core/src/main/java/org/apache/calcite/sql/fun/SqlQuantifyOperator.java

/*
 * 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.fun;

import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.sql.SqlCall;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlNodeList;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.calcite.sql.type.SqlTypeUtil;
import org.apache.calcite.sql.validate.SqlValidator;
import org.apache.calcite.sql.validate.SqlValidatorScope;

import org.checkerframework.checker.nullness.qual.Nullable;

import java.util.List;
import java.util.Objects;

import static com.google.common.base.Preconditions.checkArgument;

/**
 * Definition of the SQL <code>ALL</code> and <code>SOME</code>operators.
 *
 * <p>Each is used in combination with a relational operator:
 * <code>&lt;</code>, <code>&le;</code>,
 * <code>&gt;</code>, <code>&ge;</code>,
 * <code>=</code>, <code>&lt;&gt;</code>.
 *
 * <p><code>ANY</code> is a synonym for <code>SOME</code>.
 */
public class SqlQuantifyOperator extends SqlInOperator {
  //~ Instance fields --------------------------------------------------------

  public final SqlKind comparisonKind;

  //~ Constructors -----------------------------------------------------------

  /**
   * Creates a SqlQuantifyOperator.
   *
   * @param kind Either ALL or SOME
   * @param comparisonKind Either <code>&lt;</code>, <code>&le;</code>,
   *   <code>&gt;</code>, <code>&ge;</code>,
   *   <code>=</code> or <code>&lt;&gt;</code>.
   */
  SqlQuantifyOperator(SqlKind kind, SqlKind comparisonKind) {
    super(comparisonKind.sql + " " + kind, kind);
    this.comparisonKind = Objects.requireNonNull(comparisonKind, "comparisonKind");
    checkArgument(comparisonKind == SqlKind.EQUALS
        || comparisonKind == SqlKind.NOT_EQUALS
        || comparisonKind == SqlKind.LESS_THAN_OR_EQUAL
        || comparisonKind == SqlKind.LESS_THAN
        || comparisonKind == SqlKind.GREATER_THAN_OR_EQUAL
        || comparisonKind == SqlKind.GREATER_THAN);
    checkArgument(kind == SqlKind.SOME
        || kind == SqlKind.ALL);
  }


  @Override public RelDataType deriveType(SqlValidator validator,
      SqlValidatorScope scope, SqlCall call) {
    final List<SqlNode> operands = call.getOperandList();
    assert operands.size() == 2;

    RelDataType typeForCollectionArgument = tryDeriveTypeForCollection(validator, scope, call);
    if (typeForCollectionArgument != null) {
      return typeForCollectionArgument;
    }
    return super.deriveType(validator, scope, call);
  }

  /**
   * Derive type for SOME(collection expression), ANY (collection expression).
   *
   * @param validator Validator
   * @param scope     Scope of validation
   * @param call      Call to this operator
   * @return If SOME or ALL is applied to a collection, then the function
   * returns type of call, otherwise it returns null.
   */
  public @Nullable RelDataType tryDeriveTypeForCollection(SqlValidator validator,
      SqlValidatorScope scope, SqlCall call) {
    final SqlNode left = call.operand(0);
    final SqlNode right = call.operand(1);
    if (right instanceof SqlNodeList && ((SqlNodeList) right).size() == 1) {
      final RelDataType rightType = validator.deriveType(scope, ((SqlNodeList) right).get(0));
      if (SqlTypeUtil.isCollection(rightType)) {
        final RelDataType componentRightType = Objects.requireNonNull(rightType.getComponentType());
        final RelDataType leftType = validator.deriveType(scope, left);
        if (SqlTypeUtil.sameNamedType(componentRightType, leftType)
            || SqlTypeUtil.isNull(leftType) || SqlTypeUtil.isNull(componentRightType)) {
          return validator.getTypeFactory().createTypeWithNullability(
              validator.getTypeFactory().createSqlType(SqlTypeName.BOOLEAN),
              rightType.isNullable() || componentRightType.isNullable() || leftType.isNullable());
        }
      }
    }
    return null;
  }
}