io.questdb.griffin.engine.functions.rnd.RndSymbolFunctionFactory Maven / Gradle / Ivy

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 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2022 QuestDB
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 *  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
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 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
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package io.questdb.griffin.engine.functions.rnd;

import io.questdb.cairo.CairoConfiguration;
import io.questdb.cairo.sql.Function;
import io.questdb.cairo.sql.Record;
import io.questdb.cairo.sql.SymbolTable;
import io.questdb.cairo.sql.SymbolTableSource;
import io.questdb.griffin.FunctionFactory;
import io.questdb.griffin.SqlException;
import io.questdb.griffin.SqlExecutionContext;
import io.questdb.griffin.engine.functions.SymbolFunction;
import io.questdb.std.IntList;
import io.questdb.std.ObjList;
import io.questdb.std.Rnd;

public class RndSymbolFunctionFactory implements FunctionFactory {
    @Override
    public String getSignature() {
        return "rnd_symbol(iiii)";
    }

    @Override
    public Function newInstance(
            int position,
            ObjList args,
            IntList argPositions,
            CairoConfiguration configuration,
            SqlExecutionContext sqlExecutionContext
    ) throws SqlException {
        final int count = args.getQuick(0).getInt(null);
        final int lo = args.getQuick(1).getInt(null);
        final int hi = args.getQuick(2).getInt(null);
        final int nullRate = args.getQuick(3).getInt(null);

        if (count < 1) {
            throw SqlException.$(argPositions.getQuick(0), "invalid symbol count");
        }

        if (lo > hi || lo < 1) {
            throw SqlException.$(position, "invalid range");
        }

        if (nullRate < 0) {
            throw SqlException.position(argPositions.getQuick(3)).put("null rate must be positive");
        }

        final RndStringMemory strMem = new RndStringMemory(getSignature(), count, lo, hi, argPositions.getQuick(0), configuration);
        return new Func(strMem, count, nullRate);
    }

    private static final class Func extends SymbolFunction implements Function {
        private final int count;
        private final int nullRate;
        private final RndStringMemory strMem;
        private Rnd rnd;

        public Func(RndStringMemory strMem, int count, int nullRate) {
            this.count = count;
            this.nullRate = nullRate + 1;
            this.strMem = strMem;
        }

        @Override
        public void close() {
            strMem.close();
        }

        @Override
        public int getInt(Record rec) {
            return next();
        }

        @Override
        public CharSequence getSymbol(Record rec) {
            return strMem.getStr(next());
        }

        @Override
        public CharSequence getSymbolB(Record rec) {
            return getSymbol(rec);
        }

        @Override
        public void init(SymbolTableSource symbolTableSource, SqlExecutionContext executionContext) {
            rnd = executionContext.getRandom();
            strMem.init(rnd);
        }

        @Override
        public boolean isSymbolTableStatic() {
            return false;
        }

        @Override
        public CharSequence valueOf(int symbolKey) {
            return strMem.getStr(symbolKey);
        }

        @Override
        public CharSequence valueBOf(int symbolKey) {
            return valueOf(symbolKey);
        }

        private int next() {
            if (rnd.nextPositiveInt() % nullRate == 1) {
                return SymbolTable.VALUE_IS_NULL;
            }
            return rnd.nextPositiveInt() % count;
        }
    }
}