Merge commit 'f05a7ac82ee039c68e02dada278d2249554d40b1'

* commit 'f05a7ac82ee039c68e02dada278d2249554d40b1':
  make no value object serializable for use in model checker project
  change return type of delay to void
  mak delay external

src/main/java/org/rebecalang/compiler/modelcompiler/abstractrebeca/AbstractSemanticCheck.java

@@ -6,6 +6,8 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;
 
+import java.io.Serializable;
+
 @Component
 public abstract class AbstractSemanticCheck {
 	@Autowired
@@ -17,6 +19,14 @@ public abstract class AbstractSemanticCheck {
 	@Autowired
 	protected SymbolTable symbolTable;
 
-	public final static Object NO_VALUE = new Object();
+	public final static Object NO_VALUE = new NoValue();
+
+	private static class NoValue implements Serializable {
+		private static final long serialVersionUID = 1L;
 
+		// Ensure singleton instance
+		private Object readResolve() {
+			return NO_VALUE;
+		}
+	}
 }

src/main/java/org/rebecalang/compiler/modelcompiler/timedrebeca/TimedRebecaCompleteCompilerFacade.java

@@ -70,15 +70,9 @@ protected void initializeExpressionSemanticCheckContainer() {
 	protected void addMethodsOfRebecaExtensionToSymbolTable() {
 		super.addMethodsOfRebecaExtensionToSymbolTable();
 
-		SynchMethodDeclaration delayMethod = new SynchMethodDeclaration();
-		delayMethod.setName("delay");
+		addMethodToSymbolTable(CoreRebecaLabelUtility.BUILT_IN_METHOD, null, "delay", CoreRebecaTypeSystem.VOID_TYPE,
+				new Pair<Type, String>(CoreRebecaTypeSystem.INT_TYPE, "arg0"));
 		FormalParameterDeclaration fpd = new FormalParameterDeclaration();
-		fpd.setName("arg0");
-		fpd.setType(CoreRebecaTypeSystem.INT_TYPE);
-		delayMethod.getFormalParameters().add(fpd);
-		delayMethod.setReturnType(CoreRebecaTypeSystem.VOID_TYPE);
-
-		symbolTable.addMethod(null, delayMethod, TimedRebecaLabelUtility.DELAY);
 
 		SynchMethodDeclaration startTimerMethod = new SynchMethodDeclaration();
 		startTimerMethod.setName("startTimer");