renamed constantpool entries again. fixed some issues. ConstantPool output seems to get there

src/main/java/nl/sander/beejava/Compiler.java

@@ -24,16 +24,35 @@ public class Compiler {
 
     private byte[] doCompile() {
         ByteBuf buf = new ByteBuf();
-        buf.add(0xCA, 0xFE, 0xBA, 0xBE);
-        buf.add(beeClass.getClassFileVersion().getMinor());
-        buf.add(beeClass.getClassFileVersion().getMajor());
+        buf.addU8(0xCA, 0xFE, 0xBA, 0xBE);
+        buf.addU16(beeClass.getClassFileVersion().getMinor());
+        buf.addU16(beeClass.getClassFileVersion().getMajor());
 
         Set<NodeConstant> constantTree = constantTreeCreator.createConstantTree(beeClass);
         ConstantPool constantPool = constantPoolCreator.createConstantPool(constantTree);
 
-        buf.add(constantPool.getBytes());
+        buf.addU16(constantPool.getLength());
+        buf.addU8(constantPool.getBytes());
+
+
+
+        printBytes(buf);
+
         return buf.toBytes();
     }
 
+    //TODO remove
+    private void printBytes(ByteBuf buf) {
+        byte[] bytes = buf.toBytes();
+        int count = 0;
+        for (byte b : bytes) {
+            System.out.print(String.format("%2s", Integer.toHexString(b & 0xFF)).replace(' ', '0') + (count % 2 == 0 ? "" : " "));
+            if (++count > 15) {
+                count = 0;
+                System.out.println();
+            }
+        }
+    }
+
 
 }

src/main/java/nl/sander/beejava/ConstantPoolCreator.java

@@ -15,7 +15,7 @@ public class ConstantPoolCreator {
 
     public ConstantPool createConstantPool(Set<NodeConstant> constantTree) {
         constantPool = new ConstantPool();
-        constantPool.add(null); // dummy element to align it's index with the indexes in the elements themselves
+//        constantPool.add(null); // dummy element to align it's index with the indexes in the elements themselves
         index = 0;
         updateToplevelElements(constantTree);
         return constantPool;

src/main/java/nl/sander/beejava/ConstantTreeCreator.java

@@ -34,6 +34,7 @@ public class ConstantTreeCreator {
         beeClass.getConstructors().forEach(this::updateConstantTree);
         // TODO update constantTree for fields ?
         // TODO update constantTree for methods
+        constantTree.add(new ClassEntry(new Utf8Entry(internalName(beeClass.getName()))));
         return constantTree;
     }
 
@@ -55,23 +56,23 @@ public class ConstantTreeCreator {
     }
 
     private void addMethod(CodeLine codeline) {
-        constantTree.add(new ConstantMethodRef(createClassName(codeline), createMethodNameAndType(codeline)));
+        constantTree.add(new MethodRefEntry(createClassName(codeline), createMethodNameAndType(codeline)));
     }
 
     private void addField(CodeLine codeline) {
-        constantTree.add(new ConstantFieldRef(createClassName(codeline), createFieldNameAndType(codeline)));
+        constantTree.add(new FieldRefEntry(createClassName(codeline), createFieldNameAndType(codeline)));
     }
 
-    private ConstantNameAndType createMethodNameAndType(CodeLine codeline) {
-        return new ConstantNameAndType(new ConstantUtf8(codeline.getMethodName()), new ConstantUtf8(codeline.getMethodSignature()));
+    private NameAndTypeEntry createMethodNameAndType(CodeLine codeline) {
+        return new NameAndTypeEntry(new Utf8Entry(codeline.getMethodName()), new Utf8Entry(codeline.getMethodSignature()));
     }
 
-    private ConstantNameAndType createFieldNameAndType(CodeLine codeline) {
-        return new ConstantNameAndType(new ConstantUtf8(codeline.getField().getName()), new ConstantUtf8(TypeMapper.map(codeline.getField().getType())));
+    private NameAndTypeEntry createFieldNameAndType(CodeLine codeline) {
+        return new NameAndTypeEntry(new Utf8Entry(codeline.getField().getName()), new Utf8Entry(TypeMapper.map(codeline.getField().getType())));
     }
 
-    private ConstantClass createClassName(CodeLine codeline) {
-        return new ConstantClass(new ConstantUtf8(internalName(getNameOfClass(codeline))));
+    private ClassEntry createClassName(CodeLine codeline) {
+        return new ClassEntry(new Utf8Entry(internalName(getNameOfClass(codeline))));
     }
 
     private String getNameOfClass(CodeLine codeline) {

src/main/java/nl/sander/beejava/constantpool/ConstantPool.java

@@ -24,7 +24,14 @@ public class ConstantPool {
 
     public byte[] getBytes() {
         ByteBuf bytes = new ByteBuf();
-        entries.forEach(entry -> bytes.add(entry.getBytes()));
+        entries.forEach(entry -> bytes.addU8(entry.getBytes()));
         return bytes.toBytes();
     }
+
+    /**
+     * get the length +1
+     */
+    public int getLength() {
+        return entries.size() + 1;
+    }
 }

src/main/java/nl/sander/beejava/constantpool/entry/ClassEntry.java

@@ -1,10 +1,10 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantClass extends NodeConstant {
+public class ClassEntry extends NodeConstant {
     private static final byte TAG = 7;
-    private final ConstantUtf8 name;
+    private final Utf8Entry name;
 
-    public ConstantClass(ConstantUtf8 name) {
+    public ClassEntry(Utf8Entry name) {
         super(name);
         this.name = name;
     }
@@ -22,6 +22,6 @@ public class ConstantClass extends NodeConstant {
 
     @Override
     public byte[] getBytes() {
-        return new byte[]{TAG, upperFraction(getNameIndex()), lowerFraction(getNameIndex())};
+        return new byte[]{TAG, upperByte(getNameIndex()), lowerByte(getNameIndex())};
     }
 }

src/main/java/nl/sander/beejava/constantpool/entry/ConstantDouble.java

@@ -1,18 +0,0 @@
-package nl.sander.beejava.constantpool.entry;
-
-public class ConstantDouble extends LeafConstant {
-    private static final byte TAG = 6;
-    private final double doubleVal;
-
-    public ConstantDouble(double doubleVal) {
-        this.doubleVal = doubleVal;
-    }
-
-    @Override
-    public byte[] getBytes() {
-        long bits = Double.doubleToRawLongBits(doubleVal);
-        return new byte[]{TAG, rshift(bits, 56), rshift(bits, 48), rshift(bits, 40), rshift(bits, 32),
-                rshift(bits, 24), rshift(bits, 16), rshift(bits, 8), (byte) (bits & 0xFF)};
-    }
-
-}

src/main/java/nl/sander/beejava/constantpool/entry/ConstantFieldRef.java

@@ -1,36 +0,0 @@
-package nl.sander.beejava.constantpool.entry;
-
-public class ConstantFieldRef extends NodeConstant {
-    private static final byte TAG = 9;
-
-    private final ConstantClass constantClass;
-    private final ConstantNameAndType constantNameAndType;
-
-    public ConstantFieldRef(ConstantClass constantClass, ConstantNameAndType constantNameAndType) {
-        super(constantClass, constantNameAndType);
-        this.constantClass = constantClass;
-        this.constantNameAndType = constantNameAndType;
-    }
-
-    public int getClassIndex() {
-        return constantClass.getIndex();
-    }
-
-    public int getNameAndTypeIndex() {
-        return constantNameAndType.getIndex();
-    }
-
-    @Override
-    public String toString() {
-        return "FieldRefEntry{" +
-                "classIndex=" + getClassIndex() +
-                ", nameAndTypeIndex=" + getNameAndTypeIndex() +
-                '}';
-    }
-
-    @Override
-    public byte[] getBytes() {
-        return new byte[]{TAG};
-    }
-
-}

src/main/java/nl/sander/beejava/constantpool/entry/ConstantInterfaceMethodRef.java

@@ -1,28 +0,0 @@
-package nl.sander.beejava.constantpool.entry;
-
-public class ConstantInterfaceMethodRef extends NodeConstant {
-    private static final byte TAG = 11;
-
-    private final ConstantClass constantClass;
-    private final ConstantNameAndType constantNameAndType;
-
-    public ConstantInterfaceMethodRef(ConstantClass constantClass, ConstantNameAndType constantNameAndType) {
-        super(constantClass, constantNameAndType);
-        this.constantClass = constantClass;
-        this.constantNameAndType = constantNameAndType;
-    }
-
-    public int getClassIndex() {
-        return constantClass.getIndex();
-    }
-
-    public int getNameAndTypeIndex() {
-        return constantNameAndType.getIndex();
-    }
-
-
-    @Override
-    public byte[] getBytes() {
-        return new byte[]{TAG};
-    }
-}

src/main/java/nl/sander/beejava/constantpool/entry/ConstantMethodRef.java

@@ -1,27 +0,0 @@
-package nl.sander.beejava.constantpool.entry;
-
-public class ConstantMethodRef extends NodeConstant {
-    private static final byte TAG = 10;
-
-    private final ConstantClass constantClass;
-    private final ConstantNameAndType constantNameAndType;
-
-    public ConstantMethodRef(ConstantClass constantClass, ConstantNameAndType constantNameAndType) {
-        super(constantClass, constantNameAndType);
-        this.constantClass = constantClass;
-        this.constantNameAndType = constantNameAndType;
-    }
-
-    public int getClassIndex() {
-        return constantClass.getIndex();
-    }
-
-    public int getNameAndTypeIndex() {
-        return constantNameAndType.getIndex();
-    }
-
-
-    public byte[] getBytes() {
-        return new byte[]{TAG};
-    }
-}

src/main/java/nl/sander/beejava/constantpool/entry/DoubleEntry.java

@@ -0,0 +1,18 @@
+package nl.sander.beejava.constantpool.entry;
+
+public class DoubleEntry extends LeafConstant {
+    private static final byte TAG = 6;
+    private final double doubleVal;
+
+    public DoubleEntry(double doubleVal) {
+        this.doubleVal = doubleVal;
+    }
+
+    @Override
+    public byte[] getBytes() {
+        long bits = Double.doubleToRawLongBits(doubleVal);
+        return new byte[]{TAG, getByte(bits, 56), getByte(bits, 48), getByte(bits, 40), getByte(bits, 32),
+                getByte(bits, 24), getByte(bits, 16), getByte(bits, 8), (byte) (bits & 0xFF)};
+    }
+
+}

src/main/java/nl/sander/beejava/constantpool/entry/DynamicEntry.java

@@ -1,11 +1,11 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantDynamic extends NodeConstant {
+public class DynamicEntry extends NodeConstant {
     private static final byte TAG = 17;
     private final int bootstrapMethodIndex; // TODO
-    private final ConstantNameAndType nameAndType;
+    private final NameAndTypeEntry nameAndType;
 
-    public ConstantDynamic(int bootstrapMethodIndex, ConstantNameAndType nameAndType) {
+    public DynamicEntry(int bootstrapMethodIndex, NameAndTypeEntry nameAndType) {
         this.bootstrapMethodIndex = bootstrapMethodIndex;
         this.nameAndType = nameAndType;
     }

src/main/java/nl/sander/beejava/constantpool/entry/FieldRefEntry.java

@@ -0,0 +1,36 @@
+package nl.sander.beejava.constantpool.entry;
+
+public class FieldRefEntry extends NodeConstant {
+    private static final byte TAG = 9;
+
+    private final ClassEntry classEntry;
+    private final NameAndTypeEntry nameAndTypeEntry;
+
+    public FieldRefEntry(ClassEntry classEntry, NameAndTypeEntry nameAndTypeEntry) {
+        super(classEntry, nameAndTypeEntry);
+        this.classEntry = classEntry;
+        this.nameAndTypeEntry = nameAndTypeEntry;
+    }
+
+    public int getClassIndex() {
+        return classEntry.getIndex();
+    }
+
+    public int getNameAndTypeIndex() {
+        return nameAndTypeEntry.getIndex();
+    }
+
+    @Override
+    public String toString() {
+        return "FieldRefEntry{" +
+                "classIndex=" + getClassIndex() +
+                ", nameAndTypeIndex=" + getNameAndTypeIndex() +
+                '}';
+    }
+
+    @Override
+    public byte[] getBytes() {
+        return new byte[]{TAG};
+    }
+
+}

src/main/java/nl/sander/beejava/constantpool/entry/FloatEntry.java

@@ -1,11 +1,11 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantFloat extends LeafConstant {
+public class FloatEntry extends LeafConstant {
     private static final byte TAG = 4;
 
     private final float floatVal;
 
-    public ConstantFloat(float floatVal) {
+    public FloatEntry(float floatVal) {
         this.floatVal = floatVal;
     }
 

src/main/java/nl/sander/beejava/constantpool/entry/IntegerEntry.java

@@ -1,11 +1,11 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantInteger extends LeafConstant {
+public class IntegerEntry extends LeafConstant {
     private static final byte TAG = 3;
 
     private final int intVal;
 
-    public ConstantInteger(int integer) {
+    public IntegerEntry(int integer) {
         this.intVal = integer;
     }
 

src/main/java/nl/sander/beejava/constantpool/entry/InterfaceMethodRefEntry.java

@@ -0,0 +1,28 @@
+package nl.sander.beejava.constantpool.entry;
+
+public class InterfaceMethodRefEntry extends NodeConstant {
+    private static final byte TAG = 11;
+
+    private final ClassEntry classEntry;
+    private final NameAndTypeEntry nameAndTypeEntry;
+
+    public InterfaceMethodRefEntry(ClassEntry classEntry, NameAndTypeEntry nameAndTypeEntry) {
+        super(classEntry, nameAndTypeEntry);
+        this.classEntry = classEntry;
+        this.nameAndTypeEntry = nameAndTypeEntry;
+    }
+
+    public int getClassIndex() {
+        return classEntry.getIndex();
+    }
+
+    public int getNameAndTypeIndex() {
+        return nameAndTypeEntry.getIndex();
+    }
+
+
+    @Override
+    public byte[] getBytes() {
+        return new byte[]{TAG};
+    }
+}

src/main/java/nl/sander/beejava/constantpool/entry/InvokeDynamicEntry.java

@@ -1,14 +1,14 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantInvokeDynamic extends NodeConstant {
+public class InvokeDynamicEntry extends NodeConstant {
     private static final byte TAG = 18;
 
     private final int bootstrapMethodAttrIndex; //??
-    private final ConstantNameAndType constantNameAndType;
+    private final NameAndTypeEntry nameAndTypeEntry;
 
-    public ConstantInvokeDynamic(int bootstrapMethodAttrIndex, ConstantNameAndType constantNameAndType) {
+    public InvokeDynamicEntry(int bootstrapMethodAttrIndex, NameAndTypeEntry nameAndTypeEntry) {
         this.bootstrapMethodAttrIndex = bootstrapMethodAttrIndex;
-        this.constantNameAndType = constantNameAndType;
+        this.nameAndTypeEntry = nameAndTypeEntry;
     }
 
 
@@ -16,7 +16,7 @@ public class ConstantInvokeDynamic extends NodeConstant {
     public String toString() {
         return "InvokeDynamicEntry{" +
                 "bootstrapMethodAttrIndex=" + bootstrapMethodAttrIndex +
-                ", nameAndTypeIndex=" + constantNameAndType.getIndex() +
+                ", nameAndTypeIndex=" + nameAndTypeEntry.getIndex() +
                 '}';
     }
 

src/main/java/nl/sander/beejava/constantpool/entry/LongEntry.java

@@ -1,11 +1,11 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantLong extends LeafConstant {
+public class LongEntry extends LeafConstant {
 
     private static final byte TAG = 5;
     private final long longVal;
 
-    public ConstantLong(long longVal) {
+    public LongEntry(long longVal) {
         this.longVal = longVal;
     }
 
@@ -18,8 +18,8 @@ public class ConstantLong extends LeafConstant {
 
     @Override
     public byte[] getBytes() {
-        return new byte[]{TAG, rshift(longVal, 56), rshift(longVal, 48), rshift(longVal, 40), rshift(longVal, 32),
-                rshift(longVal, 24), rshift(longVal, 16), rshift(longVal, 8), (byte) (longVal & 0xFF)};
+        return new byte[]{TAG, getByte(longVal, 56), getByte(longVal, 48), getByte(longVal, 40), getByte(longVal, 32),
+                getByte(longVal, 24), getByte(longVal, 16), getByte(longVal, 8), (byte) (longVal & 0xFF)};
     }
 
 

src/main/java/nl/sander/beejava/constantpool/entry/MethodHandleEntry.java

@@ -1,17 +1,17 @@
 package nl.sander.beejava.constantpool.entry;
 
 //TODO implement later
-public class ConstantMethodHandle extends NodeConstant {
+public class MethodHandleEntry extends NodeConstant {
     private static final byte TAG = 15;
 
     private final int referenceKind;
 
     // only 1 of these can be present:
-    private ConstantFieldRef constantFieldRef;
-    private ConstantMethodRef constantMethodRef;
-    private ConstantInterfaceMethodRef constantInterfaceMethodRef;
+    private FieldRefEntry fieldRefEntry;
+    private MethodRefEntry methodRefEntry;
+    private InterfaceMethodRefEntry interfaceMethodRefEntry;
 
-    public ConstantMethodHandle(int referenceKind) {
+    public MethodHandleEntry(int referenceKind) {
         this.referenceKind = referenceKind;
     }
 

src/main/java/nl/sander/beejava/constantpool/entry/MethodRefEntry.java

@@ -0,0 +1,27 @@
+package nl.sander.beejava.constantpool.entry;
+
+public class MethodRefEntry extends NodeConstant {
+    private static final byte TAG = 10;
+
+    private final ClassEntry classRef;
+    private final NameAndTypeEntry nameAndType;
+
+    public MethodRefEntry(ClassEntry classRef, NameAndTypeEntry nameAndType) {
+        super(classRef, nameAndType);
+        this.classRef = classRef;
+        this.nameAndType = nameAndType;
+    }
+
+    public int getClassIndex() {
+        return classRef.getIndex();
+    }
+
+    public int getNameAndTypeIndex() {
+        return nameAndType.getIndex();
+    }
+
+
+    public byte[] getBytes() {
+        return new byte[]{TAG, upperByte(getClassIndex()), lowerByte(getClassIndex()), upperByte(getNameAndTypeIndex()), lowerByte(getNameAndTypeIndex())};
+    }
+}

src/main/java/nl/sander/beejava/constantpool/entry/MethodTypeEntry.java

@@ -1,11 +1,11 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantMethodType extends NodeConstant {
+public class MethodTypeEntry extends NodeConstant {
     private static final byte TAG = 16;
 
-    private final ConstantUtf8 methodDescriptor;
+    private final Utf8Entry methodDescriptor;
 
-    public ConstantMethodType(ConstantUtf8 methodDescriptor) {
+    public MethodTypeEntry(Utf8Entry methodDescriptor) {
         this.methodDescriptor = methodDescriptor;
     }
 

src/main/java/nl/sander/beejava/constantpool/entry/ModuleEntry.java

@@ -1,12 +1,12 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantModule extends NodeConstant {
+public class ModuleEntry extends NodeConstant {
 
     private static final byte TAG = 19;
 
-    private final ConstantUtf8 nameEntry;
+    private final Utf8Entry nameEntry;
 
-    public ConstantModule(ConstantUtf8 nameEntry) {
+    public ModuleEntry(Utf8Entry nameEntry) {
         super(nameEntry);
         this.nameEntry = nameEntry;
     }
@@ -16,6 +16,6 @@ public class ConstantModule extends NodeConstant {
     }
 
     public byte[] getBytes() {
-        return new byte[]{TAG, upperFraction(getNameIndex()), lowerFraction(getNameIndex())};
+        return new byte[]{TAG, upperByte(getNameIndex()), lowerByte(getNameIndex())};
     }
 }

src/main/java/nl/sander/beejava/constantpool/entry/NameAndTypeEntry.java

@@ -1,11 +1,11 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantNameAndType extends NodeConstant {
+public class NameAndTypeEntry extends NodeConstant {
     private static final byte TAG = 12;
-    private final ConstantUtf8 name;
-    private final ConstantUtf8 descriptor;
+    private final Utf8Entry name;
+    private final Utf8Entry descriptor;
 
-    public ConstantNameAndType(ConstantUtf8 name, ConstantUtf8 descriptor) {
+    public NameAndTypeEntry(Utf8Entry name, Utf8Entry descriptor) {
         super(name, descriptor);
         this.name = name;
         this.descriptor = descriptor;
@@ -29,6 +29,6 @@ public class ConstantNameAndType extends NodeConstant {
     }
 
     public byte[] getBytes() {
-        return new byte[]{TAG, upperFraction(getNameIndex()), lowerFraction(getNameIndex()), upperFraction(getDescriptorIndex()), lowerFraction(getDescriptorIndex())};
+        return new byte[]{TAG, upperByte(getNameIndex()), lowerByte(getNameIndex()), upperByte(getDescriptorIndex()), lowerByte(getDescriptorIndex())};
     }
 }

src/main/java/nl/sander/beejava/constantpool/entry/NodeConstant.java

@@ -47,7 +47,7 @@ public abstract class NodeConstant {
      * @param u16 is assumed to be 16 bits unsigned integer
      * @return lower 8 bits as byte
      */
-    protected byte lowerFraction(int u16) {
+    protected byte lowerByte(int u16) {
         return (byte) (u16 & 0xFF);
     }
 
@@ -57,11 +57,11 @@ public abstract class NodeConstant {
      * @param u16 is assumed to be 16 bits unsigned integer
      * @return upper 8 bits as byte
      */
-    protected byte upperFraction(int u16) {
+    protected byte upperByte(int u16) {
         return (byte) (u16 << 8);
     }
 
-    protected byte rshift(long bits, int positions) {
-        return (byte) (bits >>> positions);
+    protected byte getByte(long bits, int positions) {
+        return (byte) ((bits >>> positions) & 0xFF);
     }
 }

src/main/java/nl/sander/beejava/constantpool/entry/PackageEntry.java

@@ -1,10 +1,10 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantPackage extends NodeConstant {
+public class PackageEntry extends NodeConstant {
     private static final byte TAG = 20;
-    private final ConstantUtf8 name;
+    private final Utf8Entry name;
 
-    public ConstantPackage(ConstantUtf8 name) {
+    public PackageEntry(Utf8Entry name) {
         super(name);
         this.name = name;
     }
@@ -14,6 +14,6 @@ public class ConstantPackage extends NodeConstant {
     }
 
     public byte[] getBytes() {
-        return new byte[]{TAG, upperFraction(getNameIndex()), lowerFraction(getNameIndex())};
+        return new byte[]{TAG, upperByte(getNameIndex()), lowerByte(getNameIndex())};
     }
 }

src/main/java/nl/sander/beejava/constantpool/entry/StringEntry.java

@@ -1,10 +1,10 @@
 package nl.sander.beejava.constantpool.entry;
 
-public class ConstantString extends NodeConstant {
+public class StringEntry extends NodeConstant {
     private static final byte TAG = 8;
-    private final ConstantUtf8 utf8;
+    private final Utf8Entry utf8;
 
-    public ConstantString(ConstantUtf8 utf8) {
+    public StringEntry(Utf8Entry utf8) {
         this.utf8 = utf8;
     }
 
@@ -20,6 +20,6 @@ public class ConstantString extends NodeConstant {
     }
 
     public byte[] getBytes() {
-        return new byte[]{TAG, upperFraction(getUtf8Index()), lowerFraction(getUtf8Index())};
+        return new byte[]{TAG, upperByte(getUtf8Index()), lowerByte(getUtf8Index())};
     }
 }

src/main/java/nl/sander/beejava/constantpool/entry/Utf8Entry.java

@@ -2,11 +2,11 @@ package nl.sander.beejava.constantpool.entry;
 
 import java.nio.charset.StandardCharsets;
 
-public class ConstantUtf8 extends LeafConstant {
+public class Utf8Entry extends LeafConstant {
     private static final byte TAG = 1;
     private final String value;
 
-    public ConstantUtf8(String utf8) {
+    public Utf8Entry(String utf8) {
         this.value = utf8;
     }
 
@@ -25,8 +25,8 @@ public class ConstantUtf8 extends LeafConstant {
         byte[] utf8Bytes = value.getBytes(StandardCharsets.UTF_8);
         byte[] bytes = new byte[utf8Bytes.length + 3];
         bytes[0] = TAG;
-        bytes[1] = upperFraction(bytes.length);
-        bytes[2] = lowerFraction(bytes.length);
+        bytes[1] = upperByte(bytes.length);
+        bytes[2] = lowerByte(bytes.length);
         System.arraycopy(utf8Bytes, 0, bytes, 3, utf8Bytes.length);
         return bytes;
     }

src/main/java/nl/sander/beejava/util/ByteBuf.java

@@ -42,29 +42,33 @@ public class ByteBuf {
         data.clear();
     }
 
-    public void add(final byte c) {
+    public void addU8(final byte c) {
         if (data.remaining() == 0) {
             enlarge(1);
         }
         data.put(c);
     }
 
-    public void add(final byte[] bytes) {
+    public void addU8(final byte[] bytes) {
         if (data.remaining() < bytes.length) {
             enlarge(bytes.length);
         }
         data.put(bytes);
     }
 
-    public void add(final int... ints) {
+    public void addU8(final int... ints) {
         if (data.remaining() < ints.length) {
             enlarge(ints.length);
         }
         byte[] bytes = new byte[ints.length];
         for (int i = 0; i < ints.length; i++) {
-            bytes[i] = (byte) (i & 0xFF);
+            bytes[i] = (byte) (ints[i] & 0xFF);
         }
-        add(bytes);
+        addU8(bytes);
+    }
+
+    public void addU16(int u16) {
+        addU8((u16 >>> 8) & 0xFF, u16 & 0xFF);
     }
 
     private void enlarge(final int size) {
@@ -76,11 +80,11 @@ public class ByteBuf {
         data = newData;
     }
 
-    public int length() {
-        return data.limit() - data.remaining();
-    }
-
     public byte[] toBytes() {
-        return data.array();
+        int length = data.limit() - data.remaining();
+        data.rewind();
+        byte[] arr = new byte[length];
+        data.get(arr);
+        return arr;
     }
 }

src/test/java/nl/sander/beejava/CompilerTests.java

@@ -0,0 +1,10 @@
+package nl.sander.beejava;
+
+import org.junit.jupiter.api.Test;
+
+public class CompilerTests {
+    @Test
+    public void test(){
+        Compiler.compile(TestData.emptyClass());
+    }
+}

src/test/java/nl/sander/beejava/ConstantTreeCreatorTests.java

@@ -19,68 +19,49 @@ public class ConstantTreeCreatorTests {
     // creates simplest class possible and checks the tree, that the ConstantTreeCreator emits
     @Test // This is not a maintainable test
     public void testMethodRefEntryForSuperConstructor() {
-        BeeClass classWithIntField = createEmptyClass();
+        BeeClass classWithIntField = TestData.emptyClass();
         Set<NodeConstant> constantTree = new ConstantTreeCreator().createConstantTree(classWithIntField);
         assertEquals(1, constantTree.size());
         NodeConstant superConstructor = constantTree.iterator().next();
 
-        assertEquals(ConstantMethodRef.class, superConstructor.getClass());
-        ConstantMethodRef constantMethodRef = (ConstantMethodRef) superConstructor;
+        assertEquals(MethodRefEntry.class, superConstructor.getClass());
+        MethodRefEntry methodRefEntry = (MethodRefEntry) superConstructor;
 
-        Set<NodeConstant> methodRefEntryChildren = constantMethodRef.getChildren();
+        Set<NodeConstant> methodRefEntryChildren = methodRefEntry.getChildren();
         assertEquals(2, methodRefEntryChildren.size());
 
         Iterator<NodeConstant> firstChildren = methodRefEntryChildren.iterator();
         NodeConstant child1 = firstChildren.next();
-        assertEquals(ConstantClass.class, child1.getClass());
-        ConstantClass constantClass = (ConstantClass) child1;
+        assertEquals(ClassEntry.class, child1.getClass());
+        ClassEntry classEntry = (ClassEntry) child1;
 
-        Set<NodeConstant> classEntryChildren = constantClass.getChildren();
+        Set<NodeConstant> classEntryChildren = classEntry.getChildren();
         assertEquals(1, classEntryChildren.size());
         NodeConstant child2 = classEntryChildren.iterator().next();
 
-        assertEquals(ConstantUtf8.class, child2.getClass());
-        ConstantUtf8 className = (ConstantUtf8) child2;
+        assertEquals(Utf8Entry.class, child2.getClass());
+        Utf8Entry className = (Utf8Entry) child2;
         assertEquals("java/lang/Object", className.getUtf8());
 
         NodeConstant child3 = firstChildren.next();
-        assertEquals(ConstantNameAndType.class, child3.getClass());
-        ConstantNameAndType constantNameAndType = (ConstantNameAndType) child3;
+        assertEquals(NameAndTypeEntry.class, child3.getClass());
+        NameAndTypeEntry nameAndTypeEntry = (NameAndTypeEntry) child3;
 
-        Set<NodeConstant> nameAndTypeEntryChildren = constantNameAndType.getChildren();
+        Set<NodeConstant> nameAndTypeEntryChildren = nameAndTypeEntry.getChildren();
         assertEquals(2, nameAndTypeEntryChildren.size());
         Iterator<NodeConstant> nameAndTypeChildrenIterator = nameAndTypeEntryChildren.iterator();
 
         NodeConstant child4 = nameAndTypeChildrenIterator.next();
-        assertEquals(ConstantUtf8.class, child4.getClass());
-        ConstantUtf8 name = (ConstantUtf8) child4;
+        assertEquals(Utf8Entry.class, child4.getClass());
+        Utf8Entry name = (Utf8Entry) child4;
         assertEquals("<init>", name.getUtf8());
 
         NodeConstant child5 = nameAndTypeChildrenIterator.next();
-        assertEquals(ConstantUtf8.class, child5.getClass());
-        ConstantUtf8 type = (ConstantUtf8) child5;
+        assertEquals(Utf8Entry.class, child5.getClass());
+        Utf8Entry type = (Utf8Entry) child5;
         assertEquals("()V", type.getUtf8());
     }
 
-    private BeeClass createEmptyClass() {
-        BeeConstructor constructor = BeeConstructor.builder()
-                .withAccessFlags(MethodAccessFlag.PUBLIC)
-                .withCode(
-                        line(0, LOAD, Ref.THIS),
-                        line(1, INVOKE, Ref.SUPER, "<init>", "()"),
-                        line(5, RETURN))
-                .build();
-
-        return BeeClass.builder()
-                .withClassFileVersion(Version.V14)
-                .withPackage("nl.sander.beejava.test")
-                .withAccessFlags(PUBLIC)
-                .withSimpleName("EmptyBean")
-                .withSuperClass(Object.class) // Not mandatory, like in java sourcecode
-                .withConstructors(constructor) // There's no default constructor in beejava. The user must always add them
-                .build();
-    }
-
     private BeeClass createClassWithIntField() {
         BeeField intField = BeeField.builder()
                 .withAccessFlags(FieldAccessFlag.PRIVATE)

src/test/java/nl/sander/beejava/TestData.java

@@ -0,0 +1,32 @@
+package nl.sander.beejava;
+
+import nl.sander.beejava.api.BeeClass;
+import nl.sander.beejava.api.BeeConstructor;
+import nl.sander.beejava.api.Ref;
+import nl.sander.beejava.api.Version;
+import nl.sander.beejava.flags.MethodAccessFlag;
+
+import static nl.sander.beejava.api.CodeLine.line;
+import static nl.sander.beejava.api.Opcode.*;
+import static nl.sander.beejava.flags.ClassAccessFlag.PUBLIC;
+
+public class TestData {
+    public static BeeClass emptyClass() {
+        BeeConstructor constructor = BeeConstructor.builder()
+                .withAccessFlags(MethodAccessFlag.PUBLIC)
+                .withCode(
+                        line(0, LOAD, Ref.THIS),
+                        line(1, INVOKE, Ref.SUPER, "<init>", "()"),
+                        line(5, RETURN))
+                .build();
+
+        return BeeClass.builder()
+                .withClassFileVersion(Version.V14)
+                .withPackage("nl.sander.beejava.test")
+                .withAccessFlags(PUBLIC)
+                .withSimpleName("EmptyBean")
+                .withSuperClass(Object.class) // Not mandatory, like in java sourcecode
+                .withConstructors(constructor) // There's no default constructor in beejava. The user must always add them
+                .build();
+    }
+}

src/test/java/nl/sander/beejava/constantpool/entry/TagCorrectnessTest.java

@@ -11,39 +11,39 @@ public class TagCorrectnessTest {
     @Test
     public void testSpec() {
         assertEquals(1, utf8().getTag());
-        assertEquals(3, new ConstantInteger(0).getTag());
-        assertEquals(4, new ConstantFloat(0).getTag());
-        assertEquals(5, new ConstantLong(0).getTag());
-        assertEquals(6, new ConstantDouble(0).getTag());
+        assertEquals(3, new IntegerEntry(0).getTag());
+        assertEquals(4, new FloatEntry(0).getTag());
+        assertEquals(5, new LongEntry(0).getTag());
+        assertEquals(6, new DoubleEntry(0).getTag());
         assertEquals(7, classEntry().getTag());
-        assertEquals(8, new ConstantString(utf8()).getTag());
+        assertEquals(8, new StringEntry(utf8()).getTag());
         assertEquals(9, fieldRef().getTag());
-        assertEquals(10, new ConstantMethodRef(classEntry(), nameAndType()).getTag());
-        assertEquals(11, new ConstantInterfaceMethodRef(classEntry(), nameAndType()).getTag());
+        assertEquals(10, new MethodRefEntry(classEntry(), nameAndType()).getTag());
+        assertEquals(11, new InterfaceMethodRefEntry(classEntry(), nameAndType()).getTag());
         assertEquals(12, nameAndType().getTag());
-        assertEquals(15, new ConstantMethodHandle(0).getTag()); //TODO
-        assertEquals(16, new ConstantMethodType(utf8()).getTag()); //TODO
-        assertEquals(17, new ConstantDynamic(0, nameAndType()).getTag()); //TODO
-        assertEquals(18, new ConstantInvokeDynamic(0, nameAndType()).getTag()); //TODO
-        assertEquals(19, new ConstantModule(utf8()).getTag());
-        assertEquals(20, new ConstantPackage(utf8()).getTag());
+        assertEquals(15, new MethodHandleEntry(0).getTag()); //TODO
+        assertEquals(16, new MethodTypeEntry(utf8()).getTag()); //TODO
+        assertEquals(17, new DynamicEntry(0, nameAndType()).getTag()); //TODO
+        assertEquals(18, new InvokeDynamicEntry(0, nameAndType()).getTag()); //TODO
+        assertEquals(19, new ModuleEntry(utf8()).getTag());
+        assertEquals(20, new PackageEntry(utf8()).getTag());
 
     }
 
-    private ConstantFieldRef fieldRef() {
-        return new ConstantFieldRef(classEntry(), nameAndType());
+    private FieldRefEntry fieldRef() {
+        return new FieldRefEntry(classEntry(), nameAndType());
     }
 
-    private ConstantNameAndType nameAndType() {
-        return new ConstantNameAndType(utf8(), utf8());
+    private NameAndTypeEntry nameAndType() {
+        return new NameAndTypeEntry(utf8(), utf8());
     }
 
 
-    private ConstantClass classEntry() {
-        return new ConstantClass(utf8());
+    private ClassEntry classEntry() {
+        return new ClassEntry(utf8());
     }
 
-    private ConstantUtf8 utf8() {
-        return new ConstantUtf8("");
+    private Utf8Entry utf8() {
+        return new Utf8Entry("");
     }
 }