Makes EmitPushIsSaved virtual (#2480)

Co-authored-by: wixoa <[email protected]>

Author: Ruzihm

DMCompiler/DM/DMExpression.cs

@@ -48,6 +48,11 @@ public virtual DMReference EmitReference(ExpressionContext ctx, string endLabel,
         return DMReference.Invalid;
     }
 
+    public virtual void EmitPushIsSaved(ExpressionContext ctx) {
+        ctx.Compiler.Emit(WarningCode.BadArgument, Location, $"can't get issaved() value of {this}");
+        ctx.Proc.PushNullAndError();
+    }
+
     /// <summary>
     /// Gets the canonical name of the expression if it exists.
     /// </summary>

DMCompiler/DM/Expressions/Builtins.cs

@@ -348,21 +348,7 @@ internal sealed class IsSaved(Location location, DMExpression expr) : DMExpressi
     public override DMComplexValueType ValType => DMValueType.Num;
 
     public override void EmitPushValue(ExpressionContext ctx) {
-        switch (expr) {
-            case Dereference deref:
-                deref.EmitPushIsSaved(ctx);
-                return;
-            case Field field:
-                field.EmitPushIsSaved(ctx.Proc);
-                return;
-            case Local:
-                ctx.Proc.PushFloat(0);
-                return;
-            default:
-                ctx.Compiler.Emit(WarningCode.BadArgument, expr.Location, $"can't get saved value of {expr}");
-                ctx.Proc.PushNullAndError();
-                return;
-        }
+        expr.EmitPushIsSaved(ctx);
     }
 }
 

DMCompiler/DM/Expressions/Dereference.cs

@@ -246,7 +246,7 @@ public override void EmitPushInitial(ExpressionContext ctx) {
         ctx.Proc.AddLabel(endLabel);
     }
 
-    public void EmitPushIsSaved(ExpressionContext ctx) {
+    public override void EmitPushIsSaved(ExpressionContext ctx) {
         string endLabel = ctx.Proc.NewLabelName();
 
         if (_expression is LValue exprLValue) {

DMCompiler/DM/Expressions/LValue.cs

@@ -191,6 +191,10 @@ public override void EmitPushInitial(ExpressionContext ctx) {
     }
 
     public override string GetNameof(ExpressionContext ctx) => LocalVar.Name;
+
+    public override void EmitPushIsSaved(ExpressionContext ctx) {
+        ctx.Proc.PushFloat(0);
+    }
 }
 
 // Identifier of field
@@ -209,10 +213,10 @@ public override void EmitPushInitial(ExpressionContext ctx) {
         }
     }
 
-    public void EmitPushIsSaved(DMProc proc) {
-        proc.PushReferenceValue(DMReference.Src);
-        proc.PushString(variable.Name);
-        proc.IsSaved();
+    public override void EmitPushIsSaved(ExpressionContext ctx) {
+        ctx.Proc.PushReferenceValue(DMReference.Src);
+        ctx.Proc.PushString(variable.Name);
+        ctx.Proc.IsSaved();
     }
 
     public override DMReference EmitReference(ExpressionContext ctx, string endLabel,