Add emitters for s(:__LINE__) and s(:__FILE__)

gladtocode · gladtocode · commit 1739fd896522 · 2018-07-18T11:01:32.000-06:00
A few years ago, parser added a flag whereby parser will parse __LINE__ and __FILE__ as actual nodes rather than literals. This commit adds emitters to Unparser so that these special non-literal line and file nodes can be unparsed. See whitequark/parser@997a834 Closes mbj#69
diff --git a/lib/unparser.rb b/lib/unparser.rb
@@ -50,6 +50,7 @@ def self.unparse(node, comment_array = [])
 require 'unparser/emitter/literal/range'
 require 'unparser/emitter/literal/dynamic_body'
 require 'unparser/emitter/literal/execute_string'
+require 'unparser/emitter/meta'
 require 'unparser/emitter/send'
 require 'unparser/emitter/send/unary'
 require 'unparser/emitter/send/binary'
diff --git a/lib/unparser/emitter/meta.rb b/lib/unparser/emitter/meta.rb
@@ -0,0 +1,14 @@
+module Unparser
+  class Emitter
+    # Namespace class for meta emitters
+    class Meta < self
+      include Terminated
+
+      handle(:__FILE__, :__LINE__)
+
+      def dispatch
+        write(node.type.to_s) # (e.g. literally write '__FILE__' or '__LINE__')
+      end
+    end # Meta
+  end # Emitter
+end # Unparser
diff --git a/spec/unit/unparser_spec.rb b/spec/unit/unparser_spec.rb
@@ -323,8 +323,18 @@ def foo(bar:, baz: "value")
 
     context 'magic keywords' do
       assert_generates '__ENCODING__', 'Encoding::UTF_8'
-      assert_generates '__FILE__', '"(string)"'
-      assert_generates '__LINE__', '1'
+
+      # These two assertions don't actually need to be wrapped in this block since `true` is the default,
+      # but it is helpful to contrast with the assertions farther down.
+      with_builder_options(emit_file_line_as_literals: true) do
+        assert_generates '__FILE__', '"(string)"'
+        assert_generates '__LINE__', '1'
+      end
+
+      with_builder_options(emit_file_line_as_literals: false) do
+        assert_source '__FILE__'
+        assert_source '__LINE__'
+      end
     end
 
     context 'assignment' do
