486 lines
18 KiB
C++
486 lines
18 KiB
C++
/*
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***************************************************************************
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* Copyright (C) 1999-2003 International Business Machines Corporation *
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* and others. All rights reserved. *
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***************************************************************************
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**********************************************************************
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* Date Name Description
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* 10/22/99 alan Creation.
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* 11/11/99 rgillam Complete port from Java.
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**********************************************************************
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*/
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#ifndef RBBI_H
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#define RBBI_H
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_BREAK_ITERATION
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#include "unicode/brkiter.h"
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#include "unicode/udata.h"
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#include "unicode/parseerr.h"
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struct UTrie;
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U_NAMESPACE_BEGIN
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struct RBBIDataHeader;
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class RuleBasedBreakIteratorTables;
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class BreakIterator;
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class RBBIDataWrapper;
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/**
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* A subclass of BreakIterator whose behavior is specified using a list of rules.
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* <p>Instances of this class are most commonly created by the factory methods of
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* BreakIterator::createWordInstance(), BreakIterator::createLineInstance(), etc.,
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* and then used via the abstract API in class BreakIterator</p>
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*
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* <p>See the ICU User Guide for information on Break Iterator Rules.</p>
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*
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* <p>This class is not intended to be subclassed. (Class DictionaryBasedBreakIterator
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* is a subclass, but that relationship is effectively internal to the ICU
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* implementation. The subclassing interface to RulesBasedBreakIterator is
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* not part of the ICU API, and may not remain stable.</p>
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*
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*/
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class U_COMMON_API RuleBasedBreakIterator : public BreakIterator {
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protected:
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/**
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* The character iterator through which this BreakIterator accesses the text
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* @internal
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*/
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CharacterIterator* fText;
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/**
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* The rule data for this BreakIterator instance
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* @internal
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*/
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RBBIDataWrapper *fData;
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/** @internal */
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UTrie *fCharMappings;
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/** Rule {tag} value for the most recent match.
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* @internal
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*/
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int32_t fLastBreakTag;
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/**
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* Rule tag value valid flag.
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* Some iterator operations don't intrinsically set the correct tag value.
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* This flag lets us lazily compute the value if we are ever asked for it.
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* @internal
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*/
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UBool fLastBreakTagValid;
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/**
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* Counter for the number of characters encountered with the "dictionary"
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* flag set. Normal RBBI iterators don't use it, although the code
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* for updating it is live. Dictionary Based break iterators (a subclass
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* of us) access this field directly.
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* @internal
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*/
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uint32_t fDictionaryCharCount;
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/**
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* Debugging flag. Trace operation of state machine when true.
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* @internal
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*/
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static UBool fTrace;
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protected:
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//=======================================================================
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// constructors
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//=======================================================================
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/**
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* This constructor uses the udata interface to create a BreakIterator
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* whose internal tables live in a memory-mapped file. "image" is a pointer
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* to the beginning of that file.
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* @internal
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*/
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RuleBasedBreakIterator(UDataMemory* image, UErrorCode &status);
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/**
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* Constructor from a flattened set of RBBI data in malloced memory.
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* RulesBasedBreakIterators built from a custom set of rules
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* are created via this constructor; the rules are compiled
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* into memory, then the break iterator is constructed here.
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*
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* The break iterator adopts the memory, and will
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* free it when done.
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* @internal
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*/
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RuleBasedBreakIterator(RBBIDataHeader* data, UErrorCode &status);
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friend class RBBIRuleBuilder; /** @internal */
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friend class BreakIterator;
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public:
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/** Default constructor. Creates an empty shell of an iterator, with no
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* rules or text to iterate over. Object can subsequently be assigned to.
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* @draft ICU 2.2
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*/
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RuleBasedBreakIterator();
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/**
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* Copy constructor. Will produce a break iterator with the same behavior,
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* and which iterates over the same text, as the one passed in.
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* @param that The RuleBasedBreakIterator passed to be copied
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* @stable ICU 2.0
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*/
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RuleBasedBreakIterator(const RuleBasedBreakIterator& that);
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/**
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* Construct a RuleBasedBreakIterator from a set of rules supplied as a string.
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* @param rules The break rules to be used.
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* @param parseError In the event of a syntax error in the rules, provides the location
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* within the rules of the problem.
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* @param status Information on any errors encountered.
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* @draft ICU 2.2
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*/
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RuleBasedBreakIterator( const UnicodeString &rules,
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UParseError &parseError,
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UErrorCode &status);
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/**
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* Destructor
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* @stable ICU 2.0
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*/
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virtual ~RuleBasedBreakIterator();
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/**
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* Assignment operator. Sets this iterator to have the same behavior,
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* and iterate over the same text, as the one passed in.
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* @param that The RuleBasedBreakItertor passed in
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* @return the newly created RuleBasedBreakIterator
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* @stable ICU 2.0
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*/
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RuleBasedBreakIterator& operator=(const RuleBasedBreakIterator& that);
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/**
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* Equality operator. Returns TRUE if both BreakIterators are of the
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* same class, have the same behavior, and iterate over the same text.
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* @param that The BreakIterator to be compared for equality
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* @Return TRUE if both BreakIterators are of the
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* same class, have the same behavior, and iterate over the same text.
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* @stable ICU 2.0
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*/
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virtual UBool operator==(const BreakIterator& that) const;
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/**
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* Not-equal operator. If operator== returns TRUE, this returns FALSE,
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* and vice versa.
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* @param that The BreakIterator to be compared for inequality
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* @return TRUE if both BreakIterators are not same.
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* @stable ICU 2.0
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*/
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UBool operator!=(const BreakIterator& that) const;
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/**
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* Returns a newly-constructed RuleBasedBreakIterator with the same
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* behavior, and iterating over the same text, as this one.
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* Differs from the copy constructor in that it is polymorphic, and
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* will correctly clone (copy) a derived class.
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* clone() is thread safe. Multiple threads may simultaeneously
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* clone the same source break iterator.
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* @stable ICU 2.0
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*/
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virtual BreakIterator* clone() const;
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/**
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* Compute a hash code for this BreakIterator
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* @return A hash code
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* @stable ICU 2.0
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*/
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virtual int32_t hashCode(void) const;
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/**
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* Returns the description used to create this iterator
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* @return the description used to create this iterator
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* @stable ICU 2.0
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*/
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virtual const UnicodeString& getRules(void) const;
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//=======================================================================
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// BreakIterator overrides
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//=======================================================================
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/**
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* Return a CharacterIterator over the text being analyzed. This version
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* of this method returns the actual CharacterIterator we're using internally.
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* Changing the state of this iterator can have undefined consequences. If
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* you need to change it, clone it first.
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* @return An iterator over the text being analyzed.
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* @stable ICU 2.0
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*/
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virtual const CharacterIterator& getText(void) const;
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/**
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* Set the iterator to analyze a new piece of text. This function resets
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* the current iteration position to the beginning of the text.
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* @param newText An iterator over the text to analyze. The BreakIterator
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* takes ownership of the character iterator. The caller MUST NOT delete it!
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* @stable ICU 2.0
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*/
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virtual void adoptText(CharacterIterator* newText);
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/**
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* Set the iterator to analyze a new piece of text. This function resets
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* the current iteration position to the beginning of the text.
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* @param newText The text to analyze.
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* @stable ICU 2.0
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*/
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virtual void setText(const UnicodeString& newText);
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/**
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* Sets the current iteration position to the beginning of the text.
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* (i.e., the CharacterIterator's starting offset).
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* @return The offset of the beginning of the text.
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* @stable ICU 2.0
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*/
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virtual int32_t first(void);
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/**
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* Sets the current iteration position to the end of the text.
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* (i.e., the CharacterIterator's ending offset).
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* @return The text's past-the-end offset.
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* @stable ICU 2.0
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*/
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virtual int32_t last(void);
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/**
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* Advances the iterator either forward or backward the specified number of steps.
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* Negative values move backward, and positive values move forward. This is
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* equivalent to repeatedly calling next() or previous().
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* @param n The number of steps to move. The sign indicates the direction
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* (negative is backwards, and positive is forwards).
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* @return The character offset of the boundary position n boundaries away from
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* the current one.
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* @stable ICU 2.0
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*/
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virtual int32_t next(int32_t n);
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/**
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* Advances the iterator to the next boundary position.
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* @return The position of the first boundary after this one.
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* @stable ICU 2.0
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*/
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virtual int32_t next(void);
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/**
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* Moves the iterator backwards, to the last boundary preceding this one.
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* @return The position of the last boundary position preceding this one.
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* @stable ICU 2.0
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*/
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virtual int32_t previous(void);
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/**
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* Sets the iterator to refer to the first boundary position following
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* the specified position.
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* @param offset The position from which to begin searching for a break position.
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* @return The position of the first break after the current position.
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* @stable ICU 2.0
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*/
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virtual int32_t following(int32_t offset);
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/**
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* Sets the iterator to refer to the last boundary position before the
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* specified position.
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* @param offset The position to begin searching for a break from.
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* @return The position of the last boundary before the starting position.
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* @stable ICU 2.0
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*/
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virtual int32_t preceding(int32_t offset);
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/**
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* Returns true if the specfied position is a boundary position. As a side
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* effect, leaves the iterator pointing to the first boundary position at
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* or after "offset".
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* @param offset the offset to check.
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* @return True if "offset" is a boundary position.
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* @stable ICU 2.0
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*/
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virtual UBool isBoundary(int32_t offset);
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/**
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* Returns the current iteration position.
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* @return The current iteration position.
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* @stable ICU 2.0
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*/
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virtual int32_t current(void) const;
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/**
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* Return the status tag from the break rule that determined the most recently
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* returned break position. The values appear in the rule source
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* within brackets, {123}, for example. For rules that do not specify a
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* status, a default value of 0 is returned.
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* <p>
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* Of the standard types of ICU break iterators, only the word break
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* iterator provides status values. The values are defined in
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* <code>enum UWordBreak</code>, and allow distinguishing between words
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* that contain alphabetic letters, "words" that appear to be numbers,
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* punctuation and spaces, words containing ideographic characters, and
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* more. Call <code>getRuleStatus</code> after obtaining a boundary
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* position from <code>next()<code>, <code>previous()</code>, or
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* any other break iterator functions that returns a boundary position.
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* <p>
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* @return the status from the break rule that determined the most recently
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* returned break position.
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*
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* @see UWordBreak
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* @draft ICU 2.2
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*/
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virtual int32_t getRuleStatus() const;
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/**
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* Returns a unique class ID POLYMORPHICALLY. Pure virtual override.
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* This method is to implement a simple version of RTTI, since not all
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* C++ compilers support genuine RTTI. Polymorphic operator==() and
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* clone() methods call this method.
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*
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* @return The class ID for this object. All objects of a
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* given class have the same class ID. Objects of
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* other classes have different class IDs.
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* @stable ICU 2.0
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*/
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virtual UClassID getDynamicClassID(void) const;
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/**
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* Returns the class ID for this class. This is useful only for
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* comparing to a return value from getDynamicClassID(). For example:
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*
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* Base* polymorphic_pointer = createPolymorphicObject();
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* if (polymorphic_pointer->getDynamicClassID() ==
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* Derived::getStaticClassID()) ...
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*
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* @return The class ID for all objects of this class.
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* @stable ICU 2.0
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*/
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static UClassID getStaticClassID(void);
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/*
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* Create a clone (copy) of this break iterator in memory provided
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* by the caller. The idea is to increase performance by avoiding
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* a storage allocation. Use of this functoin is NOT RECOMMENDED.
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* Performance gains are minimal, and correct buffer management is
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* tricky. Use clone() instead.
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*
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* @param stackBuffer The pointer to the memory into which the cloned object
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* should be placed. If NULL, allocate heap memory
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* for the cloned object.
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* @param BufferSize The size of the buffer. If zero, return the required
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* buffer size, but do not clone the object. If the
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* size was too small (but not zero), allocate heap
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* storage for the cloned object.
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*
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* @param status Error status. U_SAFECLONE_ALLOCATED_WARNING will be
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* returned if the the provided buffer was too small, and
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* the clone was therefore put on the heap.
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*
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* @return Pointer to the clone object. This may differ from the stackBuffer
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* address if the byte alignment of the stack buffer was not suitable
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* or if the stackBuffer was too small to hold the clone.
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* @stable ICU 2.0
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*/
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virtual BreakIterator * createBufferClone(void *stackBuffer,
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int32_t &BufferSize,
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UErrorCode &status);
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/**
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* Return the binary form of compiled break rules,
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* which can then be used to create a new break iterator at some
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* time in the future. Creating a break iterator from pre-compiled rules
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* is much faster than building one from the source form of the
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* break rules.
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*
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* The binary data is can only be used with the same version of ICU
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* and on the same platform type (processor endian-ness)
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*
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* @param length Returns the length of the binary data. (Out paramter.)
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*
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* @return A pointer to the binary (compiled) rule data. The storage
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* belongs to the RulesBasedBreakIterator object, not the
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* caller, and must not be modified or deleted.
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* @internal
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*/
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virtual const uint8_t *getBinaryRules(uint32_t &length);
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protected:
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//=======================================================================
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// implementation
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//=======================================================================
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/**
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* This method is the actual implementation of the next() method. All iteration
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* vectors through here. This method initializes the state machine to state 1
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* and advances through the text character by character until we reach the end
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* of the text or the state machine transitions to state 0. We update our return
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* value every time the state machine passes through a possible end state.
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* @internal
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*/
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virtual int32_t handleNext(void);
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/**
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* This method backs the iterator back up to a "safe position" in the text.
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* This is a position that we know, without any context, must be a break position.
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* The various calling methods then iterate forward from this safe position to
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* the appropriate position to return. (For more information, see the description
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* of buildBackwardsStateTable() in RuleBasedBreakIterator.Builder.)
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* @internal
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*/
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virtual int32_t handlePrevious(void);
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/**
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* Dumps caches and performs other actions associated with a complete change
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* in text or iteration position. This function is a no-op in RuleBasedBreakIterator,
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* but subclasses can and do override it.
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* @internal
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*/
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virtual void reset(void);
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/**
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* Return true if the category lookup for this char
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* indicates that it is in the set of dictionary lookup chars.
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* This function is intended for use by dictionary based break iterators.
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* @return true if the category lookup for this char
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* indicates that it is in the set of dictionary lookup chars.
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* @internal
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*/
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virtual UBool isDictionaryChar(UChar32);
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/**
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* Common initialization function, used by constructors and bufferClone.
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* (Also used by DictionaryBasedBreakIterator::createBufferClone().)
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* @internal
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*/
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void init();
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};
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//------------------------------------------------------------------------------
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//
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// Inline Functions Definitions ...
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//
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//------------------------------------------------------------------------------
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inline UBool RuleBasedBreakIterator::operator!=(const BreakIterator& that) const {
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return !operator==(that);
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}
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U_NAMESPACE_END
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#endif /* #if !UCONFIG_NO_BREAK_ITERATION */
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#endif
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