io.questdb.griffin.engine.functions.eq.EqCharCharFunctionFactory Maven / Gradle / Ivy

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 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2020 QuestDB
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 *  http://www.apache.org/licenses/LICENSE-2.0
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package io.questdb.griffin.engine.functions.eq;

import io.questdb.cairo.CairoConfiguration;
import io.questdb.cairo.sql.Function;
import io.questdb.cairo.sql.Record;
import io.questdb.griffin.FunctionFactory;
import io.questdb.griffin.SqlExecutionContext;
import io.questdb.griffin.engine.functions.BinaryFunction;
import io.questdb.griffin.engine.functions.NegatableBooleanFunction;
import io.questdb.std.ObjList;

public class EqCharCharFunctionFactory implements FunctionFactory {
    @Override
    public String getSignature() {
        return "=(AA)";
    }

    @Override
    public boolean isBoolean() {
        return true;
    }

    @Override
    public Function newInstance(ObjList args, int position, CairoConfiguration configuration, SqlExecutionContext sqlExecutionContext) {
        // there are optimisation opportunities
        // 1. when one of args is constant null comparison can boil down to checking
        //    length of non-constant (must be -1)
        // 2. when one of arguments is constant, save method call and use a field

        Function chrFunc1 = args.getQuick(0);
        Function chrFunc2 = args.getQuick(1);

        return new Func(position, chrFunc1, chrFunc2);
    }

    private static class Func extends NegatableBooleanFunction implements BinaryFunction {
        private final Function chrFunc1;
        private final Function chrFunc2;

        public Func(int position, Function chrFunc1, Function chrFunc2) {
            super(position);
            this.chrFunc1 = chrFunc1;
            this.chrFunc2 = chrFunc2;
        }

        @Override
        public Function getLeft() {
            return chrFunc1;
        }

        @Override
        public Function getRight() {
            return chrFunc2;
        }

        @Override
        public boolean getBool(Record rec) {
            return negated != (chrFunc1.getChar(rec) == chrFunc2.getChar(rec));
        }
    }
}