=kMinValueLead);
return leadUnit&kValueIsFinal ?
readValue(pos, leadUnit&0x7fff) : readNodeValue(pos, leadUnit);
}
/**
* Determines whether all strings 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 strings reachable from the current state
* map to the same value.
* @stable ICU 4.8
*/
inline UBool hasUniqueValue(int32_t &uniqueValue) const {
const UChar *pos=pos_;
// Skip the rest of a pending linear-match node.
return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, FALSE, uniqueValue);
}
/**
* Finds each UChar which continues the string from the current state.
* That is, each UChar c for which it would be next(c)!=USTRINGTRIE_NO_MATCH now.
* @param out Each next UChar is appended to this object.
* @return the number of UChars which continue the string from here
* @stable ICU 4.8
*/
int32_t getNextUChars(Appendable &out) const;
/**
* Iterator for all of the (string, value) pairs in a UCharsTrie.
* @stable ICU 4.8
*/
class U_COMMON_API Iterator : public UMemory {
public:
/**
* Iterates from the root of a UChar-serialized UCharsTrie.
* @param trieUChars The trie UChars.
* @param maxStringLength If 0, the iterator returns full strings.
* 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 UChar *trieUChars, int32_t maxStringLength, UErrorCode &errorCode);
/**
* Iterates from the current state of the specified UCharsTrie.
* @param trie The trie whose state will be copied for iteration.
* @param maxStringLength If 0, the iterator returns full strings.
* 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 UCharsTrie &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 (string, value) pair if there is one.
*
* If the string 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 string for the last successful next().
* @stable ICU 4.8
*/
const UnicodeString &getString() const { return str_; }
/**
* @return The value for the last successful next().
* @stable ICU 4.8
*/
int32_t getValue() const { return value_; }
private:
UBool truncateAndStop() {
pos_=NULL;
value_=-1; // no real value for str
return TRUE;
}
const UChar *branchNext(const UChar *pos, int32_t length, UErrorCode &errorCode);
const UChar *uchars_;
const UChar *pos_;
const UChar *initialPos_;
int32_t remainingMatchLength_;
int32_t initialRemainingMatchLength_;
UBool skipValue_; // Skip intermediate value which was already delivered.
UnicodeString 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 uchars_.
// The second integer has the str_.length() from before the node in bits 15..0,
// and the remaining branch length in bits 31..16.
// (We could store the remaining branch length minus 1 in bits 30..16 and not use the sign bit,
// but the code looks more confusing that way.)
UVector32 *stack_;
};
private:
friend class UCharsTrieBuilder;
/**
* Constructs a UCharsTrie 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.
*/
UCharsTrie(UChar *adoptUChars, const UChar *trieUChars)
: ownedArray_(adoptUChars), uchars_(trieUChars),
pos_(uchars_), remainingMatchLength_(-1) {}
// No assignment operator.
UCharsTrie &operator=(const UCharsTrie &other);
inline void stop() {
pos_=NULL;
}
// Reads a compact 32-bit integer.
// pos is already after the leadUnit, and the lead unit has bit 15 reset.
static inline int32_t readValue(const UChar *pos, int32_t leadUnit) {
int32_t value;
if(leadUnit=kMinTwoUnitValueLead) {
if(leadUnit>6)-1;
} else if(leadUnit=kMinTwoUnitNodeValueLead) {
if(leadUnit=kMinTwoUnitDeltaLead) {
if(delta==kThreeUnitDeltaLead) {
delta=(pos[0]<<16)|pos[1];
pos+=2;
} else {
delta=((delta-kMinTwoUnitDeltaLead)<<16)|*pos++;
}
}
return pos+delta;
}
static const UChar *skipDelta(const UChar *pos) {
int32_t delta=*pos++;
if(delta>=kMinTwoUnitDeltaLead) {
if(delta==kThreeUnitDeltaLead) {
pos+=2;
} else {
++pos;
}
}
return pos;
}
static inline UStringTrieResult valueResult(int32_t node) {
return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node>>15));
}
// Handles a branch node for both next(uchar) and next(string).
UStringTrieResult branchNext(const UChar *pos, int32_t length, int32_t uchar);
// Requires remainingLength_<0.
UStringTrieResult nextImpl(const UChar *pos, int32_t uchar);
// Helper functions for hasUniqueValue().
// Recursively finds a unique value (or whether there is not a unique one)
// from a branch.
static const UChar *findUniqueValueFromBranch(const UChar *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 unit.
static UBool findUniqueValue(const UChar *pos, UBool haveUniqueValue, int32_t &uniqueValue);
// Helper functions for getNextUChars().
// getNextUChars() when pos is on a branch node.
static void getNextBranchUChars(const UChar *pos, int32_t length, Appendable &out);
// UCharsTrie data structure
//
// The trie consists of a series of UChar-serialized nodes for incremental
// Unicode string/UChar sequence matching. (UChar=16-bit unsigned integer)
// The root node is at the beginning of the trie data.
//
// Types of nodes are distinguished by their node lead unit ranges.
// After each node, except a final-value node, another node follows to
// encode match values or continue matching further units.
//
// Node types:
// - Final-value node: Stores a 32-bit integer in a compact, variable-length format.
// The value is for the string/UChar sequence so far.
// - Match node, optionally with an intermediate value in a different compact format.
// The value, if present, is for the string/UChar sequence so far.
//
// Aside from the value, which uses the node lead unit's high bits:
//
// - Linear-match node: Matches a number of units.
// - Branch node: Branches to other nodes according to the current input unit.
// The node unit is the length of the branch (number of units 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 unit.
// If one of the key units matches, then the value is either a final value for
// the string so far, or a "jump" delta to the next node.
// If the last unit matches, then matching continues with the next node.
// (Values have the same encoding as final-value nodes.)
// - If the length is greater than kMaxBranchLinearSubNodeLength, then
// there is one unit and one "jump" delta.
// If the input unit is less than the sub-node unit, 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.
// Match-node lead unit values, after masking off intermediate-value bits:
// 0000..002f: Branch node. If node!=0 then the length is node+1, otherwise
// the length is one more than the next unit.
// For a branch sub-node with at most this many entries, we drop down
// to a linear search.
static const int32_t kMaxBranchLinearSubNodeLength=5;
// 0030..003f: Linear-match node, match 1..16 units and continue reading the next node.
static const int32_t kMinLinearMatch=0x30;
static const int32_t kMaxLinearMatchLength=0x10;
// Match-node lead unit bits 14..6 for the optional intermediate value.
// If these bits are 0, then there is no intermediate value.
// Otherwise, see the *NodeValue* constants below.
static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength; // 0x0040
static const int32_t kNodeTypeMask=kMinValueLead-1; // 0x003f
// A final-value node has bit 15 set.
static const int32_t kValueIsFinal=0x8000;
// Compact value: After testing and masking off bit 15, use the following thresholds.
static const int32_t kMaxOneUnitValue=0x3fff;
static const int32_t kMinTwoUnitValueLead=kMaxOneUnitValue+1; // 0x4000
static const int32_t kThreeUnitValueLead=0x7fff;
static const int32_t kMaxTwoUnitValue=((kThreeUnitValueLead-kMinTwoUnitValueLead)<<16)-1; // 0x3ffeffff
// Compact intermediate-value integer, lead unit shared with a branch or linear-match node.
static const int32_t kMaxOneUnitNodeValue=0xff;
static const int32_t kMinTwoUnitNodeValueLead=kMinValueLead+((kMaxOneUnitNodeValue+1)<<6); // 0x4040
static const int32_t kThreeUnitNodeValueLead=0x7fc0;
static const int32_t kMaxTwoUnitNodeValue=
((kThreeUnitNodeValueLead-kMinTwoUnitNodeValueLead)<<10)-1; // 0xfdffff
// Compact delta integers.
static const int32_t kMaxOneUnitDelta=0xfbff;
static const int32_t kMinTwoUnitDeltaLead=kMaxOneUnitDelta+1; // 0xfc00
static const int32_t kThreeUnitDeltaLead=0xffff;
static const int32_t kMaxTwoUnitDelta=((kThreeUnitDeltaLead-kMinTwoUnitDeltaLead)<<16)-1; // 0x03feffff
UChar *ownedArray_;
// Fixed value referencing the UCharsTrie words.
const UChar *uchars_;
// Iterator variables.
// Pointer to next trie unit to read. NULL if no more matches.
const UChar *pos_;
// Remaining length of a linear-match node, minus 1. Negative if not in such a node.
int32_t remainingMatchLength_;
};
U_NAMESPACE_END
#endif // __UCHARSTRIE_H__