jpayne@69: // © 2016 and later: Unicode, Inc. and others.
jpayne@69: // License & terms of use: http://www.unicode.org/copyright.html
jpayne@69: /*
jpayne@69: *******************************************************************************
jpayne@69: *   Copyright (C) 2010-2012, International Business Machines
jpayne@69: *   Corporation and others.  All Rights Reserved.
jpayne@69: *******************************************************************************
jpayne@69: *   file name:  bytestrie.h
jpayne@69: *   encoding:   UTF-8
jpayne@69: *   tab size:   8 (not used)
jpayne@69: *   indentation:4
jpayne@69: *
jpayne@69: *   created on: 2010sep25
jpayne@69: *   created by: Markus W. Scherer
jpayne@69: */
jpayne@69: 
jpayne@69: #ifndef __BYTESTRIE_H__
jpayne@69: #define __BYTESTRIE_H__
jpayne@69: 
jpayne@69: /**
jpayne@69:  * \file
jpayne@69:  * \brief C++ API: Trie for mapping byte sequences to integer values.
jpayne@69:  */
jpayne@69: 
jpayne@69: #include "unicode/utypes.h"
jpayne@69: 
jpayne@69: #if U_SHOW_CPLUSPLUS_API
jpayne@69: 
jpayne@69: #include "unicode/stringpiece.h"
jpayne@69: #include "unicode/uobject.h"
jpayne@69: #include "unicode/ustringtrie.h"
jpayne@69: 
jpayne@69: U_NAMESPACE_BEGIN
jpayne@69: 
jpayne@69: class ByteSink;
jpayne@69: class BytesTrieBuilder;
jpayne@69: class CharString;
jpayne@69: class UVector32;
jpayne@69: 
jpayne@69: /**
jpayne@69:  * Light-weight, non-const reader class for a BytesTrie.
jpayne@69:  * Traverses a byte-serialized data structure with minimal state,
jpayne@69:  * for mapping byte sequences to non-negative integer values.
jpayne@69:  *
jpayne@69:  * This class owns the serialized trie data only if it was constructed by
jpayne@69:  * the builder's build() method.
jpayne@69:  * The public constructor and the copy constructor only alias the data (only copy the pointer).
jpayne@69:  * There is no assignment operator.
jpayne@69:  *
jpayne@69:  * This class is not intended for public subclassing.
jpayne@69:  * @stable ICU 4.8
jpayne@69:  */
jpayne@69: class U_COMMON_API BytesTrie : public UMemory {
jpayne@69: public:
jpayne@69:     /**
jpayne@69:      * Constructs a BytesTrie reader instance.
jpayne@69:      *
jpayne@69:      * The trieBytes must contain a copy of a byte sequence from the BytesTrieBuilder,
jpayne@69:      * starting with the first byte of that sequence.
jpayne@69:      * The BytesTrie object will not read more bytes than
jpayne@69:      * the BytesTrieBuilder generated in the corresponding build() call.
jpayne@69:      *
jpayne@69:      * The array is not copied/cloned and must not be modified while
jpayne@69:      * the BytesTrie object is in use.
jpayne@69:      *
jpayne@69:      * @param trieBytes The byte array that contains the serialized trie.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     BytesTrie(const void *trieBytes)
jpayne@69:             : ownedArray_(NULL), bytes_(static_cast<const uint8_t *>(trieBytes)),
jpayne@69:               pos_(bytes_), remainingMatchLength_(-1) {}
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Destructor.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     ~BytesTrie();
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Copy constructor, copies the other trie reader object and its state,
jpayne@69:      * but not the byte array which will be shared. (Shallow copy.)
jpayne@69:      * @param other Another BytesTrie object.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     BytesTrie(const BytesTrie &other)
jpayne@69:             : ownedArray_(NULL), bytes_(other.bytes_),
jpayne@69:               pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {}
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Resets this trie to its initial state.
jpayne@69:      * @return *this
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     BytesTrie &reset() {
jpayne@69:         pos_=bytes_;
jpayne@69:         remainingMatchLength_=-1;
jpayne@69:         return *this;
jpayne@69:     }
jpayne@69: 
jpayne@69: #ifndef U_HIDE_DRAFT_API
jpayne@69:     /**
jpayne@69:      * Returns the state of this trie as a 64-bit integer.
jpayne@69:      * The state value is never 0.
jpayne@69:      *
jpayne@69:      * @return opaque state value
jpayne@69:      * @see resetToState64
jpayne@69:      * @draft ICU 65
jpayne@69:      */
jpayne@69:     uint64_t getState64() const {
jpayne@69:         return (static_cast<uint64_t>(remainingMatchLength_ + 2) << kState64RemainingShift) |
jpayne@69:             (uint64_t)(pos_ - bytes_);
jpayne@69:     }
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Resets this trie to the saved state.
jpayne@69:      * Unlike resetToState(State), the 64-bit state value
jpayne@69:      * must be from getState64() from the same trie object or
jpayne@69:      * from one initialized the exact same way.
jpayne@69:      * Because of no validation, this method is faster.
jpayne@69:      *
jpayne@69:      * @param state The opaque trie state value from getState64().
jpayne@69:      * @return *this
jpayne@69:      * @see getState64
jpayne@69:      * @see resetToState
jpayne@69:      * @see reset
jpayne@69:      * @draft ICU 65
jpayne@69:      */
jpayne@69:     BytesTrie &resetToState64(uint64_t state) {
jpayne@69:         remainingMatchLength_ = static_cast<int32_t>(state >> kState64RemainingShift) - 2;
jpayne@69:         pos_ = bytes_ + (state & kState64PosMask);
jpayne@69:         return *this;
jpayne@69:     }
jpayne@69: #endif  /* U_HIDE_DRAFT_API */
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * BytesTrie state object, for saving a trie's current state
jpayne@69:      * and resetting the trie back to this state later.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     class State : public UMemory {
jpayne@69:     public:
jpayne@69:         /**
jpayne@69:          * Constructs an empty State.
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         State() { bytes=NULL; }
jpayne@69:     private:
jpayne@69:         friend class BytesTrie;
jpayne@69: 
jpayne@69:         const uint8_t *bytes;
jpayne@69:         const uint8_t *pos;
jpayne@69:         int32_t remainingMatchLength;
jpayne@69:     };
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Saves the state of this trie.
jpayne@69:      * @param state The State object to hold the trie's state.
jpayne@69:      * @return *this
jpayne@69:      * @see resetToState
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     const BytesTrie &saveState(State &state) const {
jpayne@69:         state.bytes=bytes_;
jpayne@69:         state.pos=pos_;
jpayne@69:         state.remainingMatchLength=remainingMatchLength_;
jpayne@69:         return *this;
jpayne@69:     }
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Resets this trie to the saved state.
jpayne@69:      * If the state object contains no state, or the state of a different trie,
jpayne@69:      * then this trie remains unchanged.
jpayne@69:      * @param state The State object which holds a saved trie state.
jpayne@69:      * @return *this
jpayne@69:      * @see saveState
jpayne@69:      * @see reset
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     BytesTrie &resetToState(const State &state) {
jpayne@69:         if(bytes_==state.bytes && bytes_!=NULL) {
jpayne@69:             pos_=state.pos;
jpayne@69:             remainingMatchLength_=state.remainingMatchLength;
jpayne@69:         }
jpayne@69:         return *this;
jpayne@69:     }
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Determines whether the byte sequence so far matches, whether it has a value,
jpayne@69:      * and whether another input byte can continue a matching byte sequence.
jpayne@69:      * @return The match/value Result.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     UStringTrieResult current() const;
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Traverses the trie from the initial state for this input byte.
jpayne@69:      * Equivalent to reset().next(inByte).
jpayne@69:      * @param inByte Input byte value. Values -0x100..-1 are treated like 0..0xff.
jpayne@69:      *               Values below -0x100 and above 0xff will never match.
jpayne@69:      * @return The match/value Result.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     inline UStringTrieResult first(int32_t inByte) {
jpayne@69:         remainingMatchLength_=-1;
jpayne@69:         if(inByte<0) {
jpayne@69:             inByte+=0x100;
jpayne@69:         }
jpayne@69:         return nextImpl(bytes_, inByte);
jpayne@69:     }
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Traverses the trie from the current state for this input byte.
jpayne@69:      * @param inByte Input byte value. Values -0x100..-1 are treated like 0..0xff.
jpayne@69:      *               Values below -0x100 and above 0xff will never match.
jpayne@69:      * @return The match/value Result.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     UStringTrieResult next(int32_t inByte);
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Traverses the trie from the current state for this byte sequence.
jpayne@69:      * Equivalent to
jpayne@69:      * \code
jpayne@69:      * Result result=current();
jpayne@69:      * for(each c in s)
jpayne@69:      *   if(!USTRINGTRIE_HAS_NEXT(result)) return USTRINGTRIE_NO_MATCH;
jpayne@69:      *   result=next(c);
jpayne@69:      * return result;
jpayne@69:      * \endcode
jpayne@69:      * @param s A string or byte sequence. Can be NULL if length is 0.
jpayne@69:      * @param length The length of the byte sequence. Can be -1 if NUL-terminated.
jpayne@69:      * @return The match/value Result.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     UStringTrieResult next(const char *s, int32_t length);
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Returns a matching byte sequence's value if called immediately after
jpayne@69:      * current()/first()/next() returned USTRINGTRIE_INTERMEDIATE_VALUE or USTRINGTRIE_FINAL_VALUE.
jpayne@69:      * getValue() can be called multiple times.
jpayne@69:      *
jpayne@69:      * Do not call getValue() after USTRINGTRIE_NO_MATCH or USTRINGTRIE_NO_VALUE!
jpayne@69:      * @return The value for the byte sequence so far.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     inline int32_t getValue() const {
jpayne@69:         const uint8_t *pos=pos_;
jpayne@69:         int32_t leadByte=*pos++;
jpayne@69:         // U_ASSERT(leadByte>=kMinValueLead);
jpayne@69:         return readValue(pos, leadByte>>1);
jpayne@69:     }
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Determines whether all byte sequences reachable from the current state
jpayne@69:      * map to the same value.
jpayne@69:      * @param uniqueValue Receives the unique value, if this function returns TRUE.
jpayne@69:      *                    (output-only)
jpayne@69:      * @return TRUE if all byte sequences reachable from the current state
jpayne@69:      *         map to the same value.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     inline UBool hasUniqueValue(int32_t &uniqueValue) const {
jpayne@69:         const uint8_t *pos=pos_;
jpayne@69:         // Skip the rest of a pending linear-match node.
jpayne@69:         return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, FALSE, uniqueValue);
jpayne@69:     }
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Finds each byte which continues the byte sequence from the current state.
jpayne@69:      * That is, each byte b for which it would be next(b)!=USTRINGTRIE_NO_MATCH now.
jpayne@69:      * @param out Each next byte is appended to this object.
jpayne@69:      *            (Only uses the out.Append(s, length) method.)
jpayne@69:      * @return the number of bytes which continue the byte sequence from here
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     int32_t getNextBytes(ByteSink &out) const;
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Iterator for all of the (byte sequence, value) pairs in a BytesTrie.
jpayne@69:      * @stable ICU 4.8
jpayne@69:      */
jpayne@69:     class U_COMMON_API Iterator : public UMemory {
jpayne@69:     public:
jpayne@69:         /**
jpayne@69:          * Iterates from the root of a byte-serialized BytesTrie.
jpayne@69:          * @param trieBytes The trie bytes.
jpayne@69:          * @param maxStringLength If 0, the iterator returns full strings/byte sequences.
jpayne@69:          *                        Otherwise, the iterator returns strings with this maximum length.
jpayne@69:          * @param errorCode Standard ICU error code. Its input value must
jpayne@69:          *                  pass the U_SUCCESS() test, or else the function returns
jpayne@69:          *                  immediately. Check for U_FAILURE() on output or use with
jpayne@69:          *                  function chaining. (See User Guide for details.)
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         Iterator(const void *trieBytes, int32_t maxStringLength, UErrorCode &errorCode);
jpayne@69: 
jpayne@69:         /**
jpayne@69:          * Iterates from the current state of the specified BytesTrie.
jpayne@69:          * @param trie The trie whose state will be copied for iteration.
jpayne@69:          * @param maxStringLength If 0, the iterator returns full strings/byte sequences.
jpayne@69:          *                        Otherwise, the iterator returns strings with this maximum length.
jpayne@69:          * @param errorCode Standard ICU error code. Its input value must
jpayne@69:          *                  pass the U_SUCCESS() test, or else the function returns
jpayne@69:          *                  immediately. Check for U_FAILURE() on output or use with
jpayne@69:          *                  function chaining. (See User Guide for details.)
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         Iterator(const BytesTrie &trie, int32_t maxStringLength, UErrorCode &errorCode);
jpayne@69: 
jpayne@69:         /**
jpayne@69:          * Destructor.
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         ~Iterator();
jpayne@69: 
jpayne@69:         /**
jpayne@69:          * Resets this iterator to its initial state.
jpayne@69:          * @return *this
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         Iterator &reset();
jpayne@69: 
jpayne@69:         /**
jpayne@69:          * @return TRUE if there are more elements.
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         UBool hasNext() const;
jpayne@69: 
jpayne@69:         /**
jpayne@69:          * Finds the next (byte sequence, value) pair if there is one.
jpayne@69:          *
jpayne@69:          * If the byte sequence is truncated to the maximum length and does not
jpayne@69:          * have a real value, then the value is set to -1.
jpayne@69:          * In this case, this "not a real value" is indistinguishable from
jpayne@69:          * a real value of -1.
jpayne@69:          * @param errorCode Standard ICU error code. Its input value must
jpayne@69:          *                  pass the U_SUCCESS() test, or else the function returns
jpayne@69:          *                  immediately. Check for U_FAILURE() on output or use with
jpayne@69:          *                  function chaining. (See User Guide for details.)
jpayne@69:          * @return TRUE if there is another element.
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         UBool next(UErrorCode &errorCode);
jpayne@69: 
jpayne@69:         /**
jpayne@69:          * @return The NUL-terminated byte sequence for the last successful next().
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         StringPiece getString() const;
jpayne@69:         /**
jpayne@69:          * @return The value for the last successful next().
jpayne@69:          * @stable ICU 4.8
jpayne@69:          */
jpayne@69:         int32_t getValue() const { return value_; }
jpayne@69: 
jpayne@69:     private:
jpayne@69:         UBool truncateAndStop();
jpayne@69: 
jpayne@69:         const uint8_t *branchNext(const uint8_t *pos, int32_t length, UErrorCode &errorCode);
jpayne@69: 
jpayne@69:         const uint8_t *bytes_;
jpayne@69:         const uint8_t *pos_;
jpayne@69:         const uint8_t *initialPos_;
jpayne@69:         int32_t remainingMatchLength_;
jpayne@69:         int32_t initialRemainingMatchLength_;
jpayne@69: 
jpayne@69:         CharString *str_;
jpayne@69:         int32_t maxLength_;
jpayne@69:         int32_t value_;
jpayne@69: 
jpayne@69:         // The stack stores pairs of integers for backtracking to another
jpayne@69:         // outbound edge of a branch node.
jpayne@69:         // The first integer is an offset from bytes_.
jpayne@69:         // The second integer has the str_->length() from before the node in bits 15..0,
jpayne@69:         // and the remaining branch length in bits 24..16. (Bits 31..25 are unused.)
jpayne@69:         // (We could store the remaining branch length minus 1 in bits 23..16 and not use bits 31..24,
jpayne@69:         // but the code looks more confusing that way.)
jpayne@69:         UVector32 *stack_;
jpayne@69:     };
jpayne@69: 
jpayne@69: private:
jpayne@69:     friend class BytesTrieBuilder;
jpayne@69: 
jpayne@69:     /**
jpayne@69:      * Constructs a BytesTrie reader instance.
jpayne@69:      * Unlike the public constructor which just aliases an array,
jpayne@69:      * this constructor adopts the builder's array.
jpayne@69:      * This constructor is only called by the builder.
jpayne@69:      */
jpayne@69:     BytesTrie(void *adoptBytes, const void *trieBytes)
jpayne@69:             : ownedArray_(static_cast<uint8_t *>(adoptBytes)),
jpayne@69:               bytes_(static_cast<const uint8_t *>(trieBytes)),
jpayne@69:               pos_(bytes_), remainingMatchLength_(-1) {}
jpayne@69: 
jpayne@69:     // No assignment operator.
jpayne@69:     BytesTrie &operator=(const BytesTrie &other);
jpayne@69: 
jpayne@69:     inline void stop() {
jpayne@69:         pos_=NULL;
jpayne@69:     }
jpayne@69: 
jpayne@69:     // Reads a compact 32-bit integer.
jpayne@69:     // pos is already after the leadByte, and the lead byte is already shifted right by 1.
jpayne@69:     static int32_t readValue(const uint8_t *pos, int32_t leadByte);
jpayne@69:     static inline const uint8_t *skipValue(const uint8_t *pos, int32_t leadByte) {
jpayne@69:         // U_ASSERT(leadByte>=kMinValueLead);
jpayne@69:         if(leadByte>=(kMinTwoByteValueLead<<1)) {
jpayne@69:             if(leadByte<(kMinThreeByteValueLead<<1)) {
jpayne@69:                 ++pos;
jpayne@69:             } else if(leadByte<(kFourByteValueLead<<1)) {
jpayne@69:                 pos+=2;
jpayne@69:             } else {
jpayne@69:                 pos+=3+((leadByte>>1)&1);
jpayne@69:             }
jpayne@69:         }
jpayne@69:         return pos;
jpayne@69:     }
jpayne@69:     static inline const uint8_t *skipValue(const uint8_t *pos) {
jpayne@69:         int32_t leadByte=*pos++;
jpayne@69:         return skipValue(pos, leadByte);
jpayne@69:     }
jpayne@69: 
jpayne@69:     // Reads a jump delta and jumps.
jpayne@69:     static const uint8_t *jumpByDelta(const uint8_t *pos);
jpayne@69: 
jpayne@69:     static inline const uint8_t *skipDelta(const uint8_t *pos) {
jpayne@69:         int32_t delta=*pos++;
jpayne@69:         if(delta>=kMinTwoByteDeltaLead) {
jpayne@69:             if(delta<kMinThreeByteDeltaLead) {
jpayne@69:                 ++pos;
jpayne@69:             } else if(delta<kFourByteDeltaLead) {
jpayne@69:                 pos+=2;
jpayne@69:             } else {
jpayne@69:                 pos+=3+(delta&1);
jpayne@69:             }
jpayne@69:         }
jpayne@69:         return pos;
jpayne@69:     }
jpayne@69: 
jpayne@69:     static inline UStringTrieResult valueResult(int32_t node) {
jpayne@69:         return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node&kValueIsFinal));
jpayne@69:     }
jpayne@69: 
jpayne@69:     // Handles a branch node for both next(byte) and next(string).
jpayne@69:     UStringTrieResult branchNext(const uint8_t *pos, int32_t length, int32_t inByte);
jpayne@69: 
jpayne@69:     // Requires remainingLength_<0.
jpayne@69:     UStringTrieResult nextImpl(const uint8_t *pos, int32_t inByte);
jpayne@69: 
jpayne@69:     // Helper functions for hasUniqueValue().
jpayne@69:     // Recursively finds a unique value (or whether there is not a unique one)
jpayne@69:     // from a branch.
jpayne@69:     static const uint8_t *findUniqueValueFromBranch(const uint8_t *pos, int32_t length,
jpayne@69:                                                     UBool haveUniqueValue, int32_t &uniqueValue);
jpayne@69:     // Recursively finds a unique value (or whether there is not a unique one)
jpayne@69:     // starting from a position on a node lead byte.
jpayne@69:     static UBool findUniqueValue(const uint8_t *pos, UBool haveUniqueValue, int32_t &uniqueValue);
jpayne@69: 
jpayne@69:     // Helper functions for getNextBytes().
jpayne@69:     // getNextBytes() when pos is on a branch node.
jpayne@69:     static void getNextBranchBytes(const uint8_t *pos, int32_t length, ByteSink &out);
jpayne@69:     static void append(ByteSink &out, int c);
jpayne@69: 
jpayne@69:     // BytesTrie data structure
jpayne@69:     //
jpayne@69:     // The trie consists of a series of byte-serialized nodes for incremental
jpayne@69:     // string/byte sequence matching. The root node is at the beginning of the trie data.
jpayne@69:     //
jpayne@69:     // Types of nodes are distinguished by their node lead byte ranges.
jpayne@69:     // After each node, except a final-value node, another node follows to
jpayne@69:     // encode match values or continue matching further bytes.
jpayne@69:     //
jpayne@69:     // Node types:
jpayne@69:     //  - Value node: Stores a 32-bit integer in a compact, variable-length format.
jpayne@69:     //    The value is for the string/byte sequence so far.
jpayne@69:     //    One node bit indicates whether the value is final or whether
jpayne@69:     //    matching continues with the next node.
jpayne@69:     //  - Linear-match node: Matches a number of bytes.
jpayne@69:     //  - Branch node: Branches to other nodes according to the current input byte.
jpayne@69:     //    The node byte is the length of the branch (number of bytes to select from)
jpayne@69:     //    minus 1. It is followed by a sub-node:
jpayne@69:     //    - If the length is at most kMaxBranchLinearSubNodeLength, then
jpayne@69:     //      there are length-1 (key, value) pairs and then one more comparison byte.
jpayne@69:     //      If one of the key bytes matches, then the value is either a final value for
jpayne@69:     //      the string/byte sequence so far, or a "jump" delta to the next node.
jpayne@69:     //      If the last byte matches, then matching continues with the next node.
jpayne@69:     //      (Values have the same encoding as value nodes.)
jpayne@69:     //    - If the length is greater than kMaxBranchLinearSubNodeLength, then
jpayne@69:     //      there is one byte and one "jump" delta.
jpayne@69:     //      If the input byte is less than the sub-node byte, then "jump" by delta to
jpayne@69:     //      the next sub-node which will have a length of length/2.
jpayne@69:     //      (The delta has its own compact encoding.)
jpayne@69:     //      Otherwise, skip the "jump" delta to the next sub-node
jpayne@69:     //      which will have a length of length-length/2.
jpayne@69: 
jpayne@69:     // Node lead byte values.
jpayne@69: 
jpayne@69:     // 00..0f: Branch node. If node!=0 then the length is node+1, otherwise
jpayne@69:     // the length is one more than the next byte.
jpayne@69: 
jpayne@69:     // For a branch sub-node with at most this many entries, we drop down
jpayne@69:     // to a linear search.
jpayne@69:     static const int32_t kMaxBranchLinearSubNodeLength=5;
jpayne@69: 
jpayne@69:     // 10..1f: Linear-match node, match 1..16 bytes and continue reading the next node.
jpayne@69:     static const int32_t kMinLinearMatch=0x10;
jpayne@69:     static const int32_t kMaxLinearMatchLength=0x10;
jpayne@69: 
jpayne@69:     // 20..ff: Variable-length value node.
jpayne@69:     // If odd, the value is final. (Otherwise, intermediate value or jump delta.)
jpayne@69:     // Then shift-right by 1 bit.
jpayne@69:     // The remaining lead byte value indicates the number of following bytes (0..4)
jpayne@69:     // and contains the value's top bits.
jpayne@69:     static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength;  // 0x20
jpayne@69:     // It is a final value if bit 0 is set.
jpayne@69:     static const int32_t kValueIsFinal=1;
jpayne@69: 
jpayne@69:     // Compact value: After testing bit 0, shift right by 1 and then use the following thresholds.
jpayne@69:     static const int32_t kMinOneByteValueLead=kMinValueLead/2;  // 0x10
jpayne@69:     static const int32_t kMaxOneByteValue=0x40;  // At least 6 bits in the first byte.
jpayne@69: 
jpayne@69:     static const int32_t kMinTwoByteValueLead=kMinOneByteValueLead+kMaxOneByteValue+1;  // 0x51
jpayne@69:     static const int32_t kMaxTwoByteValue=0x1aff;
jpayne@69: 
jpayne@69:     static const int32_t kMinThreeByteValueLead=kMinTwoByteValueLead+(kMaxTwoByteValue>>8)+1;  // 0x6c
jpayne@69:     static const int32_t kFourByteValueLead=0x7e;
jpayne@69: 
jpayne@69:     // A little more than Unicode code points. (0x11ffff)
jpayne@69:     static const int32_t kMaxThreeByteValue=((kFourByteValueLead-kMinThreeByteValueLead)<<16)-1;
jpayne@69: 
jpayne@69:     static const int32_t kFiveByteValueLead=0x7f;
jpayne@69: 
jpayne@69:     // Compact delta integers.
jpayne@69:     static const int32_t kMaxOneByteDelta=0xbf;
jpayne@69:     static const int32_t kMinTwoByteDeltaLead=kMaxOneByteDelta+1;  // 0xc0
jpayne@69:     static const int32_t kMinThreeByteDeltaLead=0xf0;
jpayne@69:     static const int32_t kFourByteDeltaLead=0xfe;
jpayne@69:     static const int32_t kFiveByteDeltaLead=0xff;
jpayne@69: 
jpayne@69:     static const int32_t kMaxTwoByteDelta=((kMinThreeByteDeltaLead-kMinTwoByteDeltaLead)<<8)-1;  // 0x2fff
jpayne@69:     static const int32_t kMaxThreeByteDelta=((kFourByteDeltaLead-kMinThreeByteDeltaLead)<<16)-1;  // 0xdffff
jpayne@69: 
jpayne@69:     // For getState64():
jpayne@69:     // The remainingMatchLength_ is -1..14=(kMaxLinearMatchLength=0x10)-2
jpayne@69:     // so we need at least 5 bits for that.
jpayne@69:     // We add 2 to store it as a positive value 1..16=kMaxLinearMatchLength.
jpayne@69:     static constexpr int32_t kState64RemainingShift = 59;
jpayne@69:     static constexpr uint64_t kState64PosMask = (UINT64_C(1) << kState64RemainingShift) - 1;
jpayne@69: 
jpayne@69:     uint8_t *ownedArray_;
jpayne@69: 
jpayne@69:     // Fixed value referencing the BytesTrie bytes.
jpayne@69:     const uint8_t *bytes_;
jpayne@69: 
jpayne@69:     // Iterator variables.
jpayne@69: 
jpayne@69:     // Pointer to next trie byte to read. NULL if no more matches.
jpayne@69:     const uint8_t *pos_;
jpayne@69:     // Remaining length of a linear-match node, minus 1. Negative if not in such a node.
jpayne@69:     int32_t remainingMatchLength_;
jpayne@69: };
jpayne@69: 
jpayne@69: U_NAMESPACE_END
jpayne@69: 
jpayne@69: #endif /* U_SHOW_CPLUSPLUS_API */
jpayne@69: 
jpayne@69: #endif  // __BYTESTRIE_H__