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.type;
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeField;
  import org.apache.calcite.sql.SqlCallBinding;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlOperandCountRange;
  import org.apache.calcite.sql.SqlOperator;
  import org.apache.calcite.sql.SqlSelect;
  import org.apache.calcite.sql.SqlUtil;
  import org.apache.calcite.sql.validate.SqlValidator;
  import org.apache.calcite.sql.validate.implicit.TypeCoercion;
  
  import java.util.AbstractList;
  import java.util.List;
  
  import static org.apache.calcite.util.Static.RESOURCE;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Parameter type-checking strategy for a set operator (UNION, INTERSECT,
   * EXCEPT).
   *
   * <p>Both arguments must be records with the same number of fields, and the
   * fields must be union-compatible.
   */
  public class SetopOperandTypeChecker implements SqlOperandTypeChecker {
    //~ Methods ----------------------------------------------------------------
  
    @Override public boolean checkOperandTypes(
        SqlCallBinding callBinding,
        boolean throwOnFailure) {
      assert callBinding.getOperandCount() == 2
          : "setops are binary (for now)";
      final RelDataType[] argTypes =
          new RelDataType[callBinding.getOperandCount()];
      int colCount = -1;
      final SqlValidator validator = callBinding.getValidator();
      for (int i = 0; i < argTypes.length; i++) {
        final RelDataType argType =
            argTypes[i] = callBinding.getOperandType(i);
        if (!argType.isStruct()) {
          if (throwOnFailure) {
            throw new AssertionError("setop arg must be a struct");
          } else {
            return false;
          }
        }
  
        // Each operand must have the same number of columns.
        final List<RelDataTypeField> fields = argType.getFieldList();
        if (i == 0) {
          colCount = fields.size();
          continue;
        }
  
        if (fields.size() != colCount) {
          if (throwOnFailure) {
            SqlNode node = callBinding.operand(i);
            if (node instanceof SqlSelect) {
              node = ((SqlSelect) node).getSelectList();
            }
            throw validator.newValidationError(requireNonNull(node, "node"),
                RESOURCE.columnCountMismatchInSetop(
                    callBinding.getOperator().getName()));
          } else {
            return false;
          }
        }
      }
  
      // The columns must be pairwise union compatible. For each column
      // ordinal, form a 'slice' containing the types of the ordinal'th
      // column j.
      for (int i = 0; i < colCount; i++) {
        final int i2 = i;
  
        // Get the ith column data types list for every record type fields pair.
        // For example,
        // for record type (f0: INT, f1: BIGINT, f2: VARCHAR)
        // and record type (f3: VARCHAR, f4: DECIMAL, f5: INT),
        // the list would be [[INT, VARCHAR], [BIGINT, DECIMAL], [VARCHAR, INT]].
        final List<RelDataType> columnIthTypes = new AbstractList<RelDataType>() {
          @Override public RelDataType get(int index) {
            return argTypes[index].getFieldList().get(i2)
                .getType();
          }
  
          @Override public int size() {
            return argTypes.length;
          }
        };
  
        final RelDataType type =
            callBinding.getTypeFactory().leastRestrictive(columnIthTypes);
        // If any of the types is different we need to insert a coercion.
        boolean coerced = false;
        if (callBinding.isTypeCoercionEnabled()) {
          for (int j = 0; j < callBinding.getOperandCount(); j++) {
            TypeCoercion typeCoercion = validator.getTypeCoercion();
            RelDataType widenType = typeCoercion.getWiderTypeFor(columnIthTypes, true);
            if (null != widenType) {
              coerced =
                  typeCoercion.rowTypeCoercion(callBinding.getScope(),
                      callBinding.operand(j), i, widenType) || coerced;
            }
          }
        }
        if (type == null) {
          if (!coerced) {
            if (throwOnFailure) {
              SqlNode field =
                  SqlUtil.getSelectListItem(callBinding.operand(0), i);
              throw validator.newValidationError(field,
                  RESOURCE.columnTypeMismatchInSetop(i + 1, // 1-based
                      callBinding.getOperator().getName()));
            } else {
              return false;
            }
          }
        }
      }
  
      return true;
    }
  
    @Override public SqlOperandCountRange getOperandCountRange() {
      return SqlOperandCountRanges.of(2);
    }
  
    @Override public String getAllowedSignatures(SqlOperator op, String opName) {
      return "{0} " + opName + " {1}";
    }
  }
  