/**
* Looks up the output for this input, or null if the input is not accepted. FST must be
* INPUT_TYPE.BYTE4.
*/
public static <T> T get(FST<T> fst, IntsRef input) throws IOException {
assert fst.inputType == FST.INPUT_TYPE.BYTE4;
// TODO: would be nice not to alloc this on every lookup
final FST.Arc<T> arc = fst.getFirstArc(new FST.Arc<T>());
// Accumulate output as we go
final T NO_OUTPUT = fst.outputs.getNoOutput();
T output = NO_OUTPUT;
for (int i = 0; i < input.length; i++) {
if (fst.findTargetArc(input.ints[input.offset + i], arc, arc) == null) {
return null;
} else if (arc.output != NO_OUTPUT) {
output = fst.outputs.add(output, arc.output);
}
}
if (fst.findTargetArc(FST.END_LABEL, arc, arc) == null) {
return null;
} else if (arc.output != NO_OUTPUT) {
return fst.outputs.add(output, arc.output);
} else {
return output;
}
}
/**
* Logically casts input to UTF32 ints then looks up the output or null if the input is not
* accepted. FST must be INPUT_TYPE.BYTE4.
*/
public static <T> T get(FST<T> fst, CharSequence input) throws IOException {
assert fst.inputType == FST.INPUT_TYPE.BYTE4;
// TODO: would be nice not to alloc this on every lookup
final FST.Arc<T> arc = fst.getFirstArc(new FST.Arc<T>());
int charIdx = 0;
final int charLimit = input.length();
// Accumulate output as we go
final T NO_OUTPUT = fst.outputs.getNoOutput();
T output = NO_OUTPUT;
while (charIdx < charLimit) {
final int utf32 = Character.codePointAt(input, charIdx);
charIdx += Character.charCount(utf32);
if (fst.findTargetArc(utf32, arc, arc) == null) {
return null;
} else if (arc.output != NO_OUTPUT) {
output = fst.outputs.add(output, arc.output);
}
}
if (fst.findTargetArc(FST.END_LABEL, arc, arc) == null) {
return null;
} else if (arc.output != NO_OUTPUT) {
return fst.outputs.add(output, arc.output);
} else {
return output;
}
}
/**
* Dumps an {@link FST} to a GraphViz's <code>dot</code> language description for visualization.
* Example of use:
*
* <pre>
* PrintStream ps = new PrintStream("out.dot");
* fst.toDot(ps);
* ps.close();
* </pre>
*
* and then, from command line:
*
* <pre>
* dot -Tpng -o out.png out.dot
* </pre>
*
* <p>Note: larger FSTs (a few thousand nodes) won't even render, don't bother.
*
* @param sameRank If <code>true</code>, the resulting <code>dot</code> file will try to order
* states in layers of breadth-first traversal. This may mess up arcs, but makes the output
* FST's structure a bit clearer.
* @param labelStates If <code>true</code> states will have labels equal to their offsets in their
* binary format. Expands the graph considerably.
* @see "http://www.graphviz.org/"
*/
public static <T> void toDot(FST<T> fst, Writer out, boolean sameRank, boolean labelStates)
throws IOException {
final String expandedNodeColor = "blue";
// This is the start arc in the automaton (from the epsilon state to the first state
// with outgoing transitions.
final FST.Arc<T> startArc = fst.getFirstArc(new FST.Arc<T>());
// A queue of transitions to consider for the next level.
final List<FST.Arc<T>> thisLevelQueue = new ArrayList<FST.Arc<T>>();
// A queue of transitions to consider when processing the next level.
final List<FST.Arc<T>> nextLevelQueue = new ArrayList<FST.Arc<T>>();
nextLevelQueue.add(startArc);
// A list of states on the same level (for ranking).
final List<Integer> sameLevelStates = new ArrayList<Integer>();
// A bitset of already seen states (target offset).
final BitSet seen = new BitSet();
seen.set(startArc.target);
// Shape for states.
final String stateShape = "circle";
// Emit DOT prologue.
out.write("digraph FST {\n");
out.write(" rankdir = LR; splines=true; concentrate=true; ordering=out; ranksep=2.5; \n");
if (!labelStates) {
out.write(" node [shape=circle, width=.2, height=.2, style=filled]\n");
}
emitDotState(out, "initial", "point", "white", "");
emitDotState(
out,
Integer.toString(startArc.target),
stateShape,
fst.isExpandedTarget(startArc) ? expandedNodeColor : null,
"");
out.write(" initial -> " + startArc.target + "\n");
final T NO_OUTPUT = fst.outputs.getNoOutput();
int level = 0;
while (!nextLevelQueue.isEmpty()) {
// we could double buffer here, but it doesn't matter probably.
thisLevelQueue.addAll(nextLevelQueue);
nextLevelQueue.clear();
level++;
out.write("\n // Transitions and states at level: " + level + "\n");
while (!thisLevelQueue.isEmpty()) {
final FST.Arc<T> arc = thisLevelQueue.remove(thisLevelQueue.size() - 1);
if (fst.targetHasArcs(arc)) {
// scan all arcs
final int node = arc.target;
fst.readFirstTargetArc(arc, arc);
while (true) {
// Emit the unseen state and add it to the queue for the next level.
if (arc.target >= 0 && !seen.get(arc.target)) {
final boolean isExpanded = fst.isExpandedTarget(arc);
emitDotState(
out,
Integer.toString(arc.target),
stateShape,
isExpanded ? expandedNodeColor : null,
labelStates ? Integer.toString(arc.target) : "");
seen.set(arc.target);
nextLevelQueue.add(new FST.Arc<T>().copyFrom(arc));
sameLevelStates.add(arc.target);
}
String outs;
if (arc.output != NO_OUTPUT) {
outs = "/" + fst.outputs.outputToString(arc.output);
} else {
outs = "";
}
final String cl;
if (arc.label == FST.END_LABEL) {
cl = "~";
} else {
cl = printableLabel(arc.label);
}
out.write(" " + node + " -> " + arc.target + " [label=\"" + cl + outs + "\"]\n");
// Break the loop if we're on the last arc of this state.
if (arc.isLast()) {
break;
}
fst.readNextArc(arc);
}
}
}
// Emit state ranking information.
if (sameRank && sameLevelStates.size() > 1) {
out.write(" {rank=same; ");
for (int state : sameLevelStates) {
out.write(state + "; ");
}
out.write(" }\n");
}
sameLevelStates.clear();
}
// Emit terminating state (always there anyway).
out.write(" -1 [style=filled, color=black, shape=circle, label=\"\"]\n\n");
out.write(" {rank=sink; -1 }\n");
out.write("}\n");
out.flush();
}