The Tor Browser: comparison intl/icu/source/common/unicode/bytestrie.h

--1:000000000000
+:8c7b62f5b752
+/*
+*******************************************************************************
+*   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__

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comparison: intl/icu/source/common/unicode/bytestrie.h

intl/icu/source/common/unicode/bytestrie.h