com.amazonaws.services.dynamodbv2.xspec.UpdateAction Maven / Gradle / Ivy

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The AWS SDK for Java with support for OSGi. The AWS SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2015-2016 Amazon Technologies, 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://aws.amazon.com/apache2.0
 *
 * This file 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.amazonaws.services.dynamodbv2.xspec;

import com.amazonaws.annotation.Beta;

/**
 * Represents an update action for building update expression.
 * 
 * This object is as immutable (or unmodifiable) as the underlying value (of
 * type UnitOfExpression) given during construction.
 */
@Beta
public abstract class UpdateAction extends UnitOfExpression {
    private final String operator;

    private final PathOperand attribute;
    private final UnitOfExpression value;

    UpdateAction(String operator, PathOperand attribute, UnitOfExpression value) {
        this.operator = operator;
        this.attribute = attribute;
        this.value = value;
    }

    /**
     * Returns the attribute as a string, substituted if necessary with tokens
     * using the given substitution context.
     */
    @Override
    String asSubstituted(SubstitutionContext context) {
        return value == null 
             ? attribute.asSubstituted(context)
             : attribute.asSubstituted(context) + " " + value.asSubstituted(context);
    }

    final String getOperator() {
        return operator;
    }

    final PathOperand getPathOperand() {
        return attribute;
    }

    final UnitOfExpression getValue() {
        return value;
    }
}