X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=blobdiff_plain;f=bundles%2Forg.simantics.scl.compiler%2Fsrc%2Forg%2Fsimantics%2Fscl%2Fcompiler%2Fconstants%2Fsingletons%2FNothingConstant.java;fp=bundles%2Forg.simantics.scl.compiler%2Fsrc%2Forg%2Fsimantics%2Fscl%2Fcompiler%2Fconstants%2Fsingletons%2FNothingConstant.java;h=6778af208cf0de018901cb47e7e48f3dba5788b9;hb=969bd23cab98a79ca9101af33334000879fb60c5;hp=0000000000000000000000000000000000000000;hpb=866dba5cd5a3929bbeae85991796acb212338a08;p=simantics%2Fplatform.git

diff --git a/bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/constants/singletons/NothingConstant.java b/bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/constants/singletons/NothingConstant.java
new file mode 100644
index 000000000..6778af208
--- /dev/null
+++ b/bundles/org.simantics.scl.compiler/src/org/simantics/scl/compiler/constants/singletons/NothingConstant.java
@@ -0,0 +1,50 @@
+package org.simantics.scl.compiler.constants.singletons;
+
+import org.objectweb.asm.Label;
+import org.simantics.scl.compiler.constants.Constant;
+import org.simantics.scl.compiler.internal.codegen.continuations.Cont;
+import org.simantics.scl.compiler.internal.codegen.references.IVal;
+import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilder;
+import org.simantics.scl.compiler.internal.codegen.utils.TransientClassBuilder;
+import org.simantics.scl.compiler.types.TVar;
+import org.simantics.scl.compiler.types.Types;
+import org.simantics.scl.compiler.types.kinds.Kinds;
+
+public class NothingConstant extends Constant {
+    
+    private static final TVar A = Types.var(Kinds.STAR);
+    public static final NothingConstant INSTANCE = new NothingConstant();
+    
+    private NothingConstant() {
+        super(Types.forAll(A, Types.apply(Types.MAYBE, A)));
+    }
+
+    @Override
+    public void push(MethodBuilder mb) {
+        mb.loadNull();
+    }
+    
+    @Override
+    public void deconstruct(MethodBuilder mb, IVal parameter,
+            Cont success, Label failure) {
+        if(failure != null) {    
+            parameter.push(mb);
+            mb.ifNullBranch(failure, false);
+        }
+        mb.jump(success);
+    }
+    
+    public int constructorTag() {
+        return 0;
+    }
+    
+    @Override
+    public String toString() {
+        return "Nothing";
+    }
+    
+    @Override
+    public Object realizeValue(TransientClassBuilder classBuilder) {                
+        return null;
+    }
+}