com.oracle.truffle.regex.tregex.automaton

Class StateTransitionCanonicalizer<TS extends TransitionSet,TB extends TransitionBuilder<TS>>

java.lang.Object

com.oracle.truffle.regex.tregex.automaton.StateTransitionCanonicalizer<TS,TB>

Type Parameters:

TS - represents a set of NFA transitions.

TB - represents a DFA transition fragment. This type is used for both intermediate and final results.

Direct Known Subclasses:

ASTTransitionCanonicalizer, DFATransitionCanonicalizer

public abstract class StateTransitionCanonicalizer<TS extends TransitionSet,TB extends TransitionBuilder<TS>>
extends Object

This class provides an algorithm for converting a list of NFA transitions into a set of DFA transitions.

See Also:

TransitionSet, TransitionBuilder

Constructor Summary

Constructors

Constructor and Description
StateTransitionCanonicalizer()

Method Summary

Modifier and Type	Method and Description
protected abstract TB[]	createResultArray(int size) Returns an array suitable for holding the result of StateTransitionCanonicalizer.run(List, CompilationBuffer).
protected abstract boolean	isSameTargetMergeAllowed(TB a, TB b) Returns true if two DFA transitions leading to the same target state are allowed to be merged into one.
TB[]	run(List<TB> transitions, CompilationBuffer compilationBuffer) Runs the NFA to DFA transition conversion algorithm.

Methods inherited from class java.lang.Object

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

Constructor Detail

StateTransitionCanonicalizer

public StateTransitionCanonicalizer()

Method Detail

run

public TB[] run(List<TB> transitions,
                CompilationBuffer compilationBuffer)

Runs the NFA to DFA transition conversion algorithm. This algorithm has two phases:

1. Merge NFA transitions according to their expected character sets. The result of this phase is a list of TransitionBuilders whose CharSets have no more intersections.
2. Merge TransitionBuilders generated by the first phase if their target state is equal and StateTransitionCanonicalizer.isSameTargetMergeAllowed(TransitionBuilder, TransitionBuilder) returns true.

Parameters:

transitions - The list of NFA transitions to merge. Initially, all TransitionBuilders contained in this list should represent a single NFA transition.

Returns:

a set of transition builders representing the DFA transitions generated from the given NFA transitions.

isSameTargetMergeAllowed

protected abstract boolean isSameTargetMergeAllowed(TB a,
                                                    TB b)

Returns true if two DFA transitions leading to the same target state are allowed to be merged into one.

createResultArray

protected abstract TB[] createResultArray(int size)

Returns an array suitable for holding the result of StateTransitionCanonicalizer.run(List, CompilationBuffer).