--- /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 org.apache.lucene.util.ArrayUtil;
+import org.apache.lucene.util.RamUsageEstimator;
+import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.IntsRef;
+import org.apache.lucene.util.fst.FST.INPUT_TYPE; // javadoc
+
+import java.io.IOException;
+
+/**
+ * Builds a compact FST (maps an IntsRef term to an arbitrary
+ * output) from pre-sorted terms with outputs (the FST
+ * becomes an FSA if you use NoOutputs). The FST is written
+ * on-the-fly into a compact serialized format byte array, which can
+ * be saved to / loaded from a Directory or used directly
+ * for traversal. The FST is always finite (no cycles).
+ *
+ * <p>NOTE: The algorithm is described at
+ * http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.24.3698</p>
+ *
+ * If your outputs are ByteSequenceOutput then the final FST
+ * will be minimal, but if you use PositiveIntOutput then
+ * it's only "near minimal". For example, aa/0, aab/1, bbb/2
+ * will produce 6 states when a 5 state fst is also
+ * possible.
+ *
+ * The parameterized type T is the output type. See the
+ * subclasses of {@link Outputs}.
+ *
+ * @lucene.experimental
+ */
+
+public class Builder<T> {
+ private final NodeHash<T> dedupHash;
+ private final FST<T> fst;
+ private final T NO_OUTPUT;
+
+ // simplistic pruning: we prune node (and all following
+ // nodes) if less than this number of terms go through it:
+ private final int minSuffixCount1;
+
+ // better pruning: we prune node (and all following
+ // nodes) if the prior node has less than this number of
+ // terms go through it:
+ private final int minSuffixCount2;
+
+ private final boolean doShareNonSingletonNodes;
+ private final int shareMaxTailLength;
+
+ private final IntsRef lastInput = new IntsRef();
+
+ // NOTE: cutting this over to ArrayList instead loses ~6%
+ // in build performance on 9.8M Wikipedia terms; so we
+ // left this as an array:
+ // current "frontier"
+ private UnCompiledNode<T>[] frontier;
+
+ /**
+ * Instantiates an FST/FSA builder without any pruning. A shortcut
+ * to {@link #Builder(FST.INPUT_TYPE, int, int, boolean, boolean, int, Outputs)} with
+ * pruning options turned off.
+ */
+ public Builder(FST.INPUT_TYPE inputType, Outputs<T> outputs) {
+ this(inputType, 0, 0, true, true, Integer.MAX_VALUE, outputs);
+ }
+
+ /**
+ * Instantiates an FST/FSA builder with all the possible tuning and construction
+ * tweaks. Read parameter documentation carefully.
+ *
+ * @param inputType
+ * The input type (transition labels). Can be anything from {@link INPUT_TYPE}
+ * enumeration. Shorter types will consume less memory. Strings (character sequences) are
+ * represented as {@link INPUT_TYPE#BYTE4} (full unicode codepoints).
+ *
+ * @param minSuffixCount1
+ * If pruning the input graph during construction, this threshold is used for telling
+ * if a node is kept or pruned. If transition_count(node) >= minSuffixCount1, the node
+ * is kept.
+ *
+ * @param minSuffixCount2
+ * (Note: only Mike McCandless knows what this one is really doing...)
+ *
+ * @param doShareSuffix
+ * If <code>true</code>, the shared suffixes will be compacted into unique paths.
+ * This requires an additional hash map for lookups in memory. Setting this parameter to
+ * <code>false</code> creates a single path for all input sequences. This will result in a larger
+ * graph, but may require less memory and will speed up construction.
+ *
+ * @param doShareNonSingletonNodes
+ * Only used if doShareSuffix is true. Set this to
+ * true to ensure FST is fully minimal, at cost of more
+ * CPU and more RAM during building.
+ *
+ * @param shareMaxTailLength
+ * Only used if doShareSuffix is true. Set this to
+ * Integer.MAX_VALUE to ensure FST is fully minimal, at cost of more
+ * CPU and more RAM during building.
+ *
+ * @param outputs The output type for each input sequence. Applies only if building an FST. For
+ * FSA, use {@link NoOutputs#getSingleton()} and {@link NoOutputs#getNoOutput()} as the
+ * singleton output object.
+ */
+ public Builder(FST.INPUT_TYPE inputType, int minSuffixCount1, int minSuffixCount2, boolean doShareSuffix,
+ boolean doShareNonSingletonNodes, int shareMaxTailLength, Outputs<T> outputs) {
+ this.minSuffixCount1 = minSuffixCount1;
+ this.minSuffixCount2 = minSuffixCount2;
+ this.doShareNonSingletonNodes = doShareNonSingletonNodes;
+ this.shareMaxTailLength = shareMaxTailLength;
+ fst = new FST<T>(inputType, outputs);
+ if (doShareSuffix) {
+ dedupHash = new NodeHash<T>(fst);
+ } else {
+ dedupHash = null;
+ }
+ NO_OUTPUT = outputs.getNoOutput();
+
+ @SuppressWarnings("unchecked") final UnCompiledNode<T>[] f = (UnCompiledNode<T>[]) new UnCompiledNode[10];
+ frontier = f;
+ for(int idx=0;idx<frontier.length;idx++) {
+ frontier[idx] = new UnCompiledNode<T>(this, idx);
+ }
+ }
+
+ public int getTotStateCount() {
+ return fst.nodeCount;
+ }
+
+ public long getTermCount() {
+ return frontier[0].inputCount;
+ }
+
+ public int getMappedStateCount() {
+ return dedupHash == null ? 0 : fst.nodeCount;
+ }
+
+ private CompiledNode compileNode(UnCompiledNode<T> n, int tailLength) throws IOException {
+ final int address;
+ if (dedupHash != null && (doShareNonSingletonNodes || n.numArcs <= 1) && tailLength <= shareMaxTailLength) {
+ if (n.numArcs == 0) {
+ address = fst.addNode(n);
+ } else {
+ address = dedupHash.add(n);
+ }
+ } else {
+ address = fst.addNode(n);
+ }
+ assert address != -2;
+
+ n.clear();
+
+ final CompiledNode fn = new CompiledNode();
+ fn.address = address;
+ return fn;
+ }
+
+ private void compilePrevTail(int prefixLenPlus1) throws IOException {
+ assert prefixLenPlus1 >= 1;
+ //System.out.println(" compileTail " + prefixLenPlus1);
+ for(int idx=lastInput.length; idx >= prefixLenPlus1; idx--) {
+ boolean doPrune = false;
+ boolean doCompile = false;
+
+ final UnCompiledNode<T> node = frontier[idx];
+ final UnCompiledNode<T> parent = frontier[idx-1];
+
+ if (node.inputCount < minSuffixCount1) {
+ doPrune = true;
+ doCompile = true;
+ } else if (idx > prefixLenPlus1) {
+ // prune if parent's inputCount is less than suffixMinCount2
+ if (parent.inputCount < minSuffixCount2 || minSuffixCount2 == 1 && parent.inputCount == 1) {
+ // my parent, about to be compiled, doesn't make the cut, so
+ // I'm definitely pruned
+
+ // if pruneCount2 is 1, we keep only up
+ // until the 'distinguished edge', ie we keep only the
+ // 'divergent' part of the FST. if my parent, about to be
+ // compiled, has inputCount 1 then we are already past the
+ // distinguished edge. NOTE: this only works if
+ // the FST outputs are not "compressible" (simple
+ // ords ARE compressible).
+ doPrune = true;
+ } else {
+ // my parent, about to be compiled, does make the cut, so
+ // I'm definitely not pruned
+ doPrune = false;
+ }
+ doCompile = true;
+ } else {
+ // if pruning is disabled (count is 0) we can always
+ // compile current node
+ doCompile = minSuffixCount2 == 0;
+ }
+
+ //System.out.println(" label=" + ((char) lastInput.ints[lastInput.offset+idx-1]) + " idx=" + idx + " inputCount=" + frontier[idx].inputCount + " doCompile=" + doCompile + " doPrune=" + doPrune);
+
+ if (node.inputCount < minSuffixCount2 || minSuffixCount2 == 1 && node.inputCount == 1) {
+ // drop all arcs
+ for(int arcIdx=0;arcIdx<node.numArcs;arcIdx++) {
+ @SuppressWarnings("unchecked") final UnCompiledNode<T> target = (UnCompiledNode<T>) node.arcs[arcIdx].target;
+ target.clear();
+ }
+ node.numArcs = 0;
+ }
+
+ if (doPrune) {
+ // this node doesn't make it -- deref it
+ node.clear();
+ parent.deleteLast(lastInput.ints[lastInput.offset+idx-1], node);
+ } else {
+
+ if (minSuffixCount2 != 0) {
+ compileAllTargets(node, lastInput.length-idx);
+ }
+ final T nextFinalOutput = node.output;
+
+ // We "fake" the node as being final if it has no
+ // outgoing arcs; in theory we could leave it
+ // as non-final (the FST can represent this), but
+ // FSTEnum, Util, etc., have trouble w/ non-final
+ // dead-end states:
+ final boolean isFinal = node.isFinal || node.numArcs == 0;
+
+ if (doCompile) {
+ // this node makes it and we now compile it. first,
+ // compile any targets that were previously
+ // undecided:
+ parent.replaceLast(lastInput.ints[lastInput.offset + idx-1],
+ compileNode(node, 1+lastInput.length-idx),
+ nextFinalOutput,
+ isFinal);
+ } else {
+ // replaceLast just to install
+ // nextFinalOutput/isFinal onto the arc
+ parent.replaceLast(lastInput.ints[lastInput.offset + idx-1],
+ node,
+ nextFinalOutput,
+ isFinal);
+ // this node will stay in play for now, since we are
+ // undecided on whether to prune it. later, it
+ // will be either compiled or pruned, so we must
+ // allocate a new node:
+ frontier[idx] = new UnCompiledNode<T>(this, idx);
+ }
+ }
+ }
+ }
+
+ private final IntsRef scratchIntsRef = new IntsRef(10);
+
+ public void add(BytesRef input, T output) throws IOException {
+ assert fst.getInputType() == FST.INPUT_TYPE.BYTE1;
+ scratchIntsRef.grow(input.length);
+ for(int i=0;i<input.length;i++) {
+ scratchIntsRef.ints[i] = input.bytes[i+input.offset] & 0xFF;
+ }
+ scratchIntsRef.length = input.length;
+ add(scratchIntsRef, output);
+ }
+
+ /** Sugar: adds the UTF32 codepoints from char[] slice. FST
+ * must be FST.INPUT_TYPE.BYTE4! */
+ public void add(char[] s, int offset, int length, T output) throws IOException {
+ assert fst.getInputType() == FST.INPUT_TYPE.BYTE4;
+ int charIdx = offset;
+ int intIdx = 0;
+ final int charLimit = offset + length;
+ while(charIdx < charLimit) {
+ scratchIntsRef.grow(intIdx+1);
+ final int utf32 = Character.codePointAt(s, charIdx);
+ scratchIntsRef.ints[intIdx] = utf32;
+ charIdx += Character.charCount(utf32);
+ intIdx++;
+ }
+ scratchIntsRef.length = intIdx;
+ add(scratchIntsRef, output);
+ }
+
+ /** Sugar: adds the UTF32 codepoints from CharSequence. FST
+ * must be FST.INPUT_TYPE.BYTE4! */
+ public void add(CharSequence s, T output) throws IOException {
+ assert fst.getInputType() == FST.INPUT_TYPE.BYTE4;
+ int charIdx = 0;
+ int intIdx = 0;
+ final int charLimit = s.length();
+ while(charIdx < charLimit) {
+ scratchIntsRef.grow(intIdx+1);
+ final int utf32 = Character.codePointAt(s, charIdx);
+ scratchIntsRef.ints[intIdx] = utf32;
+ charIdx += Character.charCount(utf32);
+ intIdx++;
+ }
+ scratchIntsRef.length = intIdx;
+ add(scratchIntsRef, output);
+ }
+
+ /** It's OK to add the same input twice in a row with
+ * different outputs, as long as outputs impls the merge
+ * method. */
+ public void add(IntsRef input, T output) throws IOException {
+ //System.out.println("\nFST ADD: input=" + input + " output=" + fst.outputs.outputToString(output));
+ assert lastInput.length == 0 || input.compareTo(lastInput) >= 0: "inputs are added out of order lastInput=" + lastInput + " vs input=" + input;
+ assert validOutput(output);
+
+ //System.out.println("\nadd: " + input);
+ if (input.length == 0) {
+ // empty input: only allowed as first input. we have
+ // to special case this because the packed FST
+ // format cannot represent the empty input since
+ // 'finalness' is stored on the incoming arc, not on
+ // the node
+ frontier[0].inputCount++;
+ frontier[0].isFinal = true;
+ fst.setEmptyOutput(output);
+ return;
+ }
+
+ // compare shared prefix length
+ int pos1 = 0;
+ int pos2 = input.offset;
+ final int pos1Stop = Math.min(lastInput.length, input.length);
+ while(true) {
+ //System.out.println(" incr " + pos1);
+ frontier[pos1].inputCount++;
+ if (pos1 >= pos1Stop || lastInput.ints[pos1] != input.ints[pos2]) {
+ break;
+ }
+ pos1++;
+ pos2++;
+ }
+ final int prefixLenPlus1 = pos1+1;
+
+ if (frontier.length < input.length+1) {
+ @SuppressWarnings("unchecked") final UnCompiledNode<T>[] next =
+ new UnCompiledNode[ArrayUtil.oversize(input.length+1, RamUsageEstimator.NUM_BYTES_OBJECT_REF)];
+ System.arraycopy(frontier, 0, next, 0, frontier.length);
+ for(int idx=frontier.length;idx<next.length;idx++) {
+ next[idx] = new UnCompiledNode<T>(this, idx);
+ }
+ frontier = next;
+ }
+
+ // minimize/compile states from previous input's
+ // orphan'd suffix
+ compilePrevTail(prefixLenPlus1);
+
+ // init tail states for current input
+ for(int idx=prefixLenPlus1;idx<=input.length;idx++) {
+ frontier[idx-1].addArc(input.ints[input.offset + idx - 1],
+ frontier[idx]);
+ //System.out.println(" incr tail " + idx);
+ frontier[idx].inputCount++;
+ }
+
+ final UnCompiledNode<T> lastNode = frontier[input.length];
+ lastNode.isFinal = true;
+ lastNode.output = NO_OUTPUT;
+
+ // push conflicting outputs forward, only as far as
+ // needed
+ for(int idx=1;idx<prefixLenPlus1;idx++) {
+ final UnCompiledNode<T> node = frontier[idx];
+ final UnCompiledNode<T> parentNode = frontier[idx-1];
+
+ final T lastOutput = parentNode.getLastOutput(input.ints[input.offset + idx - 1]);
+ assert validOutput(lastOutput);
+
+ final T commonOutputPrefix;
+ final T wordSuffix;
+
+ if (lastOutput != NO_OUTPUT) {
+ commonOutputPrefix = fst.outputs.common(output, lastOutput);
+ assert validOutput(commonOutputPrefix);
+ wordSuffix = fst.outputs.subtract(lastOutput, commonOutputPrefix);
+ assert validOutput(wordSuffix);
+ parentNode.setLastOutput(input.ints[input.offset + idx - 1], commonOutputPrefix);
+ node.prependOutput(wordSuffix);
+ } else {
+ commonOutputPrefix = wordSuffix = NO_OUTPUT;
+ }
+
+ output = fst.outputs.subtract(output, commonOutputPrefix);
+ assert validOutput(output);
+ }
+
+ if (lastInput.length == input.length && prefixLenPlus1 == 1+input.length) {
+ // same input more than 1 time in a row, mapping to
+ // multiple outputs
+ lastNode.output = fst.outputs.merge(lastNode.output, output);
+ } else {
+ // this new arc is private to this new input; set its
+ // arc output to the leftover output:
+ frontier[prefixLenPlus1-1].setLastOutput(input.ints[input.offset + prefixLenPlus1-1], output);
+ }
+
+ // save last input
+ lastInput.copy(input);
+
+ //System.out.println(" count[0]=" + frontier[0].inputCount);
+ }
+
+ private boolean validOutput(T output) {
+ return output == NO_OUTPUT || !output.equals(NO_OUTPUT);
+ }
+
+ /** Returns final FST. NOTE: this will return null if
+ * nothing is accepted by the FST. */
+ public FST<T> finish() throws IOException {
+
+ // minimize nodes in the last word's suffix
+ compilePrevTail(1);
+ //System.out.println("finish: inputCount=" + frontier[0].inputCount);
+ if (frontier[0].inputCount < minSuffixCount1 || frontier[0].inputCount < minSuffixCount2 || frontier[0].numArcs == 0) {
+ if (fst.emptyOutput == null) {
+ return null;
+ } else if (minSuffixCount1 > 0 || minSuffixCount2 > 0) {
+ // empty string got pruned
+ return null;
+ } else {
+ fst.finish(compileNode(frontier[0], lastInput.length).address);
+ //System.out.println("compile addr = " + fst.getStartNode());
+ return fst;
+ }
+ } else {
+ if (minSuffixCount2 != 0) {
+ compileAllTargets(frontier[0], lastInput.length);
+ }
+ //System.out.println("NOW: " + frontier[0].numArcs);
+ fst.finish(compileNode(frontier[0], lastInput.length).address);
+ }
+
+ /*
+ if (dedupHash != null) {
+ System.out.println("NH: " + dedupHash.count());
+ }
+ */
+
+ return fst;
+ }
+
+ private void compileAllTargets(UnCompiledNode<T> node, int tailLength) throws IOException {
+ for(int arcIdx=0;arcIdx<node.numArcs;arcIdx++) {
+ final Arc<T> arc = node.arcs[arcIdx];
+ if (!arc.target.isCompiled()) {
+ // not yet compiled
+ @SuppressWarnings("unchecked") final UnCompiledNode<T> n = (UnCompiledNode<T>) arc.target;
+ if (n.numArcs == 0) {
+ //System.out.println("seg=" + segment + " FORCE final arc=" + (char) arc.label);
+ arc.isFinal = n.isFinal = true;
+ }
+ arc.target = compileNode(n, tailLength-1);
+ }
+ }
+ }
+
+ static class Arc<T> {
+ public int label; // really an "unsigned" byte
+ public Node target;
+ public boolean isFinal;
+ public T output;
+ public T nextFinalOutput;
+ }
+
+ // NOTE: not many instances of Node or CompiledNode are in
+ // memory while the FST is being built; it's only the
+ // current "frontier":
+
+ static interface Node {
+ boolean isCompiled();
+ }
+
+ static final class CompiledNode implements Node {
+ int address;
+ public boolean isCompiled() {
+ return true;
+ }
+ }
+
+ static final class UnCompiledNode<T> implements Node {
+ final Builder<T> owner;
+ int numArcs;
+ Arc<T>[] arcs;
+ T output;
+ boolean isFinal;
+ long inputCount;
+
+ /** This node's depth, starting from the automaton root. */
+ final int depth;
+
+ /**
+ * @param depth
+ * The node's depth starting from the automaton root. Needed for
+ * LUCENE-2934 (node expansion based on conditions other than the
+ * fanout size).
+ */
+ @SuppressWarnings("unchecked")
+ public UnCompiledNode(Builder<T> owner, int depth) {
+ this.owner = owner;
+ arcs = (Arc<T>[]) new Arc[1];
+ arcs[0] = new Arc<T>();
+ output = owner.NO_OUTPUT;
+ this.depth = depth;
+ }
+
+ public boolean isCompiled() {
+ return false;
+ }
+
+ public void clear() {
+ numArcs = 0;
+ isFinal = false;
+ output = owner.NO_OUTPUT;
+ inputCount = 0;
+
+ // We don't clear the depth here because it never changes
+ // for nodes on the frontier (even when reused).
+ }
+
+ public T getLastOutput(int labelToMatch) {
+ assert numArcs > 0;
+ assert arcs[numArcs-1].label == labelToMatch;
+ return arcs[numArcs-1].output;
+ }
+
+ public void addArc(int label, Node target) {
+ assert label >= 0;
+ assert numArcs == 0 || label > arcs[numArcs-1].label: "arc[-1].label=" + arcs[numArcs-1].label + " new label=" + label + " numArcs=" + numArcs;
+ if (numArcs == arcs.length) {
+ @SuppressWarnings("unchecked") final Arc<T>[] newArcs =
+ new Arc[ArrayUtil.oversize(numArcs+1, RamUsageEstimator.NUM_BYTES_OBJECT_REF)];
+ System.arraycopy(arcs, 0, newArcs, 0, arcs.length);
+ for(int arcIdx=numArcs;arcIdx<newArcs.length;arcIdx++) {
+ newArcs[arcIdx] = new Arc<T>();
+ }
+ arcs = newArcs;
+ }
+ final Arc<T> arc = arcs[numArcs++];
+ arc.label = label;
+ arc.target = target;
+ arc.output = arc.nextFinalOutput = owner.NO_OUTPUT;
+ arc.isFinal = false;
+ }
+
+ public void replaceLast(int labelToMatch, Node target, T nextFinalOutput, boolean isFinal) {
+ assert numArcs > 0;
+ final Arc<T> arc = arcs[numArcs-1];
+ assert arc.label == labelToMatch: "arc.label=" + arc.label + " vs " + labelToMatch;
+ arc.target = target;
+ //assert target.address != -2;
+ arc.nextFinalOutput = nextFinalOutput;
+ arc.isFinal = isFinal;
+ }
+
+ public void deleteLast(int label, Node target) {
+ assert numArcs > 0;
+ assert label == arcs[numArcs-1].label;
+ assert target == arcs[numArcs-1].target;
+ numArcs--;
+ }
+
+ public void setLastOutput(int labelToMatch, T newOutput) {
+ assert owner.validOutput(newOutput);
+ assert numArcs > 0;
+ final Arc<T> arc = arcs[numArcs-1];
+ assert arc.label == labelToMatch;
+ arc.output = newOutput;
+ }
+
+ // pushes an output prefix forward onto all arcs
+ public void prependOutput(T outputPrefix) {
+ assert owner.validOutput(outputPrefix);
+
+ for(int arcIdx=0;arcIdx<numArcs;arcIdx++) {
+ arcs[arcIdx].output = owner.fst.outputs.add(outputPrefix, arcs[arcIdx].output);
+ assert owner.validOutput(arcs[arcIdx].output);
+ }
+
+ if (isFinal) {
+ output = owner.fst.outputs.add(outputPrefix, output);
+ assert owner.validOutput(output);
+ }
+ }
+ }
+}
fnp / pylucene.git / blobdiff