Edit: /usr/include/unicode/bytestrie.h (21268B)
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
* Copyright (C) 2010-2012, International Business Machines
* Corporation and others. All Rights Reserved.
*******************************************************************************
* file name: bytestrie.h
* encoding: UTF-8
* tab size: 8 (not used)
* indentation:4
*
* created on: 2010sep25
* created by: Markus W. Scherer
*/
#ifndef __BYTESTRIE_H__
#define __BYTESTRIE_H__
/**
* \file
* \brief C++ API: Trie for mapping byte sequences to integer values.
*/
#include "unicode/utypes.h"
#if U_SHOW_CPLUSPLUS_API
#include "unicode/stringpiece.h"
#include "unicode/uobject.h"
#include "unicode/ustringtrie.h"
class BytesTrieTest;
U_NAMESPACE_BEGIN
class ByteSink;
class BytesTrieBuilder;
class CharString;
class UVector32;
/**
* Light-weight, non-const reader class for a BytesTrie.
* Traverses a byte-serialized data structure with minimal state,
* for mapping byte sequences to non-negative integer values.
*
* This class owns the serialized trie data only if it was constructed by
* the builder's build() method.
* The public constructor and the copy constructor only alias the data (only copy the pointer).
* There is no assignment operator.
*
* This class is not intended for public subclassing.
* @stable ICU 4.8
*/
class U_COMMON_API BytesTrie : public UMemory {
public:
/**
* Constructs a BytesTrie reader instance.
*
* The trieBytes must contain a copy of a byte sequence from the BytesTrieBuilder,
* starting with the first byte of that sequence.
* The BytesTrie object will not read more bytes than
* the BytesTrieBuilder generated in the corresponding build() call.
*
* The array is not copied/cloned and must not be modified while
* the BytesTrie object is in use.
*
* @param trieBytes The byte array that contains the serialized trie.
* @stable ICU 4.8
*/
BytesTrie(const void *trieBytes)
: ownedArray_(NULL), bytes_(static_cast
(trieBytes)),
pos_(bytes_), remainingMatchLength_(-1) {}
/**
* Destructor.
* @stable ICU 4.8
*/
~BytesTrie();
/**
* Copy constructor, copies the other trie reader object and its state,
* but not the byte array which will be shared. (Shallow copy.)
* @param other Another BytesTrie object.
* @stable ICU 4.8
*/
BytesTrie(const BytesTrie &other)
: ownedArray_(NULL), bytes_(other.bytes_),
pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {}
/**
* Resets this trie to its initial state.
* @return *this
* @stable ICU 4.8
*/
BytesTrie &reset() {
pos_=bytes_;
remainingMatchLength_=-1;
return *this;
}
/**
* Returns the state of this trie as a 64-bit integer.
* The state value is never 0.
*
* @return opaque state value
* @see resetToState64
* @stable ICU 65
*/
uint64_t getState64() const {
return (static_cast(remainingMatchLength_ + 2) << kState64RemainingShift) |
(uint64_t)(pos_ - bytes_);
}
/**
* Resets this trie to the saved state.
* Unlike resetToState(State), the 64-bit state value
* must be from getState64() from the same trie object or
* from one initialized the exact same way.
* Because of no validation, this method is faster.
*
* @param state The opaque trie state value from getState64().
* @return *this
* @see getState64
* @see resetToState
* @see reset
* @stable ICU 65
*/
BytesTrie &resetToState64(uint64_t state) {
remainingMatchLength_ = static_cast(state >> kState64RemainingShift) - 2;
pos_ = bytes_ + (state & kState64PosMask);
return *this;
}
/**
* BytesTrie state object, for saving a trie's current state
* and resetting the trie back to this state later.
* @stable ICU 4.8
*/
class State : public UMemory {
public:
/**
* Constructs an empty State.
* @stable ICU 4.8
*/
State() { bytes=NULL; }
private:
friend class BytesTrie;
const uint8_t *bytes;
const uint8_t *pos;
int32_t remainingMatchLength;
};
/**
* Saves the state of this trie.
* @param state The State object to hold the trie's state.
* @return *this
* @see resetToState
* @stable ICU 4.8
*/
const BytesTrie &saveState(State &state) const {
state.bytes=bytes_;
state.pos=pos_;
state.remainingMatchLength=remainingMatchLength_;
return *this;
}
/**
* Resets this trie to the saved state.
* If the state object contains no state, or the state of a different trie,
* then this trie remains unchanged.
* @param state The State object which holds a saved trie state.
* @return *this
* @see saveState
* @see reset
* @stable ICU 4.8
*/
BytesTrie &resetToState(const State &state) {
if(bytes_==state.bytes && bytes_!=NULL) {
pos_=state.pos;
remainingMatchLength_=state.remainingMatchLength;
}
return *this;
}
/**
* Determines whether the byte sequence so far matches, whether it has a value,
* and whether another input byte can continue a matching byte sequence.
* @return The match/value Result.
* @stable ICU 4.8
*/
UStringTrieResult current() const;
/**
* Traverses the trie from the initial state for this input byte.
* Equivalent to reset().next(inByte).
* @param inByte Input byte value. Values -0x100..-1 are treated like 0..0xff.
* Values below -0x100 and above 0xff will never match.
* @return The match/value Result.
* @stable ICU 4.8
*/
inline UStringTrieResult first(int32_t inByte) {
remainingMatchLength_=-1;
if(inByte<0) {
inByte+=0x100;
}
return nextImpl(bytes_, inByte);
}
/**
* Traverses the trie from the current state for this input byte.
* @param inByte Input byte value. Values -0x100..-1 are treated like 0..0xff.
* Values below -0x100 and above 0xff will never match.
* @return The match/value Result.
* @stable ICU 4.8
*/
UStringTrieResult next(int32_t inByte);
/**
* Traverses the trie from the current state for this byte sequence.
* Equivalent to
* \code
* Result result=current();
* for(each c in s)
* if(!USTRINGTRIE_HAS_NEXT(result)) return USTRINGTRIE_NO_MATCH;
* result=next(c);
* return result;
* \endcode
* @param s A string or byte sequence. Can be NULL if length is 0.
* @param length The length of the byte sequence. Can be -1 if NUL-terminated.
* @return The match/value Result.
* @stable ICU 4.8
*/
UStringTrieResult next(const char *s, int32_t length);
/**
* Returns a matching byte sequence's value if called immediately after
* current()/first()/next() returned USTRINGTRIE_INTERMEDIATE_VALUE or USTRINGTRIE_FINAL_VALUE.
* getValue() can be called multiple times.
*
* Do not call getValue() after USTRINGTRIE_NO_MATCH or USTRINGTRIE_NO_VALUE!
* @return The value for the byte sequence so far.
* @stable ICU 4.8
*/
inline int32_t getValue() const {
const uint8_t *pos=pos_;
int32_t leadByte=*pos++;
// U_ASSERT(leadByte>=kMinValueLead);
return readValue(pos, leadByte>>1);
}
/**
* Determines whether all byte sequences reachable from the current state
* map to the same value.
* @param uniqueValue Receives the unique value, if this function returns true.
* (output-only)
* @return true if all byte sequences reachable from the current state
* map to the same value.
* @stable ICU 4.8
*/
inline UBool hasUniqueValue(int32_t &uniqueValue) const {
const uint8_t *pos=pos_;
// Skip the rest of a pending linear-match node.
return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, false, uniqueValue);
}
/**
* Finds each byte which continues the byte sequence from the current state.
* That is, each byte b for which it would be next(b)!=USTRINGTRIE_NO_MATCH now.
* @param out Each next byte is appended to this object.
* (Only uses the out.Append(s, length) method.)
* @return the number of bytes which continue the byte sequence from here
* @stable ICU 4.8
*/
int32_t getNextBytes(ByteSink &out) const;
/**
* Iterator for all of the (byte sequence, value) pairs in a BytesTrie.
* @stable ICU 4.8
*/
class U_COMMON_API Iterator : public UMemory {
public:
/**
* Iterates from the root of a byte-serialized BytesTrie.
* @param trieBytes The trie bytes.
* @param maxStringLength If 0, the iterator returns full strings/byte sequences.
* Otherwise, the iterator returns strings with this maximum length.
* @param errorCode Standard ICU error code. Its input value must
* pass the U_SUCCESS() test, or else the function returns
* immediately. Check for U_FAILURE() on output or use with
* function chaining. (See User Guide for details.)
* @stable ICU 4.8
*/
Iterator(const void *trieBytes, int32_t maxStringLength, UErrorCode &errorCode);
/**
* Iterates from the current state of the specified BytesTrie.
* @param trie The trie whose state will be copied for iteration.
* @param maxStringLength If 0, the iterator returns full strings/byte sequences.
* Otherwise, the iterator returns strings with this maximum length.
* @param errorCode Standard ICU error code. Its input value must
* pass the U_SUCCESS() test, or else the function returns
* immediately. Check for U_FAILURE() on output or use with
* function chaining. (See User Guide for details.)
* @stable ICU 4.8
*/
Iterator(const BytesTrie &trie, int32_t maxStringLength, UErrorCode &errorCode);
/**
* Destructor.
* @stable ICU 4.8
*/
~Iterator();
/**
* Resets this iterator to its initial state.
* @return *this
* @stable ICU 4.8
*/
Iterator &reset();
/**
* @return true if there are more elements.
* @stable ICU 4.8
*/
UBool hasNext() const;
/**
* Finds the next (byte sequence, value) pair if there is one.
*
* If the byte sequence is truncated to the maximum length and does not
* have a real value, then the value is set to -1.
* In this case, this "not a real value" is indistinguishable from
* a real value of -1.
* @param errorCode Standard ICU error code. Its input value must
* pass the U_SUCCESS() test, or else the function returns
* immediately. Check for U_FAILURE() on output or use with
* function chaining. (See User Guide for details.)
* @return true if there is another element.
* @stable ICU 4.8
*/
UBool next(UErrorCode &errorCode);
/**
* @return The NUL-terminated byte sequence for the last successful next().
* @stable ICU 4.8
*/
StringPiece getString() const;
/**
* @return The value for the last successful next().
* @stable ICU 4.8
*/
int32_t getValue() const { return value_; }
private:
UBool truncateAndStop();
const uint8_t *branchNext(const uint8_t *pos, int32_t length, UErrorCode &errorCode);
const uint8_t *bytes_;
const uint8_t *pos_;
const uint8_t *initialPos_;
int32_t remainingMatchLength_;
int32_t initialRemainingMatchLength_;
CharString *str_;
int32_t maxLength_;
int32_t value_;
// The stack stores pairs of integers for backtracking to another
// outbound edge of a branch node.
// The first integer is an offset from bytes_.
// The second integer has the str_->length() from before the node in bits 15..0,
// and the remaining branch length in bits 24..16. (Bits 31..25 are unused.)
// (We could store the remaining branch length minus 1 in bits 23..16 and not use bits 31..24,
// but the code looks more confusing that way.)
UVector32 *stack_;
};
private:
friend class BytesTrieBuilder;
friend class ::BytesTrieTest;
/**
* Constructs a BytesTrie reader instance.
* Unlike the public constructor which just aliases an array,
* this constructor adopts the builder's array.
* This constructor is only called by the builder.
*/
BytesTrie(void *adoptBytes, const void *trieBytes)
: ownedArray_(static_cast(adoptBytes)),
bytes_(static_cast(trieBytes)),
pos_(bytes_), remainingMatchLength_(-1) {}
// No assignment operator.
BytesTrie &operator=(const BytesTrie &other);
inline void stop() {
pos_=NULL;
}
// Reads a compact 32-bit integer.
// pos is already after the leadByte, and the lead byte is already shifted right by 1.
static int32_t readValue(const uint8_t *pos, int32_t leadByte);
static inline const uint8_t *skipValue(const uint8_t *pos, int32_t leadByte) {
// U_ASSERT(leadByte>=kMinValueLead);
if(leadByte>=(kMinTwoByteValueLead<<1)) {
if(leadByte<(kMinThreeByteValueLead<<1)) {
++pos;
} else if(leadByte<(kFourByteValueLead<<1)) {
pos+=2;
} else {
pos+=3+((leadByte>>1)&1);
}
}
return pos;
}
static inline const uint8_t *skipValue(const uint8_t *pos) {
int32_t leadByte=*pos++;
return skipValue(pos, leadByte);
}
// Reads a jump delta and jumps.
static const uint8_t *jumpByDelta(const uint8_t *pos);
static inline const uint8_t *skipDelta(const uint8_t *pos) {
int32_t delta=*pos++;
if(delta>=kMinTwoByteDeltaLead) {
if(delta>8)+1; // 0x6c
static const int32_t kFourByteValueLead=0x7e;
// A little more than Unicode code points. (0x11ffff)
static const int32_t kMaxThreeByteValue=((kFourByteValueLead-kMinThreeByteValueLead)<<16)-1;
static const int32_t kFiveByteValueLead=0x7f;
// Compact delta integers.
static const int32_t kMaxOneByteDelta=0xbf;
static const int32_t kMinTwoByteDeltaLead=kMaxOneByteDelta+1; // 0xc0
static const int32_t kMinThreeByteDeltaLead=0xf0;
static const int32_t kFourByteDeltaLead=0xfe;
static const int32_t kFiveByteDeltaLead=0xff;
static const int32_t kMaxTwoByteDelta=((kMinThreeByteDeltaLead-kMinTwoByteDeltaLead)<<8)-1; // 0x2fff
static const int32_t kMaxThreeByteDelta=((kFourByteDeltaLead-kMinThreeByteDeltaLead)<<16)-1; // 0xdffff
// For getState64():
// The remainingMatchLength_ is -1..14=(kMaxLinearMatchLength=0x10)-2
// so we need at least 5 bits for that.
// We add 2 to store it as a positive value 1..16=kMaxLinearMatchLength.
static constexpr int32_t kState64RemainingShift = 59;
static constexpr uint64_t kState64PosMask = (UINT64_C(1) << kState64RemainingShift) - 1;
uint8_t *ownedArray_;
// Fixed value referencing the BytesTrie bytes.
const uint8_t *bytes_;
// Iterator variables.
// Pointer to next trie byte to read. NULL if no more matches.
const uint8_t *pos_;
// Remaining length of a linear-match node, minus 1. Negative if not in such a node.
int32_t remainingMatchLength_;
};
U_NAMESPACE_END
#endif /* U_SHOW_CPLUSPLUS_API */
#endif // __BYTESTRIE_H__