1 // © 2016 and later: Unicode, Inc. and others. 2 // License & terms of use: http://www.unicode.org/copyright.html 3 /* 4 ********************************************************************** 5 * Copyright (c) 2000-2005, International Business Machines 6 * Corporation and others. All Rights Reserved. 7 ********************************************************************** 8 * Date Name Description 9 * 02/04/00 aliu Creation. 10 ********************************************************************** 11 */ 12 #ifndef SYMTABLE_H 13 #define SYMTABLE_H 14 15 #include "unicode/utypes.h" 16 17 #if U_SHOW_CPLUSPLUS_API 18 19 #include "unicode/uobject.h" 20 21 /** 22 * \file 23 * \brief C++ API: An interface that defines both lookup protocol and parsing of 24 * symbolic names. 25 */ 26 27 U_NAMESPACE_BEGIN 28 29 class ParsePosition; 30 class UnicodeFunctor; 31 class UnicodeSet; 32 class UnicodeString; 33 34 /** 35 * An interface that defines both lookup protocol and parsing of 36 * symbolic names. 37 * 38 * <p>A symbol table maintains two kinds of mappings. The first is 39 * between symbolic names and their values. For example, if the 40 * variable with the name "start" is set to the value "alpha" 41 * (perhaps, though not necessarily, through an expression such as 42 * "$start=alpha"), then the call lookup("start") will return the 43 * char[] array ['a', 'l', 'p', 'h', 'a']. 44 * 45 * <p>The second kind of mapping is between character values and 46 * UnicodeMatcher objects. This is used by RuleBasedTransliterator, 47 * which uses characters in the private use area to represent objects 48 * such as UnicodeSets. If U+E015 is mapped to the UnicodeSet [a-z], 49 * then lookupMatcher(0xE015) will return the UnicodeSet [a-z]. 50 * 51 * <p>Finally, a symbol table defines parsing behavior for symbolic 52 * names. All symbolic names start with the SYMBOL_REF character. 53 * When a parser encounters this character, it calls parseReference() 54 * with the position immediately following the SYMBOL_REF. The symbol 55 * table parses the name, if there is one, and returns it. 56 * 57 * @stable ICU 2.8 58 */ 59 class U_COMMON_API SymbolTable /* not : public UObject because this is an interface/mixin class */ { 60 public: 61 62 /** 63 * The character preceding a symbol reference name. 64 * @stable ICU 2.8 65 */ 66 enum { SYMBOL_REF = 0x0024 /*$*/ }; 67 68 /** 69 * Destructor. 70 * @stable ICU 2.8 71 */ 72 virtual ~SymbolTable(); 73 74 /** 75 * Lookup the characters associated with this string and return it. 76 * Return <tt>NULL</tt> if no such name exists. The resultant 77 * string may have length zero. 78 * @param s the symbolic name to lookup 79 * @return a string containing the name's value, or <tt>NULL</tt> if 80 * there is no mapping for s. 81 * @stable ICU 2.8 82 */ 83 virtual const UnicodeString* lookup(const UnicodeString& s) const = 0; 84 85 /** 86 * Lookup the UnicodeMatcher associated with the given character, and 87 * return it. Return <tt>NULL</tt> if not found. 88 * @param ch a 32-bit code point from 0 to 0x10FFFF inclusive. 89 * @return the UnicodeMatcher object represented by the given 90 * character, or NULL if there is no mapping for ch. 91 * @stable ICU 2.8 92 */ 93 virtual const UnicodeFunctor* lookupMatcher(UChar32 ch) const = 0; 94 95 /** 96 * Parse a symbol reference name from the given string, starting 97 * at the given position. If no valid symbol reference name is 98 * found, return the empty string and leave pos unchanged. That is, if the 99 * character at pos cannot start a name, or if pos is at or after 100 * text.length(), then return an empty string. This indicates an 101 * isolated SYMBOL_REF character. 102 * @param text the text to parse for the name 103 * @param pos on entry, the index of the first character to parse. 104 * This is the character following the SYMBOL_REF character. On 105 * exit, the index after the last parsed character. If the parse 106 * failed, pos is unchanged on exit. 107 * @param limit the index after the last character to be parsed. 108 * @return the parsed name, or an empty string if there is no 109 * valid symbolic name at the given position. 110 * @stable ICU 2.8 111 */ 112 virtual UnicodeString parseReference(const UnicodeString& text, 113 ParsePosition& pos, int32_t limit) const = 0; 114 }; 115 U_NAMESPACE_END 116 117 #endif /* U_SHOW_CPLUSPLUS_API */ 118 119 #endif 120