lexer, parsers/source: Add support for creating local variables without assignment

Author: RyanSquared

fusion/core/lexer.lua

@@ -210,6 +210,8 @@ local pattern = re.compile([[
 
 	assignment <- {| {:type: '' -> 'assignment' :}
 		(variable_list ws '=' ws (expression_list / r) /
+		{:is_local: 'local' -> true :} ws {:is_nil: '(' -> true :} ws local_name
+			(ws ',' ws (local_name / r))* ws ')' /
 		{:is_local: 'local' -> true :} space (name_list / r) ws ('=' / r) ws
 			(expression_list / r))
 	|}

fusion/core/parsers/source.lua

@@ -42,7 +42,7 @@ function parser:transform_expression_list(node)
 	for i=1, #list do
 		output[#output + 1] = self:transform(list[i])
 	end
-	return table.concat(output, ",")
+	return table.concat(output, ", ")
 end
 
 --- Convert a variable_list to a transformed list of variable names.
@@ -53,7 +53,7 @@ function parser:transform_variable_list(node)
 	for i=1, #list do
 		output[#output + 1] = self:transform(list[i])
 	end
-	return table.concat(output, ",")
+	return table.concat(output, ", ")
 end
 
 local _tablegen_level = 0
@@ -489,7 +489,14 @@ handlers['assignment'] = function(self, node)
 	if node.is_local then
 		output[1] = "local "
 	end
-	if node.variable_list.is_destructuring then
+	if node.is_nil then
+		local names = {}
+		for i, v in ipairs(node) do -- luacheck: ignore 213
+			table.insert(names, self:transform(v))
+		end
+		table.insert(output, table.concat(names, ", "))
+		return table.concat(output)
+	elseif node.variable_list.is_destructuring then
 		local expression = self:transform(node.expression_list[1])
 		local name
 		if node.expression_list[1].type == "variable" and

spec/in/assignment.fuse

@@ -2,6 +2,10 @@
 
 local a = 5;
 
+-- assign local nil values --
+
+local (a, b);
+
 -- assign literal to global variable --
 
 b = 0;

spec/lexer_spec.lua

@@ -45,6 +45,14 @@ describe("lexer", function()
 			}
 		}})
 	end)
+	it("can parse local nil assignment", function()
+		assert.same(lexer:match("local (a, b);"), {{type = "assignment",
+			{type = "variable", "a"},
+			{type = "variable", "b"},
+			is_local = true,
+			is_nil = true
+		}})
+	end)
 	it("can parse basic assignment", function()
 		assert.same(lexer:match("a = b;"), {
 			{type = "assignment",

spec/out/source/assignment.lua

@@ -1,4 +1,5 @@
 local a = 5
+local a, b
 b = 0
 local c = a
 local d = b

spec/out/source/class.lua

@@ -26,7 +26,7 @@ ExampleToo = class({
 		if not b then
 			b = 10
 		end
-		self.a,self.b = a,b
+		self.a, self.b = a, b
 	end);
 	print = (function()
 		print(self.b)
@@ -37,7 +37,7 @@ c:print()
 Example.print(c)
 ExampleThree = class({
 	__init = (function(self, a, b)
-		ExampleToo.__init(self,a,b)
+		ExampleToo.__init(self, a, b)
 	end);
 }, {extends = ExampleToo}, "ExampleThree")
 X = {}

spec/out/source/functions.lua

@@ -12,8 +12,8 @@ end
 for line in io.lines("test") do
 	print(line)
 end
-for k,v in pairs(x) do
-	print(k,v)
+for k, v in pairs(x) do
+	print(k, v)
 end
 function a_1()
 	return b
@@ -29,7 +29,7 @@ local function a_4()
 end
 function x()
 	return coroutine.wrap(function()
-		coroutine.yield(a,b,c)
+		coroutine.yield(a, b, c)
 	end)
 end
 function abcd.ef(self)

spec/out/source/literals.lua

@@ -41,7 +41,7 @@ local transformed_array = (function()
 end)()
 local copy_transformed_array = (function()
 	local _generator_1 = {}
-	for k,v in pairs(transformed_array) do
+	for k, v in pairs(transformed_array) do
 		_generator_1[k] = v
 	end
 	return _generator_1

spec/out/source/loops.lua

@@ -21,7 +21,7 @@ for x in y() do
 end
 for x in (y())() do
 end
-for x,y in z() do
+for x, y in z() do
 end
 while true do
 	break