From ec9f0c7af648f3a69cc2c73919a0d355ad4d264d Mon Sep 17 00:00:00 2001
From: Sam Harwell <sam@tunnelvisionlabs.com>
Date: Sat, 28 Apr 2018 13:20:40 -0500
Subject: [PATCH] Fix code generation for rules named 'keys' and 'values'

Fixes #280
---
 .../tool/templates/codegen/CSharp/CSharp.stg  |  6 ++++
 .../antlr/v4/codegen/target/CSharpTarget.java | 29 +++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/tool/resources/org/antlr/v4/tool/templates/codegen/CSharp/CSharp.stg b/tool/resources/org/antlr/v4/tool/templates/codegen/CSharp/CSharp.stg
index b40276ef..bf014113 100644
--- a/tool/resources/org/antlr/v4/tool/templates/codegen/CSharp/CSharp.stg
+++ b/tool/resources/org/antlr/v4/tool/templates/codegen/CSharp/CSharp.stg
@@ -1108,5 +1108,11 @@ csIdentifier ::= [
 	"void" : "@void",
 	"volatile" : "@volatile",
 	"while" : "@while",
+
+	// These are not keywords, but including them explicitly prevents StringTemplate from treating them as keywords.
+	// https://github.com/tunnelvisionlabs/antlr4cs/issues/280
+	"keys": "keys",
+	"values": "values",
+
 	default : key
 ]
diff --git a/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java b/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java
index cbd2ebfc..42a084bf 100644
--- a/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/CSharpTarget.java
@@ -29,16 +29,21 @@
  */
 package org.antlr.v4.codegen.target;
 
+import java.util.Map;
 import org.antlr.v4.codegen.CodeGenerator;
 import org.antlr.v4.codegen.Target;
 import org.antlr.v4.tool.ErrorType;
 import org.antlr.v4.tool.ast.GrammarAST;
+import org.stringtemplate.v4.Interpreter;
 import org.stringtemplate.v4.NumberRenderer;
+import org.stringtemplate.v4.ST;
 import org.stringtemplate.v4.STErrorListener;
 import org.stringtemplate.v4.STGroup;
 import org.stringtemplate.v4.STGroupFile;
 import org.stringtemplate.v4.StringRenderer;
+import org.stringtemplate.v4.misc.MapModelAdaptor;
 import org.stringtemplate.v4.misc.STMessage;
+import org.stringtemplate.v4.misc.STNoSuchPropertyException;
 
 public abstract class CSharpTarget extends Target {
 
@@ -138,6 +143,30 @@ protected boolean visibleGrammarSymbolCausesIssueInGeneratedCode(GrammarAST idNo
 	protected STGroup loadTemplates() {
 		// override the superclass behavior to put all C# templates in the same folder
 		STGroup result = new STGroupFile(CodeGenerator.TEMPLATE_ROOT+"/CSharp/"+getLanguage()+STGroup.GROUP_FILE_EXTENSION);
+		result.registerModelAdaptor(Map.class, new MapModelAdaptor() {
+			@Override
+			public Object getProperty(Interpreter interp, ST self, Object o, Object property, String propertyName) throws STNoSuchPropertyException {
+				// Override the default behavior to fix handling of 'keys' and 'values'.
+				// https://github.com/tunnelvisionlabs/antlr4cs/issues/280
+				Map<?, ?> map = (Map<?, ?>)o;
+				Object value;
+				if (map.containsKey(property)) {
+					value = map.get(property);
+				}
+				else if (map.containsKey(propertyName)) {
+					value = map.get(propertyName);
+				}
+				else {
+					return super.getProperty(interp, self, o, property, propertyName);
+				}
+
+				if (value == STGroup.DICT_KEY) {
+					value = property;
+				}
+
+				return value;
+			}
+		});
 		result.registerRenderer(Integer.class, new NumberRenderer());
 		result.registerRenderer(String.class, new StringRenderer());
 		result.setListener(new STErrorListener() {