New xolox#misc#path#which() function to search the $PATH

path.vim

@@ -1,10 +1,33 @@
 " Vim auto-load script
 " Author: Peter Odding <peter@peterodding.com>
-" Last Change: August 31, 2011
+" Last Change: September 26, 2011
 " URL: http://peterodding.com/code/vim/misc/
 
 let s:windows_compatible = has('win32') || has('win64')
 
+function! xolox#misc#path#which(...)
+  let extensions = s:windows_compatible ? split($PATHEXT, ';') : ['']
+  let matches = []
+  let checked = {}
+  for directory in split($PATH, s:windows_compatible ? ';' : ':')
+    let directory = xolox#misc#path#absolute(directory)
+    if !has_key(checked, directory)
+      if isdirectory(directory)
+        for program in a:000
+          for extension in extensions
+            let path = xolox#misc#path#merge(directory, program . extension)
+            if executable(path)
+              call add(matches, path)
+            endif
+          endfor
+        endfor
+      endif
+      let checked[directory] = 1
+    endif
+  endfor
+  return matches
+endfunction
+
 " Split a pathname into a list of path components.
 
 function! xolox#misc#path#split(path)