package com.artemis.weaver;
import static com.artemis.meta.ClassMetadataUtil.instanceFields;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import com.artemis.meta.ClassMetadata;
import com.artemis.meta.ClassMetadataUtil;
import com.artemis.meta.FieldDescriptor;
final class AccessorGenerator implements Opcodes {
private final ClassReader cr;
private final ClassMetadata meta;
private final ClassWriter cw;
public AccessorGenerator(ClassReader cr, ClassMetadata meta) {
this.cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
this.cr = cr;
this.meta = meta;
}
public ClassReader transform() {
return new ClassReader(injectAccessors());
}
private byte[] injectAccessors() {
ClassMetadataUtil util = new ClassMetadataUtil(meta);
for (FieldDescriptor field : instanceFields(meta)) {
if (!util.hasGetter(field)) injectGetter(field);
if (!util.hasSetter(field)) injectSetter(field);
}
cr.accept(cw, 0);
return cw.toByteArray();
}
private void injectSetter(FieldDescriptor f) {
TypedOpcodes opcodes = new TypedOpcodes(f);
MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, f.name, "(" + f.desc + ")V", null, null);
mv.visitCode();
Label l0 = new Label();
mv.visitLabel(l0);
mv.visitVarInsn(ALOAD, 0);
mv.visitVarInsn(opcodes.tLOAD(), 1);
mv.visitFieldInsn(PUTFIELD, meta.type.getInternalName(), f.name, f.desc);
Label l1 = new Label();
mv.visitLabel(l1);
mv.visitInsn(RETURN);
Label l2 = new Label();
mv.visitLabel(l2);
mv.visitLocalVariable("this", meta.type.getDescriptor(), null, l0, l2, 0);
mv.visitLocalVariable(f.name, f.desc, null, l0, l2, 1);
mv.visitEnd();
}
private void injectGetter(FieldDescriptor f) {
TypedOpcodes opcodes = new TypedOpcodes(f);
MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, f.name, "()" + f.desc, null, null);
mv.visitCode();
Label l0 = new Label();
mv.visitLabel(l0);
mv.visitVarInsn(ALOAD, 0);
mv.visitFieldInsn(GETFIELD, meta.type.getInternalName(), f.name, f.desc);
mv.visitInsn(opcodes.tRETURN());
Label l1 = new Label();
mv.visitLabel(l1);
mv.visitLocalVariable("this", meta.type.getDescriptor(), null, l0, l1, 0);
mv.visitEnd();
}
}