MethodIsEmbeddedNewOrDirty.java

package com.avaje.ebean.enhance.agent;

import java.util.List;

import com.avaje.ebean.enhance.asm.ClassVisitor;
import com.avaje.ebean.enhance.asm.Label;
import com.avaje.ebean.enhance.asm.MethodVisitor;
import com.avaje.ebean.enhance.asm.Opcodes;

/**
 * Used to detect if a class has been enhanced.
 * <p>
 * Moved to use this over just relying on the existence of the EntityBean interface
 * to make the enhancement more robust.
 * </p>
 */
public class MethodIsEmbeddedNewOrDirty implements Opcodes, EnhanceConstants {

	/**
	 * Generate the _ebean_isEmbeddedNewOrDirty() method.
	 * 
	 * <pre>
	 * public boolean _ebean_isEmbeddedNewOrDirty() {
	 *  // for each embedded bean field...
	 * 	if (entityBeanIntercept.isEmbeddedNewOrDirty(embeddedBeanField)) return true;
	 *  ...
	 *  return false;
	 * }
	 * </pre>
	 */
	public static void addMethod(ClassVisitor cv, ClassMeta classMeta) {
		
		String className = classMeta.getClassName();
		
		MethodVisitor mv;

		mv = cv.visitMethod(ACC_PUBLIC, "_ebean_isEmbeddedNewOrDirty", "()Z", null, null);
		mv.visitCode();
		
		Label labelBegin = null;
		
		Label labelNext = null;
		
		List<FieldMeta> allFields = classMeta.getAllFields();
		for (int i = 0; i < allFields.size(); i++) {
			FieldMeta fieldMeta = allFields.get(i);
			if (fieldMeta.isEmbedded()){
				
				Label l0 = labelNext;
				if (l0 == null) {
					l0 = new Label();
				}
				if (labelBegin == null){
					labelBegin = l0;
				}
				
				mv.visitLabel(l0);
				mv.visitLineNumber(0, l0);
				mv.visitVarInsn(ALOAD, 0);
				mv.visitFieldInsn(GETFIELD, className, INTERCEPT_FIELD, L_INTERCEPT);
				mv.visitVarInsn(ALOAD, 0);
				fieldMeta.appendSwitchGet(mv, classMeta, false);
				mv.visitMethodInsn(INVOKEVIRTUAL, C_INTERCEPT, "isEmbeddedNewOrDirty", "(Ljava/lang/Object;)Z");

				labelNext = new Label();
				mv.visitJumpInsn(IFEQ, labelNext);
				mv.visitInsn(ICONST_1);
				mv.visitInsn(IRETURN);
				
			}
		}
		
		if (labelNext == null){
			labelNext = new Label();
		}
		if (labelBegin == null){
			labelBegin = labelNext;
		}	
		mv.visitLabel(labelNext);
		mv.visitLineNumber(1, labelNext);
		mv.visitInsn(ICONST_0);
		mv.visitInsn(IRETURN);
		
		Label l3 = new Label();
		mv.visitLabel(l3);
		mv.visitLocalVariable("this", "L"+className+";", null, labelBegin, l3, 0);
		mv.visitMaxs(2, 1);
		mv.visitEnd();
		
	}
}