Java tutorial
/* * Copyright (c) 2013 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 */ package org.opendaylight.yangtools.yang.binding; import com.google.common.base.MoreObjects; import com.google.common.base.MoreObjects.ToStringHelper; import com.google.common.base.Preconditions; import com.google.common.collect.ImmutableCollection; import com.google.common.collect.ImmutableList; import com.google.common.collect.Iterables; import java.io.IOException; import java.io.Serializable; import java.lang.reflect.Field; import java.util.ArrayList; import java.util.Collections; import java.util.Iterator; import java.util.List; import org.opendaylight.yangtools.concepts.Builder; import org.opendaylight.yangtools.concepts.Immutable; import org.opendaylight.yangtools.concepts.Path; import org.opendaylight.yangtools.util.HashCodeBuilder; /** * * This instance identifier uniquely identifies a specific DataObject in the data tree modeled by YANG. * * For Example let's say you were trying to refer to a node in inventory which was modeled in YANG as follows, * * <pre> * module opendaylight-inventory { * .... * * container nodes { * list node { * key "id"; * ext:context-instance "node-context"; * * uses node; * } * } * * } * </pre> * * You could create an instance identifier as follows to get to a node with id "openflow:1" * * InstanceIdentifierBuilder.builder(Nodes.class).child(Node.class, new NodeKey(new NodeId("openflow:1")).build(); * * This would be the same as using a path like so, "/nodes/node/openflow:1" to refer to the openflow:1 node * */ public class InstanceIdentifier<T extends DataObject> implements Path<InstanceIdentifier<? extends DataObject>>, Immutable, Serializable { private static final Field PATHARGUMENTS_FIELD; private static final long serialVersionUID = 2L; /* * Protected to differentiate internal and external access. Internal * access is required never to modify the contents. References passed * to outside entities have to be wrapped in an unmodifiable view. */ protected transient final Iterable<PathArgument> pathArguments; private final Class<T> targetType; private final boolean wildcarded; private final int hash; static { final Field f; try { f = InstanceIdentifier.class.getDeclaredField("pathArguments"); } catch (NoSuchFieldException | SecurityException e) { throw new ExceptionInInitializerError(e); } f.setAccessible(true); PATHARGUMENTS_FIELD = f; } InstanceIdentifier(final Class<T> type, final Iterable<PathArgument> pathArguments, final boolean wildcarded, final int hash) { this.pathArguments = Preconditions.checkNotNull(pathArguments); this.targetType = Preconditions.checkNotNull(type); this.wildcarded = wildcarded; this.hash = hash; } /** * Return the type of data which this InstanceIdentifier identifies. * * @return Target type */ public final Class<T> getTargetType() { return targetType; } /** * Return the path argument chain which makes up this instance identifier. * * @return Path argument chain. Immutable and does not contain nulls. */ public final Iterable<PathArgument> getPathArguments() { return Iterables.unmodifiableIterable(pathArguments); } /** * Check whether an instance identifier contains any wildcards. A wildcard * is an path argument which has a null key. * * @return true if any of the path arguments has a null key. */ public final boolean isWildcarded() { return wildcarded; } @Override public final int hashCode() { return hash; } @Override public final boolean equals(final Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final InstanceIdentifier<?> other = (InstanceIdentifier<?>) obj; if (pathArguments == other.pathArguments) { return true; } /* * We could now just go and compare the pathArguments, but that * can be potentially expensive. Let's try to avoid that by * checking various things that we have cached from pathArguments * and trying to prove the identifiers are *not* equal. */ if (hash != other.hash) { return false; } if (wildcarded != other.wildcarded) { return false; } if (targetType != other.targetType) { return false; } if (fastNonEqual(other)) { return false; } // Everything checks out so far, so we have to do a full equals return Iterables.elementsEqual(pathArguments, other.pathArguments); } /** * Perform class-specific fast checks for non-equality. This allows * subclasses to avoid iterating over the pathArguments by performing * quick checks on their specific fields. * * @param other The other identifier, guaranteed to be the same class * @return true if the other identifier cannot be equal to this one. */ protected boolean fastNonEqual(final InstanceIdentifier<?> other) { return false; } @Override public final String toString() { return addToStringAttributes(MoreObjects.toStringHelper(this)).toString(); } /** * Add class-specific toString attributes. * * @param toStringHelper ToStringHelper instance * @return ToStringHelper instance which was passed in */ protected ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) { return toStringHelper.add("targetType", targetType).add("path", Iterables.toString(pathArguments)); } /** * Return an instance identifier trimmed at the first occurrence of a * specific component type. * * For example let's say an instance identifier was built like so, * <pre> * identifier = InstanceIdentifierBuilder.builder(Nodes.class).child(Node.class, new NodeKey(new NodeId("openflow:1")).build(); * </pre> * * And you wanted to obtain the Instance identifier which represented Nodes you would do it like so, * * <pre> * identifier.firstIdentifierOf(Nodes.class) * </pre> * * @param type component type * @return trimmed instance identifier, or null if the component type * is not present. */ public final <I extends DataObject> InstanceIdentifier<I> firstIdentifierOf(final Class<I> type) { int i = 1; for (final PathArgument a : pathArguments) { if (type.equals(a.getType())) { @SuppressWarnings("unchecked") final InstanceIdentifier<I> ret = (InstanceIdentifier<I>) internalCreate( Iterables.limit(pathArguments, i)); return ret; } ++i; } return null; } /** * Return the key associated with the first component of specified type in * an identifier. * * @param listItem component type * @param listKey component key type * @return key associated with the component, or null if the component type * is not present. * * @deprecated Use {@link #firstKeyOf(Class)} instead. */ @Deprecated public final <N extends Identifiable<K> & DataObject, K extends Identifier<N>> K firstKeyOf( final Class<N> listItem, final Class<K> listKey) { return firstKeyOf(listItem); } /** * Return the key associated with the first component of specified type in * an identifier. * * @param listItem component type * @return key associated with the component, or null if the component type * is not present. */ public final <N extends Identifiable<K> & DataObject, K extends Identifier<N>> K firstKeyOf( final Class<N> listItem) { for (final PathArgument i : pathArguments) { if (listItem.equals(i.getType())) { @SuppressWarnings("unchecked") final K ret = ((IdentifiableItem<N, K>) i).getKey(); return ret; } } return null; } /** * Check whether an identifier is contained in this identifier. This is a strict subtree check, which requires all * PathArguments to match exactly, e.g. * * * The contains method checks if the other identifier is fully contained within the current identifier. It does this * by looking at only the types of the path arguments and not by comparing the path arguments themselves. * * To illustrate here is an example which explains the working of this API. * * Let's say you have two instance identifiers as follows, * * this = /nodes/node/openflow:1 * other = /nodes/node/openflow:2 * * then this.contains(other) will return false. * * @param other * @return */ @Override public final boolean contains(final InstanceIdentifier<? extends DataObject> other) { Preconditions.checkNotNull(other, "other should not be null"); final Iterator<?> lit = pathArguments.iterator(); final Iterator<?> oit = other.pathArguments.iterator(); while (lit.hasNext()) { if (!oit.hasNext()) { return false; } if (!lit.next().equals(oit.next())) { return false; } } return true; } /** * Check whether this instance identifier contains the other identifier after wildcard expansion. This is similar * to {@link #contains(InstanceIdentifier)}, with the exception that a wildcards are assumed to match the their * non-wildcarded PathArgument counterpart. * * @param other Identifier which should be checked for inclusion. * @return true if this identifier contains the other object */ public final boolean containsWildcarded(final InstanceIdentifier<?> other) { Preconditions.checkNotNull(other, "other should not be null"); final Iterator<PathArgument> lit = pathArguments.iterator(); final Iterator<PathArgument> oit = other.pathArguments.iterator(); while (lit.hasNext()) { if (!oit.hasNext()) { return false; } final PathArgument la = lit.next(); final PathArgument oa = oit.next(); if (!la.getType().equals(oa.getType())) { return false; } if (la instanceof IdentifiableItem<?, ?> && oa instanceof IdentifiableItem<?, ?> && !la.equals(oa)) { return false; } } return true; } /** * Create a builder rooted at this key. * * @return A builder instance */ public InstanceIdentifierBuilder<T> builder() { return new InstanceIdentifierBuilderImpl<T>(new Item<T>(targetType), pathArguments, hash, isWildcarded()); } private InstanceIdentifier<?> childIdentifier(final PathArgument arg) { return trustedCreate(arg, Iterables.concat(pathArguments, Collections.singleton(arg)), HashCodeBuilder.nextHashCode(hash, arg), isWildcarded()); } @SuppressWarnings("unchecked") public final <N extends ChildOf<? super T>> InstanceIdentifier<N> child(final Class<N> container) { final PathArgument arg = new Item<>(container); return (InstanceIdentifier<N>) childIdentifier(arg); } @SuppressWarnings("unchecked") public final <N extends Identifiable<K> & ChildOf<? super T>, K extends Identifier<N>> KeyedInstanceIdentifier<N, K> child( final Class<N> listItem, final K listKey) { final PathArgument arg = new IdentifiableItem<>(listItem, listKey); return (KeyedInstanceIdentifier<N, K>) childIdentifier(arg); } @SuppressWarnings("unchecked") public final <N extends DataObject & Augmentation<? super T>> InstanceIdentifier<N> augmentation( final Class<N> container) { final PathArgument arg = new Item<>(container); return (InstanceIdentifier<N>) childIdentifier(arg); } @Deprecated private List<PathArgument> legacyCache; /** * @deprecated Use {@link #getPathArguments()} instead. */ @Deprecated public final List<PathArgument> getPath() { if (legacyCache == null) { legacyCache = ImmutableList.<PathArgument>copyOf(pathArguments); } return legacyCache; } /** * Create a new InstanceIdentifierBuilder given a base InstanceIdentifier * * @param base * @param <T> * @return * * @deprecated Use {@link #builder()} instead. */ @Deprecated public static <T extends DataObject> InstanceIdentifierBuilder<T> builder(final InstanceIdentifier<T> base) { return base.builder(); } /** * Create an InstanceIdentifierBuilder for a specific type of InstanceIdentifier as specified by container * * @param container * @param <T> * @return */ public static <T extends ChildOf<? extends DataRoot>> InstanceIdentifierBuilder<T> builder( final Class<T> container) { return new InstanceIdentifierBuilderImpl<T>().addNode(container); } /** * Create an InstanceIdentifierBuilder for a specific type of InstanceIdentifier which represents an IdentifiableItem * * @param listItem * @param listKey * @param <N> * @param <K> * @return */ public static <N extends Identifiable<K> & ChildOf<? extends DataRoot>, K extends Identifier<N>> InstanceIdentifierBuilder<N> builder( final Class<N> listItem, final K listKey) { return new InstanceIdentifierBuilderImpl<N>().addNode(listItem, listKey); } /** * Create an instance identifier for a very specific object type. This method * implements {@link #create(Iterable)} semantics, except it is used by internal * callers, which have assured that the argument is an immutable Iterable. * * * @param pathArguments The path to a specific node in the data tree * @return InstanceIdentifier instance * @throws IllegalArgumentException if pathArguments is empty or * contains a null element. */ private static InstanceIdentifier<?> internalCreate(final Iterable<PathArgument> pathArguments) { final Iterator<? extends PathArgument> it = Preconditions .checkNotNull(pathArguments, "pathArguments may not be null").iterator(); final HashCodeBuilder<PathArgument> hashBuilder = new HashCodeBuilder<>(); boolean wildcard = false; PathArgument a = null; while (it.hasNext()) { a = it.next(); Preconditions.checkArgument(a != null, "pathArguments may not contain null elements"); // TODO: sanity check ChildOf<>; hashBuilder.addArgument(a); if (Identifiable.class.isAssignableFrom(a.getType()) && !(a instanceof IdentifiableItem<?, ?>)) { wildcard = true; } } Preconditions.checkArgument(a != null, "pathArguments may not be empty"); return trustedCreate(a, pathArguments, hashBuilder.build(), wildcard); } /** * Create an instance identifier for a very specific object type. * * Example * <pre> * List<PathArgument> path = Arrays.asList(new Item(Nodes.class)) * new InstanceIdentifier(path); * </pre> * * @param pathArguments The path to a specific node in the data tree * @return InstanceIdentifier instance * @throws IllegalArgumentException if pathArguments is empty or * contains a null element. */ public static InstanceIdentifier<?> create(final Iterable<? extends PathArgument> pathArguments) { if (pathArguments instanceof ImmutableCollection<?>) { @SuppressWarnings("unchecked") final Iterable<PathArgument> immutableArguments = (Iterable<PathArgument>) pathArguments; return internalCreate(immutableArguments); } else { return internalCreate(ImmutableList.copyOf(pathArguments)); } } /** * Create an instance identifier for a very specific object type. * * For example * <pre> * new InstanceIdentifier(Nodes.class) * </pre> * would create an InstanceIdentifier for an object of type Nodes * * @param type The type of the object which this instance identifier represents * @return InstanceIdentifier instance */ @SuppressWarnings("unchecked") public static <T extends DataObject> InstanceIdentifier<T> create(final Class<T> type) { return (InstanceIdentifier<T>) create(Collections.<PathArgument>singletonList(new Item<>(type))); } /** * Return the key associated with the last component of the specified identifier. * * @param id instance identifier * @return key associated with the last component * @throws IllegalArgumentException if the supplied identifier type cannot have a key. * @throws NullPointerException if id is null. */ public static <N extends Identifiable<K> & DataObject, K extends Identifier<N>> K keyOf( final InstanceIdentifier<N> id) { Preconditions.checkNotNull(id); Preconditions.checkArgument(id instanceof KeyedInstanceIdentifier, "%s does not have a key", id); @SuppressWarnings("unchecked") final K ret = ((KeyedInstanceIdentifier<N, K>) id).getKey(); return ret; } @SuppressWarnings({ "unchecked", "rawtypes" }) static InstanceIdentifier<?> trustedCreate(final PathArgument arg, final Iterable<PathArgument> pathArguments, final int hash, boolean wildcarded) { if (Identifiable.class.isAssignableFrom(arg.getType()) && !(wildcarded)) { Identifier<?> key = null; if (arg instanceof IdentifiableItem<?, ?>) { key = ((IdentifiableItem<?, ?>) arg).key; } else { wildcarded = true; } return new KeyedInstanceIdentifier(arg.getType(), pathArguments, wildcarded, hash, key); } else { return new InstanceIdentifier(arg.getType(), pathArguments, wildcarded, hash); } } /** * Path argument of {@link InstanceIdentifier}. * <p> * Interface which implementations are used as path components of the * path in overall data tree. */ public interface PathArgument extends Comparable<PathArgument> { Class<? extends DataObject> getType(); } private static abstract class AbstractPathArgument<T extends DataObject> implements PathArgument, Serializable { private static final long serialVersionUID = 1L; private final Class<T> type; protected AbstractPathArgument(final Class<T> type) { this.type = Preconditions.checkNotNull(type, "Type may not be null."); } @Override public final Class<T> getType() { return type; } @Override public int hashCode() { return type.hashCode(); } @Override public boolean equals(final Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final AbstractPathArgument<?> other = (AbstractPathArgument<?>) obj; return type.equals(other.type); } @Override public int compareTo(final PathArgument arg) { return type.getCanonicalName().compareTo(arg.getType().getCanonicalName()); } } /** * An Item represents an object that probably is only one of it's kind. For example a Nodes object is only one of * a kind. In YANG terms this would probably represent a container. * * @param <T> */ public static final class Item<T extends DataObject> extends AbstractPathArgument<T> { private static final long serialVersionUID = 1L; public Item(final Class<T> type) { super(type); } @Override public String toString() { return getType().getName(); } } /** * An IdentifiableItem represents a object that is usually present in a collection and can be identified uniquely * by a key. In YANG terms this would probably represent an item in a list. * * @param <I> An object that is identifiable by an identifier * @param <T> The identifier of the object */ public static final class IdentifiableItem<I extends Identifiable<T> & DataObject, T extends Identifier<I>> extends AbstractPathArgument<I> { private static final long serialVersionUID = 1L; private final T key; public IdentifiableItem(final Class<I> type, final T key) { super(type); this.key = Preconditions.checkNotNull(key, "Key may not be null."); } public T getKey() { return this.key; } @Override public boolean equals(final Object obj) { return super.equals(obj) && key.equals(((IdentifiableItem<?, ?>) obj).getKey()); } @Override public int hashCode() { return super.hashCode() * 31 + key.hashCode(); } @Override public String toString() { return getType().getName() + "[key=" + key + "]"; } } public interface InstanceIdentifierBuilder<T extends DataObject> extends Builder<InstanceIdentifier<T>> { /** * Append the specified container as a child of the current InstanceIdentifier referenced by the builder. * * This method should be used when you want to build an instance identifier by appending top-level * elements * * Example, * <pre> * InstanceIdentifier.builder().child(Nodes.class).build(); * * </pre> * * NOTE :- The above example is only for illustration purposes InstanceIdentifier.builder() has been deprecated * and should not be used. Use InstanceIdentifier.builder(Nodes.class) instead * * @param container * @param <N> * @return */ <N extends ChildOf<? super T>> InstanceIdentifierBuilder<N> child(Class<N> container); /** * Append the specified listItem as a child of the current InstanceIdentifier referenced by the builder. * * This method should be used when you want to build an instance identifier by appending a specific list element * to the identifier * * @param listItem * @param listKey * @param <N> * @param <K> * @return */ <N extends Identifiable<K> & ChildOf<? super T>, K extends Identifier<N>> InstanceIdentifierBuilder<N> child( Class<N> listItem, K listKey); /** * Build an identifier which refers to a specific augmentation of the current InstanceIdentifier referenced by * the builder * * @param container * @param <N> * @return */ <N extends DataObject & Augmentation<? super T>> InstanceIdentifierBuilder<N> augmentation( Class<N> container); /** * Build the instance identifier. * * @return */ @Override InstanceIdentifier<T> build(); /* * @deprecated use #build() */ @Deprecated InstanceIdentifier<T> toInstance(); } private void writeObject(final java.io.ObjectOutputStream out) throws IOException { out.defaultWriteObject(); out.writeInt(Iterables.size(pathArguments)); for (Object o : pathArguments) { out.writeObject(o); } } private void readObject(final java.io.ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); final int size = in.readInt(); final List<PathArgument> args = new ArrayList<>(size); for (int i = 0; i < size; ++i) { args.add((PathArgument) in.readObject()); } try { PATHARGUMENTS_FIELD.set(this, ImmutableList.copyOf(args)); } catch (IllegalArgumentException | IllegalAccessException e) { throw new IOException(e); } } }