530 lines
19 KiB
C++
530 lines
19 KiB
C++
/*
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*******************************************************************************
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* Copyright (C) 2010-2011, International Business Machines
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* Corporation and others. All Rights Reserved.
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*******************************************************************************
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* file name: ucharstrie.h
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* encoding: US-ASCII
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 2010nov14
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* created by: Markus W. Scherer
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*/
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#ifndef __UCHARSTRIE_H__
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#define __UCHARSTRIE_H__
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/**
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* \file
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* \brief C++ API: Trie for mapping Unicode strings (or 16-bit-unit sequences)
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* to integer values.
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*/
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#include "unicode/utypes.h"
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#include "unicode/unistr.h"
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#include "unicode/uobject.h"
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#include "uassert.h"
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#include "ustringtrie.h"
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U_NAMESPACE_BEGIN
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class UCharsTrieBuilder;
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class UVector32;
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/**
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* Base class for objects to which Unicode characters and strings can be appended.
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* Combines elements of Java Appendable and ICU4C ByteSink.
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* TODO: Should live in separate files, could be public API.
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*/
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class U_TOOLUTIL_API Appendable : public UObject {
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public:
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/**
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* Appends a 16-bit code unit.
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* @param c code unit
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* @return *this
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*/
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virtual Appendable &append(UChar c) = 0;
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/**
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* Appends a code point; has a default implementation.
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* @param c code point
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* @return *this
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*/
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virtual Appendable &appendCodePoint(UChar32 c);
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/**
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* Appends a string; has a default implementation.
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* @param s string
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* @param length string length, or -1 if NUL-terminated
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* @return *this
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*/
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virtual Appendable &append(const UChar *s, int32_t length);
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// TODO: getAppendBuffer(), see ByteSink
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// TODO: flush() (?) see ByteSink
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private:
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// No ICU "poor man's RTTI" for this class nor its subclasses.
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virtual UClassID getDynamicClassID() const;
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};
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/**
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* Light-weight, non-const reader class for a UCharsTrie.
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* Traverses a UChar-serialized data structure with minimal state,
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* for mapping strings (16-bit-unit sequences) to non-negative integer values.
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*/
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class U_TOOLUTIL_API UCharsTrie : public UMemory {
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public:
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/**
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* Constructs a UCharsTrie reader instance.
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* @param trieBytes The trie UChars.
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*/
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UCharsTrie(const UChar *trieUChars)
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: uchars_(trieUChars),
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pos_(uchars_), remainingMatchLength_(-1) {}
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/**
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* Resets this trie to its initial state.
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*/
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UCharsTrie &reset() {
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pos_=uchars_;
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remainingMatchLength_=-1;
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return *this;
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}
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/**
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* UCharsTrie state object, for saving a trie's current state
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* and resetting the trie back to this state later.
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*/
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class State : public UMemory {
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public:
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State() { uchars=NULL; }
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private:
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friend class UCharsTrie;
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const UChar *uchars;
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const UChar *pos;
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int32_t remainingMatchLength;
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};
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/**
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* Saves the state of this trie.
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* @see resetToState
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*/
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const UCharsTrie &saveState(State &state) const {
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state.uchars=uchars_;
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state.pos=pos_;
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state.remainingMatchLength=remainingMatchLength_;
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return *this;
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}
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/**
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* Resets this trie to the saved state.
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* If the state object contains no state, or the state of a different trie,
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* then this trie remains unchanged.
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* @see saveState
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* @see reset
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*/
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UCharsTrie &resetToState(const State &state) {
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if(uchars_==state.uchars && uchars_!=NULL) {
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pos_=state.pos;
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remainingMatchLength_=state.remainingMatchLength;
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}
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return *this;
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}
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/**
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* Determines whether the string so far matches, whether it has a value,
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* and whether another input UChar can continue a matching string.
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* @return The match/value Result.
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*/
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UStringTrieResult current() const;
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/**
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* Traverses the trie from the initial state for this input UChar.
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* Equivalent to reset().next(uchar).
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* @return The match/value Result.
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*/
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inline UStringTrieResult first(int32_t uchar) {
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remainingMatchLength_=-1;
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return nextImpl(uchars_, uchar);
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}
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/**
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* Traverses the trie from the initial state for the
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* one or two UTF-16 code units for this input code point.
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* Equivalent to reset().nextForCodePoint(cp).
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* @return The match/value Result.
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*/
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inline UStringTrieResult firstForCodePoint(UChar32 cp) {
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return cp<=0xffff ?
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first(cp) :
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(USTRINGTRIE_HAS_NEXT(first(U16_LEAD(cp))) ?
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next(U16_TRAIL(cp)) :
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USTRINGTRIE_NO_MATCH);
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}
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/**
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* Traverses the trie from the current state for this input UChar.
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* @return The match/value Result.
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*/
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UStringTrieResult next(int32_t uchar);
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/**
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* Traverses the trie from the current state for the
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* one or two UTF-16 code units for this input code point.
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* @return The match/value Result.
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*/
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inline UStringTrieResult nextForCodePoint(UChar32 cp) {
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return cp<=0xffff ?
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next(cp) :
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(USTRINGTRIE_HAS_NEXT(next(U16_LEAD(cp))) ?
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next(U16_TRAIL(cp)) :
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USTRINGTRIE_NO_MATCH);
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}
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/**
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* Traverses the trie from the current state for this string.
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* Equivalent to
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* \code
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* Result result=current();
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* for(each c in s)
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* if(!USTRINGTRIE_HAS_NEXT(result)) return USTRINGTRIE_NO_MATCH;
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* result=next(c);
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* return result;
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* \endcode
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* @return The match/value Result.
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*/
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UStringTrieResult next(const UChar *s, int32_t length);
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/**
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* Returns a matching string's value if called immediately after
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* current()/first()/next() returned USTRINGTRIE_INTERMEDIATE_VALUE or USTRINGTRIE_FINAL_VALUE.
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* getValue() can be called multiple times.
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*
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* Do not call getValue() after USTRINGTRIE_NO_MATCH or USTRINGTRIE_NO_VALUE!
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*/
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inline int32_t getValue() const {
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const UChar *pos=pos_;
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int32_t leadUnit=*pos++;
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U_ASSERT(leadUnit>=kMinValueLead);
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return leadUnit&kValueIsFinal ?
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readValue(pos, leadUnit&0x7fff) : readNodeValue(pos, leadUnit);
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}
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/**
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* Determines whether all strings reachable from the current state
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* map to the same value.
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* @param uniqueValue Receives the unique value, if this function returns TRUE.
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* (output-only)
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* @return TRUE if all strings reachable from the current state
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* map to the same value.
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*/
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inline UBool hasUniqueValue(int32_t &uniqueValue) const {
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const UChar *pos=pos_;
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// Skip the rest of a pending linear-match node.
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return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, FALSE, uniqueValue);
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}
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/**
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* Finds each UChar which continues the string from the current state.
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* That is, each UChar c for which it would be next(c)!=USTRINGTRIE_NO_MATCH now.
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* @param out Each next UChar is appended to this object.
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* (Only uses the out.append(c) method.)
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* @return the number of UChars which continue the string from here
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*/
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int32_t getNextUChars(Appendable &out) const;
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/**
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* Iterator for all of the (string, value) pairs in a UCharsTrie.
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*/
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class Iterator : public UMemory {
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public:
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/**
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* Iterates from the root of a UChar-serialized UCharsTrie.
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* @param trieUChars The trie UChars.
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* @param maxStringLength If 0, the iterator returns full strings.
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* Otherwise, the iterator returns strings with this maximum length.
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* @param errorCode Standard ICU error code. Its input value must
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* pass the U_SUCCESS() test, or else the function returns
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* immediately. Check for U_FAILURE() on output or use with
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* function chaining. (See User Guide for details.)
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*/
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Iterator(const UChar *trieUChars, int32_t maxStringLength, UErrorCode &errorCode);
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/**
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* Iterates from the current state of the specified UCharsTrie.
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* @param trie The trie whose state will be copied for iteration.
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* @param maxStringLength If 0, the iterator returns full strings.
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* Otherwise, the iterator returns strings with this maximum length.
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* @param errorCode Standard ICU error code. Its input value must
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* pass the U_SUCCESS() test, or else the function returns
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* immediately. Check for U_FAILURE() on output or use with
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* function chaining. (See User Guide for details.)
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*/
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Iterator(const UCharsTrie &trie, int32_t maxStringLength, UErrorCode &errorCode);
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~Iterator();
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/**
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* Resets this iterator to its initial state.
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*/
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Iterator &reset();
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/**
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* @return TRUE if there are more elements.
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*/
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UBool hasNext() const;
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/**
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* Finds the next (string, value) pair if there is one.
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*
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* If the string is truncated to the maximum length and does not
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* have a real value, then the value is set to -1.
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* In this case, this "not a real value" is indistinguishable from
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* a real value of -1.
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* @return TRUE if there is another element.
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*/
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UBool next(UErrorCode &errorCode);
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/**
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* @return The string for the last successful next().
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*/
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const UnicodeString &getString() const { return str_; }
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/**
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* @return The value for the last successful next().
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*/
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int32_t getValue() const { return value_; }
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private:
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UBool truncateAndStop() {
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pos_=NULL;
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value_=-1; // no real value for str
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return TRUE;
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}
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const UChar *branchNext(const UChar *pos, int32_t length, UErrorCode &errorCode);
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const UChar *uchars_;
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const UChar *pos_;
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const UChar *initialPos_;
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int32_t remainingMatchLength_;
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int32_t initialRemainingMatchLength_;
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UBool skipValue_; // Skip intermediate value which was already delivered.
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UnicodeString str_;
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int32_t maxLength_;
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int32_t value_;
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// The stack stores pairs of integers for backtracking to another
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// outbound edge of a branch node.
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// The first integer is an offset from uchars_.
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// The second integer has the str_.length() from before the node in bits 15..0,
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// and the remaining branch length in bits 31..16.
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// (We could store the remaining branch length minus 1 in bits 30..16 and not use the sign bit,
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// but the code looks more confusing that way.)
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UVector32 *stack_;
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};
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private:
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friend class UCharsTrieBuilder;
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inline void stop() {
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pos_=NULL;
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}
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// Reads a compact 32-bit integer.
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// pos is already after the leadUnit, and the lead unit has bit 15 reset.
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static inline int32_t readValue(const UChar *pos, int32_t leadUnit) {
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int32_t value;
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if(leadUnit<kMinTwoUnitValueLead) {
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value=leadUnit;
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} else if(leadUnit<kThreeUnitValueLead) {
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value=((leadUnit-kMinTwoUnitValueLead)<<16)|*pos;
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} else {
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value=(pos[0]<<16)|pos[1];
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}
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return value;
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}
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static inline const UChar *skipValue(const UChar *pos, int32_t leadUnit) {
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if(leadUnit>=kMinTwoUnitValueLead) {
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if(leadUnit<kThreeUnitValueLead) {
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++pos;
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} else {
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pos+=2;
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}
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}
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return pos;
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}
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static inline const UChar *skipValue(const UChar *pos) {
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int32_t leadUnit=*pos++;
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return skipValue(pos, leadUnit&0x7fff);
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}
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static inline int32_t readNodeValue(const UChar *pos, int32_t leadUnit) {
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U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal);
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int32_t value;
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if(leadUnit<kMinTwoUnitNodeValueLead) {
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value=(leadUnit>>6)-1;
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} else if(leadUnit<kThreeUnitNodeValueLead) {
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value=(((leadUnit&0x7fc0)-kMinTwoUnitNodeValueLead)<<10)|*pos;
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} else {
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value=(pos[0]<<16)|pos[1];
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}
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return value;
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}
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static inline const UChar *skipNodeValue(const UChar *pos, int32_t leadUnit) {
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U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal);
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if(leadUnit>=kMinTwoUnitNodeValueLead) {
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if(leadUnit<kThreeUnitNodeValueLead) {
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++pos;
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} else {
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pos+=2;
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}
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}
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return pos;
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}
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static inline const UChar *jumpByDelta(const UChar *pos) {
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int32_t delta=*pos++;
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if(delta>=kMinTwoUnitDeltaLead) {
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if(delta==kThreeUnitDeltaLead) {
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delta=(pos[0]<<16)|pos[1];
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pos+=2;
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} else {
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delta=((delta-kMinTwoUnitDeltaLead)<<16)|*pos++;
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}
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}
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return pos+delta;
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}
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static const UChar *skipDelta(const UChar *pos) {
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int32_t delta=*pos++;
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if(delta>=kMinTwoUnitDeltaLead) {
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if(delta==kThreeUnitDeltaLead) {
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pos+=2;
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} else {
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++pos;
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}
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}
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return pos;
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}
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static inline UStringTrieResult valueResult(int32_t node) {
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return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node>>15));
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}
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// Handles a branch node for both next(uchar) and next(string).
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UStringTrieResult branchNext(const UChar *pos, int32_t length, int32_t uchar);
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// Requires remainingLength_<0.
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UStringTrieResult nextImpl(const UChar *pos, int32_t uchar);
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// Helper functions for hasUniqueValue().
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// Recursively finds a unique value (or whether there is not a unique one)
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// from a branch.
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static const UChar *findUniqueValueFromBranch(const UChar *pos, int32_t length,
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UBool haveUniqueValue, int32_t &uniqueValue);
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// Recursively finds a unique value (or whether there is not a unique one)
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// starting from a position on a node lead unit.
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static UBool findUniqueValue(const UChar *pos, UBool haveUniqueValue, int32_t &uniqueValue);
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// Helper functions for getNextUChars().
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// getNextUChars() when pos is on a branch node.
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static void getNextBranchUChars(const UChar *pos, int32_t length, Appendable &out);
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// UCharsTrie data structure
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//
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// The trie consists of a series of UChar-serialized nodes for incremental
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// Unicode string/UChar sequence matching. (UChar=16-bit unsigned integer)
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// The root node is at the beginning of the trie data.
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//
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// Types of nodes are distinguished by their node lead unit ranges.
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// After each node, except a final-value node, another node follows to
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// encode match values or continue matching further units.
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//
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// Node types:
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// - Final-value node: Stores a 32-bit integer in a compact, variable-length format.
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// The value is for the string/UChar sequence so far.
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// - Match node, optionally with an intermediate value in a different compact format.
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// The value, if present, is for the string/UChar sequence so far.
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//
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// Aside from the value, which uses the node lead unit's high bits:
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//
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// - Linear-match node: Matches a number of units.
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// - Branch node: Branches to other nodes according to the current input unit.
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// The node unit is the length of the branch (number of units to select from)
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// minus 1. It is followed by a sub-node:
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// - If the length is at most kMaxBranchLinearSubNodeLength, then
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// there are length-1 (key, value) pairs and then one more comparison unit.
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// If one of the key units matches, then the value is either a final value for
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// the string so far, or a "jump" delta to the next node.
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// If the last unit matches, then matching continues with the next node.
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// (Values have the same encoding as final-value nodes.)
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// - If the length is greater than kMaxBranchLinearSubNodeLength, then
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// there is one unit and one "jump" delta.
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// If the input unit is less than the sub-node unit, then "jump" by delta to
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// the next sub-node which will have a length of length/2.
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// (The delta has its own compact encoding.)
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// Otherwise, skip the "jump" delta to the next sub-node
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// which will have a length of length-length/2.
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// Match-node lead unit values, after masking off intermediate-value bits:
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// 0000..002f: Branch node. If node!=0 then the length is node+1, otherwise
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// the length is one more than the next unit.
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// For a branch sub-node with at most this many entries, we drop down
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// to a linear search.
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static const int32_t kMaxBranchLinearSubNodeLength=5;
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// 0030..003f: Linear-match node, match 1..16 units and continue reading the next node.
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static const int32_t kMinLinearMatch=0x30;
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static const int32_t kMaxLinearMatchLength=0x10;
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// Match-node lead unit bits 14..6 for the optional intermediate value.
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// If these bits are 0, then there is no intermediate value.
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// Otherwise, see the *NodeValue* constants below.
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static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength; // 0x0040
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static const int32_t kNodeTypeMask=kMinValueLead-1; // 0x003f
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// A final-value node has bit 15 set.
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static const int32_t kValueIsFinal=0x8000;
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// Compact value: After testing and masking off bit 15, use the following thresholds.
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static const int32_t kMaxOneUnitValue=0x3fff;
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static const int32_t kMinTwoUnitValueLead=kMaxOneUnitValue+1; // 0x4000
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static const int32_t kThreeUnitValueLead=0x7fff;
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static const int32_t kMaxTwoUnitValue=((kThreeUnitValueLead-kMinTwoUnitValueLead)<<16)-1; // 0x3ffeffff
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// Compact intermediate-value integer, lead unit shared with a branch or linear-match node.
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static const int32_t kMaxOneUnitNodeValue=0xff;
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static const int32_t kMinTwoUnitNodeValueLead=kMinValueLead+((kMaxOneUnitNodeValue+1)<<6); // 0x4040
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static const int32_t kThreeUnitNodeValueLead=0x7fc0;
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static const int32_t kMaxTwoUnitNodeValue=
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((kThreeUnitNodeValueLead-kMinTwoUnitNodeValueLead)<<10)-1; // 0xfdffff
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// Compact delta integers.
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static const int32_t kMaxOneUnitDelta=0xfbff;
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static const int32_t kMinTwoUnitDeltaLead=kMaxOneUnitDelta+1; // 0xfc00
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static const int32_t kThreeUnitDeltaLead=0xffff;
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static const int32_t kMaxTwoUnitDelta=((kThreeUnitDeltaLead-kMinTwoUnitDeltaLead)<<16)-1; // 0x03feffff
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// Fixed value referencing the UCharsTrie words.
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|
const UChar *uchars_;
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|
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// Iterator variables.
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// Pointer to next trie unit to read. NULL if no more matches.
|
|
const UChar *pos_;
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// Remaining length of a linear-match node, minus 1. Negative if not in such a node.
|
|
int32_t remainingMatchLength_;
|
|
};
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U_NAMESPACE_END
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#endif // __UCHARSTRIE_H__
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