CollectionTableRef.java

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// Copyright 2012 Cloudera Inc.
//
// Licensed 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 com.cloudera.impala.analysis;

import com.cloudera.impala.common.AnalysisException;
import com.google.common.base.Preconditions;

public class CollectionTableRef extends TableRef {
  // Expr that returns the referenced collection. Typically a SlotRef into the
  // parent scan's tuple. Result of analysis. Fully resolved against base tables.
  private Expr collectionExpr_;

  public CollectionTableRef(TableRef tableRef, Path resolvedPath) {
    super(tableRef);
    resolvedPath_ = resolvedPath;
    // Use the last path element as an implicit alias if no explicit alias was given.
    if (hasExplicitAlias()) return;
    String implicitAlias = rawPath_.get(rawPath_.size() - 1).toLowerCase();
    aliases_ = new String[] { implicitAlias };
  }

  public CollectionTableRef(CollectionTableRef other) {
    super(other);
    collectionExpr_ =
        (other.collectionExpr_ != null) ? other.collectionExpr_.clone() : null;
  }

  @Override
  public void analyze(Analyzer analyzer) throws AnalysisException {
    Preconditions.checkNotNull(getPrivilegeRequirement());
    desc_ = analyzer.registerTableRef(this);
    if (resolvedPath_.getRootDesc() != null) {
      SlotDescriptor parentSlotDesc = analyzer.registerSlotRef(resolvedPath_);
      collectionExpr_ = new SlotRef(parentSlotDesc);
      // Must always be materialized to ensure the correct cardinality after unnesting.
      analyzer.materializeSlots(collectionExpr_);
    }
    isAnalyzed_ = true;
    analyzeJoin(analyzer);
  }

  @Override
  public boolean isChildRef() {
    Preconditions.checkNotNull(resolvedPath_);
    return resolvedPath_.getRootDesc() != null;
  }

  public Expr getCollectionExpr() { return collectionExpr_; }

  @Override
  public TableRef clone() { return new CollectionTableRef(this); }
}