--- /dev/null
+package org.apache.lucene.util.fst;
+
+/**
+ * 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.io.IOException;
+
+import org.apache.lucene.store.DataInput;
+import org.apache.lucene.store.DataOutput;
+import org.apache.lucene.util.ArrayUtil;
+import org.apache.lucene.util.CodecUtil;
+import org.apache.lucene.util.fst.Builder.UnCompiledNode;
+
+// TODO: if FST is pure prefix trie we can do a more compact
+// job, ie, once we are at a 'suffix only', just store the
+// completion labels as a string not as a series of arcs.
+
+// NOTE: while the FST is able to represent a non-final
+// dead-end state (NON_FINAL_END_NODE=0), the layers above
+// (FSTEnum, Util) have problems with this!!
+
+/** Represents an FST using a compact byte[] format.
+ * <p> The format is similar to what's used by Morfologik
+ * (http://sourceforge.net/projects/morfologik).
+ *
+ * <p><b>NOTE</b>: the FST cannot be larger than ~2.1 GB
+ * because it uses int to address the byte[].
+ *
+ * @lucene.experimental
+ */
+public class FST<T> {
+ public static enum INPUT_TYPE {BYTE1, BYTE2, BYTE4};
+ public final INPUT_TYPE inputType;
+
+ private final static int BIT_FINAL_ARC = 1 << 0;
+ private final static int BIT_LAST_ARC = 1 << 1;
+ private final static int BIT_TARGET_NEXT = 1 << 2;
+ private final static int BIT_STOP_NODE = 1 << 3;
+ private final static int BIT_ARC_HAS_OUTPUT = 1 << 4;
+ private final static int BIT_ARC_HAS_FINAL_OUTPUT = 1 << 5;
+
+ // Arcs are stored as fixed-size (per entry) array, so
+ // that we can find an arc using binary search. We do
+ // this when number of arcs is > NUM_ARCS_ARRAY:
+ private final static int BIT_ARCS_AS_FIXED_ARRAY = 1 << 6;
+
+ /**
+ * @see #shouldExpand(UnCompiledNode)
+ */
+ final static int FIXED_ARRAY_SHALLOW_DISTANCE = 3; // 0 => only root node.
+
+ /**
+ * @see #shouldExpand(UnCompiledNode)
+ */
+ final static int FIXED_ARRAY_NUM_ARCS_SHALLOW = 5;
+
+ /**
+ * @see #shouldExpand(UnCompiledNode)
+ */
+ final static int FIXED_ARRAY_NUM_ARCS_DEEP = 10;
+
+ private int[] bytesPerArc = new int[0];
+
+ // Increment version to change it
+ private final static String FILE_FORMAT_NAME = "FST";
+ private final static int VERSION_START = 0;
+
+ /** Changed numBytesPerArc for array'd case from byte to int. */
+ private final static int VERSION_INT_NUM_BYTES_PER_ARC = 1;
+
+ private final static int VERSION_CURRENT = VERSION_INT_NUM_BYTES_PER_ARC;
+
+ // Never serialized; just used to represent the virtual
+ // final node w/ no arcs:
+ private final static int FINAL_END_NODE = -1;
+
+ // Never serialized; just used to represent the virtual
+ // non-final node w/ no arcs:
+ private final static int NON_FINAL_END_NODE = 0;
+
+ // if non-null, this FST accepts the empty string and
+ // produces this output
+ T emptyOutput;
+ private byte[] emptyOutputBytes;
+
+ private byte[] bytes;
+ int byteUpto = 0;
+
+ private int startNode = -1;
+
+ public final Outputs<T> outputs;
+
+ private int lastFrozenNode;
+
+ private final T NO_OUTPUT;
+
+ public int nodeCount;
+ public int arcCount;
+ public int arcWithOutputCount;
+
+ // If arc has this label then that arc is final/accepted
+ public static final int END_LABEL = -1;
+
+ private Arc<T> cachedRootArcs[];
+
+ public final static class Arc<T> {
+ public int label;
+ public T output;
+
+ int target;
+
+ byte flags;
+ public T nextFinalOutput;
+ int nextArc;
+
+ // This is non-zero if current arcs are fixed array:
+ int posArcsStart;
+ int bytesPerArc;
+ int arcIdx;
+ int numArcs;
+
+ /** Returns this */
+ public Arc<T> copyFrom(Arc<T> other) {
+ label = other.label;
+ target = other.target;
+ flags = other.flags;
+ output = other.output;
+ nextFinalOutput = other.nextFinalOutput;
+ nextArc = other.nextArc;
+ if (other.bytesPerArc != 0) {
+ bytesPerArc = other.bytesPerArc;
+ posArcsStart = other.posArcsStart;
+ arcIdx = other.arcIdx;
+ numArcs = other.numArcs;
+ } else {
+ bytesPerArc = 0;
+ }
+ return this;
+ }
+
+ boolean flag(int flag) {
+ return FST.flag(flags, flag);
+ }
+
+ public boolean isLast() {
+ return flag(BIT_LAST_ARC);
+ }
+
+ public boolean isFinal() {
+ return flag(BIT_FINAL_ARC);
+ }
+ };
+
+ static boolean flag(int flags, int bit) {
+ return (flags & bit) != 0;
+ }
+
+ private final BytesWriter writer;
+
+ // make a new empty FST, for building
+ public FST(INPUT_TYPE inputType, Outputs<T> outputs) {
+ this.inputType = inputType;
+ this.outputs = outputs;
+ bytes = new byte[128];
+ NO_OUTPUT = outputs.getNoOutput();
+
+ writer = new BytesWriter();
+
+ emptyOutput = null;
+ }
+
+ // create an existing FST
+ public FST(DataInput in, Outputs<T> outputs) throws IOException {
+ this.outputs = outputs;
+ writer = null;
+ CodecUtil.checkHeader(in, FILE_FORMAT_NAME, VERSION_INT_NUM_BYTES_PER_ARC, VERSION_INT_NUM_BYTES_PER_ARC);
+ if (in.readByte() == 1) {
+ // accepts empty string
+ int numBytes = in.readVInt();
+ // messy
+ bytes = new byte[numBytes];
+ in.readBytes(bytes, 0, numBytes);
+ emptyOutput = outputs.read(getBytesReader(numBytes-1));
+ } else {
+ emptyOutput = null;
+ }
+ final byte t = in.readByte();
+ switch(t) {
+ case 0:
+ inputType = INPUT_TYPE.BYTE1;
+ break;
+ case 1:
+ inputType = INPUT_TYPE.BYTE2;
+ break;
+ case 2:
+ inputType = INPUT_TYPE.BYTE4;
+ break;
+ default:
+ throw new IllegalStateException("invalid input type " + t);
+ }
+ startNode = in.readVInt();
+ nodeCount = in.readVInt();
+ arcCount = in.readVInt();
+ arcWithOutputCount = in.readVInt();
+
+ bytes = new byte[in.readVInt()];
+ in.readBytes(bytes, 0, bytes.length);
+ NO_OUTPUT = outputs.getNoOutput();
+
+ cacheRootArcs();
+ }
+
+ public INPUT_TYPE getInputType() {
+ return inputType;
+ }
+
+ /** Returns bytes used to represent the FST */
+ public int sizeInBytes() {
+ return bytes.length;
+ }
+
+ void finish(int startNode) throws IOException {
+ if (startNode == FINAL_END_NODE && emptyOutput != null) {
+ startNode = 0;
+ }
+ if (this.startNode != -1) {
+ throw new IllegalStateException("already finished");
+ }
+ byte[] finalBytes = new byte[writer.posWrite];
+ System.arraycopy(bytes, 0, finalBytes, 0, writer.posWrite);
+ bytes = finalBytes;
+ this.startNode = startNode;
+
+ cacheRootArcs();
+ }
+
+ // Caches first 128 labels
+ @SuppressWarnings("unchecked")
+ private void cacheRootArcs() throws IOException {
+ cachedRootArcs = (FST.Arc<T>[]) new FST.Arc[0x80];
+ final FST.Arc<T> arc = new FST.Arc<T>();
+ getFirstArc(arc);
+ final BytesReader in = getBytesReader(0);
+ if (targetHasArcs(arc)) {
+ readFirstRealArc(arc.target, arc);
+ while(true) {
+ assert arc.label != END_LABEL;
+ if (arc.label < cachedRootArcs.length) {
+ cachedRootArcs[arc.label] = new Arc<T>().copyFrom(arc);
+ } else {
+ break;
+ }
+ if (arc.isLast()) {
+ break;
+ }
+ readNextRealArc(arc, in);
+ }
+ }
+ }
+
+ void setEmptyOutput(T v) throws IOException {
+ if (emptyOutput != null) {
+ emptyOutput = outputs.merge(emptyOutput, v);
+ } else {
+ emptyOutput = v;
+ }
+
+ // TODO: this is messy -- replace with sillyBytesWriter; maybe make
+ // bytes private
+ final int posSave = writer.posWrite;
+ outputs.write(emptyOutput, writer);
+ emptyOutputBytes = new byte[writer.posWrite-posSave];
+
+ // reverse
+ final int stopAt = (writer.posWrite - posSave)/2;
+ int upto = 0;
+ while(upto < stopAt) {
+ final byte b = bytes[posSave + upto];
+ bytes[posSave+upto] = bytes[writer.posWrite-upto-1];
+ bytes[writer.posWrite-upto-1] = b;
+ upto++;
+ }
+ System.arraycopy(bytes, posSave, emptyOutputBytes, 0, writer.posWrite-posSave);
+ writer.posWrite = posSave;
+ }
+
+ public void save(DataOutput out) throws IOException {
+ if (startNode == -1) {
+ throw new IllegalStateException("call finish first");
+ }
+ CodecUtil.writeHeader(out, FILE_FORMAT_NAME, VERSION_CURRENT);
+ // TODO: really we should encode this as an arc, arriving
+ // to the root node, instead of special casing here:
+ if (emptyOutput != null) {
+ out.writeByte((byte) 1);
+ out.writeVInt(emptyOutputBytes.length);
+ out.writeBytes(emptyOutputBytes, 0, emptyOutputBytes.length);
+ } else {
+ out.writeByte((byte) 0);
+ }
+ final byte t;
+ if (inputType == INPUT_TYPE.BYTE1) {
+ t = 0;
+ } else if (inputType == INPUT_TYPE.BYTE2) {
+ t = 1;
+ } else {
+ t = 2;
+ }
+ out.writeByte(t);
+ out.writeVInt(startNode);
+ out.writeVInt(nodeCount);
+ out.writeVInt(arcCount);
+ out.writeVInt(arcWithOutputCount);
+ out.writeVInt(bytes.length);
+ out.writeBytes(bytes, 0, bytes.length);
+ }
+
+ private void writeLabel(int v) throws IOException {
+ assert v >= 0: "v=" + v;
+ if (inputType == INPUT_TYPE.BYTE1) {
+ assert v <= 255: "v=" + v;
+ writer.writeByte((byte) v);
+ } else if (inputType == INPUT_TYPE.BYTE2) {
+ assert v <= 65535: "v=" + v;
+ writer.writeVInt(v);
+ } else {
+ //writeInt(v);
+ writer.writeVInt(v);
+ }
+ }
+
+ int readLabel(DataInput in) throws IOException {
+ final int v;
+ if (inputType == INPUT_TYPE.BYTE1) {
+ v = in.readByte()&0xFF;
+ } else {
+ v = in.readVInt();
+ }
+ return v;
+ }
+
+ // returns true if the node at this address has any
+ // outgoing arcs
+ public boolean targetHasArcs(Arc<T> arc) {
+ return arc.target > 0;
+ }
+
+ // serializes new node by appending its bytes to the end
+ // of the current byte[]
+ int addNode(Builder.UnCompiledNode<T> node) throws IOException {
+ //System.out.println("FST.addNode pos=" + posWrite + " numArcs=" + node.numArcs);
+ if (node.numArcs == 0) {
+ if (node.isFinal) {
+ return FINAL_END_NODE;
+ } else {
+ return NON_FINAL_END_NODE;
+ }
+ }
+
+ int startAddress = writer.posWrite;
+ //System.out.println(" startAddr=" + startAddress);
+
+ final boolean doFixedArray = shouldExpand(node);
+ final int fixedArrayStart;
+ if (doFixedArray) {
+ if (bytesPerArc.length < node.numArcs) {
+ bytesPerArc = new int[ArrayUtil.oversize(node.numArcs, 1)];
+ }
+ // write a "false" first arc:
+ writer.writeByte((byte) BIT_ARCS_AS_FIXED_ARRAY);
+ writer.writeVInt(node.numArcs);
+ // placeholder -- we'll come back and write the number
+ // of bytes per arc (int) here:
+ // TODO: we could make this a vInt instead
+ writer.writeInt(0);
+ fixedArrayStart = writer.posWrite;
+ //System.out.println(" do fixed arcs array arcsStart=" + fixedArrayStart);
+ } else {
+ fixedArrayStart = 0;
+ }
+
+ nodeCount++;
+ arcCount += node.numArcs;
+
+ final int lastArc = node.numArcs-1;
+
+ int lastArcStart = writer.posWrite;
+ int maxBytesPerArc = 0;
+ for(int arcIdx=0;arcIdx<node.numArcs;arcIdx++) {
+ final Builder.Arc<T> arc = node.arcs[arcIdx];
+ final Builder.CompiledNode target = (Builder.CompiledNode) arc.target;
+ int flags = 0;
+
+ if (arcIdx == lastArc) {
+ flags += BIT_LAST_ARC;
+ }
+
+ if (lastFrozenNode == target.address && !doFixedArray) {
+ flags += BIT_TARGET_NEXT;
+ }
+
+ if (arc.isFinal) {
+ flags += BIT_FINAL_ARC;
+ if (arc.nextFinalOutput != NO_OUTPUT) {
+ flags += BIT_ARC_HAS_FINAL_OUTPUT;
+ }
+ } else {
+ assert arc.nextFinalOutput == NO_OUTPUT;
+ }
+
+ boolean targetHasArcs = target.address > 0;
+
+ if (!targetHasArcs) {
+ flags += BIT_STOP_NODE;
+ }
+
+ if (arc.output != NO_OUTPUT) {
+ flags += BIT_ARC_HAS_OUTPUT;
+ }
+
+ writer.writeByte((byte) flags);
+ writeLabel(arc.label);
+
+ //System.out.println(" write arc: label=" + arc.label + " flags=" + flags);
+
+ if (arc.output != NO_OUTPUT) {
+ outputs.write(arc.output, writer);
+ arcWithOutputCount++;
+ }
+ if (arc.nextFinalOutput != NO_OUTPUT) {
+ outputs.write(arc.nextFinalOutput, writer);
+ }
+
+ if (targetHasArcs && (doFixedArray || lastFrozenNode != target.address)) {
+ assert target.address > 0;
+ writer.writeInt(target.address);
+ }
+
+ // just write the arcs "like normal" on first pass,
+ // but record how many bytes each one took, and max
+ // byte size:
+ if (doFixedArray) {
+ bytesPerArc[arcIdx] = writer.posWrite - lastArcStart;
+ lastArcStart = writer.posWrite;
+ maxBytesPerArc = Math.max(maxBytesPerArc, bytesPerArc[arcIdx]);
+ //System.out.println(" bytes=" + bytesPerArc[arcIdx]);
+ }
+ }
+
+ // TODO: if arc'd arrays will be "too wasteful" by some
+ // measure, eg if arcs have vastly different sized
+ // outputs, then we should selectively disable array for
+ // such cases
+
+ if (doFixedArray) {
+ assert maxBytesPerArc > 0;
+ // 2nd pass just "expands" all arcs to take up a fixed
+ // byte size
+ final int sizeNeeded = fixedArrayStart + node.numArcs * maxBytesPerArc;
+ bytes = ArrayUtil.grow(bytes, sizeNeeded);
+ // TODO: we could make this a vInt instead
+ bytes[fixedArrayStart-4] = (byte) (maxBytesPerArc >> 24);
+ bytes[fixedArrayStart-3] = (byte) (maxBytesPerArc >> 16);
+ bytes[fixedArrayStart-2] = (byte) (maxBytesPerArc >> 8);
+ bytes[fixedArrayStart-1] = (byte) maxBytesPerArc;
+
+ // expand the arcs in place, backwards
+ int srcPos = writer.posWrite;
+ int destPos = fixedArrayStart + node.numArcs*maxBytesPerArc;
+ writer.posWrite = destPos;
+ for(int arcIdx=node.numArcs-1;arcIdx>=0;arcIdx--) {
+ //System.out.println(" repack arcIdx=" + arcIdx + " srcPos=" + srcPos + " destPos=" + destPos);
+ destPos -= maxBytesPerArc;
+ srcPos -= bytesPerArc[arcIdx];
+ if (srcPos != destPos) {
+ assert destPos > srcPos;
+ System.arraycopy(bytes, srcPos, bytes, destPos, bytesPerArc[arcIdx]);
+ }
+ }
+ }
+
+ // reverse bytes in-place; we do this so that the
+ // "BIT_TARGET_NEXT" opto can work, ie, it reads the
+ // node just before the current one
+ final int endAddress = lastFrozenNode = writer.posWrite - 1;
+
+ int left = startAddress;
+ int right = endAddress;
+ while (left < right) {
+ final byte b = bytes[left];
+ bytes[left++] = bytes[right];
+ bytes[right--] = b;
+ }
+
+ return endAddress;
+ }
+
+ /** Fills virtual 'start' arc, ie, an empty incoming arc to
+ * the FST's start node */
+ public Arc<T> getFirstArc(Arc<T> arc) {
+ if (emptyOutput != null) {
+ arc.flags = BIT_FINAL_ARC | BIT_LAST_ARC;
+ arc.nextFinalOutput = emptyOutput;
+ } else {
+ arc.flags = BIT_LAST_ARC;
+ arc.nextFinalOutput = NO_OUTPUT;
+ }
+ arc.output = NO_OUTPUT;
+
+ // If there are no nodes, ie, the FST only accepts the
+ // empty string, then startNode is 0, and then readFirstTargetArc
+ arc.target = startNode;
+ return arc;
+ }
+
+ /** Follows the <code>follow</code> arc and reads the last
+ * arc of its target; this changes the provided
+ * <code>arc</code> (2nd arg) in-place and returns it.
+ *
+ * @return Returns the second argument
+ * (<code>arc</code>). */
+ public Arc<T> readLastTargetArc(Arc<T> follow, Arc<T> arc) throws IOException {
+ //System.out.println("readLast");
+ if (!targetHasArcs(follow)) {
+ //System.out.println(" end node");
+ assert follow.isFinal();
+ arc.label = END_LABEL;
+ arc.output = follow.nextFinalOutput;
+ arc.flags = BIT_LAST_ARC;
+ return arc;
+ } else {
+ final BytesReader in = getBytesReader(follow.target);
+ arc.flags = in.readByte();
+ if (arc.flag(BIT_ARCS_AS_FIXED_ARRAY)) {
+ // array: jump straight to end
+ arc.numArcs = in.readVInt();
+ arc.bytesPerArc = in.readInt();
+ //System.out.println(" array numArcs=" + arc.numArcs + " bpa=" + arc.bytesPerArc);
+ arc.posArcsStart = in.pos;
+ arc.arcIdx = arc.numArcs - 2;
+ } else {
+ // non-array: linear scan
+ arc.bytesPerArc = 0;
+ //System.out.println(" scan");
+ while(!arc.isLast()) {
+ // skip this arc:
+ readLabel(in);
+ if (arc.flag(BIT_ARC_HAS_OUTPUT)) {
+ outputs.read(in);
+ }
+ if (arc.flag(BIT_ARC_HAS_FINAL_OUTPUT)) {
+ outputs.read(in);
+ }
+ if (arc.flag(BIT_STOP_NODE)) {
+ } else if (arc.flag(BIT_TARGET_NEXT)) {
+ } else {
+ in.pos -= 4;
+ }
+ arc.flags = in.readByte();
+ }
+ arc.nextArc = in.pos+1;
+ }
+ readNextRealArc(arc, in);
+ assert arc.isLast();
+ return arc;
+ }
+ }
+
+ /**
+ * Follow the <code>follow</code> arc and read the first arc of its target;
+ * this changes the provided <code>arc</code> (2nd arg) in-place and returns
+ * it.
+ *
+ * @return Returns the second argument (<code>arc</code>).
+ */
+ public Arc<T> readFirstTargetArc(Arc<T> follow, Arc<T> arc) throws IOException {
+ //int pos = address;
+ //System.out.println(" readFirstTarget follow.target=" + follow.target + " isFinal=" + follow.isFinal());
+ if (follow.isFinal()) {
+ // Insert "fake" final first arc:
+ arc.label = END_LABEL;
+ arc.output = follow.nextFinalOutput;
+ if (follow.target <= 0) {
+ arc.flags = BIT_LAST_ARC;
+ } else {
+ arc.flags = 0;
+ arc.nextArc = follow.target;
+ }
+ //System.out.println(" insert isFinal; nextArc=" + follow.target + " isLast=" + arc.isLast() + " output=" + outputs.outputToString(arc.output));
+ return arc;
+ } else {
+ return readFirstRealArc(follow.target, arc);
+ }
+ }
+
+ // Not private because NodeHash needs access:
+ Arc<T> readFirstRealArc(int address, Arc<T> arc) throws IOException {
+
+ final BytesReader in = getBytesReader(address);
+
+ arc.flags = in.readByte();
+
+ if (arc.flag(BIT_ARCS_AS_FIXED_ARRAY)) {
+ //System.out.println(" fixedArray");
+ // this is first arc in a fixed-array
+ arc.numArcs = in.readVInt();
+ arc.bytesPerArc = in.readInt();
+ arc.arcIdx = -1;
+ arc.nextArc = arc.posArcsStart = in.pos;
+ //System.out.println(" bytesPer=" + arc.bytesPerArc + " numArcs=" + arc.numArcs + " arcsStart=" + pos);
+ } else {
+ arc.nextArc = address;
+ arc.bytesPerArc = 0;
+ }
+ return readNextRealArc(arc, in);
+ }
+
+ /**
+ * Checks if <code>arc</code>'s target state is in expanded (or vector) format.
+ *
+ * @return Returns <code>true</code> if <code>arc</code> points to a state in an
+ * expanded array format.
+ */
+ boolean isExpandedTarget(Arc<T> follow) throws IOException {
+ if (!targetHasArcs(follow)) {
+ return false;
+ } else {
+ final BytesReader in = getBytesReader(follow.target);
+ final byte b = in.readByte();
+ return (b & BIT_ARCS_AS_FIXED_ARRAY) != 0;
+ }
+ }
+
+ /** In-place read; returns the arc. */
+ public Arc<T> readNextArc(Arc<T> arc) throws IOException {
+ if (arc.label == END_LABEL) {
+ // This was a fake inserted "final" arc
+ if (arc.nextArc <= 0) {
+ // This arc went to virtual final node, ie has no outgoing arcs
+ return null;
+ }
+ return readFirstRealArc(arc.nextArc, arc);
+ } else {
+ return readNextRealArc(arc, getBytesReader(0));
+ }
+ }
+
+ /** Peeks at next arc's label; does not alter arc. Do
+ * not call this if arc.isLast()! */
+ public int readNextArcLabel(Arc<T> arc) throws IOException {
+ assert !arc.isLast();
+
+ final BytesReader in;
+ if (arc.label == END_LABEL) {
+ //System.out.println(" nextArc fake " + arc.nextArc);
+ in = getBytesReader(arc.nextArc);
+ byte flags = bytes[in.pos];
+ if (flag(flags, BIT_ARCS_AS_FIXED_ARRAY)) {
+ //System.out.println(" nextArc fake array");
+ in.pos--;
+ in.readVInt();
+ in.readInt();
+ }
+ } else {
+ if (arc.bytesPerArc != 0) {
+ //System.out.println(" nextArc real array");
+ // arcs are at fixed entries
+ in = getBytesReader(arc.posArcsStart - (1+arc.arcIdx)*arc.bytesPerArc);
+ } else {
+ // arcs are packed
+ //System.out.println(" nextArc real packed");
+ in = getBytesReader(arc.nextArc);
+ }
+ }
+ // skip flags
+ in.readByte();
+ return readLabel(in);
+ }
+
+ Arc<T> readNextRealArc(Arc<T> arc, final BytesReader in) throws IOException {
+ // this is a continuing arc in a fixed array
+ if (arc.bytesPerArc != 0) {
+ // arcs are at fixed entries
+ arc.arcIdx++;
+ assert arc.arcIdx < arc.numArcs;
+ in.pos = arc.posArcsStart - arc.arcIdx*arc.bytesPerArc;
+ } else {
+ // arcs are packed
+ in.pos = arc.nextArc;
+ }
+ arc.flags = in.readByte();
+ arc.label = readLabel(in);
+
+ if (arc.flag(BIT_ARC_HAS_OUTPUT)) {
+ arc.output = outputs.read(in);
+ } else {
+ arc.output = outputs.getNoOutput();
+ }
+
+ if (arc.flag(BIT_ARC_HAS_FINAL_OUTPUT)) {
+ arc.nextFinalOutput = outputs.read(in);
+ } else {
+ arc.nextFinalOutput = outputs.getNoOutput();
+ }
+
+ if (arc.flag(BIT_STOP_NODE)) {
+ if (arc.flag(BIT_FINAL_ARC)) {
+ arc.target = FINAL_END_NODE;
+ } else {
+ arc.target = NON_FINAL_END_NODE;
+ }
+ arc.nextArc = in.pos;
+ } else if (arc.flag(BIT_TARGET_NEXT)) {
+ arc.nextArc = in.pos;
+ if (!arc.flag(BIT_LAST_ARC)) {
+ if (arc.bytesPerArc == 0) {
+ // must scan
+ seekToNextNode(in);
+ } else {
+ in.pos = arc.posArcsStart - arc.bytesPerArc * arc.numArcs;
+ }
+ }
+ arc.target = in.pos;
+ } else {
+ arc.target = in.readInt();
+ arc.nextArc = in.pos;
+ }
+
+ return arc;
+ }
+
+ /** Finds an arc leaving the incoming arc, replacing the arc in place.
+ * This returns null if the arc was not found, else the incoming arc. */
+ public Arc<T> findTargetArc(int labelToMatch, Arc<T> follow, Arc<T> arc) throws IOException {
+ assert cachedRootArcs != null;
+ // Short-circuit if this arc is in the root arc cache:
+ if (follow.target == startNode && labelToMatch != END_LABEL && labelToMatch < cachedRootArcs.length) {
+ final Arc<T> result = cachedRootArcs[labelToMatch];
+ if (result == null) {
+ return result;
+ } else {
+ arc.copyFrom(result);
+ return arc;
+ }
+ }
+
+ if (labelToMatch == END_LABEL) {
+ if (follow.isFinal()) {
+ arc.output = follow.nextFinalOutput;
+ arc.label = END_LABEL;
+ return arc;
+ } else {
+ return null;
+ }
+ }
+
+ if (!targetHasArcs(follow)) {
+ return null;
+ }
+
+ // TODO: maybe make an explicit thread state that holds
+ // reusable stuff eg BytesReader:
+ final BytesReader in = getBytesReader(follow.target);
+
+ // System.out.println("fta label=" + (char) labelToMatch);
+
+ if ((in.readByte() & BIT_ARCS_AS_FIXED_ARRAY) != 0) {
+ // Arcs are full array; do binary search:
+ arc.numArcs = in.readVInt();
+ //System.out.println(" bs " + arc.numArcs);
+ arc.bytesPerArc = in.readInt();
+ arc.posArcsStart = in.pos;
+ int low = 0;
+ int high = arc.numArcs-1;
+ while (low <= high) {
+ //System.out.println(" cycle");
+ int mid = (low + high) >>> 1;
+ in.pos = arc.posArcsStart - arc.bytesPerArc*mid - 1;
+ int midLabel = readLabel(in);
+ final int cmp = midLabel - labelToMatch;
+ if (cmp < 0)
+ low = mid + 1;
+ else if (cmp > 0)
+ high = mid - 1;
+ else {
+ arc.arcIdx = mid-1;
+ //System.out.println(" found!");
+ return readNextRealArc(arc, in);
+ }
+ }
+
+ return null;
+ }
+
+ // Linear scan
+ readFirstTargetArc(follow, arc);
+ while(true) {
+ //System.out.println(" non-bs cycle");
+ // TODO: we should fix this code to not have to create
+ // object for the output of every arc we scan... only
+ // for the matching arc, if found
+ if (arc.label == labelToMatch) {
+ //System.out.println(" found!");
+ return arc;
+ } else if (arc.label > labelToMatch) {
+ return null;
+ } else if (arc.isLast()) {
+ return null;
+ } else {
+ readNextArc(arc);
+ }
+ }
+ }
+
+ private void seekToNextNode(BytesReader in) throws IOException {
+
+ while(true) {
+
+ final int flags = in.readByte();
+ readLabel(in);
+
+ if (flag(flags, BIT_ARC_HAS_OUTPUT)) {
+ outputs.read(in);
+ }
+
+ if (flag(flags, BIT_ARC_HAS_FINAL_OUTPUT)) {
+ outputs.read(in);
+ }
+
+ if (!flag(flags, BIT_STOP_NODE) && !flag(flags, BIT_TARGET_NEXT)) {
+ in.readInt();
+ }
+
+ if (flag(flags, BIT_LAST_ARC)) {
+ return;
+ }
+ }
+ }
+
+ public int getNodeCount() {
+ // 1+ in order to count the -1 implicit final node
+ return 1+nodeCount;
+ }
+
+ public int getArcCount() {
+ return arcCount;
+ }
+
+ public int getArcWithOutputCount() {
+ return arcWithOutputCount;
+ }
+
+ /**
+ * Nodes will be expanded if their depth (distance from the root node) is
+ * <= this value and their number of arcs is >=
+ * {@link #FIXED_ARRAY_NUM_ARCS_SHALLOW}.
+ *
+ * <p>
+ * Fixed array consumes more RAM but enables binary search on the arcs
+ * (instead of a linear scan) on lookup by arc label.
+ *
+ * @return <code>true</code> if <code>node</code> should be stored in an
+ * expanded (array) form.
+ *
+ * @see #FIXED_ARRAY_NUM_ARCS_DEEP
+ * @see Builder.UnCompiledNode#depth
+ */
+ private boolean shouldExpand(UnCompiledNode<T> node) {
+ return (node.depth <= FIXED_ARRAY_SHALLOW_DISTANCE && node.numArcs >= FIXED_ARRAY_NUM_ARCS_SHALLOW) ||
+ node.numArcs >= FIXED_ARRAY_NUM_ARCS_DEEP;
+ }
+
+ // Non-static: writes to FST's byte[]
+ class BytesWriter extends DataOutput {
+ int posWrite;
+
+ public BytesWriter() {
+ // pad: ensure no node gets address 0 which is reserved to mean
+ // the stop state w/ no arcs
+ posWrite = 1;
+ }
+
+ @Override
+ public void writeByte(byte b) {
+ if (bytes.length == posWrite) {
+ bytes = ArrayUtil.grow(bytes);
+ }
+ assert posWrite < bytes.length: "posWrite=" + posWrite + " bytes.length=" + bytes.length;
+ bytes[posWrite++] = b;
+ }
+
+ @Override
+ public void writeBytes(byte[] b, int offset, int length) {
+ final int size = posWrite + length;
+ bytes = ArrayUtil.grow(bytes, size);
+ System.arraycopy(b, offset, bytes, posWrite, length);
+ posWrite += length;
+ }
+ }
+
+ final BytesReader getBytesReader(int pos) {
+ // TODO: maybe re-use via ThreadLocal?
+ return new BytesReader(pos);
+ }
+
+ // Non-static: reads byte[] from FST
+ final class BytesReader extends DataInput {
+ int pos;
+
+ public BytesReader(int pos) {
+ this.pos = pos;
+ }
+
+ @Override
+ public byte readByte() {
+ return bytes[pos--];
+ }
+
+ @Override
+ public void readBytes(byte[] b, int offset, int len) {
+ for(int i=0;i<len;i++) {
+ b[offset+i] = bytes[pos--];
+ }
+ }
+ }
+}
fnp / pylucene.git / blobdiff