remove filtering of nil values from loop expressions (use continue instead) #66

Author: leafo

moonscript/transform.lua

@@ -88,7 +88,7 @@ is_singular = function(body)
   if "group" == ntype(body) then
     return is_singular(body[2])
   else
-    return true
+    return body[1]
   end
 end
 local find_assigns
@@ -1243,17 +1243,12 @@ do
         self.accum_name
       })
     end,
-    mutate_body = function(self, body, skip_nil)
-      if skip_nil == nil then
-        skip_nil = true
-      end
+    mutate_body = function(self, body)
+      local single_stm = is_singular(body)
       local val
-      if not skip_nil and is_singular(body) then
-        do
-          local _with_0 = body[1]
-          body = { }
-          val = _with_0
-        end
+      if single_stm and types.is_value(single_stm) then
+        body = { }
+        val = single_stm
       else
         body = apply_to_last(body, function(n)
           if types.is_value(n) then
@@ -1281,19 +1276,7 @@ do
           1
         }
       }
-      if skip_nil then
-        table.insert(body, build["if"]({
-          cond = {
-            "exp",
-            self.value_name,
-            "!=",
-            "nil"
-          },
-          ["then"] = update
-        }))
-      else
-        table.insert(body, build.group(update))
-      end
+      insert(body, build.group(update))
       return body
     end
   }
@@ -1427,7 +1410,7 @@ local Value = Transformer({
     node = self.transform.statement(node, function(exp)
       return a:mutate_body({
         exp
-      }, false)
+      })
     end)
     return a:wrap(node)
   end,

moonscript/transform.moon

@@ -42,7 +42,7 @@ is_singular = (body) ->
   if "group" == ntype body
     is_singular body[2]
   else
-    true
+    body[1]
 
 find_assigns = (body, out={}) ->
   for thing in *body
@@ -697,11 +697,12 @@ class Accumulator
     }
 
   -- mutates the body of a loop construct to save last value into accumulator
-  -- can optionally skip nil results
-  mutate_body: (body, skip_nil=true) =>
-    val = if not skip_nil and is_singular body
-      with body[1]
-        body = {}
+  mutate_body: (body) =>
+    -- shortcut to write simpler code if body is a single expression
+    single_stm = is_singular body
+    val = if single_stm and types.is_value single_stm
+      body = {}
+      single_stm
     else
       body = apply_to_last body, (n) ->
         if types.is_value n
@@ -719,14 +720,7 @@ class Accumulator
       {"update", @len_name, "+=", 1}
     }
 
-    if skip_nil
-      table.insert body, build["if"] {
-        cond: {"exp", @value_name, "!=", "nil"}
-        then: update
-      }
-    else
-      table.insert body, build.group update
-
+    insert body, build.group update
     body
 
 default_accumulator = (node) =>
@@ -799,7 +793,7 @@ Value = Transformer {
   comprehension: (node) =>
     a = Accumulator!
     node = @transform.statement node, (exp) ->
-      a\mutate_body {exp}, false
+      a\mutate_body {exp}
     a\wrap node
 
   tblcomprehension: (node) =>

test2.moon

@@ -84,7 +84,8 @@ output_fname = (base) ->
 
 describe "input tests", ->
   inputs = for file in lfs.dir options.in_dir
-    file\match options.input_pattern
+    with match = file\match options.input_pattern
+      continue unless match
 
   table.sort inputs
 

tests/outputs/bubbling.lua

@@ -33,14 +33,10 @@ local j = (function()
   local _accum_0 = { }
   local _len_0 = 1
   for i = 1, 10 do
-    local _value_0
-    _value_0 = function(...)
+    _accum_0[_len_0] = function(...)
       return print(...)
     end
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()
@@ -70,11 +66,8 @@ local x = (function(...)
   }
   for _index_0 = 1, #_list_0 do
     local i = _list_0[_index_0]
-    local _value_0 = i
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _accum_0[_len_0] = i
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)(...)
@@ -106,26 +99,19 @@ local a = (function(...)
   local _accum_0 = { }
   local _len_0 = 1
   for i = 1, 10 do
-    local _value_0 = ...
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _accum_0[_len_0] = ...
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)(...)
 local b = (function()
   local _accum_0 = { }
   local _len_0 = 1
   for i = 1, 10 do
-    local _value_0
-    _value_0 = function()
+    _accum_0[_len_0] = function()
       return print(...)
     end
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()

tests/outputs/loops.lua

@@ -54,14 +54,10 @@ x = (function()
   local _list_1 = hello
   for _index_0 = 1, #_list_1 do
     local y = _list_1[_index_0]
-    local _value_0
     if y % 2 == 0 then
-      _value_0 = y
-    end
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
+      _accum_0[_len_0] = y
     end
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()
@@ -76,11 +72,8 @@ local t = (function()
   local _accum_0 = { }
   local _len_0 = 1
   for i = 10, 20 do
-    local _value_0 = i * 2
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _accum_0[_len_0] = i * 2
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()
@@ -91,10 +84,8 @@ local y = (function()
   for j = 3, 30, 8 do
     hmm = hmm + 1
     local _value_0 = j * hmm
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _accum_0[_len_0] = _value_0
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()
@@ -109,11 +100,8 @@ _ = function()
     local _accum_0 = { }
     local _len_0 = 1
     for k = 10, 40 do
-      local _value_0 = "okay"
-      if _value_0 ~= nil then
-        _accum_0[_len_0] = _value_0
-        _len_0 = _len_0 + 1
-      end
+      _accum_0[_len_0] = "okay"
+      _len_0 = _len_0 + 1
     end
     return _accum_0
   end)()
@@ -136,10 +124,8 @@ x = (function()
   while i < 10 do
     local _value_0
     i = i + 1
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _accum_0[_len_0] = _value_0
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()
@@ -151,10 +137,8 @@ x = (function()
     local thing = _list_1[_index_0]
     local _value_0
     y = "hello"
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _accum_0[_len_0] = _value_0
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()
@@ -164,10 +148,8 @@ x = (function()
   for x = 1, 2 do
     local _value_0
     y = "hello"
-    if _value_0 ~= nil then
-      _accum_0[_len_0] = _value_0
-      _len_0 = _len_0 + 1
-    end
+    _accum_0[_len_0] = _value_0
+    _len_0 = _len_0 + 1
   end
   return _accum_0
 end)()
@@ -214,10 +196,8 @@ local list = (function()
         break
       end
       local _value_0 = x
-      if _value_0 ~= nil then
-        _accum_0[_len_0] = _value_0
-        _len_0 = _len_0 + 1
-      end
+      _accum_0[_len_0] = _value_0
+      _len_0 = _len_0 + 1
       _continue_0 = true
     until true
     if not _continue_0 then