Add $token() user code block expansion

assets/parser.d.erb

@@ -184,7 +184,7 @@ class <%= @classname %>
 <% @grammar.patterns.each do |pattern| %>
 <%   if pattern.code_id %>
             case <%= pattern.code_id %>u: {
-<%= pattern.code %>
+<%= expand_code(pattern.code) %>
             } break;
 <%   end %>
 <% end %>

lib/propane/generator.rb

@@ -142,6 +142,19 @@ class Propane
       end
     end
 
+    # Expand expansions in user code block.
+    #
+    # @param code [String]
+    #   User code block.
+    #
+    # @return [String]
+    #   Expanded user code block.
+    def expand_code(code)
+      code.gsub(/\$token\(([$\w]+)\)/) do |match|
+        "TOKEN_#{Token.code_name($1)}"
+      end
+    end
+
   end
 
 end

spec/propane_spec.rb

@@ -169,4 +169,27 @@ EOF
       "pass2",
     ])
   end
+
+  it "supports returning tokens from pattern code blocks" do
+    write_grammar <<EOF
+token abc;
+/def/ <<
+  writeln("def!");
+>>
+/ghi/ <<
+  writeln("ghi!");
+  return $token(abc);
+>>
+Start -> abc;
+EOF
+    build_parser
+    compile("spec/test_return_token_from_pattern.d")
+    results = run
+    expect(results.status).to eq 0
+    verify_lines(results.stdout, [
+      "def!",
+      "ghi!",
+      "def!",
+    ])
+  end
 end

spec/test_return_token_from_pattern.d

@@ -0,0 +1,14 @@
+import testparser;
+import std.stdio;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "defghidef";
+    auto parser = new Testparser.Parser(cast(const(ubyte) *)input.ptr, input.length);
+    assert(parser.parse() == true);
+}