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.advise;
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.runtime.CalciteException;
  import org.apache.calcite.sql.SqlCall;
  import org.apache.calcite.sql.SqlIdentifier;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlOperatorTable;
  import org.apache.calcite.sql.SqlSelect;
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.sql.type.SqlTypeUtil;
  import org.apache.calcite.sql.validate.OverScope;
  import org.apache.calcite.sql.validate.SelectScope;
  import org.apache.calcite.sql.validate.SqlModality;
  import org.apache.calcite.sql.validate.SqlValidatorCatalogReader;
  import org.apache.calcite.sql.validate.SqlValidatorImpl;
  import org.apache.calcite.sql.validate.SqlValidatorNamespace;
  import org.apache.calcite.sql.validate.SqlValidatorScope;
  import org.apache.calcite.util.Util;
  
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * <code>SqlAdvisorValidator</code> is used by {@link SqlAdvisor} to traverse
   * the parse tree of a SQL statement, not for validation purpose but for setting
   * up the scopes and namespaces to facilitate retrieval of SQL statement
   * completion hints.
   */
  public class SqlAdvisorValidator extends SqlValidatorImpl {
    //~ Instance fields --------------------------------------------------------
  
    private final Set<SqlValidatorNamespace> activeNamespaces = new HashSet<>();
  
    private final RelDataType emptyStructType =
        SqlTypeUtil.createEmptyStructType(typeFactory);
  
    //~ Constructors -----------------------------------------------------------
  
    /**
     * Creates a SqlAdvisor validator.
     *
     * @param opTab         Operator table
     * @param catalogReader Catalog reader
     * @param typeFactory   Type factory
     * @param config        Config
     */
    public SqlAdvisorValidator(
        SqlOperatorTable opTab,
        SqlValidatorCatalogReader catalogReader,
        RelDataTypeFactory typeFactory,
        Config config) {
      super(opTab, catalogReader, typeFactory, config);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    /**
     * Registers the identifier and its scope into a map keyed by ParserPosition.
     */
    @Override public void validateIdentifier(SqlIdentifier id, SqlValidatorScope scope) {
      registerId(id, scope);
      try {
        super.validateIdentifier(id, scope);
      } catch (CalciteException e) {
        Util.swallow(e, TRACER);
      }
    }
  
    private void registerId(SqlIdentifier id, SqlValidatorScope scope) {
      for (int i = 0; i < id.names.size(); i++) {
        final SqlParserPos subPos = id.getComponentParserPosition(i);
        SqlIdentifier subId =
            i == id.names.size() - 1
                ? id
                : new SqlIdentifier(id.names.subList(0, i + 1), subPos);
        idPositions.put(subPos.toString(), new IdInfo(scope, subId));
      }
    }
  
    @Override public SqlNode expand(SqlNode expr, SqlValidatorScope scope) {
      // Disable expansion. It doesn't help us come up with better hints.
      return expr;
    }
  
    @Override public SqlNode expandSelectExpr(SqlNode expr,
        SelectScope scope, SqlSelect select, Map<String, SqlNode> expansions) {
      // Disable expansion. It doesn't help us come up with better hints.
      return expr;
    }
  
    @Override public SqlNode expandOrderExpr(SqlSelect select, SqlNode orderExpr) {
      // Disable expansion. It doesn't help us come up with better hints.
      return orderExpr;
    }
  
    /**
     * Calls the parent class method and mask Farrago exception thrown.
     */
    @Override public RelDataType deriveType(
        SqlValidatorScope scope,
        SqlNode operand) {
      // REVIEW Do not mask Error (indicates a serious system problem) or
      // UnsupportedOperationException (a bug). I have to mask
      // UnsupportedOperationException because
      // SqlValidatorImpl.getValidatedNodeType throws it for an unrecognized
      // identifier node I have to mask Error as well because
      // AbstractNamespace.getRowType  called in super.deriveType can do a
      // Util.permAssert that throws Error
      try {
        return super.deriveType(scope, operand);
      } catch (CalciteException | UnsupportedOperationException | Error e) {
        return unknownType;
      }
    }
  
    // we do not need to validate from clause for traversing the parse tree
    // because there is no SqlIdentifier in from clause that need to be
    // registered into {@link #idPositions} map
    @Override protected void validateFrom(
        SqlNode node,
        RelDataType targetRowType,
        SqlValidatorScope scope) {
      try {
        super.validateFrom(node, targetRowType, scope);
      } catch (CalciteException e) {
        Util.swallow(e, TRACER);
      }
    }
  
    /**
     * Calls the parent class method and masks Farrago exception thrown.
     */
    @Override protected void validateWhereClause(SqlSelect select) {
      try {
        super.validateWhereClause(select);
      } catch (CalciteException e) {
        Util.swallow(e, TRACER);
      }
    }
  
    /**
     * Calls the parent class method and masks Farrago exception thrown.
     */
    @Override protected void validateHavingClause(SqlSelect select) {
      try {
        super.validateHavingClause(select);
      } catch (CalciteException e) {
        Util.swallow(e, TRACER);
      }
    }
  
    @Override protected void validateOver(SqlCall call, SqlValidatorScope scope) {
      try {
        final OverScope overScope = (OverScope) getOverScope(call);
        final SqlNode relation = call.operand(0);
        validateFrom(relation, unknownType, scope);
        final SqlNode window = call.operand(1);
        SqlValidatorScope opScope = scopes.get(relation);
        if (opScope == null) {
          opScope = overScope;
        }
        validateWindow(window, opScope, null);
      } catch (CalciteException e) {
        Util.swallow(e, TRACER);
      }
    }
  
    @Override protected void validateNamespace(final SqlValidatorNamespace namespace,
        RelDataType targetRowType) {
      // Only attempt to validate each namespace once. Otherwise, if
      // validation fails, we may end up cycling.
      if (activeNamespaces.add(namespace)) {
        super.validateNamespace(namespace, targetRowType);
      } else {
        namespace.setType(emptyStructType);
      }
    }
  
    @Override public boolean validateModality(SqlSelect select,
        SqlModality modality, boolean fail) {
      return true;
    }
  
    @Override protected boolean shouldAllowOverRelation() {
      return true; // no reason not to be lenient
    }
  }
  