com.intel.ssg.dcst.panthera.parse.sql.transformer.SubQUnnestTransformer.java Source code

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/*
 * 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 com.intel.ssg.dcst.panthera.parse.sql.transformer;

import java.util.HashSet;
import java.util.Set;
import java.util.Stack;

import org.antlr.runtime.tree.CommonTree;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.intel.ssg.dcst.panthera.parse.sql.SqlXlateException;
import com.intel.ssg.dcst.panthera.parse.sql.TranslateContext;
import com.intel.ssg.dcst.panthera.parse.sql.transformer.fb.FilterBlock;
import com.intel.ssg.dcst.panthera.parse.sql.transformer.fb.FilterBlockContext;
import com.intel.ssg.dcst.panthera.parse.sql.transformer.fb.QueryBlock;
import com.intel.ssg.dcst.panthera.parse.sql.transformer.fb.SubQFilterBlock;

/**
 * Transform filter block tree with every QueryInfo.
 *
 * SubQUnnestTransformer.
 *
 */
public class SubQUnnestTransformer extends BaseSqlASTTransformer {

    private static final Log LOG = LogFactory.getLog(SubQUnnestTransformer.class);
    SqlASTTransformer tf;

    public SubQUnnestTransformer(SqlASTTransformer tf) {
        this.tf = tf;
    }

    @Override
    public void transform(CommonTree tree, TranslateContext context) throws SqlXlateException {
        tf.transformAST(tree, context);
        this.transformQInfoDeepFirst(tree, context);
    }

    /**
     * Transform inline view firstly.
     *
     * @param tree
     * @param context
     * @throws SqlXlateException
     */
    void transformQInfoDeepFirst(CommonTree tree, TranslateContext context) throws SqlXlateException {
        QueryInfo qInfo = context.getQInfoRoot();
        transformQInfoDeepFirst(qInfo, context);
    }

    void transformQInfoDeepFirst(QueryInfo qf, TranslateContext context) throws SqlXlateException {

        for (QueryInfo qinfo : qf.getChildren()) {
            transformQInfoDeepFirst(qinfo, context);
        }
        if (!qf.isQInfoTreeRoot()) {
            this.transformFilterBlock(qf, context);
        } else {
            // do nothing
        }
    }

    void transformFilterBlock(QueryInfo qf, TranslateContext context) throws SqlXlateException {
        if (!this.hasSubQuery(qf)) {
            LOG.info("skip subq transform:" + qf.toStringTree());
            return;
        }
        FilterBlock fb = qf.getFilterBlockTreeRoot();
        if (!(fb instanceof QueryBlock)) {
            throw new SqlXlateException(null, "Error FilterBlock tree" + fb.toStringTree());
        }
        // prefetch columns from filterBlocks and store them in QueryBlock in FilterBLockContext.
        fb.prepare(new FilterBlockContext(qf), context, new Stack<CommonTree>());
        // process QueryBlock
        fb.process(new FilterBlockContext(qf), context);
    }

    /**
     * check whether this QueryBlock have SubQFilterBlock.
     * @param qf
     * @return
     */
    boolean hasSubQuery(QueryInfo qf) {
        FilterBlock fb = qf.getFilterBlockTreeRoot();
        Set<Boolean> result = new HashSet<Boolean>();
        this.isSubQFilterBlock(fb, result);
        if (result.contains(true)) {
            return true;
        }
        return false;
    }

    void isSubQFilterBlock(FilterBlock fb, Set<Boolean> result) {
        if (fb instanceof SubQFilterBlock) {
            result.add(true);
            return;
        }
        for (FilterBlock child : fb.getChildren()) {
            isSubQFilterBlock(child, result);
        }
    }
}