Add a PSymbolConstString class

- Constants can be strings, but the existing PSymbolConst couldn't handle
  them. The old PSymbolConst is now PSymbolConstNumeric, and the new
  PSymbolConst is a now a baseclass for it and PSymbolConstString.

src/dobjtype.cpp

@@ -2287,6 +2287,8 @@ CCMD(typetable)
 
 IMPLEMENT_ABSTRACT_CLASS(PSymbol);
 IMPLEMENT_CLASS(PSymbolConst);
+IMPLEMENT_CLASS(PSymbolConstNumeric);
+IMPLEMENT_CLASS(PSymbolConstString);
 IMPLEMENT_POINTY_CLASS(PSymbolVMFunction)
  DECLARE_POINTER(Function)
 END_POINTERS

src/dobjtype.h

@@ -32,23 +32,6 @@ protected:
 	PSymbol(FName name) { SymbolName = name; }
 };
 
-// A constant value ---------------------------------------------------------
-
-class PSymbolConst : public PSymbol
-{
-	DECLARE_CLASS(PSymbolConst, PSymbol);
-public:
-	class PType *ValueType;
-	union
-	{
-		int Value;
-		double Float;
-	};
-
-	PSymbolConst(FName name) : PSymbol(name) {}
-	PSymbolConst() : PSymbol(NAME_None) {}
-};
-
 // An action function -------------------------------------------------------
 
 struct FState;
@@ -654,4 +637,44 @@ extern PStatePointer *TypeState;
 extern PFixed *TypeFixed;
 extern PAngle *TypeAngle;
 
+// A constant value ---------------------------------------------------------
+
+class PSymbolConst : public PSymbol
+{
+	DECLARE_CLASS(PSymbolConst, PSymbol);
+public:
+	PType *ValueType;
+
+	PSymbolConst(FName name, PType *type=NULL) : PSymbol(name), ValueType(type) {}
+	PSymbolConst() : PSymbol(NAME_None), ValueType(NULL) {}
+};
+
+// A constant numeric value -------------------------------------------------
+
+class PSymbolConstNumeric : public PSymbolConst
+{
+	DECLARE_CLASS(PSymbolConstNumeric, PSymbolConst);
+public:
+	union
+	{
+		int Value;
+		double Float;
+	};
+
+	PSymbolConstNumeric(FName name, PType *type=NULL) : PSymbolConst(name, type) {}
+	PSymbolConstNumeric() {}
+};
+
+// A constant string value --------------------------------------------------
+
+class PSymbolConstString : public PSymbolConst
+{
+	DECLARE_CLASS(PSymbolConstString, PSymbolConst);
+public:
+	FString Str;
+
+	PSymbolConstString(FName name, FString &str) : PSymbolConst(name, TypeString), Str(str) {}
+	PSymbolConstString() {}
+};
+
 #endif

src/thingdef/thingdef_expression.cpp

@@ -294,7 +294,7 @@ ExpEmit FxParameter::Emit(VMFunctionBuilder *build)
 FxExpression *FxConstant::MakeConstant(PSymbol *sym, const FScriptPosition &pos)
 {
 	FxExpression *x;
-	PSymbolConst *csym = dyn_cast<PSymbolConst>(sym);
+	PSymbolConstNumeric *csym = dyn_cast<PSymbolConstNumeric>(sym);
 	if (csym != NULL)
 	{
 		if (csym->ValueType->IsA(RUNTIME_CLASS(PInt)))

src/thingdef/thingdef_parse.cpp

@@ -202,15 +202,15 @@ static void ParseConstant (FScanner &sc, PSymbolTable *symt, PClassActor *cls)
 		{
 			ExpVal val = static_cast<FxConstant *>(expr)->GetValue();
 			delete expr;
-			PSymbolConst *sym = new PSymbolConst(symname);
+			PSymbolConstNumeric *sym;
 			if (type == TK_Int)
 			{
-				sym->ValueType = TypeSInt32;
+				sym = new PSymbolConstNumeric(symname, TypeSInt32);
 				sym->Value = val.GetInt();
 			}
 			else
 			{
-				sym->ValueType = TypeFloat64;
+				sym = new PSymbolConstNumeric(symname, TypeFloat64);
 				sym->Float = val.GetFloat();
 			}
 			if (symt->AddSymbol (sym) == NULL)
@@ -260,8 +260,7 @@ static void ParseEnum (FScanner &sc, PSymbolTable *symt, PClassActor *cls)
 			}
 			delete expr;
 		}
-		PSymbolConst *sym = new PSymbolConst(symname);
+		PSymbolConstNumeric *sym = new PSymbolConstNumeric(symname, TypeSInt32);
-		sym->ValueType = TypeSInt32;
 		sym->Value = currvalue;
 		if (symt->AddSymbol (sym) == NULL)
 		{