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

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Here is the source code for io.druid.query.expression.LookupExprMacro.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 com.google.inject.Inject;
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 io.druid.query.lookup.LookupReferencesManager;
import io.druid.query.lookup.RegisteredLookupExtractionFn;

import javax.annotation.Nonnull;
import java.util.List;

public class LookupExprMacro implements ExprMacroTable.ExprMacro {
    private final LookupReferencesManager lookupReferencesManager;

    @Inject
    public LookupExprMacro(final LookupReferencesManager lookupReferencesManager) {
        this.lookupReferencesManager = lookupReferencesManager;
    }

    @Override
    public String name() {
        return "lookup";
    }

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

        final Expr arg = args.get(0);
        final Expr lookupExpr = args.get(1);

        if (!lookupExpr.isLiteral() || lookupExpr.getLiteralValue() == null) {
            throw new IAE("Function[%s] second argument must be a registered lookup name", name());
        }

        final String lookupName = lookupExpr.getLiteralValue().toString();
        final RegisteredLookupExtractionFn extractionFn = new RegisteredLookupExtractionFn(lookupReferencesManager,
                lookupName, false, null, false, null);

        class LookupExpr implements Expr {
            @Nonnull
            @Override
            public ExprEval eval(final ObjectBinding bindings) {
                return ExprEval.of(extractionFn.apply(Strings.emptyToNull(arg.eval(bindings).asString())));
            }

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

        return new LookupExpr();
    }
}