+++ /dev/null
-package org.apache.lucene.util;
-
-/**
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You 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.
- */
-
-import java.lang.ref.WeakReference;
-import java.util.Collections;
-import java.util.NoSuchElementException;
-import java.util.Iterator;
-import java.util.LinkedHashMap;
-import java.util.WeakHashMap;
-import java.util.LinkedList;
-import java.util.Map;
-import java.util.Map.Entry;
-
-import org.apache.lucene.analysis.TokenStream; // for javadocs
-import org.apache.lucene.analysis.tokenattributes.TermAttribute;
-import org.apache.lucene.analysis.tokenattributes.CharTermAttributeImpl;
-
-/**
- * An AttributeSource contains a list of different {@link AttributeImpl}s,
- * and methods to add and get them. There can only be a single instance
- * of an attribute in the same AttributeSource instance. This is ensured
- * by passing in the actual type of the Attribute (Class<Attribute>) to
- * the {@link #addAttribute(Class)}, which then checks if an instance of
- * that type is already present. If yes, it returns the instance, otherwise
- * it creates a new instance and returns it.
- */
-public class AttributeSource {
- /**
- * An AttributeFactory creates instances of {@link AttributeImpl}s.
- */
- public static abstract class AttributeFactory {
- /**
- * returns an {@link AttributeImpl} for the supplied {@link Attribute} interface class.
- */
- public abstract AttributeImpl createAttributeInstance(Class<? extends Attribute> attClass);
-
- /**
- * This is the default factory that creates {@link AttributeImpl}s using the
- * class name of the supplied {@link Attribute} interface class by appending <code>Impl</code> to it.
- */
- public static final AttributeFactory DEFAULT_ATTRIBUTE_FACTORY = new DefaultAttributeFactory();
-
- private static final class DefaultAttributeFactory extends AttributeFactory {
- private static final WeakHashMap<Class<? extends Attribute>, WeakReference<Class<? extends AttributeImpl>>> attClassImplMap =
- new WeakHashMap<Class<? extends Attribute>, WeakReference<Class<? extends AttributeImpl>>>();
-
- private DefaultAttributeFactory() {}
-
- @Override
- public AttributeImpl createAttributeInstance(Class<? extends Attribute> attClass) {
- try {
- return getClassForInterface(attClass).newInstance();
- } catch (InstantiationException e) {
- throw new IllegalArgumentException("Could not instantiate implementing class for " + attClass.getName());
- } catch (IllegalAccessException e) {
- throw new IllegalArgumentException("Could not instantiate implementing class for " + attClass.getName());
- }
- }
-
- private static Class<? extends AttributeImpl> getClassForInterface(Class<? extends Attribute> attClass) {
- synchronized(attClassImplMap) {
- final WeakReference<Class<? extends AttributeImpl>> ref = attClassImplMap.get(attClass);
- Class<? extends AttributeImpl> clazz = (ref == null) ? null : ref.get();
- if (clazz == null) {
- try {
- // TODO: Remove when TermAttribute is removed!
- // This is a "sophisticated backwards compatibility hack"
- // (enforce new impl for this deprecated att):
- if (TermAttribute.class.equals(attClass)) {
- clazz = CharTermAttributeImpl.class;
- } else {
- clazz = Class.forName(attClass.getName() + "Impl", true, attClass.getClassLoader())
- .asSubclass(AttributeImpl.class);
- }
- attClassImplMap.put(attClass,
- new WeakReference<Class<? extends AttributeImpl>>(clazz)
- );
- } catch (ClassNotFoundException e) {
- throw new IllegalArgumentException("Could not find implementing class for " + attClass.getName());
- }
- }
- return clazz;
- }
- }
- }
- }
-
- /**
- * This class holds the state of an AttributeSource.
- * @see #captureState
- * @see #restoreState
- */
- public static final class State implements Cloneable {
- AttributeImpl attribute;
- State next;
-
- @Override
- public Object clone() {
- State clone = new State();
- clone.attribute = (AttributeImpl) attribute.clone();
-
- if (next != null) {
- clone.next = (State) next.clone();
- }
-
- return clone;
- }
- }
-
- // These two maps must always be in sync!!!
- // So they are private, final and read-only from the outside (read-only iterators)
- private final Map<Class<? extends Attribute>, AttributeImpl> attributes;
- private final Map<Class<? extends AttributeImpl>, AttributeImpl> attributeImpls;
- private final State[] currentState;
-
- private AttributeFactory factory;
-
- /**
- * An AttributeSource using the default attribute factory {@link AttributeSource.AttributeFactory#DEFAULT_ATTRIBUTE_FACTORY}.
- */
- public AttributeSource() {
- this(AttributeFactory.DEFAULT_ATTRIBUTE_FACTORY);
- }
-
- /**
- * An AttributeSource that uses the same attributes as the supplied one.
- */
- public AttributeSource(AttributeSource input) {
- if (input == null) {
- throw new IllegalArgumentException("input AttributeSource must not be null");
- }
- this.attributes = input.attributes;
- this.attributeImpls = input.attributeImpls;
- this.currentState = input.currentState;
- this.factory = input.factory;
- }
-
- /**
- * An AttributeSource using the supplied {@link AttributeFactory} for creating new {@link Attribute} instances.
- */
- public AttributeSource(AttributeFactory factory) {
- this.attributes = new LinkedHashMap<Class<? extends Attribute>, AttributeImpl>();
- this.attributeImpls = new LinkedHashMap<Class<? extends AttributeImpl>, AttributeImpl>();
- this.currentState = new State[1];
- this.factory = factory;
- }
-
- /**
- * returns the used AttributeFactory.
- */
- public AttributeFactory getAttributeFactory() {
- return this.factory;
- }
-
- /** Returns a new iterator that iterates the attribute classes
- * in the same order they were added in.
- */
- public Iterator<Class<? extends Attribute>> getAttributeClassesIterator() {
- return Collections.unmodifiableSet(attributes.keySet()).iterator();
- }
-
- /** Returns a new iterator that iterates all unique Attribute implementations.
- * This iterator may contain less entries that {@link #getAttributeClassesIterator},
- * if one instance implements more than one Attribute interface.
- */
- public Iterator<AttributeImpl> getAttributeImplsIterator() {
- final State initState = getCurrentState();
- if (initState != null) {
- return new Iterator<AttributeImpl>() {
- private State state = initState;
-
- public void remove() {
- throw new UnsupportedOperationException();
- }
-
- public AttributeImpl next() {
- if (state == null)
- throw new NoSuchElementException();
- final AttributeImpl att = state.attribute;
- state = state.next;
- return att;
- }
-
- public boolean hasNext() {
- return state != null;
- }
- };
- } else {
- return Collections.<AttributeImpl>emptySet().iterator();
- }
- }
-
- /** a cache that stores all interfaces for known implementation classes for performance (slow reflection) */
- private static final WeakHashMap<Class<? extends AttributeImpl>,LinkedList<WeakReference<Class<? extends Attribute>>>> knownImplClasses =
- new WeakHashMap<Class<? extends AttributeImpl>,LinkedList<WeakReference<Class<? extends Attribute>>>>();
-
- static LinkedList<WeakReference<Class<? extends Attribute>>> getAttributeInterfaces(final Class<? extends AttributeImpl> clazz) {
- synchronized(knownImplClasses) {
- LinkedList<WeakReference<Class<? extends Attribute>>> foundInterfaces = knownImplClasses.get(clazz);
- if (foundInterfaces == null) {
- // we have a strong reference to the class instance holding all interfaces in the list (parameter "att"),
- // so all WeakReferences are never evicted by GC
- knownImplClasses.put(clazz, foundInterfaces = new LinkedList<WeakReference<Class<? extends Attribute>>>());
- // find all interfaces that this attribute instance implements
- // and that extend the Attribute interface
- Class<?> actClazz = clazz;
- do {
- for (Class<?> curInterface : actClazz.getInterfaces()) {
- if (curInterface != Attribute.class && Attribute.class.isAssignableFrom(curInterface)) {
- foundInterfaces.add(new WeakReference<Class<? extends Attribute>>(curInterface.asSubclass(Attribute.class)));
- }
- }
- actClazz = actClazz.getSuperclass();
- } while (actClazz != null);
- }
- return foundInterfaces;
- }
- }
-
- /** <b>Expert:</b> Adds a custom AttributeImpl instance with one or more Attribute interfaces.
- * <p><font color="red"><b>Please note:</b> It is not guaranteed, that <code>att</code> is added to
- * the <code>AttributeSource</code>, because the provided attributes may already exist.
- * You should always retrieve the wanted attributes using {@link #getAttribute} after adding
- * with this method and cast to your class.
- * The recommended way to use custom implementations is using an {@link AttributeFactory}.
- * </font></p>
- */
- public void addAttributeImpl(final AttributeImpl att) {
- final Class<? extends AttributeImpl> clazz = att.getClass();
- if (attributeImpls.containsKey(clazz)) return;
- final LinkedList<WeakReference<Class<? extends Attribute>>> foundInterfaces =
- getAttributeInterfaces(clazz);
-
- // add all interfaces of this AttributeImpl to the maps
- for (WeakReference<Class<? extends Attribute>> curInterfaceRef : foundInterfaces) {
- final Class<? extends Attribute> curInterface = curInterfaceRef.get();
- assert (curInterface != null) :
- "We have a strong reference on the class holding the interfaces, so they should never get evicted";
- // Attribute is a superclass of this interface
- if (!attributes.containsKey(curInterface)) {
- // invalidate state to force recomputation in captureState()
- this.currentState[0] = null;
- attributes.put(curInterface, att);
- attributeImpls.put(clazz, att);
- }
- }
- }
-
- /**
- * The caller must pass in a Class<? extends Attribute> value.
- * This method first checks if an instance of that class is
- * already in this AttributeSource and returns it. Otherwise a
- * new instance is created, added to this AttributeSource and returned.
- */
- public <A extends Attribute> A addAttribute(Class<A> attClass) {
- AttributeImpl attImpl = attributes.get(attClass);
- if (attImpl == null) {
- if (!(attClass.isInterface() && Attribute.class.isAssignableFrom(attClass))) {
- throw new IllegalArgumentException(
- "addAttribute() only accepts an interface that extends Attribute, but " +
- attClass.getName() + " does not fulfil this contract."
- );
- }
- addAttributeImpl(attImpl = this.factory.createAttributeInstance(attClass));
- }
- return attClass.cast(attImpl);
- }
-
- /** Returns true, iff this AttributeSource has any attributes */
- public boolean hasAttributes() {
- return !this.attributes.isEmpty();
- }
-
- /**
- * The caller must pass in a Class<? extends Attribute> value.
- * Returns true, iff this AttributeSource contains the passed-in Attribute.
- */
- public boolean hasAttribute(Class<? extends Attribute> attClass) {
- return this.attributes.containsKey(attClass);
- }
-
- /**
- * The caller must pass in a Class<? extends Attribute> value.
- * Returns the instance of the passed in Attribute contained in this AttributeSource
- *
- * @throws IllegalArgumentException if this AttributeSource does not contain the
- * Attribute. It is recommended to always use {@link #addAttribute} even in consumers
- * of TokenStreams, because you cannot know if a specific TokenStream really uses
- * a specific Attribute. {@link #addAttribute} will automatically make the attribute
- * available. If you want to only use the attribute, if it is available (to optimize
- * consuming), use {@link #hasAttribute}.
- */
- public <A extends Attribute> A getAttribute(Class<A> attClass) {
- AttributeImpl attImpl = attributes.get(attClass);
- if (attImpl == null) {
- throw new IllegalArgumentException("This AttributeSource does not have the attribute '" + attClass.getName() + "'.");
- }
- return attClass.cast(attImpl);
- }
-
- private State getCurrentState() {
- State s = currentState[0];
- if (s != null || !hasAttributes()) {
- return s;
- }
- State c = s = currentState[0] = new State();
- final Iterator<AttributeImpl> it = attributeImpls.values().iterator();
- c.attribute = it.next();
- while (it.hasNext()) {
- c.next = new State();
- c = c.next;
- c.attribute = it.next();
- }
- return s;
- }
-
- /**
- * Resets all Attributes in this AttributeSource by calling
- * {@link AttributeImpl#clear()} on each Attribute implementation.
- */
- public void clearAttributes() {
- for (State state = getCurrentState(); state != null; state = state.next) {
- state.attribute.clear();
- }
- }
-
- /**
- * Captures the state of all Attributes. The return value can be passed to
- * {@link #restoreState} to restore the state of this or another AttributeSource.
- */
- public State captureState() {
- final State state = this.getCurrentState();
- return (state == null) ? null : (State) state.clone();
- }
-
- /**
- * Restores this state by copying the values of all attribute implementations
- * that this state contains into the attributes implementations of the targetStream.
- * The targetStream must contain a corresponding instance for each argument
- * contained in this state (e.g. it is not possible to restore the state of
- * an AttributeSource containing a TermAttribute into a AttributeSource using
- * a Token instance as implementation).
- * <p>
- * Note that this method does not affect attributes of the targetStream
- * that are not contained in this state. In other words, if for example
- * the targetStream contains an OffsetAttribute, but this state doesn't, then
- * the value of the OffsetAttribute remains unchanged. It might be desirable to
- * reset its value to the default, in which case the caller should first
- * call {@link TokenStream#clearAttributes()} on the targetStream.
- */
- public void restoreState(State state) {
- if (state == null) return;
-
- do {
- AttributeImpl targetImpl = attributeImpls.get(state.attribute.getClass());
- if (targetImpl == null) {
- throw new IllegalArgumentException("State contains AttributeImpl of type " +
- state.attribute.getClass().getName() + " that is not in in this AttributeSource");
- }
- state.attribute.copyTo(targetImpl);
- state = state.next;
- } while (state != null);
- }
-
- @Override
- public int hashCode() {
- int code = 0;
- for (State state = getCurrentState(); state != null; state = state.next) {
- code = code * 31 + state.attribute.hashCode();
- }
- return code;
- }
-
- @Override
- public boolean equals(Object obj) {
- if (obj == this) {
- return true;
- }
-
- if (obj instanceof AttributeSource) {
- AttributeSource other = (AttributeSource) obj;
-
- if (hasAttributes()) {
- if (!other.hasAttributes()) {
- return false;
- }
-
- if (this.attributeImpls.size() != other.attributeImpls.size()) {
- return false;
- }
-
- // it is only equal if all attribute impls are the same in the same order
- State thisState = this.getCurrentState();
- State otherState = other.getCurrentState();
- while (thisState != null && otherState != null) {
- if (otherState.attribute.getClass() != thisState.attribute.getClass() || !otherState.attribute.equals(thisState.attribute)) {
- return false;
- }
- thisState = thisState.next;
- otherState = otherState.next;
- }
- return true;
- } else {
- return !other.hasAttributes();
- }
- } else
- return false;
- }
-
- /**
- * Returns a string representation of the object. In general, the {@code toString} method
- * returns a string that "textually represents" this object.
- *
- * <p><b>WARNING:</b> For backwards compatibility this method is implemented as
- * in Lucene 2.9/3.0. In Lucene 4.0 this default implementation
- * will be removed.
- *
- * <p>It is recommeneded to use {@link #reflectAsString} or {@link #reflectWith}
- * to get a well-defined output of AttributeSource's internals.
- */
- // TODO: @deprecated remove this method in 4.0
- @Override
- public String toString() {
- final StringBuilder sb = new StringBuilder().append('(');
- if (hasAttributes()) {
- for (State state = getCurrentState(); state != null; state = state.next) {
- if (sb.length() > 1) sb.append(',');
- sb.append(state.attribute.toString());
- }
- }
- return sb.append(')').toString();
- }
-
- /**
- * This method returns the current attribute values as a string in the following format
- * by calling the {@link #reflectWith(AttributeReflector)} method:
- *
- * <ul>
- * <li><em>iff {@code prependAttClass=true}:</em> {@code "AttributeClass#key=value,AttributeClass#key=value"}
- * <li><em>iff {@code prependAttClass=false}:</em> {@code "key=value,key=value"}
- * </ul>
- *
- * @see #reflectWith(AttributeReflector)
- */
- public final String reflectAsString(final boolean prependAttClass) {
- final StringBuilder buffer = new StringBuilder();
- reflectWith(new AttributeReflector() {
- public void reflect(Class<? extends Attribute> attClass, String key, Object value) {
- if (buffer.length() > 0) {
- buffer.append(',');
- }
- if (prependAttClass) {
- buffer.append(attClass.getName()).append('#');
- }
- buffer.append(key).append('=').append((value == null) ? "null" : value);
- }
- });
- return buffer.toString();
- }
-
- /**
- * This method is for introspection of attributes, it should simply
- * add the key/values this AttributeSource holds to the given {@link AttributeReflector}.
- *
- * <p>This method iterates over all Attribute implementations and calls the
- * corresponding {@link AttributeImpl#reflectWith} method.</p>
- *
- * @see AttributeImpl#reflectWith
- */
- public final void reflectWith(AttributeReflector reflector) {
- for (State state = getCurrentState(); state != null; state = state.next) {
- state.attribute.reflectWith(reflector);
- }
- }
-
- /**
- * Performs a clone of all {@link AttributeImpl} instances returned in a new
- * {@code AttributeSource} instance. This method can be used to e.g. create another TokenStream
- * with exactly the same attributes (using {@link #AttributeSource(AttributeSource)}).
- * You can also use it as a (non-performant) replacement for {@link #captureState}, if you need to look
- * into / modify the captured state.
- */
- public AttributeSource cloneAttributes() {
- final AttributeSource clone = new AttributeSource(this.factory);
-
- if (hasAttributes()) {
- // first clone the impls
- for (State state = getCurrentState(); state != null; state = state.next) {
- clone.attributeImpls.put(state.attribute.getClass(), (AttributeImpl) state.attribute.clone());
- }
-
- // now the interfaces
- for (Entry<Class<? extends Attribute>, AttributeImpl> entry : this.attributes.entrySet()) {
- clone.attributes.put(entry.getKey(), clone.attributeImpls.get(entry.getValue().getClass()));
- }
- }
-
- return clone;
- }
-
- /**
- * Copies the contents of this {@code AttributeSource} to the given target {@code AttributeSource}.
- * The given instance has to provide all {@link Attribute}s this instance contains.
- * The actual attribute implementations must be identical in both {@code AttributeSource} instances;
- * ideally both AttributeSource instances should use the same {@link AttributeFactory}.
- * You can use this method as a replacement for {@link #restoreState}, if you use
- * {@link #cloneAttributes} instead of {@link #captureState}.
- */
- public final void copyTo(AttributeSource target) {
- for (State state = getCurrentState(); state != null; state = state.next) {
- final AttributeImpl targetImpl = target.attributeImpls.get(state.attribute.getClass());
- if (targetImpl == null) {
- throw new IllegalArgumentException("This AttributeSource contains AttributeImpl of type " +
- state.attribute.getClass().getName() + " that is not in the target");
- }
- state.attribute.copyTo(targetImpl);
- }
- }
-
-}
fnp / pylucene.git / blobdiff