transform last stm

moonscript/transform/statements.lua

@@ -44,7 +44,32 @@ last_stm = function(stms)
   end
   return stms[last_exp_id], last_exp_id, stms
 end
+local transform_last_stm
+transform_last_stm = function(stms, fn)
+  local _, last_idx, _stms = last_stm(stms)
+  if _stms ~= stms then
+    error("cannot transform last node in group")
+  end
+  return (function()
+    local _accum_0 = { }
+    local _len_0 = 1
+    for i, stm in ipairs(stms) do
+      if i == last_idx then
+        _accum_0[_len_0] = {
+          "transform",
+          stm,
+          fn
+        }
+      else
+        _accum_0[_len_0] = stm
+      end
+      _len_0 = _len_0 + 1
+    end
+    return _accum_0
+  end)()
+end
 return {
+  Run = Run,
   last_stm = last_stm,
-  Run = Run
+  transform_last_stm = transform_last_stm
 }

moonscript/transform/statements.moon

@@ -26,5 +26,20 @@ last_stm = (stms) ->
 
   stms[last_exp_id], last_exp_id, stms
 
-{:last_stm, :Run}
+-- transform the last stm is a list of stms
+-- will puke on group
+transform_last_stm = (stms, fn) ->
+  _, last_idx, _stms = last_stm stms
+
+  if _stms != stms
+    error "cannot transform last node in group"
+
+  return for i, stm in ipairs stms
+    if i == last_idx
+      {"transform", stm, fn}
+    else
+      stm
+
+
+{:Run, :last_stm, :transform_last_stm}
 

spec/transform_spec.moon

@@ -45,4 +45,43 @@ describe "moonscript.transform.statements", ->
       assert.same 2, idx
       assert t == stms[2][2], "should get correct table"
 
+  describe "transform_last_stm", ->
+    import transform_last_stm, Run from require "moonscript.transform.statements"
+
+    it "transforms empty stms", ->
+      before = {}
+      after = transform_last_stm before, (n) -> {"wrapped", n}
+
+      assert.same before, after
+      assert before != after
+
+    it "transforms stms", ->
+      before = {
+        {"ref", "butt_world"}
+        {"ref", "hello_world"}
+      }
+
+      transformer = (n) -> n
+      after = transform_last_stm before, transformer
+
+      assert.same {
+        {"ref", "butt_world"}
+        {"transform", {"ref", "hello_world"}, transformer}
+      }, after
+
+    it "transforms empty stms ignoring runs", ->
+      before = {
+        {"ref", "butt_world"}
+        {"ref", "hello_world"}
+        Run => print "hi"
+      }
+
+      transformer = (n) -> n
+      after = transform_last_stm before, transformer
+
+      assert.same {
+        {"ref", "butt_world"}
+        {"transform", {"ref", "hello_world"}, transformer}
+        before[3]
+      }, after