com.bazaarvoice.jolt.shiftr.spec.ShiftrSpec Maven / Gradle / Ivy

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/*
 * Copyright 2013 Bazaarvoice, Inc.
 *
 * 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.bazaarvoice.jolt.shiftr.spec;

import com.bazaarvoice.jolt.common.PathElementBuilder;
import com.bazaarvoice.jolt.common.pathelement.MatchablePathElement;
import com.bazaarvoice.jolt.common.spec.BaseSpec;

/**
 * A Spec Object represents a single line from the JSON Shiftr Spec.
 *
 * At a minimum a single Spec has :
 *   Raw LHS spec value
 *   Some kind of PathElement (based off that raw LHS value)
 *
 * Additionally there are 2 distinct subclasses of the base Spec
 *  LeafSpec : where the RHS is a String or Array of Strings, that specify an write path for the data from this level in the tree
 *  CompositeSpec : where the RHS is a map of children Specs
 *
 * Mapping of JSON Shiftr Spec to Spec objects :
 * {
 *   rating-*" : {      // CompositeSpec with one child and a Star PathElement
 *     "&(1)" : {       // CompositeSpec with one child and a Reference PathElement
 *       "foo: {        // CompositeSpec with one child and a Literal PathElement
 *         "value" : "Rating-&1.value"  // OutputtingSpec with a Literal PathElement and one write path
 *       }
 *     }
 *   }
 * }
 *
 * The tree structure of formed by the CompositeSpecs is what is used during Shiftr transforms
 *  to do the parallel tree walk with the input data tree.
 *
 * During the parallel tree walk a stack of data (a WalkedPath) is maintained, and used when
 *  a tree walk encounters an Outputting spec to evaluate the wildcards in the write DotNotationPath.
 */
public abstract class ShiftrSpec implements BaseSpec {

    // The processed key from the JSON config
    protected final MatchablePathElement pathElement;

    public ShiftrSpec(String rawJsonKey) {
        this.pathElement = PathElementBuilder.buildMatchablePathElement( rawJsonKey );
    }

    @Override
    public MatchablePathElement getPathElement() {
        return pathElement;
    }
}