--- /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