Bug fixes and support for function signatures

 * Bug fix for xolox#lua#dofile(): Unless I'm severely misunderstanding
   Vim I've probably found a bug in the Lua Interface for Vim: When you
   print() a very long line and try to intercept the output with :redir
   commands, the long line is repeated once more after the initial (and
   expected) output. This makes it impossible to send large blobs of
   serialized data from Lua to Vim. The workaround is simple though:
   Simply print() each matching entry individually and join the printed
   lines in Vim script before evaluating the expression.

 * The dynamic completion sometimes wouldn't use omni completion even
   when it was enabled and the best choice. This is now fixed.

 * The new xolox#lua#getsignature() function returns the signatures of
   standard library functions and is used to show signatures in tool
   tips and completion menus.

 * The standard library signatures in autoload/xolox/lua_data.vim were
   generated using a simple Lua script which I'm also committing.

autoload/xolox/lua.vim

@@ -250,22 +250,45 @@ function! xolox#lua#completefunc(init, base) " {{{1
   endif
   let items = []
   if xolox#lua#getopt('lua_complete_keywords', 1)
-    call extend(items, g:xolox#lua_complete#keywords)
+    call extend(items, g:xolox#lua_data#keywords)
   endif
   if xolox#lua#getopt('lua_complete_globals', 1)
-    call extend(items, g:xolox#lua_complete#globals)
+    call extend(items, g:xolox#lua_data#globals)
   endif
   if xolox#lua#getopt('lua_complete_library', 1)
-    call extend(items, g:xolox#lua_complete#library)
+    call extend(items, g:xolox#lua_data#library)
   endif
   let pattern = xolox#misc#escape#pattern(a:base)
-  return filter(items, 'v:val.word =~ pattern')
+  call filter(items, 'v:val.word =~ pattern')
+  return s:addsignatures(items)
 endfunction
 
 function! s:get_completion_prefix()
   return match(strpart(getline('.'), 0, col('.') - 2), '\w\+\.\?\w*$')
 endfunction
 
+function! s:addsignatures(entries)
+  for entry in a:entries
+    let signature = xolox#lua#getsignature(entry.word)
+    if !empty(signature)
+      let entry.menu = signature
+    endif
+  endfor
+  return a:entries
+endfunction
+
+function! xolox#lua#getsignature(identifier) " {{{1
+  let identifier = substitute(a:identifier, '()$', '', '')
+  let signature = get(g:xolox#lua_data#signatures, identifier, '')
+  if empty(signature)
+    let signature = get(g:xolox#lua_data#signatures, 'string.' . identifier, '')
+  endif
+  if empty(signature)
+    let signature = get(g:xolox#lua_data#signatures, 'file:' . identifier, '')
+  endif
+  return signature
+endfunction
+
 function! xolox#lua#omnifunc(init, base) " {{{1
   if a:init
     return s:get_completion_prefix()
@@ -277,6 +300,7 @@ function! xolox#lua#omnifunc(init, base) " {{{1
   endif
   if !exists('s:omnifunc_variables')
     let s:omnifunc_variables = xolox#lua#getomnivariables(s:omnifunc_modules)
+    call s:addsignatures(s:omnifunc_variables)
   endif
   " FIXME When you type "require'" without a space in between
   " the getline('.') call below returns an empty string?!
@@ -287,7 +311,7 @@ function! xolox#lua#omnifunc(init, base) " {{{1
     return s:omnifunc_variables
   else
     let pattern = xolox#misc#escape#pattern(a:base)
-    return filter(copy(s:omnifunc_variables), 'v:val =~ pattern')
+    return filter(copy(s:omnifunc_variables), 'v:val.word =~ pattern')
   endif
 endfunction
 
@@ -346,8 +370,7 @@ endfunction
 function! xolox#lua#getomnivariables(modules) " {{{1
   let starttime = xolox#misc#timer#start()
   let output = xolox#lua#dofile(s:omnicomplete_script, a:modules)
-  let variables = split(output, "\n")
-  call sort(variables, 1)
+  let variables = eval('[' . substitute(output, '\_s\+', ',', 'g') . ']')
   let msg = "%s: Collected %i variables for omni completion in %s"
   call xolox#misc#timer#stop(msg, s:script, len(variables), starttime)
   return variables
@@ -369,37 +392,33 @@ function! xolox#lua#completedynamic(type) " {{{1
         " are available, which is kind of annoying. But I don't know of an
         " alternative to :silent that can be used inside of <expr>
         " mappings?!
-        return a:type . "\<C-x>\<C-u>"
+        if xolox#lua#getopt('lua_complete_omni', 0)
+          return a:type . "\<C-x>\<C-o>"
+        else
+          return a:type . "\<C-x>\<C-u>"
+        endif
       endif
     endif
   endif
   return a:type
 endfunction
 
 function! xolox#lua#dofile(pathname, arguments) " {{{1
-  " First try to use the Lua Interface for Vim.
-  try
-    call xolox#misc#msg#debug("%s: Trying Lua Interface for Vim ..", s:script)
+  if has('lua')
+    " Use the Lua Interface for Vim.
     redir => output
     lua arg = vim.eval('a:arguments')
     execute 'silent luafile' fnameescape(a:pathname)
     redir END
-    if !empty(output)
-      return output
-    endif
-  catch
-    redir END
-    call xolox#misc#msg#warn("%s: %s (at %s)", s:script, v:exception, v:throwpoint)
-  endtry
-  " Fall back to the command line Lua interpreter.
-  call xolox#misc#msg#debug("Falling back to external Lua interpreter ..")
-  let output = system(join(['lua', a:pathname] + a:arguments))
-  if v:shell_error
-    let msg = "%s: Failed to retrieve omni completion candidates (output: '%s')"
-    call xolox#misc#msg#warn(msg, s:script, output)
-    return ''
   else
-  return output
+    " Use the command line Lua interpreter.
+    let output = xolox#misc#str#trim(system(join(['lua', a:pathname] + a:arguments)))
+    if v:shell_error
+      let msg = "%s: Failed to retrieve omni completion candidates (output: '%s')"
+      call xolox#misc#msg#warn(msg, s:script, output)
+    endif
+  endif
+  return xolox#misc#str#trim(output)
 endfunction
 
 " vim: ts=2 sw=2 et