120 lines
4.3 KiB
C++
120 lines
4.3 KiB
C++
// © 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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/*
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**********************************************************************
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* Copyright (c) 2000-2005, International Business Machines
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* Corporation and others. All Rights Reserved.
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**********************************************************************
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* Date Name Description
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* 02/04/00 aliu Creation.
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**********************************************************************
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*/
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#ifndef SYMTABLE_H
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#define SYMTABLE_H
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#include "unicode/utypes.h"
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#if U_SHOW_CPLUSPLUS_API
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#include "unicode/uobject.h"
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/**
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* \file
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* \brief C++ API: An interface that defines both lookup protocol and parsing of
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* symbolic names.
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*/
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U_NAMESPACE_BEGIN
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class ParsePosition;
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class UnicodeFunctor;
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class UnicodeSet;
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class UnicodeString;
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/**
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* An interface that defines both lookup protocol and parsing of
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* symbolic names.
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*
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* <p>A symbol table maintains two kinds of mappings. The first is
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* between symbolic names and their values. For example, if the
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* variable with the name "start" is set to the value "alpha"
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* (perhaps, though not necessarily, through an expression such as
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* "$start=alpha"), then the call lookup("start") will return the
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* char[] array ['a', 'l', 'p', 'h', 'a'].
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*
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* <p>The second kind of mapping is between character values and
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* UnicodeMatcher objects. This is used by RuleBasedTransliterator,
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* which uses characters in the private use area to represent objects
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* such as UnicodeSets. If U+E015 is mapped to the UnicodeSet [a-z],
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* then lookupMatcher(0xE015) will return the UnicodeSet [a-z].
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*
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* <p>Finally, a symbol table defines parsing behavior for symbolic
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* names. All symbolic names start with the SYMBOL_REF character.
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* When a parser encounters this character, it calls parseReference()
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* with the position immediately following the SYMBOL_REF. The symbol
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* table parses the name, if there is one, and returns it.
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*
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* @stable ICU 2.8
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*/
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class U_COMMON_API SymbolTable /* not : public UObject because this is an interface/mixin class */ {
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public:
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/**
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* The character preceding a symbol reference name.
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* @stable ICU 2.8
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*/
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enum { SYMBOL_REF = 0x0024 /*$*/ };
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/**
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* Destructor.
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* @stable ICU 2.8
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*/
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virtual ~SymbolTable();
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/**
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* Lookup the characters associated with this string and return it.
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* Return <tt>nullptr</tt> if no such name exists. The resultant
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* string may have length zero.
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* @param s the symbolic name to lookup
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* @return a string containing the name's value, or <tt>nullptr</tt> if
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* there is no mapping for s.
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* @stable ICU 2.8
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*/
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virtual const UnicodeString* lookup(const UnicodeString& s) const = 0;
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/**
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* Lookup the UnicodeMatcher associated with the given character, and
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* return it. Return <tt>nullptr</tt> if not found.
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* @param ch a 32-bit code point from 0 to 0x10FFFF inclusive.
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* @return the UnicodeMatcher object represented by the given
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* character, or nullptr if there is no mapping for ch.
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* @stable ICU 2.8
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*/
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virtual const UnicodeFunctor* lookupMatcher(UChar32 ch) const = 0;
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/**
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* Parse a symbol reference name from the given string, starting
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* at the given position. If no valid symbol reference name is
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* found, return the empty string and leave pos unchanged. That is, if the
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* character at pos cannot start a name, or if pos is at or after
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* text.length(), then return an empty string. This indicates an
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* isolated SYMBOL_REF character.
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* @param text the text to parse for the name
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* @param pos on entry, the index of the first character to parse.
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* This is the character following the SYMBOL_REF character. On
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* exit, the index after the last parsed character. If the parse
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* failed, pos is unchanged on exit.
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* @param limit the index after the last character to be parsed.
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* @return the parsed name, or an empty string if there is no
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* valid symbolic name at the given position.
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* @stable ICU 2.8
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*/
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virtual UnicodeString parseReference(const UnicodeString& text,
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ParsePosition& pos, int32_t limit) const = 0;
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};
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U_NAMESPACE_END
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#endif /* U_SHOW_CPLUSPLUS_API */
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#endif
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