Support field names that are Ruby keywords

This commit adds support for field names that are also Ruby keywords.
For example, you can have a proto message with a field named `end` and
we need to support that

lib/protoboeuf/codegen.rb

@@ -549,11 +549,11 @@ def initialize_oneof(oneof)
         "@#{oneof.name} = nil # oneof field\n" +
           oneof.fields.map { |field|
             <<~RUBY
-              if #{field.name} == NONE
-                @#{field.name} = #{default_for(field)}
+              if #{field.lvar_read} == NONE
+                #{field.iv_name} = #{default_for(field)}
               else
                 @#{oneof.name} = :#{field.name}
-                @#{field.name} = #{field.name}
+                #{field.iv_name} = #{field.lvar_read}
               end
             RUBY
           }.join("\n")
@@ -571,11 +571,11 @@ def initialize_field(field)
 
       def initialize_optional_field(field)
         <<~RUBY
-          if #{field.name} == NONE
-            @#{field.name} = #{default_for(field)}
+          if #{field.lvar_read} == NONE
+            #{field.iv_name} = #{default_for(field)}
           else
             #{set_bitmask(field)}
-            @#{field.name} = #{field.name}
+            #{field.iv_name} = #{field.lvar_read}
           end
         RUBY
       end
@@ -864,13 +864,13 @@ def initialize_signature
         self.fields.flat_map { |f|
           if f.field?
             if f.optional?
-              "#{f.name}: NONE"
+              "#{f.lvar_name}: NONE"
             else
-              "#{f.name}: #{default_for(f)}"
+              "#{f.lvar_name}: #{default_for(f)}"
             end
           elsif f.oneof?
             f.fields.map { |child|
-              "#{child.name}: NONE"
+              "#{child.lvar_name}: NONE"
             }
           else
             raise NotImplementedError
@@ -1139,7 +1139,8 @@ def to_ruby
 
       tail = "\n" + packages.map { "end" }.join("\n")
 
-      SyntaxTree.format(head + body + tail)
+      #SyntaxTree.format(head + body + tail)
+      head + body + tail
     end
   end
 end

lib/protoboeuf/parser.rb

@@ -116,6 +116,30 @@ def oneof?
 
     alias :enum? :enum
 
+    # Return a local variable name for use in generated code
+    def lvar_name
+      name
+    end
+
+    RUBY_KEYWORDS = %w{ __ENCODING__ __LINE__ __FILE__ BEGIN END alias and
+    begin break case class def defined?  do else elsif end ensure false for if
+    in module next nil not or redo rescue retry return self super then true
+    undef unless until when while yield }.to_set
+
+    # Return code for reading the local variable returned by `lvar_name`
+    def lvar_read
+      if RUBY_KEYWORDS.include?(name)
+        "binding.local_variable_get(:#{name})"
+      else
+        name
+      end
+    end
+
+    # Return an instance variable name for use in generated code
+    def iv_name
+      "@#{name}"
+    end
+
     def map?
       MapType === type
     end

test/codegen_test.rb

@@ -31,5 +31,29 @@ def test_fixture_file
 
       assert_equal [], klass::TestRepeatedField.new.e
     end
+
+    def test_fields_keyword_end
+      unit = ProtoBoeuf.parse_string('message Test1 { optional int32 end = 1; }')
+      gen = CodeGen.new unit
+      klass = Class.new { self.class_eval gen.to_ruby }
+      obj = klass::Test1.new(end: 1234)
+      assert_equal 1234, obj.end
+    end
+
+    def test_fields_keyword_class
+      unit = ProtoBoeuf.parse_string('message Test1 { optional int32 class = 1; }')
+      gen = CodeGen.new unit
+      klass = Class.new { self.class_eval gen.to_ruby }
+      obj = klass::Test1.new(class: 1234)
+      assert_equal 1234, obj.class
+    end
+
+    def test_fields_keyword_nil
+      unit = ProtoBoeuf.parse_string('message Test1 { optional int32 nil = 1; }')
+      gen = CodeGen.new unit
+      klass = Class.new { self.class_eval gen.to_ruby }
+      obj = klass::Test1.new(nil: 1234)
+      assert_equal 1234, obj.nil
+    end
   end
 end