Macros: allow iterating a TypeNode whose type is a tuple

crystal-lang · Jun 3, 2016 · 86a90e1 · 86a90e1
1 parent 5c49190
commit 86a90e1
Showing 2 changed files with 34 additions and 7 deletions.
diff --git a/spec/compiler/type_inference/tuple_spec.cr b/spec/compiler/type_inference/tuple_spec.cr
@@ -191,4 +191,21 @@ describe "Type inference: tuples" do
       a[0]
       )) { tuple_of [types["Foo"].virtual_type!, types["Foo"].virtual_type!] }
   end
+
+  it "can iterate T" do
+    assert_type(%(
+      struct Tuple
+        def self.types
+          {% begin %}
+            {
+              {% for type in T %}
+                {{type}},
+              {% end %}
+            }
+          {% end %}
+        end
+      end
+      Tuple(Int32, String).types
+      )) { tuple_of([int32.metaclass, string.metaclass]) }
+  end
 end
diff --git a/src/compiler/crystal/macros/macros.cr b/src/compiler/crystal/macros/macros.cr
@@ -318,12 +318,18 @@ module Crystal
           @vars.delete index_var.name if index_var
         when TypeNode
           type = exp.type
-          unless type.is_a?(NamedTupleInstanceType)
-            exp.raise "can't interate TypeNode of type #{type}, only named tuple types"
-          end
 
-          visit_macro_for_hash_like(node, exp, type.entries) do |entry|
-            {MacroId.new(entry.name), TypeNode.new(entry.type)}
+          case type
+          when TupleInstanceType
+            visit_macro_for_array_like(node, exp, type.tuple_types) do |type|
+              TypeNode.new(type)
+            end
+          when NamedTupleInstanceType
+            visit_macro_for_hash_like(node, exp, type.entries) do |entry|
+              {MacroId.new(entry.name), TypeNode.new(entry.type)}
+            end
+          else
+            exp.raise "can't interate TypeNode of type #{type}, only tuple or named tuple types"
           end
         else
           node.exp.raise "for expression must be an array, hash or tuple literal, not #{exp.class_desc}:\n\n#{exp}"
@@ -333,11 +339,15 @@ module Crystal
       end
 
       def visit_macro_for_array_like(node, exp)
+        visit_macro_for_array_like node, exp, exp.elements, &.itself
+      end
+
+      def visit_macro_for_array_like(node, exp, entries)
         element_var = node.vars[0]
         index_var = node.vars[1]?
 
-        exp.elements.each_with_index do |element, index|
-          @vars[element_var.name] = element
+        entries.each_with_index do |element, index|
+          @vars[element_var.name] = yield element
           if index_var
             @vars[index_var.name] = NumberLiteral.new(index)
           end