org.apache.drill.common.logical.data.Project.java Source code

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Here is the source code for org.apache.drill.common.logical.data.Project.java

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/*******************************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.
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package org.apache.drill.common.logical.data;

import org.apache.drill.common.exceptions.ExpressionParsingException;
import org.apache.drill.common.expression.PathSegment;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonTypeName;

@JsonTypeName("project")
public class Project extends SingleInputOperator {

    private final NamedExpression[] selections;

    @JsonCreator
    public Project(@JsonProperty("projections") NamedExpression[] selections) {
        this.selections = selections;
        if (selections == null || selections.length == 0)
            throw new ExpressionParsingException(
                    "Project did not provide any projection selections.  At least one projection must be provided.");
        for (int i = 0; i < selections.length; i++) {
            PathSegment segment = selections[i].getRef().getRootSegment();
            CharSequence path = segment.getNameSegment().getPath();
            if (!segment.isNamed() || !path.equals("output"))
                throw new ExpressionParsingException(String.format(
                        "Outputs for projections always have to start with named path of output. First segment was named '%s' or was named [%s]",
                        path, segment.isNamed()));

        }
    }

    @JsonProperty("exprs")
    public NamedExpression[] getSelections() {
        return selections;
    }

}