com.avaje.ebean.enhance.agent.InterceptField Maven / Gradle / Ivy

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package com.avaje.ebean.enhance.agent;

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

/**
 * Generate the _ebean_getIntercept() method and field.
 */
public class InterceptField implements Opcodes, EnhanceConstants {

  /**
   * Add the _ebean_intercept field.
   */
  public static void addField(ClassVisitor cv, boolean transientInternalFields) {

    int access = ACC_PROTECTED + (transientInternalFields ? ACC_TRANSIENT : 0);
    FieldVisitor f1 = cv.visitField(access, INTERCEPT_FIELD, L_INTERCEPT, null, null);
    f1.visitEnd();
  }

  /**
   * Generate the _ebean_getIntercept() method.
   * 
   * 
   * public EntityBeanIntercept _ebean_getIntercept() {
   *     return _ebean_intercept;
   * }
   * 
   */
  public static void addGetterSetter(ClassVisitor cv, String className) {

    String lClassName = "L" + className + ";";

    MethodVisitor mv;
    Label l0, l1;

    mv = cv.visitMethod(ACC_PUBLIC, "_ebean_getIntercept", "()" + L_INTERCEPT, null, null);
    mv.visitCode();
    l0 = new Label();
    mv.visitLabel(l0);
    mv.visitLineNumber(1, l0);
    mv.visitVarInsn(ALOAD, 0);
    mv.visitFieldInsn(GETFIELD, className, INTERCEPT_FIELD, L_INTERCEPT);
    mv.visitInsn(ARETURN);
    l1 = new Label();
    mv.visitLabel(l1);
    mv.visitLocalVariable("this", lClassName, null, l0, l1, 0);
    mv.visitMaxs(0, 0);
    mv.visitEnd();

    addInitInterceptMethod(cv, className);
  }

  /**
   * Add _ebean_intercept() method that includes initialisation of the
   * EntityBeanIntercept.
   * 
   * This is only required when transientInternalFields=true with enhancement.
   * In that case the EntityBeanIntercept is transient and can be null after
   * deserialization - in which case it needs to be initialised.
   * 
   * 
   * 
   * public EntityBeanIntercept _ebean_intercept() {
   *     if (_ebean_intercept == null) {
   *         _ebean_intercept = new EntityBeanIntercept(this);
   *     }
   *     return _ebean_intercept;
   * }
   * 
   */
  private static void addInitInterceptMethod(ClassVisitor cv, String className) {

    MethodVisitor mv = cv.visitMethod(ACC_PUBLIC, "_ebean_intercept", "()" + L_INTERCEPT, null, null);
    mv.visitCode();
    Label l0 = new Label();
    mv.visitLabel(l0);
    mv.visitLineNumber(1, l0);
    mv.visitVarInsn(ALOAD, 0);
    mv.visitFieldInsn(GETFIELD, className, INTERCEPT_FIELD, L_INTERCEPT);
    Label l1 = new Label();
    mv.visitJumpInsn(IFNONNULL, l1);
    Label l2 = new Label();
    mv.visitLabel(l2);
    mv.visitLineNumber(2, l2);
    mv.visitVarInsn(ALOAD, 0);
    mv.visitTypeInsn(NEW, C_INTERCEPT);
    mv.visitInsn(DUP);
    mv.visitVarInsn(ALOAD, 0);
    mv.visitMethodInsn(INVOKESPECIAL, C_INTERCEPT, "", "(Ljava/lang/Object;)V", false);
    mv.visitFieldInsn(PUTFIELD, className, INTERCEPT_FIELD, L_INTERCEPT);
    mv.visitLabel(l1);
    mv.visitLineNumber(3, l1);
    mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
    mv.visitVarInsn(ALOAD, 0);
    mv.visitFieldInsn(GETFIELD, className, INTERCEPT_FIELD, L_INTERCEPT);
    mv.visitInsn(ARETURN);
    Label l3 = new Label();
    mv.visitLabel(l3);
    mv.visitLocalVariable("this", "L" + className + ";", null, l0, l3, 0);
    mv.visitMaxs(4, 1);
    mv.visitEnd();
  }
}