io.questdb.griffin.SqlUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of core Show documentation
QuestDB is High Performance Time Series Database
The newest version!
/*******************************************************************************
 *     ___                  _   ____  ____
 *    / _ \ _   _  ___  ___| |_|  _ \| __ )
 *   | | | | | | |/ _ \/ __| __| | | |  _ \
 *   | |_| | |_| |  __/\__ \ |_| |_| | |_) |
 *    \__\_\\__,_|\___||___/\__|____/|____/
 *
 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2020 QuestDB
 *
 *  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 io.questdb.griffin;

import io.questdb.griffin.model.ExpressionNode;
import io.questdb.griffin.model.QueryColumn;
import io.questdb.std.*;

public class SqlUtil {

    static final CharSequenceHashSet disallowedAliases = new CharSequenceHashSet();

    static {
        for (int i = 0, n = OperatorExpression.operators.size(); i < n; i++) {
            SqlUtil.disallowedAliases.add(OperatorExpression.operators.getQuick(i).token);
        }
    }

    public static CharSequence fetchNext(GenericLexer lexer) {
        int blockCount = 0;
        boolean lineComment = false;
        while (lexer.hasNext()) {
            CharSequence cs = lexer.next();

            if (lineComment) {
                if (Chars.equals(cs, '\n') || Chars.equals(cs, '\r')) {
                    lineComment = false;
                }
                continue;
            }

            if (Chars.equals("--", cs)) {
                lineComment = true;
                continue;
            }

            if (Chars.equals("/*", cs)) {
                blockCount++;
                continue;
            }

            if (Chars.equals("*/", cs) && blockCount > 0) {
                blockCount--;
                continue;
            }

            if (blockCount == 0 && GenericLexer.WHITESPACE.excludes(cs)) {
                return cs;
            }
        }
        return null;
    }

    static ExpressionNode nextLiteral(ObjectPool pool, CharSequence token, int position) {
        return pool.next().of(ExpressionNode.LITERAL, token, 0, position);
    }

    static CharSequence createColumnAlias(
            CharacterStore store,
            CharSequence base,
            int indexOfDot,
            CharSequenceObjHashMap aliasToColumnMap
    ) {
        final boolean disallowed = disallowedAliases.contains(base);

        // short and sweet version
        if (indexOfDot == -1 && !disallowed && aliasToColumnMap.excludes(base)) {
            return base;
        }

        final CharacterStoreEntry characterStoreEntry = store.newEntry();

        if (indexOfDot == -1) {
            if (disallowed) {
                characterStoreEntry.put("column");
            } else {
                characterStoreEntry.put(base);
            }
        } else {
            characterStoreEntry.put(base, indexOfDot + 1, base.length());
        }


        int len = characterStoreEntry.length();
        int sequence = 0;
        while (true) {
            if (sequence > 0) {
                characterStoreEntry.trimTo(len);
                characterStoreEntry.put(sequence);
            }
            sequence++;
            CharSequence alias = characterStoreEntry.toImmutable();
            if (aliasToColumnMap.excludes(alias)) {
                return alias;
            }
        }
    }

    static QueryColumn nextColumn(
            ObjectPool queryColumnPool,
            ObjectPool sqlNodePool,
            CharSequence alias,
            CharSequence column
    ) {
        return queryColumnPool.next().of(alias, nextLiteral(sqlNodePool, column, 0));
    }
}