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public static GetCommonPrefix ( |
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/// <summary>
/// Returns the longest string that is a suffix of all accepted strings and
/// visits each state at most once.
/// </summary>
/// <returns> Common suffix. </returns>
public static string GetCommonSuffix(Automaton a)
{
if (a.IsSingleton) // if singleton, the suffix is the string itself.
{
return(a.singleton);
}
// reverse the language of the automaton, then reverse its common prefix.
Automaton r = (Automaton)a.Clone();
Reverse(r);
r.Determinize();
return((new StringBuilder(SpecialOperations.GetCommonPrefix(r))).Reverse().ToString());
}
public CompiledAutomaton(Automaton automaton, bool?finite, bool simplify)
{
if (simplify)
{
// Test whether the automaton is a "simple" form and
// if so, don't create a runAutomaton. Note that on a
// large automaton these tests could be costly:
if (BasicOperations.IsEmpty(automaton))
{
// matches nothing
Type = AUTOMATON_TYPE.NONE;
Term = null;
CommonSuffixRef = null;
RunAutomaton = null;
sortedTransitions = null;
this.Finite = null;
return;
}
else if (BasicOperations.IsTotal(automaton))
{
// matches all possible strings
Type = AUTOMATON_TYPE.ALL;
Term = null;
CommonSuffixRef = null;
RunAutomaton = null;
sortedTransitions = null;
this.Finite = null;
return;
}
else
{
string commonPrefix;
string singleton;
if (automaton.Singleton == null)
{
commonPrefix = SpecialOperations.GetCommonPrefix(automaton);
if (commonPrefix.Length > 0 && BasicOperations.SameLanguage(automaton, BasicAutomata.MakeString(commonPrefix)))
{
singleton = commonPrefix;
}
else
{
singleton = null;
}
}
else
{
commonPrefix = null;
singleton = automaton.Singleton;
}
if (singleton != null)
{
// matches a fixed string in singleton or expanded
// representation
Type = AUTOMATON_TYPE.SINGLE;
Term = new BytesRef(singleton);
CommonSuffixRef = null;
RunAutomaton = null;
sortedTransitions = null;
this.Finite = null;
return;
}
else if (BasicOperations.SameLanguage(automaton, BasicOperations.Concatenate(BasicAutomata.MakeString(commonPrefix), BasicAutomata.MakeAnyString())))
{
// matches a constant prefix
Type = AUTOMATON_TYPE.PREFIX;
Term = new BytesRef(commonPrefix);
CommonSuffixRef = null;
RunAutomaton = null;
sortedTransitions = null;
this.Finite = null;
return;
}
}
}
Type = AUTOMATON_TYPE.NORMAL;
Term = null;
if (finite == null)
{
this.Finite = SpecialOperations.IsFinite(automaton);
}
else
{
this.Finite = finite;
}
Automaton utf8 = (new UTF32ToUTF8()).Convert(automaton);
if (this.Finite == true)
{
CommonSuffixRef = null;
}
else
{
CommonSuffixRef = SpecialOperations.GetCommonSuffixBytesRef(utf8);
}
RunAutomaton = new ByteRunAutomaton(utf8, true);
sortedTransitions = utf8.GetSortedTransitions();
}