content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you 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.apache.calcite.linq4j.tree;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.Modifier;
  import java.util.Objects;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Represents accessing a field or property.
   */
  public class MemberExpression extends Expression {
    public final @Nullable Expression expression;
    public final PseudoField field;
  
    public MemberExpression(Expression expression, Field field) {
      this(expression, Types.field(field));
    }
  
    public MemberExpression(@Nullable Expression expression, PseudoField field) {
      super(ExpressionType.MemberAccess, field.getType());
      this.expression = expression;
      this.field = requireNonNull(field, "field");
      if (!Modifier.isStatic(field.getModifiers())) {
        requireNonNull(expression,
            "must specify expression if field is not static");
      }
    }
  
    @Override public Expression accept(Shuttle shuttle) {
      shuttle = shuttle.preVisit(this);
      Expression expression1 = expression == null
          ? null
          : expression.accept(shuttle);
      return shuttle.visit(this, expression1);
    }
  
    @Override public <R> R accept(Visitor<R> visitor) {
      return visitor.visit(this);
    }
  
    @Override public @Nullable Object evaluate(Evaluator evaluator) {
      final Object o = expression == null
          ? null
          : expression.evaluate(evaluator);
      try {
        return field.get(o);
      } catch (IllegalAccessException e) {
        throw new RuntimeException("error while evaluating " + this, e);
      }
    }
  
    @Override void accept(ExpressionWriter writer, int lprec, int rprec) {
      if (writer.requireParentheses(this, lprec, rprec)) {
        return;
      }
      if (expression != null) {
        expression.accept(writer, lprec, nodeType.lprec);
      } else {
        assert (field.getModifiers() & Modifier.STATIC) != 0;
        writer.append(field.getDeclaringClass());
      }
      writer.append('.').append(field.getName());
    }
  
    @Override public boolean equals(@Nullable Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }
      if (!super.equals(o)) {
        return false;
      }
  
      MemberExpression that = (MemberExpression) o;
  
      if (expression != null ? !expression.equals(that.expression) : that
          .expression != null) {
        return false;
      }
      if (!field.equals(that.field)) {
        return false;
      }
  
      return true;
    }
  
    @Override public int hashCode() {
      return Objects.hash(nodeType, type, expression, field);
    }
  }
  