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Diffstat (limited to 'deps/icu-small/source/common/unicode/bytestrie.h')
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diff --git a/deps/icu-small/source/common/unicode/bytestrie.h b/deps/icu-small/source/common/unicode/bytestrie.h new file mode 100644 index 0000000000..9c7782740d --- /dev/null +++ b/deps/icu-small/source/common/unicode/bytestrie.h @@ -0,0 +1,519 @@ +/* +******************************************************************************* +* 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__ |