Automatic real nesting for languages with support

Removes the placeholder workaround (forceNested) for languages which
allow truly nested comments and automatically applies them.
Enabled for haskell, racket, scheme, scala, lisp, ocaml, sml.
Fixes issue #131

plugin/NERD_commenter.vim

@@ -195,7 +195,7 @@ let s:delimiterMap = {
     \ 'groovy': { 'left': '//', 'leftAlt': '/*', 'rightAlt': '*/' },
     \ 'gsp': { 'left': '<%--', 'right': '--%>', 'leftAlt': '<!--','rightAlt': '-->'},
     \ 'gtkrc': { 'left': '#' },
-    \ 'haskell': { 'left': '{-','right': '-}', 'leftAlt': '--' },
+    \ 'haskell': { 'left': '{-','right': '-}', 'nested': 1, 'leftAlt': '--', 'nestedAlt': 1 },
     \ 'hb': { 'left': '#' },
     \ 'h': { 'left': '//', 'leftAlt': '/*', 'rightAlt': '*/' },
     \ 'haml': { 'left': '-#', 'leftAlt': '/' },
@@ -240,7 +240,7 @@ let s:delimiterMap = {
     \ 'lilo': { 'left': '#' },
     \ 'lilypond': { 'left': '%' },
     \ 'liquid': { 'left': '{% comment %}', 'right': '{% endcomment %}' },
-    \ 'lisp': { 'left': ';', 'leftAlt': '#|', 'rightAlt': '|#' },
+    \ 'lisp': { 'left': ';', 'nested': 1, 'leftAlt': '#|', 'rightAlt': '|#', 'nestedAlt': 1 },
     \ 'llvm': { 'left': ';' },
     \ 'lotos': { 'left': '(*', 'right': '*)' },
     \ 'lout': { 'left': '#' },
@@ -288,7 +288,7 @@ let s:delimiterMap = {
     \ 'objc': { 'left': '//', 'leftAlt': '/*', 'rightAlt': '*/' },
     \ 'objcpp': { 'left': '//', 'leftAlt': '/*', 'rightAlt': '*/' },
     \ 'objj': { 'left': '//', 'leftAlt': '/*', 'rightAlt': '*/' },
-    \ 'ocaml': { 'left': '(*', 'right': '*)' },
+    \ 'ocaml': { 'left': '(*', 'right': '*)', 'nested': 1 },
     \ 'occam': { 'left': '--' },
     \ 'octave': { 'left': '%', 'leftAlt': '#' },
     \ 'omlet': { 'left': '(*', 'right': '*)' },
@@ -329,7 +329,7 @@ let s:delimiterMap = {
     \ 'puppet': { 'left': '#' },
     \ 'pyrex': { 'left': '# ', 'leftAlt': '#' },
     \ 'python': { 'left': '# ', 'leftAlt': '#' },
-    \ 'racket': { 'left': ';', 'leftAlt': '#|', 'rightAlt': '|#' },
+    \ 'racket': { 'left': ';', 'nested': 1, 'leftAlt': '#|', 'rightAlt': '|#', 'nestedAlt': 1 },
     \ 'radiance': { 'left': '#' },
     \ 'ratpoison': { 'left': '#' },
     \ 'r': { 'left': '#' },
@@ -349,9 +349,9 @@ let s:delimiterMap = {
     \ 'samba': { 'left': ';', 'leftAlt': '#' },
     \ 'sass': { 'left': '//', 'leftAlt': '/*' },
     \ 'sather': { 'left': '--' },
-    \ 'scala': { 'left': '//', 'leftAlt': '/*', 'rightAlt': '*/' },
+    \ 'scala': { 'left': '//', 'nested': 1, 'leftAlt': '/*', 'rightAlt': '*/', 'nestedAlt': 1 },
     \ 'scons': { 'left': '#' },
-    \ 'scheme': { 'left': ';', 'leftAlt': '#|', 'rightAlt': '|#' },
+    \ 'scheme': { 'left': ';', 'nested': 1, 'leftAlt': '#|', 'rightAlt': '|#', 'nestedAlt': 1 },
     \ 'scilab': { 'left': '//' },
     \ 'scsh': { 'left': ';' },
     \ 'scss': { 'left': '//', 'leftAlt': '/*', 'rightAlt': '*/'},
@@ -373,7 +373,7 @@ let s:delimiterMap = {
     \ 'smarty': { 'left': '{*', 'right': '*}' },
     \ 'smil': { 'left': '<!', 'right': '>' },
     \ 'smith': { 'left': ';' },
-    \ 'sml': { 'left': '(*', 'right': '*)' },
+    \ 'sml': { 'left': '(*', 'right': '*)', 'nested': 1 },
     \ 'snippets': { 'left': '#' },
     \ 'snnsnet': { 'left': '#' },
     \ 'snnspat': { 'left': '#' },
@@ -505,6 +505,11 @@ function s:SetUpForNewFiletype(filetype, forceReset)
                 let b:NERDCommenterDelims[i] = ''
             endif
         endfor
+        for i in ['nested', 'nestedAlt']
+            if !has_key(b:NERDCommenterDelims, i)
+                let b:NERDCommenterDelims[i] = 0
+            endif
+        endfor
     else
         let b:NERDCommenterDelims = s:CreateDelimMapFromCms()
     endif
@@ -524,8 +529,10 @@ function s:CreateDelimMapFromCms()
     return {
         \ 'left': substitute(&commentstring, '\([^ \t]*\)\s*%s.*', '\1', ''),
         \ 'right': substitute(&commentstring, '.*%s\s*\(.*\)', '\1', 'g'),
+        \ 'nested': 0,
         \ 'leftAlt': '',
-        \ 'rightAlt': '' }
+        \ 'rightAlt': '',
+        \ 'nestedAlt': 0}
 endfunction
 
 " Function: s:SwitchToAlternativeDelimiters(printMsgs) function {{{2
@@ -550,14 +557,18 @@ function s:SwitchToAlternativeDelimiters(printMsgs)
     "save the current delimiters
     let tempLeft = s:Left()
     let tempRight = s:Right()
+    let tempNested = s:Nested()
 
     "swap current delimiters for alternative
     let b:NERDCommenterDelims['left'] = b:NERDCommenterDelims['leftAlt']
     let b:NERDCommenterDelims['right'] = b:NERDCommenterDelims['rightAlt']
+    "set information on whether these are nested
+    let b:NERDCommenterDelims['nested'] = b:NERDCommenterDelims['nestedAlt']
 
     "set the previously current delimiters to be the new alternative ones
     let b:NERDCommenterDelims['leftAlt'] = tempLeft
     let b:NERDCommenterDelims['rightAlt'] = tempRight
+    let b:NERDCommenterDelims['nestedAlt'] = tempNested
 
     "tell the user what comment delimiters they are now using
     if a:printMsgs
@@ -755,7 +766,7 @@ function s:CommentLines(forceNested, align, firstLine, lastLine)
         if s:CanCommentLine(a:forceNested, currentLine)
             "if the user has specified forceNesting then we check to see if we
             "need to switch delimiters for place-holders
-            if a:forceNested && g:NERDUsePlaceHolders
+            if a:forceNested && g:NERDUsePlaceHolders && !s:Nested()
                 let theLine = s:SwapOuterMultiPartDelimsForPlaceHolders(theLine)
             endif
 
@@ -801,9 +812,11 @@ function s:CommentLinesMinimal(firstLine, lastLine)
         throw 'NERDCommenter.Delimiters exception: Minimal comments can only be used for filetypes that have multipart delimiters'
     endif
 
+    let sexyNested = s:SexyNested()
+
     "if we need to use place holders for the comment, make sure they are
-    "enabled for this filetype
+    "enabled for this filetype, or the delims allow nesting
-    if !g:NERDUsePlaceHolders && s:DoesBlockHaveMultipartDelim(a:firstLine, a:lastLine)
+    if !g:NERDUsePlaceHolders && !sexyNested && s:DoesBlockHaveMultipartDelim(a:firstLine, a:lastLine)
         throw 'NERDCommenter.Settings exception: Place holders are required but disabled.'
     endif
 
@@ -813,6 +826,7 @@ function s:CommentLinesMinimal(firstLine, lastLine)
 
     "make sure all multipart delimiters on the lines are replaced with
     "placeholders to prevent illegal syntax
+    if !sexyNested
         let currentLine = a:firstLine
         while(currentLine <= a:lastLine)
             let theLine = getline(currentLine)
@@ -820,6 +834,7 @@ function s:CommentLinesMinimal(firstLine, lastLine)
             call setline(currentLine, theLine)
             let currentLine = currentLine + 1
         endwhile
+    endif
 
     "add the delimiter to the top line
     let theLine = getline(a:firstLine)
@@ -859,7 +874,7 @@ function s:CommentLinesSexy(topline, bottomline)
         throw 'NERDCommenter.Delimiters exception: cannot perform sexy comments with available delimiters.'
     endif
 
-    "make sure the lines aren't already commented sexually
+    "make sure the lines aren't already commented sexually or we can nest
     if !s:CanSexyCommentLines(a:topline, a:bottomline)
         throw 'NERDCommenter.Nesting exception: cannot nest sexy comments'
     endif
@@ -884,7 +899,9 @@ function s:CommentLinesSexy(topline, bottomline)
         if lineHasTabs
             let theLine = s:ConvertLeadingTabsToSpaces(theLine)
         endif
+        if !s:SexyNested()
             let theLine = s:SwapOuterMultiPartDelimsForPlaceHolders(theLine)
+        endif
         let theLine = s:AddLeftDelimAligned(left . spaceString, theLine, leftAlignIndx)
         if lineHasTabs
             let theLine = s:ConvertLeadingSpacesToTabs(theLine)
@@ -898,8 +915,10 @@ function s:CommentLinesSexy(topline, bottomline)
             if lineHasTabs
                 let theLine = s:ConvertLeadingTabsToSpaces(theLine)
             endif
+            if !s:SexyNested()
                 let theLine = s:SwapOuterMultiPartDelimsForPlaceHolders(theLine)
             endif
+        endif
         let theLine = s:AddRightDelim(spaceString . right, theLine)
         if lineHasTabs
             let theLine = s:ConvertLeadingSpacesToTabs(theLine)
@@ -943,7 +962,9 @@ function s:CommentLinesSexy(topline, bottomline)
             let theLine = s:ConvertLeadingTabsToSpaces(theLine)
         endif
 
+        if !s:SexyNested()
             let theLine = s:SwapOuterMultiPartDelimsForPlaceHolders(theLine)
+        endif
 
         " add the sexyComMarker
         let theLine = repeat(' ', leftAlignIndx) . repeat(' ', strlen(left)-strlen(sexyComMarker)) . sexyComMarkerSpaced . strpart(theLine, leftAlignIndx)
@@ -985,7 +1006,7 @@ function s:CommentLinesToggle(forceNested, firstLine, lastLine)
 
             "if the user has specified forceNesting then we check to see if we
             "need to switch delimiters for place-holders
-            if g:NERDUsePlaceHolders
+            if g:NERDUsePlaceHolders && !s:Nested()
                 let theLine = s:SwapOuterMultiPartDelimsForPlaceHolders(theLine)
             endif
 
@@ -1305,7 +1326,7 @@ function s:RemoveDelimiters(left, right, line)
     endif
 
     "look for the right delimiter, if we find it, remove it
-    let rightIndx = s:FindDelimiterIndex(a:right, line)
+    let rightIndx = s:LastIndexOfDelim(a:right, line)
     if rightIndx != -1
         let line = strpart(line, 0, rightIndx) . strpart(line, rightIndx+lenRight)
 
@@ -1537,8 +1558,8 @@ function s:UncommentLineNormal(line)
     "get the positions of all delimiter types on the line
     let indxLeft = s:FindDelimiterIndex(s:Left(), line)
     let indxLeftAlt = s:FindDelimiterIndex(s:Left({'alt': 1}), line)
-    let indxRight = s:FindDelimiterIndex(s:Right(), line)
+    let indxRight = s:LastIndexOfDelim(s:Right(), line)
-    let indxRightAlt = s:FindDelimiterIndex(s:Right({'alt': 1}), line)
+    let indxRightAlt = s:LastIndexOfDelim(s:Right({'alt': 1}), line)
 
     "get the comment status on the line so we know how it is commented
     let lineCommentStatus =  s:IsCommentedOutermost(s:Left(), s:Right(), s:Left({'alt': 1}), s:Right({'alt': 1}), line)
@@ -1671,6 +1692,12 @@ function s:AltMultipart()
     return b:NERDCommenterDelims['rightAlt'] != ''
 endfunction
 
+" Function: s:AltNested() {{{2
+" returns 1 if the alternate multipart (if any) delims allow nesting
+function s:AltNested()
+    return b:NERDCommenterDelims['nestedAlt']
+endfunction
+
 " Function: s:CanCommentLine(forceNested, line) {{{2
 "This function is used to determine whether the given line can be commented.
 "It returns 1 if it can be and 0 otherwise
@@ -1701,7 +1728,7 @@ function s:CanCommentLine(forceNested, lineNum)
     endif
 
     "if the line is commented but nesting is allowed then return true
-    if a:forceNested && (!s:Multipart() || g:NERDUsePlaceHolders)
+    if s:Nested() || (a:forceNested && (!s:Multipart() || g:NERDUsePlaceHolders))
         return 1
     endif
 
@@ -1723,6 +1750,11 @@ endfunction
 " Return: 1 if the given lines can be commented sexually, 0 otherwise
 function s:CanSexyCommentLines(topline, bottomline)
     " see if the selected regions have any sexy comments
+    " however, if the language allows nested comments,
+    " we allow nested sexy comments
+    if s:SexyNested()
+        return 1
+    endif
     let currentLine = a:topline
     while(currentLine <= a:bottomline)
         if s:IsInSexyComment(currentLine)
@@ -2056,6 +2088,29 @@ function s:GetSexyComMarker(space, esc)
     return sexyComMarker
 endfunction
 
+" Function: s:SexyNested() {{{2
+" Returns 1 if the sexy delimeters allow nesting
+" TODO this is ugly copy&paste from the GetSexyComLeft/Right functions,
+" these could all be cleaned up
+function s:SexyNested()
+    let lenLeft = strlen(s:Left())
+    let lenLeftAlt = strlen(s:Left({'alt': 1}))
+
+    "assume c style sexy comments if possible
+    if s:HasCStyleComments()
+        return (s:Left() == '/*' && s:Nested()) || (s:Left({'alt': 1}) == '/*' && s:AltNested())
+    else
+        "grab the longest left delim that has a right
+        if s:Multipart() && lenLeft >= lenLeftAlt
+            return s:Nested()
+        elseif s:AltMultipart()
+            return s:AltNested()
+        else
+            return 0
+        endif
+    endif
+endfunction
+
 " Function: s:GetSexyComLeft(space, esc) {{{2
 " Returns the left delimiter for sexy comments for this filetype or -1 if
 " there is none. C style sexy comments are used if possible
@@ -2183,7 +2238,7 @@ endfunction
 "   -left/right: the left and right delimiters to check for
 function s:IsCommented(left, right, line)
     "if the line isn't commented return true
-    if s:FindDelimiterIndex(a:left, a:line) != -1 && (s:FindDelimiterIndex(a:right, a:line) != -1 || !s:Multipart())
+    if s:FindDelimiterIndex(a:left, a:line) != -1 && (s:LastIndexOfDelim(a:right, a:line) != -1 || !s:Multipart())
         return 1
     endif
     return 0
@@ -2407,7 +2462,7 @@ function s:IsSexyComment(topline, bottomline)
     endif
 
     "if there is a right delimiter on the top line then this isn't a sexy comment
-    if s:FindDelimiterIndex(right, getline(a:topline)) != -1
+    if s:LastIndexOfDelim(right, getline(a:topline)) != -1
         return 0
     endif
 
@@ -2436,7 +2491,7 @@ function s:IsSexyComment(topline, bottomline)
 
         "if there is a right delimiter in an intermediate line then the block isn't
         "a sexy comment
-        if s:FindDelimiterIndex(right, theLine) != -1
+        if s:LastIndexOfDelim(right, theLine) != -1
             return 0
         endif
 
@@ -2573,6 +2628,12 @@ function s:NerdEcho(msg, typeOfMsg)
     endif
 endfunction
 
+" Function: s:Nested() {{{2
+" returns 1 if the current multipart (if any) delims allow nesting
+function s:Nested()
+    return b:NERDCommenterDelims['nested']
+endfunction
+
 " Function: s:NumberOfLeadingTabs(s) {{{2
 " returns the number of leading tabs in the given string
 function s:NumberOfLeadingTabs(s)