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 **********************************************************************
13 #include "unicode/utypes.h"
14 #include "unicode/uobject.h"
18 * \brief C++ API: An interface that defines both lookup protocol and parsing of
30 * An interface that defines both lookup protocol and parsing of
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 * "$start=alpha"), then the call lookup("start") will return the
38 * char[] array ['a', 'l', 'p', 'h', 'a'].
40 * <p>The second kind of mapping is between character values and
41 * UnicodeMatcher objects. This is used by RuleBasedTransliterator,
42 * which uses characters in the private use area to represent objects
43 * such as UnicodeSets. If U+E015 is mapped to the UnicodeSet [a-z],
44 * then lookupMatcher(0xE015) will return the UnicodeSet [a-z].
46 * <p>Finally, a symbol table defines parsing behavior for symbolic
47 * names. All symbolic names start with the SYMBOL_REF character.
48 * When a parser encounters this character, it calls parseReference()
49 * with the position immediately following the SYMBOL_REF. The symbol
50 * table parses the name, if there is one, and returns it.
54 class U_COMMON_API SymbolTable /* not : public UObject because this is an interface/mixin class */ {
58 * The character preceding a symbol reference name.
61 enum { SYMBOL_REF = 0x0024 /*$*/ };
67 virtual ~SymbolTable();
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.
78 virtual const UnicodeString* lookup(const UnicodeString& s) const = 0;
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.
88 virtual const UnicodeFunctor* lookupMatcher(UChar32 ch) const = 0;
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.
107 virtual UnicodeString parseReference(const UnicodeString& text,
108 ParsePosition& pos, int32_t limit) const = 0;