com.amazonaws.services.dynamodbv2.xspec.PathOperand Maven / Gradle / Ivy
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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 static com.amazonaws.services.dynamodbv2.xspec.ExpressionSpecBuilder.attribute_exists;
import static com.amazonaws.services.dynamodbv2.xspec.ExpressionSpecBuilder.attribute_not_exists;
import org.apache.http.annotation.Immutable;
import com.amazonaws.annotation.Beta;
/**
* A path operand used in building DynamooDB expressions such as update
* expressions and condition (aka filter) expressions. In general, a path
* operand refers to an attribute of some specific type in DynamoDB.
*
* Use {@link ExpressionSpecBuilder#S(String)},
* {@link ExpressionSpecBuilder#N(String)}, etc. to instantiate path operands to
* refer to attributes of specific data types. You can also use
* {@link ExpressionSpecBuilder#attribute(String)} to instantiate a path operand
* with an unspecified data type.
*
* @see ExpressionSpecBuilder
*/
@Beta
@Immutable
public class PathOperand extends Operand {
private final Path path;
private final String pathString; // This is a performance optimization; not strictly necessary.
/**
* Constructs a path operand for building expressions.
*
* @param path
* a document path in which nested elements are assumed to be
* delimited by either "." or array indexing such as "[1]".
*/
PathOperand(String path) {
this.path = new Path(path);
this.pathString = path;
}
@Override
String asSubstituted(SubstitutionContext context) {
return path.asSubstituted(context);
}
/**
* Returns a function condition (that evaluates to true if the attribute referred
* to by this path operand exists) for building condition expression.
*/
public final FunctionCondition exists() {
return attribute_exists(this);
}
/**
* Returns a function condition (that evaluates to true if the attribute referred
* to by this path operand does not exist) for building condition
* expression.
*/
public final FunctionCondition notExists() {
return attribute_not_exists(this);
}
/**
* Returns a RemoveAction for removing the attribute referred
* to by this path operand from an item; used for building update
* expression.
*/
public final RemoveAction remove() {
return new RemoveAction(this);
}
/**
* Returns the path of this path operand as a string.
*/
final String getPath() {
return pathString;
}
@Override
public final String toString() {
return pathString;
}
@Override
public final int hashCode() {
return pathString.hashCode();
}
/**
* Returns true if the given object is a path operand with the same path as
* that of the current path operand; false otherwise.
*/
@Override
public final boolean equals(Object o) {
if (!(o instanceof PathOperand))
return false;
PathOperand that = (PathOperand)o;
return this.getPath().equals(that.getPath());
}
}