| /* |
| ******************************************************************************* |
| * Copyright (C) 2010-2012, International Business Machines |
| * Corporation and others. All Rights Reserved. |
| ******************************************************************************* |
| * file name: bytestrie.h |
| * encoding: US-ASCII |
| * 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" |
| #include "unicode/stringpiece.h" |
| #include "unicode/uobject.h" |
| #include "unicode/ustringtrie.h" |
| |
| 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<const uint8_t *>(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; |
| } |
| |
| /** |
| * 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 |
| */ |
| const StringPiece &getString() const { return sp_; } |
| /** |
| * @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_; |
| StringPiece sp_; |
| 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; |
| |
| /** |
| * 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<uint8_t *>(adoptBytes)), |
| bytes_(static_cast<const uint8_t *>(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<kMinThreeByteDeltaLead) { |
| ++pos; |
| } else if(delta<kFourByteDeltaLead) { |
| pos+=2; |
| } else { |
| pos+=3+(delta&1); |
| } |
| } |
| return pos; |
| } |
| |
| static inline UStringTrieResult valueResult(int32_t node) { |
| return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node&kValueIsFinal)); |
| } |
| |
| // Handles a branch node for both next(byte) and next(string). |
| UStringTrieResult branchNext(const uint8_t *pos, int32_t length, int32_t inByte); |
| |
| // Requires remainingLength_<0. |
| UStringTrieResult nextImpl(const uint8_t *pos, int32_t inByte); |
| |
| // Helper functions for hasUniqueValue(). |
| // Recursively finds a unique value (or whether there is not a unique one) |
| // from a branch. |
| static const uint8_t *findUniqueValueFromBranch(const uint8_t *pos, int32_t length, |
| UBool haveUniqueValue, int32_t &uniqueValue); |
| // Recursively finds a unique value (or whether there is not a unique one) |
| // starting from a position on a node lead byte. |
| static UBool findUniqueValue(const uint8_t *pos, UBool haveUniqueValue, int32_t &uniqueValue); |
| |
| // Helper functions for getNextBytes(). |
| // getNextBytes() when pos is on a branch node. |
| static void getNextBranchBytes(const uint8_t *pos, int32_t length, ByteSink &out); |
| static void append(ByteSink &out, int c); |
| |
| // BytesTrie data structure |
| // |
| // The trie consists of a series of byte-serialized nodes for incremental |
| // string/byte sequence matching. The root node is at the beginning of the trie data. |
| // |
| // Types of nodes are distinguished by their node lead byte ranges. |
| // After each node, except a final-value node, another node follows to |
| // encode match values or continue matching further bytes. |
| // |
| // Node types: |
| // - Value node: Stores a 32-bit integer in a compact, variable-length format. |
| // The value is for the string/byte sequence so far. |
| // One node bit indicates whether the value is final or whether |
| // matching continues with the next node. |
| // - Linear-match node: Matches a number of bytes. |
| // - Branch node: Branches to other nodes according to the current input byte. |
| // The node byte is the length of the branch (number of bytes to select from) |
| // minus 1. It is followed by a sub-node: |
| // - If the length is at most kMaxBranchLinearSubNodeLength, then |
| // there are length-1 (key, value) pairs and then one more comparison byte. |
| // If one of the key bytes matches, then the value is either a final value for |
| // the string/byte sequence so far, or a "jump" delta to the next node. |
| // If the last byte matches, then matching continues with the next node. |
| // (Values have the same encoding as value nodes.) |
| // - If the length is greater than kMaxBranchLinearSubNodeLength, then |
| // there is one byte and one "jump" delta. |
| // If the input byte is less than the sub-node byte, then "jump" by delta to |
| // the next sub-node which will have a length of length/2. |
| // (The delta has its own compact encoding.) |
| // Otherwise, skip the "jump" delta to the next sub-node |
| // which will have a length of length-length/2. |
| |
| // Node lead byte values. |
| |
| // 00..0f: Branch node. If node!=0 then the length is node+1, otherwise |
| // the length is one more than the next byte. |
| |
| // For a branch sub-node with at most this many entries, we drop down |
| // to a linear search. |
| static const int32_t kMaxBranchLinearSubNodeLength=5; |
| |
| // 10..1f: Linear-match node, match 1..16 bytes and continue reading the next node. |
| static const int32_t kMinLinearMatch=0x10; |
| static const int32_t kMaxLinearMatchLength=0x10; |
| |
| // 20..ff: Variable-length value node. |
| // If odd, the value is final. (Otherwise, intermediate value or jump delta.) |
| // Then shift-right by 1 bit. |
| // The remaining lead byte value indicates the number of following bytes (0..4) |
| // and contains the value's top bits. |
| static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength; // 0x20 |
| // It is a final value if bit 0 is set. |
| static const int32_t kValueIsFinal=1; |
| |
| // Compact value: After testing bit 0, shift right by 1 and then use the following thresholds. |
| static const int32_t kMinOneByteValueLead=kMinValueLead/2; // 0x10 |
| static const int32_t kMaxOneByteValue=0x40; // At least 6 bits in the first byte. |
| |
| static const int32_t kMinTwoByteValueLead=kMinOneByteValueLead+kMaxOneByteValue+1; // 0x51 |
| static const int32_t kMaxTwoByteValue=0x1aff; |
| |
| static const int32_t kMinThreeByteValueLead=kMinTwoByteValueLead+(kMaxTwoByteValue>>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 |
| |
| 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 // __BYTESTRIE_H__ |
