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.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.lang.reflect.Type;
  import java.util.List;
  import java.util.Objects;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Represents a call to either a static or an instance method.
   */
  public class MethodCallExpression extends Expression {
    public final Method method;
    public final @Nullable Expression targetExpression; // null for call to static method
    public final List<Expression> expressions;
    /** Cached hash code for the expression. */
    private int hash;
  
    MethodCallExpression(Type returnType, Method method,
        @Nullable Expression targetExpression, List<Expression> expressions) {
      super(ExpressionType.Call, returnType);
      checkArgument((targetExpression == null)
          == Modifier.isStatic(method.getModifiers()),
          "static method requires target expression "
              + "[static: %s, targetExpression: %s]",
          Modifier.isStatic(method.getModifiers()),
          targetExpression);
      checkArgument(Types.toClass(returnType) == method.getReturnType());
      this.method = requireNonNull(method, "method");
      this.targetExpression = targetExpression;
      this.expressions = requireNonNull(expressions, "expressions");
    }
  
    MethodCallExpression(Method method, @Nullable Expression targetExpression,
        List<Expression> expressions) {
      this(method.getReturnType(), method, targetExpression, expressions);
    }
  
    @Override public Expression accept(Shuttle shuttle) {
      shuttle = shuttle.preVisit(this);
      Expression targetExpression =
          this.targetExpression == null
              ? null
              : this.targetExpression.accept(shuttle);
      List<Expression> expressions =
          Expressions.acceptExpressions(this.expressions, shuttle);
      return shuttle.visit(this, targetExpression, expressions);
    }
  
    @Override public <R> R accept(Visitor<R> visitor) {
      return visitor.visit(this);
    }
  
    @Override public @Nullable Object evaluate(Evaluator evaluator) {
      final Object target;
      if (targetExpression == null) {
        target = null;
      } else {
        target = targetExpression.evaluate(evaluator);
      }
      final @Nullable Object[] args = new Object[expressions.size()];
      for (int i = 0; i < expressions.size(); i++) {
        Expression expression = expressions.get(i);
        args[i] = expression.evaluate(evaluator);
      }
      try {
        return method.invoke(target, args);
      } catch (IllegalAccessException | InvocationTargetException 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 (targetExpression != null) {
        // instance method
        targetExpression.accept(writer, lprec, nodeType.lprec);
      } else {
        // static method
        writer.append(method.getDeclaringClass());
      }
      writer.append('.').append(method.getName()).append('(');
      int k = 0;
      for (Expression expression : expressions) {
        if (k++ > 0) {
          writer.append(", ");
        }
        expression.accept(writer, 0, 0);
      }
      writer.append(')');
    }
  
    @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;
      }
  
      MethodCallExpression that = (MethodCallExpression) o;
      return expressions.equals(that.expressions)
          && method.equals(that.method)
          && Objects.equals(targetExpression, that.targetExpression);
    }
  
    @Override public int hashCode() {
      int result = hash;
      if (result == 0) {
        result =
            Objects.hash(nodeType, type, method, targetExpression, expressions);
        if (result == 0) {
          result = 1;
        }
        hash = result;
      }
      return result;
    }
  }
  