From dcfafe59956e493f4bcd41adb2bddc02b735afc2 Mon Sep 17 00:00:00 2001
From: Daniel Holle <dholle@hb.dhbw-stuttgart.de>
Date: Mon, 5 Feb 2024 14:46:00 +0100
Subject: [PATCH] Fix null literal

---
 resources/bytecode/javFiles/Literal.jav              |  3 +++
 src/main/java/de/dhbwstuttgart/bytecode/Codegen.java |  1 +
 .../target/generate/StatementToTargetExpression.java |  2 ++
 .../target/tree/expression/TargetLiteral.java        | 12 ++++++++++++
 .../typeinference/typeAlgo/TYPEStmt.java             |  3 ++-
 src/test/java/TestComplete.java                      |  9 +++++++++
 6 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 resources/bytecode/javFiles/Literal.jav

diff --git a/resources/bytecode/javFiles/Literal.jav b/resources/bytecode/javFiles/Literal.jav
new file mode 100644
index 00000000..1d081e27
--- /dev/null
+++ b/resources/bytecode/javFiles/Literal.jav
@@ -0,0 +1,3 @@
+public class Literal {
+    m() { return null; }
+}
\ No newline at end of file
diff --git a/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java b/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java
index 630982b2..aef180d3 100644
--- a/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java
+++ b/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java
@@ -806,6 +806,7 @@ public class Codegen {
                 case StringLiteral stringLiteral -> mv.visitLdcInsn(stringLiteral.value());
                 case CharLiteral charLiteral -> mv.visitIntInsn(BIPUSH, charLiteral.value());
                 case DoubleLiteral doubleLiteral -> mv.visitLdcInsn(doubleLiteral.value());
+                case Null ignored -> mv.visitInsn(ACONST_NULL);
                 case BooleanLiteral booleanLiteral -> {
                     if (booleanLiteral.value()) {
                         mv.visitInsn(ICONST_1);
diff --git a/src/main/java/de/dhbwstuttgart/target/generate/StatementToTargetExpression.java b/src/main/java/de/dhbwstuttgart/target/generate/StatementToTargetExpression.java
index c79dd3bb..702432a0 100644
--- a/src/main/java/de/dhbwstuttgart/target/generate/StatementToTargetExpression.java
+++ b/src/main/java/de/dhbwstuttgart/target/generate/StatementToTargetExpression.java
@@ -320,6 +320,8 @@ public class StatementToTargetExpression implements ASTVisitor {
             result = new TargetLiteral.StringLiteral((String) literal.value);
         } else if (literal.value instanceof Boolean) {
             result = new TargetLiteral.BooleanLiteral((boolean) literal.value);
+        } else if (literal.value == null) {
+            result = new TargetLiteral.Null();
         }
     }
 
diff --git a/src/main/java/de/dhbwstuttgart/target/tree/expression/TargetLiteral.java b/src/main/java/de/dhbwstuttgart/target/tree/expression/TargetLiteral.java
index c4673682..c120f966 100644
--- a/src/main/java/de/dhbwstuttgart/target/tree/expression/TargetLiteral.java
+++ b/src/main/java/de/dhbwstuttgart/target/tree/expression/TargetLiteral.java
@@ -53,4 +53,16 @@ public sealed interface TargetLiteral extends TargetExpression {
             return TargetType.String;
         }
     }
+
+    record Null() implements TargetLiteral {
+        @Override
+        public TargetType type() {
+            return TargetType.Object;
+        }
+
+        @Override
+        public Object value() {
+            return null;
+        }
+    }
 }
diff --git a/src/main/java/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java b/src/main/java/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java
index 5d6ce725..440bee30 100644
--- a/src/main/java/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java
+++ b/src/main/java/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java
@@ -451,7 +451,8 @@ public class TYPEStmt implements StatementVisitor {
         if (literal.value instanceof Boolean) {
             constraintsSet.addUndConstraint(new Pair(literal.getType(), bool, PairOperator.EQUALSDOT));
             return;
-        } else {
+        }
+        if (literal.value != null) {
             throw new NotImplementedException();
         }
     }
diff --git a/src/test/java/TestComplete.java b/src/test/java/TestComplete.java
index 784df1fc..56dc7aa5 100644
--- a/src/test/java/TestComplete.java
+++ b/src/test/java/TestComplete.java
@@ -816,4 +816,13 @@ public class TestComplete {
             }
         }
     }
+
+    @Test
+    public void testLiteral() throws Exception {
+        var classFiles = generateClassFiles(new ByteArrayClassLoader(), "Literal.jav");
+        var clazz = classFiles.get("Literal");
+        var instance = clazz.getDeclaredConstructor().newInstance();
+
+        assertNull(clazz.getDeclaredMethod("m").invoke(instance));
+    }
 }