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.validate;
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.StructKind;
  import org.apache.calcite.sql.SqlMatchRecognize;
  import org.apache.calcite.sql.SqlNode;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * Scope for expressions in a {@code MATCH_RECOGNIZE} clause.
   *
   * <p>Defines variables and uses them as prefix of columns reference.
   */
  public class MatchRecognizeScope extends ListScope {
    private static final String STAR = "*";
  
    //~ Instance fields ---------------------------------------------
    private final SqlMatchRecognize matchRecognize;
    private final Set<String> patternVars;
  
    /** Creates a MatchRecognizeScope. */
    public MatchRecognizeScope(SqlValidatorScope parent,
        SqlMatchRecognize matchRecognize) {
      super(parent);
      this.matchRecognize = matchRecognize;
      patternVars = validator.getCatalogReader().nameMatcher().createSet();
      patternVars.add(STAR);
    }
  
    @Override public SqlNode getNode() {
      return matchRecognize;
    }
  
    public SqlMatchRecognize getMatchRecognize() {
      return matchRecognize;
    }
  
    public Set<String> getPatternVars() {
      return patternVars;
    }
  
    public void addPatternVar(String str) {
      patternVars.add(str);
    }
  
    @Override public Map<String, ScopeChild>
    findQualifyingTableNames(String columnName, SqlNode ctx,
        SqlNameMatcher nameMatcher) {
      final Map<String, ScopeChild> map = new HashMap<>();
      for (ScopeChild child : children) {
        final RelDataType rowType = child.namespace.getRowType();
        if (nameMatcher.field(rowType, columnName) != null) {
          map.put(STAR, child);
        }
      }
      switch (map.size()) {
      case 0:
        return parent.findQualifyingTableNames(columnName, ctx, nameMatcher);
      default:
        return map;
      }
    }
  
    @Override public void resolve(List<String> names, SqlNameMatcher nameMatcher,
       boolean deep, Resolved resolved) {
      if (patternVars.contains(names.get(0))) {
        final Step path = new EmptyPath().plus(null, 0, "", StructKind.FULLY_QUALIFIED);
        final ScopeChild child = children.get(0);
        resolved.found(child.namespace, child.nullable, this, path, names);
        if (resolved.count() > 0) {
          return;
        }
      }
      super.resolve(names, nameMatcher, deep, resolved);
    }
  
  }
  