1 /* 2 ********************************************************************** 3 * Copyright (c) 2003-2007, International Business Machines 4 * Corporation and others. All Rights Reserved. 5 ********************************************************************** 6 * Author: Alan Liu 7 * Created: September 24 2003 8 * Since: ICU 2.8 9 ********************************************************************** 10 */ 11 #ifndef _RULEITER_H_ 12 #define _RULEITER_H_ 13 14 #include "unicode/uobject.h" 15 16 U_NAMESPACE_BEGIN 17 18 class UnicodeString; 19 class ParsePosition; 20 class SymbolTable; 21 22 /** 23 * An iterator that returns 32-bit code points. This class is deliberately 24 * <em>not</em> related to any of the ICU character iterator classes 25 * in order to minimize complexity. 26 * @author Alan Liu 27 * @since ICU 2.8 28 */ 29 class RuleCharacterIterator : public UMemory { 30 31 // TODO: Ideas for later. (Do not implement if not needed, lest the 32 // code coverage numbers go down due to unused methods.) 33 // 1. Add a copy constructor, operator==() method. 34 // 2. Rather than return DONE, throw an exception if the end 35 // is reached -- this is an alternate usage model, probably not useful. 36 37 private: 38 /** 39 * Text being iterated. 40 */ 41 const UnicodeString& text; 42 43 /** 44 * Position of iterator. 45 */ 46 ParsePosition& pos; 47 48 /** 49 * Symbol table used to parse and dereference variables. May be 0. 50 */ 51 const SymbolTable* sym; 52 53 /** 54 * Current variable expansion, or 0 if none. 55 */ 56 const UnicodeString* buf; 57 58 /** 59 * Position within buf. Meaningless if buf == 0. 60 */ 61 int32_t bufPos; 62 63 public: 64 /** 65 * Value returned when there are no more characters to iterate. 66 */ 67 enum { DONE = -1 }; 68 69 /** 70 * Bitmask option to enable parsing of variable names. If (options & 71 * PARSE_VARIABLES) != 0, then an embedded variable will be expanded to 72 * its value. Variables are parsed using the SymbolTable API. 73 */ 74 enum { PARSE_VARIABLES = 1 }; 75 76 /** 77 * Bitmask option to enable parsing of escape sequences. If (options & 78 * PARSE_ESCAPES) != 0, then an embedded escape sequence will be expanded 79 * to its value. Escapes are parsed using Utility.unescapeAt(). 80 */ 81 enum { PARSE_ESCAPES = 2 }; 82 83 /** 84 * Bitmask option to enable skipping of whitespace. If (options & 85 * SKIP_WHITESPACE) != 0, then whitespace characters will be silently 86 * skipped, as if they were not present in the input. Whitespace 87 * characters are defined by UCharacterProperty.isRuleWhiteSpace(). 88 */ 89 enum { SKIP_WHITESPACE = 4 }; 90 91 /** 92 * Constructs an iterator over the given text, starting at the given 93 * position. 94 * @param text the text to be iterated 95 * @param sym the symbol table, or null if there is none. If sym is null, 96 * then variables will not be deferenced, even if the PARSE_VARIABLES 97 * option is set. 98 * @param pos upon input, the index of the next character to return. If a 99 * variable has been dereferenced, then pos will <em>not</em> increment as 100 * characters of the variable value are iterated. 101 */ 102 RuleCharacterIterator(const UnicodeString& text, const SymbolTable* sym, 103 ParsePosition& pos); 104 105 /** 106 * Returns true if this iterator has no more characters to return. 107 */ 108 UBool atEnd() const; 109 110 /** 111 * Returns the next character using the given options, or DONE if there 112 * are no more characters, and advance the position to the next 113 * character. 114 * @param options one or more of the following options, bitwise-OR-ed 115 * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. 116 * @param isEscaped output parameter set to TRUE if the character 117 * was escaped 118 * @param ec input-output error code. An error will only be set by 119 * this routing if options includes PARSE_VARIABLES and an unknown 120 * variable name is seen, or if options includes PARSE_ESCAPES and 121 * an invalid escape sequence is seen. 122 * @return the current 32-bit code point, or DONE 123 */ 124 UChar32 next(int32_t options, UBool& isEscaped, UErrorCode& ec); 125 126 /** 127 * Returns true if this iterator is currently within a variable expansion. 128 */ 129 inline UBool inVariable() const; 130 131 /** 132 * An opaque object representing the position of a RuleCharacterIterator. 133 */ 134 struct Pos : public UMemory { 135 private: 136 const UnicodeString* buf; 137 int32_t pos; 138 int32_t bufPos; 139 friend class RuleCharacterIterator; 140 }; 141 142 /** 143 * Sets an object which, when later passed to setPos(), will 144 * restore this iterator's position. Usage idiom: 145 * 146 * RuleCharacterIterator iterator = ...; 147 * RuleCharacterIterator::Pos pos; 148 * iterator.getPos(pos); 149 * for (;;) { 150 * iterator.getPos(pos); 151 * int c = iterator.next(...); 152 * ... 153 * } 154 * iterator.setPos(pos); 155 * 156 * @param p a position object to be set to this iterator's 157 * current position. 158 */ 159 void getPos(Pos& p) const; 160 161 /** 162 * Restores this iterator to the position it had when getPos() 163 * set the given object. 164 * @param p a position object previously set by getPos() 165 */ 166 void setPos(const Pos& p); 167 168 /** 169 * Skips ahead past any ignored characters, as indicated by the given 170 * options. This is useful in conjunction with the lookahead() method. 171 * 172 * Currently, this only has an effect for SKIP_WHITESPACE. 173 * @param options one or more of the following options, bitwise-OR-ed 174 * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. 175 */ 176 void skipIgnored(int32_t options); 177 178 /** 179 * Returns a string containing the remainder of the characters to be 180 * returned by this iterator, without any option processing. If the 181 * iterator is currently within a variable expansion, this will only 182 * extend to the end of the variable expansion. This method is provided 183 * so that iterators may interoperate with string-based APIs. The typical 184 * sequence of calls is to call skipIgnored(), then call lookahead(), then 185 * parse the string returned by lookahead(), then call jumpahead() to 186 * resynchronize the iterator. 187 * @param result a string to receive the characters to be returned 188 * by future calls to next() 189 * @param maxLookAhead The maximum to copy into the result. 190 * @return a reference to result 191 */ 192 UnicodeString& lookahead(UnicodeString& result, int32_t maxLookAhead = -1) const; 193 194 /** 195 * Advances the position by the given number of 16-bit code units. 196 * This is useful in conjunction with the lookahead() method. 197 * @param count the number of 16-bit code units to jump over 198 */ 199 void jumpahead(int32_t count); 200 201 /** 202 * Returns a string representation of this object, consisting of the 203 * characters being iterated, with a '|' marking the current position. 204 * Position within an expanded variable is <em>not</em> indicated. 205 * @param result output parameter to receive a string 206 * representation of this object 207 */ 208 // UnicodeString& toString(UnicodeString& result) const; 209 210 private: 211 /** 212 * Returns the current 32-bit code point without parsing escapes, parsing 213 * variables, or skipping whitespace. 214 * @return the current 32-bit code point 215 */ 216 UChar32 _current() const; 217 218 /** 219 * Advances the position by the given amount. 220 * @param count the number of 16-bit code units to advance past 221 */ 222 void _advance(int32_t count); 223 }; 224 225 inline UBool RuleCharacterIterator::inVariable() const { 226 return buf != 0; 227 } 228 229 U_NAMESPACE_END 230 231 #endif // _RULEITER_H_ 232 //eof 233
