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Diffstat (limited to 'intl/icu/source/common/ruleiter.h')
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1 files changed, 233 insertions, 0 deletions
diff --git a/intl/icu/source/common/ruleiter.h b/intl/icu/source/common/ruleiter.h new file mode 100644 index 0000000000..41731407da --- /dev/null +++ b/intl/icu/source/common/ruleiter.h @@ -0,0 +1,233 @@ +// © 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* +********************************************************************** +* 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. + */ + static constexpr int32_t 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. + */ + static constexpr int32_t 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(). + */ + static constexpr int32_t 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. + */ + static constexpr int32_t 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 dereferenced, 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 |