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.linq4j.Ord;
  import org.apache.calcite.rel.type.RelDataType;
  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.util.Pair;
  
  import com.google.common.collect.ImmutableList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  /**
   * AssignableOperandTypeChecker implements {@link SqlOperandTypeChecker} by
   * verifying that the type of each argument is assignable to a predefined set of
   * parameter types (under the SQL definition of "assignable").
   */
  public class AssignableOperandTypeChecker implements SqlOperandTypeChecker {
    //~ Instance fields --------------------------------------------------------
  
    private final List<RelDataType> paramTypes;
    private final @Nullable ImmutableList<String> paramNames;
  
    //~ Constructors -----------------------------------------------------------
  
    /**
     * Instantiates this strategy with a specific set of parameter types.
     *
     * @param paramTypes parameter types for operands; index in this array
     *                   corresponds to operand number
     * @param paramNames parameter names, or null
     */
    public AssignableOperandTypeChecker(List<RelDataType> paramTypes,
        @Nullable List<String> paramNames) {
      this.paramTypes = ImmutableList.copyOf(paramTypes);
      this.paramNames =
          paramNames == null ? null : ImmutableList.copyOf(paramNames);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public SqlOperandCountRange getOperandCountRange() {
      return SqlOperandCountRanges.of(paramTypes.size());
    }
  
    @Override public boolean checkOperandTypes(
        SqlCallBinding callBinding,
        boolean throwOnFailure) {
      // Do not use callBinding.operands(). We have not resolved to a function
      // yet, therefore we do not know the ordered parameter names.
      final List<SqlNode> operands = callBinding.getCall().getOperandList();
      for (Pair<RelDataType, SqlNode> pair : Pair.zip(paramTypes, operands)) {
        RelDataType argType = SqlTypeUtil.deriveType(callBinding, pair.right);
        if (!SqlTypeUtil.canAssignFrom(pair.left, argType)) {
          // TODO: add in unresolved function type cast.
          if (throwOnFailure) {
            throw callBinding.newValidationSignatureError();
          } else {
            return false;
          }
        }
      }
      return true;
    }
  
    @Override public String getAllowedSignatures(SqlOperator op, String opName) {
      StringBuilder sb = new StringBuilder();
      sb.append(opName);
      sb.append("(");
      for (Ord<RelDataType> paramType : Ord.zip(paramTypes)) {
        if (paramType.i > 0) {
          sb.append(", ");
        }
        if (paramNames != null) {
          sb.append(paramNames.get(paramType.i))
              .append(" => ");
        }
        sb.append("<");
        sb.append(paramType.e.getFamily());
        sb.append(">");
      }
      sb.append(")");
      return sb.toString();
    }
  }
  