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