Alternate between test and implementation

Closes #33.

doc/foreplay.txt

@@ -91,6 +91,21 @@ gf                      Go to the file for the namespace under the cursor.
 :Dsplit {symbol}        Jump to the definition for the given symbol in a
                         split.
 
+                                                *foreplay-:A*
+:A                      In a test file, edit the implementation, and vice
+                        versa.  Basically adds or removes -test from the end
+                        of the current namespace and searches for it in the
+                        class path.
+
+                                                *foreplay-:AS*
+:AS                     Like :A, but in a split.
+
+                                                *foreplay-:AV*
+:AV                     Like :A, but in a vertical split.
+
+                                                *foreplay-:AT*
+:AT                     Like :A, but in a tab.
+
 EVALUATING CODE                                 *foreplay-eval*
 
 All code is evaluated in the namespace of the current file, requiring it if

plugin/foreplay.vim

@@ -966,6 +966,40 @@ augroup foreplay_doc
   autocmd FileType clojure command! -buffer -bar -nargs=1 -complete=customlist,foreplay#eval_complete Source  :exe s:Lookup('clojure.repl', 'source', <q-args>)
 augroup END
 
+" }}}1
+" Alternate {{{1
+
+augroup foreplay_alternate
+  autocmd!
+  autocmd FileType clojure command! -buffer -bar -bang A :exe s:Alternate('edit<bang>')
+  autocmd FileType clojure command! -buffer -bar AS :exe s:Alternate('split')
+  autocmd FileType clojure command! -buffer -bar AV :exe s:Alternate('vsplit')
+  autocmd FileType clojure command! -buffer -bar AT :exe s:Alternate('tabedit')
+augroup END
+
+function! s:alternates() abort
+  let ns = foreplay#ns()
+  if ns =~# '-test$'
+    let alt = [ns[0:-6]]
+  elseif ns =~# '\.test\.'
+    let alt = [substitute(ns, '\.test\.', '.', '')]
+  else
+    let alt = [ns . '-test', substitute(ns, '\.', '.test.', '')]
+  endif
+  return map(alt, 'tr(v:val, ".-", "/_") . ".clj"')
+endfunction
+
+function! s:Alternate(cmd) abort
+  let alternates = s:alternates()
+  for file in alternates
+    let path = foreplay#findresource(file)
+    if !empty(path)
+      return a:cmd . ' ' . fnameescape(path)
+    endif
+  endfor
+  return 'echoerr '.string("Couldn't find " . alternates[0] . "in class path")
+endfunction
+
 " }}}1
 " Leiningen {{{1