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.sql;
  
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.util.ImmutableNullableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  import static org.apache.calcite.linq4j.Nullness.castNonNull;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Implementation of {@link SqlCall} that keeps its operands in an array.
   */
  public class SqlBasicCall extends SqlCall {
    private SqlOperator operator;
    private List<@Nullable SqlNode> operandList;
    private final @Nullable SqlLiteral functionQuantifier;
  
    @Deprecated // to be removed before 2.0
    public SqlBasicCall(
        SqlOperator operator,
        @Nullable SqlNode[] operands,
        SqlParserPos pos) {
      this(operator, ImmutableNullableList.copyOf(operands), pos, null);
    }
  
    /** Creates a SqlBasicCall.
     *
     * <p>It is not expanded; call {@link #withExpanded withExpanded(true)}
     * to expand. */
    public SqlBasicCall(
        SqlOperator operator,
        List<? extends @Nullable SqlNode> operandList,
        SqlParserPos pos) {
      this(operator, operandList, pos, null);
    }
  
    @Deprecated // to be removed before 2.0
    public SqlBasicCall(
        SqlOperator operator,
        @Nullable SqlNode[] operands,
        SqlParserPos pos,
        @Nullable SqlLiteral functionQualifier) {
      this(operator, ImmutableNullableList.copyOf(operands), pos,
          functionQualifier);
    }
  
    /** Creates a SqlBasicCall with an optional function qualifier.
     *
     * <p>It is not expanded; call {@link #withExpanded withExpanded(true)}
     * to expand. */
    public SqlBasicCall(
        SqlOperator operator,
        List<? extends @Nullable SqlNode> operandList,
        SqlParserPos pos,
        @Nullable SqlLiteral functionQualifier) {
      super(pos);
      this.operator = requireNonNull(operator, "operator");
      this.operandList = ImmutableNullableList.copyOf(operandList);
      this.functionQuantifier = functionQualifier;
    }
  
    @Override public SqlKind getKind() {
      return operator.getKind();
    }
  
    /** Sets whether this call is expanded.
     *
     * @see #isExpanded() */
    public SqlCall withExpanded(boolean expanded) {
      return !expanded
          ? this
          : new ExpandedBasicCall(operator, operandList, pos,
              functionQuantifier);
    }
  
    @Override public void setOperand(int i, @Nullable SqlNode operand) {
      operandList = set(operandList, i, operand);
    }
  
    /** Sets the operator (or function) that is being called.
     *
     * <p>This method is used by the validator to set a more refined version of
     * the same operator (for instance, a version where overloading has been
     * resolved); use with care. */
    public void setOperator(SqlOperator operator) {
      this.operator = requireNonNull(operator, "operator");
    }
  
    @Override public SqlOperator getOperator() {
      return operator;
    }
  
    @SuppressWarnings("nullness")
    @Override public List<SqlNode> getOperandList() {
      return operandList;
    }
  
    @SuppressWarnings("unchecked")
    @Override public <S extends SqlNode> S operand(int i) {
      return (S) castNonNull(operandList.get(i));
    }
  
    @Override public int operandCount() {
      return operandList.size();
    }
  
    @Override public @Nullable SqlLiteral getFunctionQuantifier() {
      return functionQuantifier;
    }
  
    @Override public SqlNode clone(SqlParserPos pos) {
      return getOperator().createCall(getFunctionQuantifier(), pos, operandList);
    }
  
    /** Sets the {@code i}th element of {@code list} to value {@code e}, creating
     * an immutable copy of the list. */
    private static <E> List<@Nullable E> set(List<E> list, int i, @Nullable E e) {
      if (i == 0 && list.size() == 1) {
        // short-cut case where the contents of the previous list can be ignored
        return ImmutableNullableList.of(e);
      }
      //noinspection unchecked
      @Nullable E[] objects = (E[]) list.toArray();
      objects[i] = e;
      return ImmutableNullableList.copyOf(objects);
    }
  
    /** Sub-class of {@link org.apache.calcite.sql.SqlBasicCall}
     * for which {@link #isExpanded()} returns true. */
    private static class ExpandedBasicCall extends SqlBasicCall {
      ExpandedBasicCall(SqlOperator operator,
          List<? extends @Nullable SqlNode> operandList, SqlParserPos pos,
          @Nullable SqlLiteral functionQualifier) {
        super(operator, operandList, pos, functionQualifier);
      }
  
      @Override public boolean isExpanded() {
        return true;
      }
  
      @Override public SqlCall withExpanded(boolean expanded) {
        return expanded
            ? this
            : new SqlBasicCall(getOperator(), getOperandList(), pos,
                getFunctionQuantifier());
      }
    }
  }
  