hoist name declarations from statements inside of a class to the top of the class body

moonscript/transform.lua

@@ -205,6 +205,42 @@ is_singular = function(body)
     return true
   end
 end
+local find_assigns
+find_assigns = function(body, out)
+  if out == nil then
+    out = { }
+  end
+  local _list_0 = body
+  for _index_0 = 1, #_list_0 do
+    local thing = _list_0[_index_0]
+    local _exp_0 = thing[1]
+    if "group" == _exp_0 then
+      find_assigns(thing[2], out)
+    elseif "assign" == _exp_0 then
+      table.insert(out, thing[2])
+    end
+  end
+  return out
+end
+local hoist_declarations
+hoist_declarations = function(body, rules)
+  local assigns = { }
+  local _list_0 = find_assigns(body)
+  for _index_0 = 1, #_list_0 do
+    local names = _list_0[_index_0]
+    local _list_1 = names
+    for _index_0 = 1, #_list_1 do
+      local name = _list_1[_index_0]
+      if type(name) == "string" then
+        table.insert(assigns, name)
+      end
+    end
+  end
+  return table.insert(body, 1, {
+    "declare",
+    assigns
+  })
+end
 local constructor_name = "new"
 local Transformer
 Transformer = (function()
@@ -806,7 +842,7 @@ Statement = Transformer({
     local value = nil
     do
       local _with_0 = build
-      value = _with_0.block_exp({
+      local out_body = {
         Run(function(self)
           return self:set("super", function(block, chain)
             if chain then
@@ -915,7 +951,8 @@ Statement = Transformer({
           end
         end)()),
         cls_name
-      })
+      }
+      hoist_declarations(out_body)
       value = _with_0.group({
         _with_0.declare({
           names = {
@@ -927,7 +964,7 @@ Statement = Transformer({
             name
           },
           values = {
-            value
+            _with_0.block_exp(out_body)
           }
         })
       })

moonscript/transform.moon

@@ -81,6 +81,25 @@ is_singular = (body) ->
   else
     true
 
+find_assigns = (body, out={}) ->
+  for thing in *body
+    switch thing[1]
+      when "group"
+        find_assigns thing[2], out
+      when "assign"
+        table.insert out, thing[2] -- extract names
+  out
+
+hoist_declarations = (body, rules) ->
+  assigns = {}
+
+  -- hoist the plain old assigns
+  for names in *find_assigns body
+    for name in *names
+      table.insert assigns, name if type(name) == "string"
+
+  table.insert body, 1, {"declare", assigns}
+
 constructor_name = "new"
 
 class Transformer
@@ -407,7 +426,7 @@ Statement = Transformer {
 
     value = nil
     with build
-      value = .block_exp {
+      out_body = {
         Run =>
           @set "super", (block, chain) ->
             if chain
@@ -470,11 +489,13 @@ Statement = Transformer {
         cls_name
       }
 
+      hoist_declarations out_body
+
       value = .group {
         .declare names: {name}
         .assign {
           names: {name}
-          values: {value}
+          values: {.block_exp out_body}
         }
       }
 

tests/outputs/class.lua

@@ -507,6 +507,7 @@ local _ = hello[self].world
 if something then
   local Whacko
   Whacko = (function()
+    local hello
     local _parent_0 = nil
     local _base_0 = { }
     _base_0.__index = _base_0
@@ -543,7 +544,7 @@ if something then
     if something then
       print("hello world")
     end
-    local hello = "world"
+    hello = "world"
     self.another = "day"
     print("yeah")
     return _class_0