Add :AS and Ctrl+H binding to vimrc

vim/plugin/a.vim

@@ -0,0 +1,840 @@
+" Copyright (c) 1998-2006
+" Michael Sharpe <feline@irendi.com>
+"
+" We grant permission to use, copy modify, distribute, and sell this
+" software for any purpose without fee, provided that the above copyright
+" notice and this text are not removed. We make no guarantee about the
+" suitability of this software for any purpose and we are not liable
+" for any damages resulting from its use. Further, we are under no
+" obligation to maintain or extend this software. It is provided on an
+" "as is" basis without any expressed or implied warranty.
+
+" Directory & regex enhancements added by Bindu Wavell who is well known on
+" vim.sf.net
+"
+" Patch for spaces in files/directories from Nathan Stien (also reported by
+" Soeren Sonnenburg)
+
+" Do not load a.vim if is has already been loaded.
+if exists("loaded_alternateFile")
+    finish
+endif
+if (v:progname == "ex")
+   finish
+endif
+let loaded_alternateFile = 1
+
+let alternateExtensionsDict = {}
+
+" setup the default set of alternate extensions. The user can override in thier
+" .vimrc if the defaults are not suitable. To override in a .vimrc simply set a
+" g:alternateExtensions_<EXT> variable to a comma separated list of alternates,
+" where <EXT> is the extension to map.
+" E.g. let g:alternateExtensions_CPP = "inc,h,H,HPP,hpp"
+"      let g:alternateExtensions_{'aspx.cs'} = "aspx"
+
+
+" This variable will be increased when an extension with greater number of dots
+" is added by the AddAlternateExtensionMapping call.
+let s:maxDotsInExtension = 1
+
+" Function : AddAlternateExtensionMapping (PRIVATE)
+" Purpose  : simple helper function to add the default alternate extension
+"            mappings.
+" Args     : extension -- the extension to map
+"            alternates -- comma separated list of alternates extensions
+" Returns  : nothing
+" Author   : Michael Sharpe <feline@irendi.com>
+function! <SID>AddAlternateExtensionMapping(extension, alternates)
+   " This code does not actually work for variables like foo{'a.b.c.d.e'}
+   "let varName = "g:alternateExtensions_" . a:extension
+   "if (!exists(varName))
+   "   let g:alternateExtensions_{a:extension} = a:alternates
+   "endif
+
+   " This code handles extensions which contains a dot. exists() fails with
+   " such names.
+   "let v:errmsg = ""
+   " FIXME this line causes ex to return 1 instead of 0 for some reason??
+   "silent! echo g:alternateExtensions_{a:extension}
+   "if (v:errmsg != "")
+      "let g:alternateExtensions_{a:extension} = a:alternates
+   "endif
+
+   let g:alternateExtensionsDict[a:extension] = a:alternates
+   let dotsNumber = strlen(substitute(a:extension, "[^.]", "", "g"))
+   if s:maxDotsInExtension < dotsNumber
+     let s:maxDotsInExtension = dotsNumber
+   endif
+endfunction
+
+
+" Add all the default extensions
+" Mappings for C and C++
+call <SID>AddAlternateExtensionMapping('h',"c,cpp,cxx,cc,CC")
+call <SID>AddAlternateExtensionMapping('H',"C,CPP,CXX,CC")
+call <SID>AddAlternateExtensionMapping('hpp',"cpp,c")
+call <SID>AddAlternateExtensionMapping('HPP',"CPP,C")
+call <SID>AddAlternateExtensionMapping('c',"h")
+call <SID>AddAlternateExtensionMapping('C',"H")
+call <SID>AddAlternateExtensionMapping('cpp',"h,hpp")
+call <SID>AddAlternateExtensionMapping('CPP',"H,HPP")
+call <SID>AddAlternateExtensionMapping('cc',"h")
+call <SID>AddAlternateExtensionMapping('CC',"H,h")
+call <SID>AddAlternateExtensionMapping('cxx',"h")
+call <SID>AddAlternateExtensionMapping('CXX',"H")
+" Mappings for PSL7
+call <SID>AddAlternateExtensionMapping('psl',"ph")
+call <SID>AddAlternateExtensionMapping('ph',"psl")
+" Mappings for ADA
+call <SID>AddAlternateExtensionMapping('adb',"ads")
+call <SID>AddAlternateExtensionMapping('ads',"adb")
+" Mappings for lex and yacc files
+call <SID>AddAlternateExtensionMapping('l',"y,yacc,ypp")
+call <SID>AddAlternateExtensionMapping('lex',"yacc,y,ypp")
+call <SID>AddAlternateExtensionMapping('lpp',"ypp,y,yacc")
+call <SID>AddAlternateExtensionMapping('y',"l,lex,lpp")
+call <SID>AddAlternateExtensionMapping('yacc',"lex,l,lpp")
+call <SID>AddAlternateExtensionMapping('ypp',"lpp,l,lex")
+" Mappings for OCaml
+call <SID>AddAlternateExtensionMapping('ml',"mli")
+call <SID>AddAlternateExtensionMapping('mli',"ml")
+" ASP stuff
+call <SID>AddAlternateExtensionMapping('aspx.cs', 'aspx')
+call <SID>AddAlternateExtensionMapping('aspx.vb', 'aspx')
+call <SID>AddAlternateExtensionMapping('aspx', 'aspx.cs,aspx.vb')
+
+" Setup default search path, unless the user has specified
+" a path in their [._]vimrc. 
+if (!exists('g:alternateSearchPath'))
+  let g:alternateSearchPath = 'sfr:../source,sfr:../src,sfr:../include,sfr:../inc'
+endif
+
+" If this variable is true then a.vim will not alternate to a file/buffer which
+" does not exist. E.g while editing a.c and the :A will not swtich to a.h
+" unless it exists.
+if (!exists('g:alternateNoDefaultAlternate'))
+   " by default a.vim will alternate to a file which does not exist
+   let g:alternateNoDefaultAlternate = 0
+endif
+
+" If this variable is true then a.vim will convert the alternate filename to a
+" filename relative to the current working directory.
+" Feature by Nathan Huizinga
+if (!exists('g:alternateRelativeFiles'))                                        
+   " by default a.vim will not convert the filename to one relative to the
+   " current working directory
+   let g:alternateRelativeFiles = 0
+endif
+
+
+" Function : GetNthItemFromList (PRIVATE)
+" Purpose  : Support reading items from a comma seperated list
+"            Used to iterate all the extensions in an extension spec
+"            Used to iterate all path prefixes
+" Args     : list -- the list (extension spec, file paths) to iterate
+"            n -- the extension to get
+" Returns  : the nth item (extension, path) from the list (extension 
+"            spec), or "" for failure
+" Author   : Michael Sharpe <feline@irendi.com>
+" History  : Renamed from GetNthExtensionFromSpec to GetNthItemFromList
+"            to reflect a more generic use of this function. -- Bindu
+function! <SID>GetNthItemFromList(list, n) 
+   let itemStart = 0
+   let itemEnd = -1
+   let pos = 0
+   let item = ""
+   let i = 0
+   while (i != a:n)
+      let itemStart = itemEnd + 1
+      let itemEnd = match(a:list, ",", itemStart)
+      let i = i + 1
+      if (itemEnd == -1)
+         if (i == a:n)
+            let itemEnd = strlen(a:list)
+         endif
+         break
+      endif
+   endwhile 
+   if (itemEnd != -1) 
+      let item = strpart(a:list, itemStart, itemEnd - itemStart)
+   endif
+   return item 
+endfunction
+
+" Function : ExpandAlternatePath (PRIVATE)
+" Purpose  : Expand path info.  A path with a prefix of "wdr:" will be 
+"            treated as relative to the working directory (i.e. the 
+"            directory where vim was started.) A path prefix of "abs:" will 
+"            be treated as absolute. No prefix or "sfr:" will result in the 
+"            path being treated as relative to the source file (see sfPath 
+"            argument). 
+"
+"            A prefix of "reg:" will treat the pathSpec as a regular
+"            expression substitution that is applied to the source file 
+"            path. The format is:
+"
+"              reg:<sep><pattern><sep><subst><sep><flag><sep>
+"          
+"            <sep> seperator character, we often use one of [/|%#] 
+"            <pattern> is what you are looking for
+"            <subst> is the output pattern
+"            <flag> can be g for global replace or empty
+"
+"            EXAMPLE: 'reg:/inc/src/g/' will replace every instance 
+"            of 'inc' with 'src' in the source file path. It is possible
+"            to use match variables so you could do something like:
+"            'reg:|src/\([^/]*\)|inc/\1||' (see 'help :substitute', 
+"            'help pattern' and 'help sub-replace-special' for more details
+"
+"            NOTE: a.vim uses ',' (comma) internally so DON'T use it
+"            in your regular expressions or other pathSpecs unless you update 
+"            the rest of the a.vim code to use some other seperator.
+"
+" Args     : pathSpec -- path component (or substitution patterns)
+"            sfPath -- source file path
+" Returns  : a path that can be used by AlternateFile()
+" Author   : Bindu Wavell <bindu@wavell.net>
+function! <SID>ExpandAlternatePath(pathSpec, sfPath) 
+   let prfx = strpart(a:pathSpec, 0, 4)
+   if (prfx == "wdr:" || prfx == "abs:")
+      let path = strpart(a:pathSpec, 4)
+   elseif (prfx == "reg:")
+      let re = strpart(a:pathSpec, 4)
+      let sep = strpart(re, 0, 1)
+      let patend = match(re, sep, 1)
+      let pat = strpart(re, 1, patend - 1)
+      let subend = match(re, sep, patend + 1)
+      let sub = strpart(re, patend+1, subend - patend - 1)
+      let flag = strpart(re, strlen(re) - 2)
+      if (flag == sep)
+        let flag = ''
+      endif
+      let path = substitute(a:sfPath, pat, sub, flag)
+      "call confirm('PAT: [' . pat . '] SUB: [' . sub . ']')
+      "call confirm(a:sfPath . ' => ' . path)
+   else
+      let path = a:pathSpec
+      if (prfx == "sfr:")
+         let path = strpart(path, 4)
+      endif
+      let path = a:sfPath . "/" . path
+   endif
+   return path
+endfunction
+
+" Function : FindFileInSearchPath (PRIVATE)
+" Purpose  : Searches for a file in the search path list
+" Args     : filename -- name of the file to search for
+"            pathList -- the path list to search
+"            relPathBase -- the path which relative paths are expanded from
+" Returns  : An expanded filename if found, the empty string otherwise
+" Author   : Michael Sharpe (feline@irendi.com)
+" History  : inline code written by Bindu Wavell originally
+function! <SID>FindFileInSearchPath(fileName, pathList, relPathBase)
+   let filepath = ""
+   let m = 1
+   let pathListLen = strlen(a:pathList)
+   if (pathListLen > 0)
+      while (1)
+         let pathSpec = <SID>GetNthItemFromList(a:pathList, m) 
+         if (pathSpec != "")
+            let path = <SID>ExpandAlternatePath(pathSpec, a:relPathBase)
+            let fullname = path . "/" . a:fileName
+            let foundMatch = <SID>BufferOrFileExists(fullname)
+            if (foundMatch)
+               let filepath = fullname
+               break
+            endif
+         else
+            break
+         endif
+         let m = m + 1
+      endwhile
+   endif
+   return filepath
+endfunction
+
+" Function : FindFileInSearchPathEx (PRIVATE)
+" Purpose  : Searches for a file in the search path list
+" Args     : filename -- name of the file to search for
+"            pathList -- the path list to search
+"            relPathBase -- the path which relative paths are expanded from
+"            count -- find the count'th occurence of the file on the path
+" Returns  : An expanded filename if found, the empty string otherwise
+" Author   : Michael Sharpe (feline@irendi.com)
+" History  : Based on <SID>FindFileInSearchPath() but with extensions
+function! <SID>FindFileInSearchPathEx(fileName, pathList, relPathBase, count)
+   let filepath = ""
+   let m = 1
+   let spath = ""
+   let pathListLen = strlen(a:pathList)
+   if (pathListLen > 0)
+      while (1)
+         let pathSpec = <SID>GetNthItemFromList(a:pathList, m) 
+         if (pathSpec != "")
+            let path = <SID>ExpandAlternatePath(pathSpec, a:relPathBase)
+            if (spath != "")
+               let spath = spath . ','
+            endif
+            let spath = spath . path
+         else
+            break
+         endif
+         let m = m + 1
+      endwhile
+   endif
+
+   if (&path != "")
+      if (spath != "")
+         let spath = spath . ','
+      endif
+      let spath = spath . &path
+   endif
+
+   let filepath = findfile(a:fileName, spath, a:count)
+   return filepath
+endfunction
+
+" Function : EnumerateFilesByExtension (PRIVATE)
+" Purpose  : enumerates all files by a particular list of alternate extensions.
+" Args     : path -- path of a file (not including the file)
+"            baseName -- base name of the file to be expanded
+"            extension -- extension whose alternates are to be enumerated
+" Returns  : comma separated list of files with extensions
+" Author   : Michael Sharpe <feline@irendi.com>
+function! EnumerateFilesByExtension(path, baseName, extension)
+   let enumeration = ""
+   let extSpec = ""
+   let v:errmsg = ""
+   silent! echo g:alternateExtensions_{a:extension}
+   if (v:errmsg == "")
+      let extSpec = g:alternateExtensions_{a:extension}
+   endif
+   if (extSpec == "")
+      if (has_key(g:alternateExtensionsDict, a:extension))
+         let extSpec = g:alternateExtensionsDict[a:extension]
+      endif
+   endif
+   if (extSpec != "") 
+      let n = 1
+      let done = 0
+      while (!done)
+         let ext = <SID>GetNthItemFromList(extSpec, n)
+         if (ext != "")
+            if (a:path != "")
+               let newFilename = a:path . "/" . a:baseName . "." . ext
+            else
+               let newFilename =  a:baseName . "." . ext
+            endif
+            if (enumeration == "")
+               let enumeration = newFilename
+            else
+               let enumeration = enumeration . "," . newFilename
+            endif
+         else
+            let done = 1
+         endif
+         let n = n + 1
+      endwhile
+   endif
+   return enumeration
+endfunction
+
+" Function : EnumerateFilesByExtensionInPath (PRIVATE)
+" Purpose  : enumerates all files by expanding the path list and the extension
+"            list.
+" Args     : baseName -- base name of the file
+"            extension -- extension whose alternates are to be enumerated
+"            pathList -- the list of paths to enumerate
+"            relPath -- the path of the current file for expansion of relative
+"                       paths in the path list.
+" Returns  : A comma separated list of paths with extensions
+" Author   : Michael Sharpe <feline@irendi.com>
+function! EnumerateFilesByExtensionInPath(baseName, extension, pathList, relPathBase)
+   let enumeration = ""
+   let filepath = ""
+   let m = 1
+   let pathListLen = strlen(a:pathList)
+   if (pathListLen > 0)
+      while (1)
+         let pathSpec = <SID>GetNthItemFromList(a:pathList, m) 
+         if (pathSpec != "")
+            let path = <SID>ExpandAlternatePath(pathSpec, a:relPathBase)
+            let pe = EnumerateFilesByExtension(path, a:baseName, a:extension)
+            if (enumeration == "")
+               let enumeration = pe
+            else
+               let enumeration = enumeration . "," . pe
+            endif
+         else
+            break
+         endif
+         let m = m + 1
+      endwhile
+   endif
+   return enumeration
+endfunction
+
+" Function : DetermineExtension (PRIVATE)
+" Purpose  : Determines the extension of a filename based on the register
+"            alternate extension. This allow extension which contain dots to 
+"            be considered. E.g. foo.aspx.cs to foo.aspx where an alternate
+"            exists for the aspx.cs extension. Note that this will only accept
+"            extensions which contain less than 5 dots. This is only
+"            implemented in this manner for simplicity...it is doubtful that 
+"            this will be a restriction in non-contrived situations.
+" Args     : The path to the file to find the extension in
+" Returns  : The matched extension if any
+" Author   : Michael Sharpe (feline@irendi.com)
+" History  : idea from Tom-Erik Duestad
+" Notes    : there is some magic occuring here. The exists() function does not
+"            work well when the curly brace variable has dots in it. And why
+"            should it, dots are not valid in variable names. But the exists
+"            function is wierd too. Lets say foo_c does exist. Then
+"            exists("foo_c.e.f") will be true...even though the variable does 
+"            not exist. However the curly brace variables do work when the
+"            variable has dots in it. E.g foo_{'c'} is different from 
+"            foo_{'c.d.e'}...and foo_{'c'} is identical to foo_c and
+"            foo_{'c.d.e'} is identical to foo_c.d.e right? Yes in the current
+"            implementation of vim. To trick vim to test for existence of such
+"            variables echo the curly brace variable and look for an error 
+"            message.
+function! DetermineExtension(path) 
+  let mods = ":t"
+  let i = 0
+  while i <= s:maxDotsInExtension
+    let mods = mods . ":e"
+    let extension = fnamemodify(a:path, mods)
+    if (has_key(g:alternateExtensionsDict, extension))
+       return extension
+    endif
+    let v:errmsg = ""
+    silent! echo g:alternateExtensions_{extension}
+    if (v:errmsg == "")
+      return extension
+    endif
+    let i = i + 1
+  endwhile
+  return ""
+endfunction
+
+" Function : AlternateFile (PUBLIC)
+" Purpose  : Opens a new buffer by looking at the extension of the current
+"            buffer and finding the corresponding file. E.g. foo.c <--> foo.h
+" Args     : accepts one argument. If present it used the argument as the new
+"            extension.
+" Returns  : nothing
+" Author   : Michael Sharpe <feline@irendi.com>
+" History  : + When an alternate can't be found in the same directory as the
+"              source file, a search path will be traversed looking for the
+"              alternates.
+"            + Moved some code into a separate function, minor optimization
+"            + rework to favor files in memory based on complete enumeration of
+"              all files extensions and paths
+function! AlternateFile(splitWindow, ...)
+  let extension   = DetermineExtension(expand("%:p"))
+  let baseName    = substitute(expand("%:t"), "\." . extension . '$', "", "")
+  let currentPath = expand("%:p:h")
+
+  if (a:0 != 0)
+     let newFullname = currentPath . "/" .  baseName . "." . a:1
+     call <SID>FindOrCreateBuffer(newFullname, a:splitWindow, 0)
+  else
+     let allfiles = ""
+     if (extension != "")
+        let allfiles1 = EnumerateFilesByExtension(currentPath, baseName, extension)
+        let allfiles2 = EnumerateFilesByExtensionInPath(baseName, extension, g:alternateSearchPath, currentPath)
+
+        if (allfiles1 != "")
+           if (allfiles2 != "")
+              let allfiles = allfiles1 . ',' . allfiles2
+           else
+              let allfiles = allfiles1
+           endif
+        else 
+           let allfiles = allfiles2
+        endif
+     endif
+
+     if (allfiles != "") 
+        let bestFile = ""
+        let bestScore = 0
+        let score = 0
+        let n = 1
+         
+        let onefile = <SID>GetNthItemFromList(allfiles, n)
+        let bestFile = onefile
+        while (onefile != "" && score < 2)
+           let score = <SID>BufferOrFileExists(onefile)
+           if (score > bestScore)
+              let bestScore = score
+              let bestFile = onefile
+           endif
+           let n = n + 1
+           let onefile = <SID>GetNthItemFromList(allfiles, n)
+        endwhile
+
+        if (bestScore == 0 && g:alternateNoDefaultAlternate == 1)
+           echo "No existing alternate available"
+        else
+           call <SID>FindOrCreateBuffer(bestFile, a:splitWindow, 1)
+           let b:AlternateAllFiles = allfiles
+        endif
+     else
+        echo "No alternate file/buffer available"
+     endif
+   endif
+endfunction
+
+" Function : AlternateOpenFileUnderCursor (PUBLIC)
+" Purpose  : Opens file under the cursor
+" Args     : splitWindow -- indicates how to open the file
+" Returns  : Nothing
+" Author   : Michael Sharpe (feline@irendi.com) www.irendi.com
+function! AlternateOpenFileUnderCursor(splitWindow,...)
+   let cursorFile = (a:0 > 0) ? a:1 : expand("<cfile>") 
+   let currentPath = expand("%:p:h")
+   let openCount = 1
+
+   let fileName = <SID>FindFileInSearchPathEx(cursorFile, g:alternateSearchPath, currentPath, openCount)
+   if (fileName != "")
+      call <SID>FindOrCreateBuffer(fileName, a:splitWindow, 1)
+      let b:openCount = openCount
+      let b:cursorFile = cursorFile
+      let b:currentPath = currentPath
+   else
+      echo "Can't find file"
+   endif
+endfunction
+
+" Function : AlternateOpenNextFile (PUBLIC)
+" Purpose  : Opens the next file corresponding to the search which found the 
+"            current file
+" Args     : bang -- indicates what to do if the current file has not been 
+"                    saved
+" Returns  : nothing
+" Author   : Michael Sharpe (feline@irendi.com) www.irendi.com
+function! AlternateOpenNextFile(bang)
+   let cursorFile = ""
+   if (exists("b:cursorFile"))
+      let cursorFile = b:cursorFile
+   endif
+
+   let currentPath = ""
+   if (exists("b:currentPath"))
+      let currentPath = b:currentPath
+   endif
+
+   let openCount = 0
+   if (exists("b:openCount"))
+      let openCount = b:openCount + 1
+   endif
+
+   if (cursorFile != ""  && currentPath != ""  && openCount != 0)
+      let fileName = <SID>FindFileInSearchPathEx(cursorFile, g:alternateSearchPath, currentPath, openCount)
+      if (fileName != "")
+         call <SID>FindOrCreateBuffer(fileName, "n".a:bang, 0)
+         let b:openCount = openCount
+         let b:cursorFile = cursorFile
+         let b:currentPath = currentPath
+      else 
+         let fileName = <SID>FindFileInSearchPathEx(cursorFile, g:alternateSearchPath, currentPath, 1)
+         if (fileName != "")
+            call <SID>FindOrCreateBuffer(fileName, "n".a:bang, 0)
+            let b:openCount = 1
+            let b:cursorFile = cursorFile
+            let b:currentPath = currentPath
+         else
+            echo "Can't find next file"
+         endif
+      endif
+   endif
+endfunction
+
+comm! -nargs=? -bang IH call AlternateOpenFileUnderCursor("n<bang>", <f-args>)
+comm! -nargs=? -bang IHS call AlternateOpenFileUnderCursor("h<bang>", <f-args>)
+comm! -nargs=? -bang IHV call AlternateOpenFileUnderCursor("v<bang>", <f-args>)
+comm! -nargs=? -bang IHT call AlternateOpenFileUnderCursor("t<bang>", <f-args>)
+comm! -nargs=? -bang IHN call AlternateOpenNextFile("<bang>")
+imap <Leader>ih <ESC>:IHS<CR>
+nmap <Leader>ih :IHS<CR>
+imap <Leader>is <ESC>:IHS<CR>:A<CR>
+nmap <Leader>is :IHS<CR>:A<CR>
+imap <Leader>ihn <ESC>:IHN<CR>
+nmap <Leader>ihn :IHN<CR>
+
+"function! <SID>PrintList(theList) 
+"   let n = 1
+"   let oneFile = <SID>GetNthItemFromList(a:theList, n)
+"   while (oneFile != "")
+"      let n = n + 1
+"      let oneFile = <SID>GetNthItemFromList(a:theList, n)
+"   endwhile
+"endfunction
+
+" Function : NextAlternate (PUBLIC)
+" Purpose  : Used to cycle through any other alternate file which existed on
+"            the search path.
+" Args     : bang (IN) - used to implement the AN vs AN! functionality
+" Returns  : nothing
+" Author   : Michael Sharpe <feline@irendi.com>
+function! NextAlternate(bang)
+   if (exists('b:AlternateAllFiles'))
+      let currentFile = expand("%")
+      let n = 1
+      let onefile = <SID>GetNthItemFromList(b:AlternateAllFiles, n)
+      while (onefile != "" && !<SID>EqualFilePaths(fnamemodify(onefile,":p"), fnamemodify(currentFile,":p")))
+         let n = n + 1
+         let onefile = <SID>GetNthItemFromList(b:AlternateAllFiles, n)
+      endwhile
+
+      if (onefile != "")
+         let stop = n
+         let n = n + 1
+         let foundAlternate = 0
+         let nextAlternate = ""
+         while (n != stop)
+            let nextAlternate = <SID>GetNthItemFromList(b:AlternateAllFiles, n)
+            if (nextAlternate == "")
+               let n = 1
+               continue
+            endif
+            let n = n + 1
+            if (<SID>EqualFilePaths(fnamemodify(nextAlternate, ":p"), fnamemodify(currentFile, ":p")))
+                continue
+            endif
+            if (filereadable(nextAlternate))
+                " on cygwin filereadable("foo.H") returns true if "foo.h" exists
+               if (has("unix") && $WINDIR != "" && fnamemodify(nextAlternate, ":p") ==? fnamemodify(currentFile, ":p")) 
+                  continue
+               endif
+               let foundAlternate = 1
+               break
+            endif
+         endwhile
+         if (foundAlternate == 1)
+            let s:AlternateAllFiles = b:AlternateAllFiles
+            "silent! execute ":e".a:bang." " . nextAlternate
+            call <SID>FindOrCreateBuffer(nextAlternate, "n".a:bang, 0)
+            let b:AlternateAllFiles = s:AlternateAllFiles
+         else 
+            echo "Only this alternate file exists"
+         endif
+      else 
+         echo "Could not find current file in alternates list"
+      endif
+   else 
+      echo "No other alternate files exist"
+   endif
+endfunction
+
+comm! -nargs=? -bang A call AlternateFile("n<bang>", <f-args>)
+comm! -nargs=? -bang AS call AlternateFile("h<bang>", <f-args>)
+comm! -nargs=? -bang AV call AlternateFile("v<bang>", <f-args>)
+comm! -nargs=? -bang AT call AlternateFile("t<bang>", <f-args>)
+comm! -nargs=? -bang AN call NextAlternate("<bang>")
+
+" Function : BufferOrFileExists (PRIVATE)
+" Purpose  : determines if a buffer or a readable file exists
+" Args     : fileName (IN) - name of the file to check
+" Returns  : 2 if it exists in memory, 1 if it exists, 0 otherwise
+" Author   : Michael Sharpe <feline@irendi.com>
+" History  : Updated code to handle buffernames using just the
+"            filename and not the path.
+function! <SID>BufferOrFileExists(fileName)
+   let result = 0
+
+   let lastBuffer = bufnr("$")
+   let i = 1
+   while i <= lastBuffer
+     if <SID>EqualFilePaths(expand("#".i.":p"), a:fileName)
+       let result = 2
+       break
+     endif
+     let i = i + 1
+   endwhile
+
+   if (!result) 
+      let bufName = fnamemodify(a:fileName,":t")
+      let memBufName = bufname(bufName)
+      if (memBufName != "")
+         let memBufBasename = fnamemodify(memBufName, ":t")
+         if (bufName == memBufBasename)
+            let result = 2
+         endif
+      endif
+
+      if (!result)
+         let result  = bufexists(bufName) || bufexists(a:fileName) || filereadable(a:fileName)
+      endif
+   endif
+
+   if (!result)
+      let result = filereadable(a:fileName)
+   endif
+   return result
+endfunction
+
+" Function : FindOrCreateBuffer (PRIVATE)
+" Purpose  : searches the buffer list (:ls) for the specified filename. If
+"            found, checks the window list for the buffer. If the buffer is in
+"            an already open window, it switches to the window. If the buffer
+"            was not in a window, it switches to that buffer. If the buffer did
+"            not exist, it creates it.
+" Args     : filename (IN) -- the name of the file
+"            doSplit (IN) -- indicates whether the window should be split
+"                            ("v", "h", "n", "v!", "h!", "n!", "t", "t!") 
+"            findSimilar (IN) -- indicate weather existing buffers should be
+"                                prefered
+" Returns  : nothing
+" Author   : Michael Sharpe <feline@irendi.com>
+" History  : + bufname() was not working very well with the possibly strange
+"            paths that can abound with the search path so updated this
+"            slightly.  -- Bindu
+"            + updated window switching code to make it more efficient -- Bindu
+"            Allow ! to be applied to buffer/split/editing commands for more
+"            vim/vi like consistency
+"            + implemented fix from Matt Perry
+function! <SID>FindOrCreateBuffer(fileName, doSplit, findSimilar)
+  " Check to see if the buffer is already open before re-opening it.
+  let FILENAME = escape(a:fileName, ' ')
+  let bufNr = -1
+  let lastBuffer = bufnr("$")
+  let i = 1
+  if (a:findSimilar) 
+     while i <= lastBuffer
+       if <SID>EqualFilePaths(expand("#".i.":p"), a:fileName)
+         let bufNr = i
+         break
+       endif
+       let i = i + 1
+     endwhile
+
+     if (bufNr == -1)
+        let bufName = bufname(a:fileName)
+        let bufFilename = fnamemodify(a:fileName,":t")
+
+        if (bufName == "")
+           let bufName = bufname(bufFilename)
+        endif
+
+        if (bufName != "")
+           let tail = fnamemodify(bufName, ":t")
+           if (tail != bufFilename)
+              let bufName = ""
+           endif
+        endif
+        if (bufName != "")
+           let bufNr = bufnr(bufName)
+           let FILENAME = bufName
+        endif
+     endif
+  endif
+
+  if (g:alternateRelativeFiles == 1)                                            
+        let FILENAME = fnamemodify(FILENAME, ":p:.")
+  endif
+
+  let splitType = a:doSplit[0]
+  let bang = a:doSplit[1]
+  if (bufNr == -1)
+     " Buffer did not exist....create it
+     let v:errmsg=""
+     if (splitType == "h")
+        silent! execute ":split".bang." " . FILENAME
+     elseif (splitType == "v")
+        silent! execute ":vsplit".bang." " . FILENAME
+     elseif (splitType == "t")
+        silent! execute ":tab split".bang." " . FILENAME
+     else
+        silent! execute ":e".bang." " . FILENAME
+     endif
+     if (v:errmsg != "")
+        echo v:errmsg
+     endif
+  else
+
+     " Find the correct tab corresponding to the existing buffer
+     let tabNr = -1
+     " iterate tab pages
+     for i in range(tabpagenr('$'))
+        " get the list of buffers in the tab
+        let tabList =  tabpagebuflist(i + 1)
+        let idx = 0
+        " iterate each buffer in the list
+        while idx < len(tabList)
+           " if it matches the buffer we are looking for...
+           if (tabList[idx] == bufNr)
+              " ... save the number
+              let tabNr = i + 1
+              break
+           endif
+           let idx = idx + 1
+        endwhile
+        if (tabNr != -1)
+           break
+        endif
+     endfor
+     " switch the the tab containing the buffer
+     if (tabNr != -1)
+        execute "tabn ".tabNr
+     endif
+
+     " Buffer was already open......check to see if it is in a window
+     let bufWindow = bufwinnr(bufNr)
+     if (bufWindow == -1) 
+        " Buffer was not in a window so open one
+        let v:errmsg=""
+        if (splitType == "h")
+           silent! execute ":sbuffer".bang." " . FILENAME
+        elseif (splitType == "v")
+           silent! execute ":vert sbuffer " . FILENAME
+        elseif (splitType == "t")
+           silent! execute ":tab sbuffer " . FILENAME
+        else
+           silent! execute ":buffer".bang." " . FILENAME
+        endif
+        if (v:errmsg != "")
+           echo v:errmsg
+        endif
+     else
+        " Buffer is already in a window so switch to the window
+        execute bufWindow."wincmd w"
+        if (bufWindow != winnr()) 
+           " something wierd happened...open the buffer
+           let v:errmsg=""
+           if (splitType == "h")
+              silent! execute ":split".bang." " . FILENAME
+           elseif (splitType == "v")
+              silent! execute ":vsplit".bang." " . FILENAME
+           elseif (splitType == "t")
+              silent! execute ":tab split".bang." " . FILENAME
+           else
+              silent! execute ":e".bang." " . FILENAME
+           endif
+           if (v:errmsg != "")
+              echo v:errmsg
+           endif
+        endif
+     endif
+  endif
+endfunction
+
+" Function : EqualFilePaths (PRIVATE)
+" Purpose  : Compares two paths. Do simple string comparison anywhere but on
+"            Windows. On Windows take into account that file paths could differ
+"            in usage of separators and the fact that case does not matter.
+"            "c:\WINDOWS" is the same path as "c:/windows". has("win32unix") Vim
+"            version does not count as one having Windows path rules.
+" Args     : path1 (IN) -- first path
+"            path2 (IN) -- second path
+" Returns  : 1 if path1 is equal to path2, 0 otherwise.
+" Author   : Ilya Bobir <ilya@po4ta.com>
+function! <SID>EqualFilePaths(path1, path2)
+  if has("win16") || has("win32") || has("win64") || has("win95")
+    return substitute(a:path1, "\/", "\\", "g") ==? substitute(a:path2, "\/", "\\", "g")
+  else
+    return a:path1 == a:path2
+  endif
+endfunction

vimrc

@@ -33,6 +33,7 @@ map \l :w<CR>:make<CR>
 map - $
 map <C-n> gt
 map <C-p> gT
+map <C-h> :AS<CR>
 vmap P "_dp
 
 filetype plugin indent on