io.questdb.griffin.engine.functions.conditional.CaseFunctionFactory 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.conditional;

import io.questdb.cairo.CairoConfiguration;
import io.questdb.cairo.ColumnType;
import io.questdb.cairo.sql.Function;
import io.questdb.griffin.FunctionFactory;
import io.questdb.griffin.SqlException;
import io.questdb.griffin.SqlExecutionContext;
import io.questdb.griffin.engine.functions.constants.Constants;
import io.questdb.std.ObjList;
import io.questdb.std.Transient;

public class CaseFunctionFactory implements FunctionFactory {
    @Override
    public String getSignature() {
        return "case(V)";
    }

    @Override
    public Function newInstance(@Transient ObjList args, int position, CairoConfiguration configuration, SqlExecutionContext sqlExecutionContext) throws SqlException {
        int n = args.size();
        int returnType = -1;
        final ObjList vars = new ObjList<>(n);
        final ObjList argsToPoke = new ObjList<>(n);

        Function elseBranch;
        if (n % 2 == 1) {
            elseBranch = args.getQuick(n - 1);
            n--;
        } else {
            elseBranch = null;
        }

        // compute return type in this loop
        for (int i = 0; i < n; i += 2) {
            Function bool = args.getQuick(i);
            Function value = args.getQuick(i + 1);

            if (bool.getType() != ColumnType.BOOLEAN) {
                throw SqlException.position(bool.getPosition()).put("BOOLEAN expected, found ").put(ColumnType.nameOf(bool.getType()));
            }

            returnType = CaseCommon.getCommonType(returnType, value.getType(), value.getPosition());

            vars.add(bool);
            vars.add(value);

            argsToPoke.add(bool);
            argsToPoke.add(value);
        }

        if (elseBranch != null) {
            returnType = CaseCommon.getCommonType(returnType, elseBranch.getType(), elseBranch.getPosition());
            argsToPoke.add(elseBranch);
        }

        // next calculate cast functions
        for (int i = 1; i < n; i += 2) {
            vars.setQuick(i, CaseCommon.getCastFunction(
                    vars.getQuick(i),
                    returnType,
                    configuration,
                    sqlExecutionContext
            ));
        }

        if (elseBranch != null) {
            elseBranch = CaseCommon.getCastFunction(elseBranch, returnType, configuration, sqlExecutionContext);
        }

        final int argsLen = vars.size();
        final Function elseB = elseBranch != null ? elseBranch : Constants.getNullConstant(returnType);

        final CaseFunctionPicker picker = record -> {
            for (int i = 0; i < argsLen; i += 2) {
                if (vars.getQuick(i).getBool(record)) {
                    return vars.getQuick(i + 1);
                }
            }
            return elseB;
        };

        return CaseCommon.getCaseFunction(position, returnType, picker, argsToPoke);
    }
}