io.druid.query.expression.RegexpExtractExprMacro.java Source code

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Here is the source code for io.druid.query.expression.RegexpExtractExprMacro.java

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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets licenses this file
 * to you 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.druid.query.expression;

import com.google.common.base.Strings;
import io.druid.java.util.common.IAE;
import io.druid.math.expr.Expr;
import io.druid.math.expr.ExprEval;
import io.druid.math.expr.ExprMacroTable;

import javax.annotation.Nonnull;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexpExtractExprMacro implements ExprMacroTable.ExprMacro {
    @Override
    public String name() {
        return "regexp_extract";
    }

    @Override
    public Expr apply(final List<Expr> args) {
        if (args.size() < 2 || args.size() > 3) {
            throw new IAE("Function[%s] must have 2 to 3 arguments", name());
        }

        final Expr arg = args.get(0);
        final Expr patternExpr = args.get(1);
        final Expr indexExpr = args.size() > 2 ? args.get(2) : null;

        if (!patternExpr.isLiteral() || (indexExpr != null && !indexExpr.isLiteral())) {
            throw new IAE("Function[%s] pattern and index must be literals", name());
        }

        // Precompile the pattern.
        final Pattern pattern = Pattern.compile(String.valueOf(patternExpr.getLiteralValue()));

        final int index = indexExpr == null ? 0 : ((Number) indexExpr.getLiteralValue()).intValue();
        class RegexpExtractExpr implements Expr {
            @Nonnull
            @Override
            public ExprEval eval(final ObjectBinding bindings) {
                final Matcher matcher = pattern.matcher(Strings.nullToEmpty(arg.eval(bindings).asString()));
                final String retVal = matcher.find() ? matcher.group(index) : null;
                return ExprEval.of(Strings.emptyToNull(retVal));
            }

            @Override
            public void visit(final Visitor visitor) {
                arg.visit(visitor);
                visitor.visit(this);
            }
        }
        return new RegexpExtractExpr();
    }
}