/*
* Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*/
/**
* Meta model of YANG model as was defined in RFC6020 and extracted by analysis
* of YANG text.
*
* <p>
* Existence of meta-model allows for better evolution of YANG language as it evolves
* and allows for better support of different serializations of YANG model.
*
* <h2>Statements</h2>
* YANG source is defined as sequence of statement in
* <a href="https://tools.ietf.org/html/rfc6020#section-6.3">RFC6020, Section 6.3</a>.
* this model is also correct for YIN, which is XML serialisation of YANG source.
* <p>
* Statements are represented as instances / subclasses of {@link org.opendaylight.yangtools.yang.model.api.meta.ModelStatement}
* concept and its two subconcepts which are:
* <ul>
* <li>
* {@link org.opendaylight.yangtools.yang.model.api.meta.DeclaredStatement} - this contains navigable
* set of statements model as they was defined / present in original processed
* sources.
* </li>
* <li>{@link org.opendaylight.yangtools.yang.model.api.meta.EffectiveStatement} - navigable set of statements
* which represents effective model of parsed YANG sources, which is derived by rules
* present in YANG specification and/or was introduced in form of extensions.
* </li>
* </ul>
* <p>
* Clear separation of declared / effective model is needed, since statement definition also
* contains information how effective model is computed and there is no one to one mapping
* between declared and effective model thanks to statements such as {@code uses},
* {@code augment},{@code deviate},{@code refine}.
*
* <h2>Identifiers and Namespaces</h2>
* Effective model of YANG has several identifier types and namespaces, which behaves differently
* and are mostly used during processing data and/or during computing effective (semantic) model.
* <p>
* Common abstraction for various types of namespaces is {@link org.opendaylight.yangtools.yang.model.api.meta.IdentifierNamespace}
* from which concrete effective model namespaces are derived.
*
*/
package org.opendaylight.yangtools.yang.model.api.meta;