/* ********************************************************************** * Copyright (c) 2003-2011, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * Author: Alan Liu * Created: September 24 2003 * Since: ICU 2.8 ********************************************************************** */ #ifndef _RULEITER_H_ #define _RULEITER_H_ #include "unicode/uobject.h" U_NAMESPACE_BEGIN class UnicodeString; class ParsePosition; class SymbolTable; /** * An iterator that returns 32-bit code points. This class is deliberately * <em>not</em> related to any of the ICU character iterator classes * in order to minimize complexity. * @author Alan Liu * @since ICU 2.8 */ class RuleCharacterIterator : public UMemory { // TODO: Ideas for later. (Do not implement if not needed, lest the // code coverage numbers go down due to unused methods.) // 1. Add a copy constructor, operator==() method. // 2. Rather than return DONE, throw an exception if the end // is reached -- this is an alternate usage model, probably not useful. private: /** * Text being iterated. */ const UnicodeString& text; /** * Position of iterator. */ ParsePosition& pos; /** * Symbol table used to parse and dereference variables. May be 0. */ const SymbolTable* sym; /** * Current variable expansion, or 0 if none. */ const UnicodeString* buf; /** * Position within buf. Meaningless if buf == 0. */ int32_t bufPos; public: /** * Value returned when there are no more characters to iterate. */ enum { DONE = -1 }; /** * Bitmask option to enable parsing of variable names. If (options & * PARSE_VARIABLES) != 0, then an embedded variable will be expanded to * its value. Variables are parsed using the SymbolTable API. */ enum { PARSE_VARIABLES = 1 }; /** * Bitmask option to enable parsing of escape sequences. If (options & * PARSE_ESCAPES) != 0, then an embedded escape sequence will be expanded * to its value. Escapes are parsed using Utility.unescapeAt(). */ enum { PARSE_ESCAPES = 2 }; /** * Bitmask option to enable skipping of whitespace. If (options & * SKIP_WHITESPACE) != 0, then Pattern_White_Space characters will be silently * skipped, as if they were not present in the input. */ enum { SKIP_WHITESPACE = 4 }; /** * Constructs an iterator over the given text, starting at the given * position. * @param text the text to be iterated * @param sym the symbol table, or null if there is none. If sym is null, * then variables will not be deferenced, even if the PARSE_VARIABLES * option is set. * @param pos upon input, the index of the next character to return. If a * variable has been dereferenced, then pos will <em>not</em> increment as * characters of the variable value are iterated. */ RuleCharacterIterator(const UnicodeString& text, const SymbolTable* sym, ParsePosition& pos); /** * Returns true if this iterator has no more characters to return. */ UBool atEnd() const; /** * Returns the next character using the given options, or DONE if there * are no more characters, and advance the position to the next * character. * @param options one or more of the following options, bitwise-OR-ed * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. * @param isEscaped output parameter set to TRUE if the character * was escaped * @param ec input-output error code. An error will only be set by * this routing if options includes PARSE_VARIABLES and an unknown * variable name is seen, or if options includes PARSE_ESCAPES and * an invalid escape sequence is seen. * @return the current 32-bit code point, or DONE */ UChar32 next(int32_t options, UBool& isEscaped, UErrorCode& ec); /** * Returns true if this iterator is currently within a variable expansion. */ inline UBool inVariable() const; /** * An opaque object representing the position of a RuleCharacterIterator. */ struct Pos : public UMemory { private: const UnicodeString* buf; int32_t pos; int32_t bufPos; friend class RuleCharacterIterator; }; /** * Sets an object which, when later passed to setPos(), will * restore this iterator's position. Usage idiom: * * RuleCharacterIterator iterator = ...; * RuleCharacterIterator::Pos pos; * iterator.getPos(pos); * for (;;) { * iterator.getPos(pos); * int c = iterator.next(...); * ... * } * iterator.setPos(pos); * * @param p a position object to be set to this iterator's * current position. */ void getPos(Pos& p) const; /** * Restores this iterator to the position it had when getPos() * set the given object. * @param p a position object previously set by getPos() */ void setPos(const Pos& p); /** * Skips ahead past any ignored characters, as indicated by the given * options. This is useful in conjunction with the lookahead() method. * * Currently, this only has an effect for SKIP_WHITESPACE. * @param options one or more of the following options, bitwise-OR-ed * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. */ void skipIgnored(int32_t options); /** * Returns a string containing the remainder of the characters to be * returned by this iterator, without any option processing. If the * iterator is currently within a variable expansion, this will only * extend to the end of the variable expansion. This method is provided * so that iterators may interoperate with string-based APIs. The typical * sequence of calls is to call skipIgnored(), then call lookahead(), then * parse the string returned by lookahead(), then call jumpahead() to * resynchronize the iterator. * @param result a string to receive the characters to be returned * by future calls to next() * @param maxLookAhead The maximum to copy into the result. * @return a reference to result */ UnicodeString& lookahead(UnicodeString& result, int32_t maxLookAhead = -1) const; /** * Advances the position by the given number of 16-bit code units. * This is useful in conjunction with the lookahead() method. * @param count the number of 16-bit code units to jump over */ void jumpahead(int32_t count); /** * Returns a string representation of this object, consisting of the * characters being iterated, with a '|' marking the current position. * Position within an expanded variable is <em>not</em> indicated. * @param result output parameter to receive a string * representation of this object */ // UnicodeString& toString(UnicodeString& result) const; private: /** * Returns the current 32-bit code point without parsing escapes, parsing * variables, or skipping whitespace. * @return the current 32-bit code point */ UChar32 _current() const; /** * Advances the position by the given amount. * @param count the number of 16-bit code units to advance past */ void _advance(int32_t count); }; inline UBool RuleCharacterIterator::inVariable() const { return buf != 0; } U_NAMESPACE_END #endif // _RULEITER_H_ //eof