org.carrot2.text.suffixtree
Class SuffixTree

java.lang.Object
  org.carrot2.text.suffixtree.SuffixTree

public final class SuffixTree
extends Object

Builds a suffix tree (or generalized suffix tree) on a sequence of any integers (or objects that can be represented as unique integers). A direct implementation of Esko Ukkonen's algorithm, but optimized for Java to use primitive data types instead of objects (or boxed types).

See Also:

"E. Ukkonen, On-line construction of suffix trees, Algorithmica, 1995, volume 14, number 3, pages 249-260."

Nested Class Summary

static interface	SuffixTree.IProgressCallback Progress callback is invoked when iterating forward through the input sequence elements.
static interface	SuffixTree.IStateCallback A callback invoked when new states are added to the tree.
static interface	SuffixTree.IVisitor Visitor interface for traversals.
static class	SuffixTree.VisitorAdapter Empty implementation recursively walking the entire suffix tree.

Field Summary

static int

NO_EDGE Marker for the state's last edge in transitions.

Constructor Summary

SuffixTree(ISequence sequence, SuffixTree.IStateCallback newStateCallback, SuffixTree.IProgressCallback progressCallback)
Build a suffix tree for a given input sequence of symbols.

Method Summary

boolean	containsSuffix(ISequence seq)
int	findEdge(int state, int symbol) Find a transition from state state, labeled with a given symbol.
int	firstEdge(int state) Returns the index of the first edge from a given state or NO_EDGE if a given state has no edges.
int	getEndIndex(int edge) Returns the edge label's end index (inclusive).
int	getRootState() For procedural traversals (not visitors).
int	getStartIndex(int edge) Returns the edge label's start index (inclusive).
int	getStatesCount()
int	getToState(int edge) Returns the target state for a given edge.
int	getTransitionsCount()
boolean	isLeaf(int state) Check if state is a leaf (has no outgoing edges).
int	nextEdge(int edge) Returns the index of the next edge (sibling) or NO_EDGE if edge is the last edge in its state.
void	visit(SuffixTree.IVisitor visitor) Walks the states and edges of the suffix tree, depth-first.
void	visitState(int state, SuffixTree.IVisitor visitor) Start visiting from a given state.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NO_EDGE

public static final int NO_EDGE

Marker for the state's last edge in transitions.

See Also:

Constant Field Values

Constructor Detail

SuffixTree

public SuffixTree(ISequence sequence,
                  SuffixTree.IStateCallback newStateCallback,
                  SuffixTree.IProgressCallback progressCallback)

Build a suffix tree for a given input sequence of symbols.

Method Detail

getTransitionsCount

public final int getTransitionsCount()

Returns:

Return the number of transitions (edges) in the tree.

getStatesCount

public final int getStatesCount()

Returns:

Return the number of states in the tree.

containsSuffix

public boolean containsSuffix(ISequence seq)

Returns:

true if this suffix tree has a path from the root state to a leaf state corresponding to a given sequence of objects. This indicates the input sequence had a suffix identical to sequence.

visit

public final void visit(SuffixTree.IVisitor visitor)

Walks the states and edges of the suffix tree, depth-first.

visitState

public final void visitState(int state,
                             SuffixTree.IVisitor visitor)

Start visiting from a given state.

getRootState

public int getRootState()

For procedural traversals (not visitors).

isLeaf

public final boolean isLeaf(int state)

Check if state is a leaf (has no outgoing edges).

firstEdge

public final int firstEdge(int state)

Returns the index of the first edge from a given state or NO_EDGE if a given state has no edges. Does not perform any sanity check on the input state.

nextEdge

public final int nextEdge(int edge)

Returns the index of the next edge (sibling) or NO_EDGE if edge is the last edge in its state.

findEdge

public final int findEdge(int state,
                          int symbol)

Find a transition from state state, labeled with a given symbol. NO_EDGE is returned if there is no such edge.

getToState

public int getToState(int edge)

Returns the target state for a given edge.

getStartIndex

public int getStartIndex(int edge)

Returns the edge label's start index (inclusive).

getEndIndex

public int getEndIndex(int edge)

Returns the edge label's end index (inclusive).