Merge pull request #290 from ydah/fix-182

Reject symbols prefixed with colon

Author: ydah

lib/racc/grammarfileparser.rb

@@ -405,6 +405,7 @@ def initialize(str, filename = '-')
       @filename = filename
       @lineno = -1
       @line_head   = true
+      @allow_colon2 = false
       @in_rule_blk = false
       @in_conv_blk = false
       @in_block = nil
@@ -437,11 +438,17 @@ def yylex(&block)
     def yylex0
       begin
         until @line.empty?
-          @line.sub!(/\A\s+/, '')
+          @allow_colon2 = false if @line.sub!(/\A\s+/, '')
           if /\A\#/ =~ @line
             break
           elsif /\A\/\*/ =~ @line
             skip_comment
+          elsif @allow_colon2 && @line.start_with?(':')
+            @allow_colon2 = false
+            read(1)
+            yield [':', ':']
+          elsif @line.start_with?(':') && (s = reads(/\A:(?!:)[a-zA-Z_]\w*/))
+            scan_error! "terminal and nonterminal symbols cannot start with ':', but got #{s}"
           elsif s = reads(/\A[a-zA-Z_]\w*/)
             yield [atom_symbol(s), s.intern]
           elsif s = reads(/\A\d+/)
@@ -457,6 +464,7 @@ def yylex0
               if ch == '|'
                 @line_head = false
               end
+              @allow_colon2 = ch == ':' && @line.start_with?(':')
               yield [ch, ch]
             end
           else

test/test_grammar_file_parser.rb

@@ -11,5 +11,62 @@ def test_parse
       parser = Racc::GrammarFileParser.new(debug_flags)
       parser.parse(File.read(file), File.basename(file))
     end
+
+    def test_allow_double_colon_in_class_name
+      parser = Racc::GrammarFileParser.new
+
+      result = parser.parse(<<~RACC, 'namespace.y')
+        class Foo::Bar
+        rule
+          target : TERM
+        end
+      RACC
+
+      assert_equal 'Foo::Bar', result.params.classname
+    end
+
+    def test_reject_colon_prefixed_symbol_in_rule_body
+      parser = Racc::GrammarFileParser.new
+      error = assert_raise(CompileError) do
+        parser.parse(<<~RACC, 'colon_prefixed_symbol.y')
+          class Parse
+          rule
+            target : :TERM1
+          end
+        RACC
+      end
+
+      assert_equal "3: terminal and nonterminal symbols cannot start with ':', but got :TERM1", error.message
+    end
+
+    def test_reject_colon_prefixed_symbol_in_rule_alternative
+      parser = Racc::GrammarFileParser.new
+      error = assert_raise(CompileError) do
+        parser.parse(<<~RACC, 'colon_prefixed_symbol.y')
+          class Parse
+          rule
+            target : TERM1
+                   | :TERM2
+          end
+        RACC
+      end
+
+      assert_equal "4: terminal and nonterminal symbols cannot start with ':', but got :TERM2", error.message
+    end
+
+    def test_reject_colon_prefixed_symbol_after_rhs_symbol
+      parser = Racc::GrammarFileParser.new
+      error = assert_raise(CompileError) do
+        parser.parse(<<~RACC, 'colon_prefixed_symbol.y')
+          class Parse
+          rule
+            target : TERM1
+                   | term :TERM2
+          end
+        RACC
+      end
+
+      assert_equal "4: terminal and nonterminal symbols cannot start with ':', but got :TERM2", error.message
+    end
   end
 end