with can take an assignment statement #46

Author: leafo

moonscript/parse.lua

@@ -205,7 +205,7 @@ end
 
 -- the if statement only takes a single lhs, so we wrap in table to git to
 -- "assign" tuple format
-local function format_assign_for_if(lhs, assign)
+local function format_single_assign(lhs, assign)
 	if assign then
 		return format_assign({lhs}, assign)
 	end
@@ -413,15 +413,16 @@ local build_grammar = wrap_env(function()
 
 		Return = key"return" * (ExpListLow/mark"explist" + C"") / mark"return",
 
-		With = key"with" * DisableDo * ensure(Exp, PopDo) * key"do"^-1 * Body / mark"with",
+		WithExp = Ct(ExpList) * Assign^-1 / format_assign,
+		With = key"with" * DisableDo * ensure(WithExp, PopDo) * key"do"^-1 * Body / mark"with",
 
 		Switch = key"switch" * DisableDo * ensure(Exp, PopDo) * key"do"^-1 * Space^-1 * Break * SwitchBlock / mark"switch",
 
 		SwitchBlock = EmptyLine^0 * Advance * Ct(SwitchCase * (Break^1 * SwitchCase)^0 * (Break^1 * SwitchElse)^-1) * PopIndent,
 		SwitchCase = key"when" * Exp * key"then"^-1 * Body / mark"case",
 		SwitchElse = key"else" * Body / mark"else",
 
-		IfCond = Exp * Assign^-1 / format_assign_for_if,
+		IfCond = Exp * Assign^-1 / format_single_assign,
 
 		If = key"if" * IfCond * key"then"^-1 * Body *
 			((Break * CheckIndent)^-1 * EmptyLine^0 * key"elseif" * pos(IfCond) * key"then"^-1 * Body / mark"elseif")^0 *

moonscript/transform.lua

@@ -746,11 +746,26 @@ Statement = Transformer({
   with = function(self, node, ret)
     local _, exp, block = unpack(node)
     local scope_name = NameProxy("with")
+    local named_assign
+    if ntype(exp) == "assign" then
+      local names, values = unpack(exp, 2)
+      local assign_name = names[1]
+      exp = values[1]
+      values[1] = scope_name
+      named_assign = {
+        "assign",
+        names,
+        values
+      }
+    end
     return build["do"]({
-      build.assign_one(scope_name, exp),
       Run(function(self)
         return self:set("scope_var", scope_name)
       end),
+      build.assign_one(scope_name, exp),
+      build.group({
+        named_assign
+      }),
       build.group(block),
       (function()
         if ret then

moonscript/transform.moon

@@ -347,11 +347,22 @@ Statement = Transformer {
 
   with: (node, ret) =>
     _, exp, block = unpack node
+
     scope_name = NameProxy "with"
-    build["do"] {
-      build.assign_one scope_name, exp
+
+    named_assign = if ntype(exp) == "assign"
+      names, values = unpack exp, 2
+      assign_name = names[1]
+      exp = values[1]
+      values[1] = scope_name
+      {"assign", names, values}
+
+    build.do {
       Run => @set "scope_var", scope_name
+      build.assign_one scope_name, exp
+      build.group { named_assign }
       build.group block
+
       if ret
         ret scope_name
     }

tests/inputs/with.moon

@@ -36,3 +36,29 @@ with foo
   .prop\send(one)
   .prop\send one
 
+
+--
+
+with a, b -- b is lost
+  print .world
+
+mod = with _M = {}
+  .Thing = "hi"
+
+-- operate on a only
+with a, b = something, pooh
+  print .world
+
+x = with a, b = 1, 2
+  print a + b
+
+print with a, b = 1, 2
+  print a + b
+
+-- assignment lhs must be evaluated in the order they appear
+p = with hello!.x, world!.y = 1, 2
+  print a + b
+
+
+
+

tests/outputs/with.lua

@@ -45,5 +45,44 @@ do
   local _ = _with_0:prop("something").hello
   _with_0.prop:send(one)
   _with_0.prop:send(one)
-  return _with_0
+end
+do
+  local _with_0 = a, b
+  print(_with_0.world)
+end
+local mod
+do
+  local _with_0 = { }
+  local _M = _with_0
+  _with_0.Thing = "hi"
+  mod = _with_0
+end
+do
+  local _with_0 = something
+  local b
+  a, b = _with_0, pooh
+  print(_with_0.world)
+end
+do
+  local _with_0 = 1
+  local b
+  a, b = _with_0, 2
+  print(a + b)
+  x = _with_0
+end
+print((function()
+  do
+    local _with_0 = 1
+    local b
+    a, b = _with_0, 2
+    print(a + b)
+    return _with_0
+  end
+end)())
+local p
+do
+  local _with_0 = 1
+  hello().x, world().y = _with_0, 2
+  print(a + b)
+  p = _with_0
 end