FieldAccessor.java

/**
 * MVEL (The MVFLEX Expression Language)
 *
 * Copyright (C) 2007 Christopher Brock, MVFLEX/Valhalla Project and the Codehaus
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package org.mvel2.optimizers.impl.refl.nodes;

import org.mvel2.compiler.AccessorNode;
import org.mvel2.integration.VariableResolverFactory;
import org.mvel2.util.PropertyTools;

import java.lang.reflect.Field;

import static org.mvel2.DataConversion.convert;

public class FieldAccessor implements AccessorNode {
  private AccessorNode nextNode;
  private Field field;
  private boolean coercionRequired = false;
  private boolean primitive;


  public FieldAccessor() {
  }

  public FieldAccessor(Field field) {
    primitive = (this.field = field).getType().isPrimitive();
  }

  public Object getValue(Object ctx, Object elCtx, VariableResolverFactory vars) {
    try {
      if (nextNode != null) {
        return nextNode.getValue(field.get(ctx), elCtx, vars);
      }
      else {
        return field.get(ctx);
      }
    }
    catch (Exception e) {
      throw new RuntimeException("unable to access field: " + field.getName(), e);
    }
  }

  public Object setValue(Object ctx, Object elCtx, VariableResolverFactory variableFactory, Object value) {
    if (nextNode != null) {
      try {
        return nextNode.setValue(field.get(ctx), elCtx, variableFactory, value == null && primitive ? PropertyTools.getPrimitiveInitialValue(field.getType()) : value);
      }
      catch (Exception e) {
        throw new RuntimeException("unable to access field", e);
      }
    }

    // this local field is required to make sure exception block works with the same coercionRequired value
    // and it is not changed by another thread while setter is invoked 
    boolean attemptedCoercion = coercionRequired;
    try {

      if (coercionRequired) {
        field.set(ctx, value = convert(ctx, field.getClass()));
        return value;
      }
      else {
        field.set(ctx, value);
        return value;
      }
    }
    catch (IllegalArgumentException e) {
      if (!attemptedCoercion) {
        coercionRequired = true;
        return setValue(ctx, elCtx, variableFactory, value);
      }
      throw new RuntimeException("unable to bind property", e);
    }
    catch (Exception e) {
      throw new RuntimeException("unable to access field", e);
    }
  }

  public Field getField() {
    return field;
  }

  public void setField(Field field) {
    this.field = field;
  }

  public AccessorNode getNextNode() {
    return nextNode;
  }

  public AccessorNode setNextNode(AccessorNode nextNode) {
    return this.nextNode = nextNode;
  }

  public Class getKnownEgressType() {
    return field.getClass();
  }
}