74 lines
2.6 KiB
C++
74 lines
2.6 KiB
C++
/*
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**********************************************************************
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* Copyright (C) 1999, International Business Machines Corporation and others. All Rights Reserved.
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**********************************************************************
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* Date Name Description
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* 11/17/99 aliu Creation.
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**********************************************************************
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*/
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#ifndef UNIFLTLG_H
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#define UNIFLTLG_H
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#include "unicode/utypes.h"
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class UnicodeFilter;
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/**
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* <code>UnicodeFilterLogic</code> provides logical operators on
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* {@link UnicodeFilter} objects. This class cannot be instantiated;
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* it consists only of static methods. The static methods return
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* filter objects that perform logical inversion (<tt>not</tt>),
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* intersection (<tt>and</tt>), or union (<tt>or</tt>) of the given
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* filter objects.
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*
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* If a UnicodeFilter* f is passed in, where f == NULL, then that
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* is treated as a filter that contains all Unicode characters.
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* Therefore, createNot(NULL) returns a filter that contains no
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* Unicode characters. Likewise, createAnd(g, NULL) returns g->clone(),
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* and createAnd(NULL, NULL) returns NULL.
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*/
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class U_I18N_API UnicodeFilterLogic {
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public:
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/**
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* Returns a <tt>UnicodeFilter</tt> that implements the inverse of
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* the given filter.
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* @param f may be NULL
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* @result always non-NULL
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*/
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static UnicodeFilter* createNot(const UnicodeFilter* f);
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/**
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* Returns a <tt>UnicodeFilter</tt> that implements a short
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* circuit AND of the result of the two given filters. That is,
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* if <tt>f.contains()</tt> is <tt>false</tt>, then <tt>g.contains()</tt>
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* is not called, and <tt>contains()</tt> returns <tt>false</tt>.
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* @param f may be NULL
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* @param g may be NULL
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* @result will be NULL if and only if f == g == NULL
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*/
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static UnicodeFilter* createAnd(const UnicodeFilter* f,
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const UnicodeFilter* g);
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/**
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* Returns a <tt>UnicodeFilter</tt> that implements a short
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* circuit OR of the result of the two given filters. That is, if
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* <tt>f.contains()</tt> is <tt>true</tt>, then <tt>g.contains()</tt> is
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* not called, and <tt>contains()</tt> returns <tt>true</tt>.
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* @param f may be NULL
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* @param g may be NULL
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* @result will be NULL if and only if f == g == NULL
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*/
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static UnicodeFilter* createOr(const UnicodeFilter* f,
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const UnicodeFilter* g);
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private:
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// Disallow instantiation
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UnicodeFilterLogic();
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};
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inline UnicodeFilterLogic::UnicodeFilterLogic() {}
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#endif
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