:ClosestMatch(match1, match2)
 	endif
 endfunction
 
+" Wrapper around "searchpairpos" that will automatically set "s:best_match" to
+" the closest pair match and continuously optimise the "stopline" value for
+" later searches.  This results in a significant performance gain by reducing
+" the number of syntax lookups that need to take place.
+function! s:CheckPair(name, start, end, skipfn)
+	let pos = searchpairpos(a:start, '', a:end, 'bznW', a:skipfn, s:best_match[1][0])
+	let s:best_match = s:ClosestMatch(s:best_match, [a:name, pos])
+endfunction
+
 " Only need to search up.  Never down.
 function! s:GetClojureIndent()
 	let lnum = v:lnum
 
 	" Move cursor to the first column of the line we want to indent.
 	cursor(lnum, 0)
 
-	let matches = [
-		\  ['lst', searchpairpos( '(', '',  ')', 'bznW', function('<SID>IgnoredRegion'))],
-		\  ['vec', searchpairpos('\[', '', '\]', 'bznW', function('<SID>IgnoredRegion'))],
-		\  ['map', searchpairpos( '{', '',  '}', 'bznW', function('<SID>IgnoredRegion'))],
-		\  ['reg', s:IsInRegex() ? searchpairpos('#\zs"', '', '"', 'bznW', function('<SID>NotARegexpDelimiter')) : [0, 0]],
-		\  ['str', s:IsInString() ? searchpairpos('"', '', '"', 'bznW', function('<SID>NotAStringDelimiter')) : [0, 0]]
-		\ ]
-	echom 'Matches' matches
+	let s:best_match = ['top', [0, 0]]
+
+	call s:CheckPair('lst',  '(',  ')', function('<SID>IgnoredRegion'))
+	call s:CheckPair('vec', '\[', '\]', function('<SID>IgnoredRegion'))
+	call s:CheckPair('map',  '{',  '}', function('<SID>IgnoredRegion'))
+
+	if s:IsInString()
+		call s:CheckPair('str', '"', '"', function('<SID>NotAStringDelimiter'))
+	elseif s:IsInRegex()
+		call s:CheckPair('reg', '#\zs"', '"', function('<SID>NotARegexpDelimiter'))
+	endif
 
 	" Find closest matching higher form.
-	let [formtype, coord] = reduce(matches, function('<SID>ClosestMatch'), ['top', [0, 0]])
-	echom 'Match' formtype coord
+	let [formtype, coord] = s:best_match
+	" echom 'Match' formtype coord
 
 	if formtype == 'top'
 		" At the top level, no indent.
-		echom 'At the top level!'
+		" echom 'At the top level!'
 		return 0
 	elseif formtype == 'lst'
-		echom 'Special format rules!'
+		" echom 'Special format rules!'
 		" TODO
 		" Grab text!
-		echom getline(coord[0], lnum - 1)
+		" echom getline(coord[0], lnum - 1)
 		" Begin lexing!
 		return coord[1] + 1
 	elseif formtype == 'vec' || formtype == 'map'
 		" Inside a vector, map or set.
 		return coord[1]
 	elseif formtype == 'reg'
 		" Inside a regex.
-		echom 'Inside a regex!'
+		" echom 'Inside a regex!'
 		return coord[1] - (s:ShouldAlignMultiLineStrings() ? 0 : 2)
 	elseif formtype == 'str'
 		" Inside a string.
-		echom 'Inside a string!'
+		" echom 'Inside a string!'
 		return coord[1] - (s:ShouldAlignMultiLineStrings() ? 0 : 1)
 	endif