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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 * "$start=alpha"), then the call lookup("start") will return the | |
38 * char[] array ['a', 'l', 'p', 'h', 'a']. | |
39 * | |
40 * <p>The second kind of mapping is between character values and | |
41 * UnicodeMatcher objects. This is used by RuleBasedTransliterator, | |
42 * which uses characters in the private use area to represent objects | |
43 * such as UnicodeSets. If U+E015 is mapped to the UnicodeSet [a-z], | |
44 * then lookupMatcher(0xE015) will return the UnicodeSet [a-z]. | |
45 * | |
46 * <p>Finally, a symbol table defines parsing behavior for symbolic | |
47 * names. All symbolic names start with the SYMBOL_REF character. | |
48 * When a parser encounters this character, it calls parseReference() | |
49 * with the position immediately following the SYMBOL_REF. The symbol | |
50 * table parses the name, if there is one, and returns it. | |
51 * | |
52 * @stable ICU 2.8 | |
53 */ | |
54 class U_COMMON_API SymbolTable /* not : public UObject because this is an interf
ace/mixin class */ { | |
55 public: | |
56 | |
57 /** | |
58 * The character preceding a symbol reference name. | |
59 * @stable ICU 2.8 | |
60 */ | |
61 enum { SYMBOL_REF = 0x0024 /*$*/ }; | |
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) cons
t = 0; | |
109 }; | |
110 U_NAMESPACE_END | |
111 | |
112 #endif | |
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