1 /* 2 ********************************************************************** 3 * Copyright (c) 2003-2011, 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 Pattern_White_Space characters will be silently 86 * skipped, as if they were not present in the input. 87 */ 88 enum { SKIP_WHITESPACE = 4 }; 89 90 /** 91 * Constructs an iterator over the given text, starting at the given 92 * position. 93 * @param text the text to be iterated 94 * @param sym the symbol table, or null if there is none. If sym is null, 95 * then variables will not be deferenced, even if the PARSE_VARIABLES 96 * option is set. 97 * @param pos upon input, the index of the next character to return. If a 98 * variable has been dereferenced, then pos will <em>not</em> increment as 99 * characters of the variable value are iterated. 100 */ 101 RuleCharacterIterator(const UnicodeString& text, const SymbolTable* sym, 102 ParsePosition& pos); 103 104 /** 105 * Returns true if this iterator has no more characters to return. 106 */ 107 UBool atEnd() const; 108 109 /** 110 * Returns the next character using the given options, or DONE if there 111 * are no more characters, and advance the position to the next 112 * character. 113 * @param options one or more of the following options, bitwise-OR-ed 114 * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. 115 * @param isEscaped output parameter set to TRUE if the character 116 * was escaped 117 * @param ec input-output error code. An error will only be set by 118 * this routing if options includes PARSE_VARIABLES and an unknown 119 * variable name is seen, or if options includes PARSE_ESCAPES and 120 * an invalid escape sequence is seen. 121 * @return the current 32-bit code point, or DONE 122 */ 123 UChar32 next(int32_t options, UBool& isEscaped, UErrorCode& ec); 124 125 /** 126 * Returns true if this iterator is currently within a variable expansion. 127 */ 128 inline UBool inVariable() const; 129 130 /** 131 * An opaque object representing the position of a RuleCharacterIterator. 132 */ 133 struct Pos : public UMemory { 134 private: 135 const UnicodeString* buf; 136 int32_t pos; 137 int32_t bufPos; 138 friend class RuleCharacterIterator; 139 }; 140 141 /** 142 * Sets an object which, when later passed to setPos(), will 143 * restore this iterator's position. Usage idiom: 144 * 145 * RuleCharacterIterator iterator = ...; 146 * RuleCharacterIterator::Pos pos; 147 * iterator.getPos(pos); 148 * for (;;) { 149 * iterator.getPos(pos); 150 * int c = iterator.next(...); 151 * ... 152 * } 153 * iterator.setPos(pos); 154 * 155 * @param p a position object to be set to this iterator's 156 * current position. 157 */ 158 void getPos(Pos& p) const; 159 160 /** 161 * Restores this iterator to the position it had when getPos() 162 * set the given object. 163 * @param p a position object previously set by getPos() 164 */ 165 void setPos(const Pos& p); 166 167 /** 168 * Skips ahead past any ignored characters, as indicated by the given 169 * options. This is useful in conjunction with the lookahead() method. 170 * 171 * Currently, this only has an effect for SKIP_WHITESPACE. 172 * @param options one or more of the following options, bitwise-OR-ed 173 * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. 174 */ 175 void skipIgnored(int32_t options); 176 177 /** 178 * Returns a string containing the remainder of the characters to be 179 * returned by this iterator, without any option processing. If the 180 * iterator is currently within a variable expansion, this will only 181 * extend to the end of the variable expansion. This method is provided 182 * so that iterators may interoperate with string-based APIs. The typical 183 * sequence of calls is to call skipIgnored(), then call lookahead(), then 184 * parse the string returned by lookahead(), then call jumpahead() to 185 * resynchronize the iterator. 186 * @param result a string to receive the characters to be returned 187 * by future calls to next() 188 * @param maxLookAhead The maximum to copy into the result. 189 * @return a reference to result 190 */ 191 UnicodeString& lookahead(UnicodeString& result, int32_t maxLookAhead = -1) const; 192 193 /** 194 * Advances the position by the given number of 16-bit code units. 195 * This is useful in conjunction with the lookahead() method. 196 * @param count the number of 16-bit code units to jump over 197 */ 198 void jumpahead(int32_t count); 199 200 /** 201 * Returns a string representation of this object, consisting of the 202 * characters being iterated, with a '|' marking the current position. 203 * Position within an expanded variable is <em>not</em> indicated. 204 * @param result output parameter to receive a string 205 * representation of this object 206 */ 207 // UnicodeString& toString(UnicodeString& result) const; 208 209 private: 210 /** 211 * Returns the current 32-bit code point without parsing escapes, parsing 212 * variables, or skipping whitespace. 213 * @return the current 32-bit code point 214 */ 215 UChar32 _current() const; 216 217 /** 218 * Advances the position by the given amount. 219 * @param count the number of 16-bit code units to advance past 220 */ 221 void _advance(int32_t count); 222 }; 223 224 inline UBool RuleCharacterIterator::inVariable() const { 225 return buf != 0; 226 } 227 228 U_NAMESPACE_END 229 230 #endif // _RULEITER_H_ 231 //eof 232
