com.hazelcast.sql.impl.calcite.validate.operators.HazelcastSqlTrimFunction Maven / Gradle / Ivy

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SQL Parser and Optimizer
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/*
 * Copyright (c) 2008-2020, Hazelcast, Inc. All Rights Reserved.
 *
 * 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 com.hazelcast.sql.impl.calcite.validate.operators;

import com.hazelcast.sql.impl.calcite.validate.types.ReplaceUnknownOperandTypeInference;
import com.hazelcast.org.apache.calcite.sql.SqlCall;
import com.hazelcast.org.apache.calcite.sql.SqlFunction;
import com.hazelcast.org.apache.calcite.sql.SqlFunctionCategory;
import com.hazelcast.org.apache.calcite.sql.SqlKind;
import com.hazelcast.org.apache.calcite.sql.SqlLiteral;
import com.hazelcast.org.apache.calcite.sql.SqlNode;
import com.hazelcast.org.apache.calcite.sql.SqlWriter;
import com.hazelcast.org.apache.calcite.sql.fun.SqlTrimFunction;
import com.hazelcast.org.apache.calcite.sql.parser.SqlParserPos;
import com.hazelcast.org.apache.calcite.sql.type.OperandTypes;
import com.hazelcast.org.apache.calcite.sql.type.ReturnTypes;
import com.hazelcast.org.apache.calcite.sql.type.SqlTypeName;

import java.util.Arrays;

import static com.hazelcast.sql.impl.calcite.validate.types.HazelcastOperandTypes.notAny;
import static com.hazelcast.org.apache.calcite.sql.type.SqlTypeFamily.ANY;
import static com.hazelcast.org.apache.calcite.sql.type.SqlTypeFamily.STRING;

/**
 * Our own implementation of the TRIM function that has custom operand type inference to allow for dynamic parameters.
 * 
 * Code of some methods is copy-pasted from the Calcite's {@link SqlTrimFunction}, because it is not extensible enough.
 */
public class HazelcastSqlTrimFunction extends SqlFunction {
    public HazelcastSqlTrimFunction() {
        super(
            "TRIM",
            SqlKind.TRIM,
            ReturnTypes.ARG2_NULLABLE,
            new ReplaceUnknownOperandTypeInference(SqlTypeName.VARCHAR),
            notAny(OperandTypes.family(ANY, STRING, STRING)),
            SqlFunctionCategory.STRING
        );
    }

    @Override
    public void unparse(SqlWriter writer, SqlCall call, int leftPrec, int rightPrec) {
        SqlWriter.Frame frame = writer.startFunCall(getName());

        assert call.operand(0) instanceof SqlLiteral : call.operand(0);

        call.operand(0).unparse(writer, leftPrec, rightPrec);
        call.operand(1).unparse(writer, leftPrec, rightPrec);
        writer.sep("FROM");
        call.operand(2).unparse(writer, leftPrec, rightPrec);
        writer.endFunCall(frame);
    }

    @Override
    public String getSignatureTemplate(final int operandsCount) {
        assert operandsCount == 3;

        return "{0}([BOTH|LEADING|TRAILING] {1} FROM {2})";
    }

    @Override
    public SqlCall createCall(SqlLiteral functionQualifier, SqlParserPos pos, SqlNode... operands) {
        switch (operands.length) {
            case 1:
                // This variant occurs when someone writes TRIM(string)
                // as opposed to the sugared syntax TRIM(string FROM string).
                operands = new SqlNode[]{
                    SqlTrimFunction.Flag.BOTH.symbol(SqlParserPos.ZERO),
                    SqlLiteral.createCharString(" ", pos),
                    operands[0]
                };

                break;

            case 3:
                assert operands[0] instanceof SqlLiteral && ((SqlLiteral) operands[0]).getValue() instanceof SqlTrimFunction.Flag;

                if (operands[1] == null) {
                    operands[1] = SqlLiteral.createCharString(" ", pos);
                }

                break;

            default:
                throw new IllegalArgumentException("invalid operand count " + Arrays.toString(operands));
        }

        return super.createCall(functionQualifier, pos, operands);
    }
}