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/*
 * Based on JUEL 2.2.1 code, 2006-2009 Odysseus Software GmbH
 *
 * 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.activiti.engine.impl.juel;

import org.activiti.engine.impl.javax.el.ELContext;
import org.activiti.engine.impl.javax.el.ELException;

public class AstUnary extends AstRightValue {
  public interface Operator {
    public Object eval(Bindings bindings, ELContext context, AstNode node);
  }

  public static abstract class SimpleOperator implements Operator {
    public Object eval(Bindings bindings, ELContext context, AstNode node) {
      return apply(bindings, node.eval(bindings, context));
    }

    protected abstract Object apply(TypeConverter converter, Object o);
  }

  public static final Operator EMPTY = new SimpleOperator() {
    @Override
    public Object apply(TypeConverter converter, Object o) {
      return BooleanOperations.empty(converter, o);
    }

    @Override
    public String toString() {
      return "empty";
    }
  };
  public static final Operator NEG = new SimpleOperator() {
    @Override
    public Object apply(TypeConverter converter, Object o) {
      return NumberOperations.neg(converter, o);
    }

    @Override
    public String toString() {
      return "-";
    }
  };
  public static final Operator NOT = new SimpleOperator() {
    @Override
    public Object apply(TypeConverter converter, Object o) {
      return !converter.convert(o, Boolean.class);
    }

    @Override
    public String toString() {
      return "!";
    }
  };

  private final Operator operator;
  private final AstNode child;

  public AstUnary(AstNode child, AstUnary.Operator operator) {
    this.child = child;
    this.operator = operator;
  }

  public Operator getOperator() {
    return operator;
  }

  @Override
  public Object eval(Bindings bindings, ELContext context) throws ELException {
    return operator.eval(bindings, context, child);
  }

  @Override
  public String toString() {
    return "'" + operator.toString() + "'";
  }

  @Override
  public void appendStructure(StringBuilder b, Bindings bindings) {
    b.append(operator);
    b.append(' ');
    child.appendStructure(b, bindings);
  }

  public int getCardinality() {
    return 1;
  }

  public AstNode getChild(int i) {
    return i == 0 ? child : null;
  }
}