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// © 2019 and later: Unicode, Inc. and others.
// License & terms of use:
// locdistance.h
// created: 2019may08 Markus W. Scherer
#ifndef __LOCDISTANCE_H__
#define __LOCDISTANCE_H__
#include "unicode/utypes.h"
#include "unicode/bytestrie.h"
#include "unicode/localematcher.h"
#include "unicode/locid.h"
#include "unicode/uobject.h"
#include "lsr.h"
struct LocaleDistanceData;
* Offline-built data for LocaleMatcher.
* Mostly but not only the data for mapping locales to their maximized forms.
class LocaleDistance final : public UMemory {
static const LocaleDistance *getSingleton(UErrorCode &errorCode);
static int32_t shiftDistance(int32_t distance) {
return distance << DISTANCE_SHIFT;
static int32_t getShiftedDistance(int32_t indexAndDistance) {
return indexAndDistance & DISTANCE_MASK;
static double getDistanceDouble(int32_t indexAndDistance) {
double shiftedDistance = getShiftedDistance(indexAndDistance);
return shiftedDistance / (1 << DISTANCE_SHIFT);
static int32_t getDistanceFloor(int32_t indexAndDistance) {
return (indexAndDistance & DISTANCE_MASK) >> DISTANCE_SHIFT;
static int32_t getIndex(int32_t indexAndDistance) {
// assert indexAndDistance >= 0;
return indexAndDistance >> INDEX_SHIFT;
* Finds the supported LSR with the smallest distance from the desired one.
* Equivalent LSR subtags must be normalized into a canonical form.
* <p>Returns the index of the lowest-distance supported LSR in the high bits
* (negative if none has a distance below the threshold),
* and its distance (0..ABOVE_THRESHOLD) in the low bits.
int32_t getBestIndexAndDistance(const LSR &desired,
const LSR **supportedLSRs, int32_t supportedLSRsLength,
int32_t shiftedThreshold,
ULocMatchFavorSubtag favorSubtag,
ULocMatchDirection direction) const;
UBool isParadigmLSR(const LSR &lsr) const;
int32_t getDefaultScriptDistance() const {
return defaultScriptDistance;
int32_t getDefaultDemotionPerDesiredLocale() const {
return defaultDemotionPerDesiredLocale;
// The distance is shifted left to gain some fraction bits.
static constexpr int32_t DISTANCE_SHIFT = 3;
static constexpr int32_t DISTANCE_FRACTION_MASK = 7;
// 7 bits for 0..100
static constexpr int32_t DISTANCE_INT_SHIFT = 7;
static constexpr int32_t DISTANCE_MASK = 0x3ff;
// tic constexpr int32_t MAX_INDEX = 0x1fffff; // avoids sign bit
static constexpr int32_t INDEX_NEG_1 = 0xfffffc00;
LocaleDistance(const LocaleDistanceData &data, const XLikelySubtags &likely);
LocaleDistance(const LocaleDistance &other) = delete;
LocaleDistance &operator=(const LocaleDistance &other) = delete;
static void initLocaleDistance(UErrorCode &errorCode);
UBool isMatch(const LSR &desired, const LSR &supported,
int32_t shiftedThreshold, ULocMatchFavorSubtag favorSubtag) const {
const LSR *pSupp = &supported;
return getBestIndexAndDistance(
desired, &pSupp, 1,
shiftedThreshold, favorSubtag, ULOCMATCH_DIRECTION_WITH_ONE_WAY) >= 0;
static int32_t getDesSuppScriptDistance(BytesTrie &iter, uint64_t startState,
const char *desired, const char *supported);
static int32_t getRegionPartitionsDistance(
BytesTrie &iter, uint64_t startState,
const char *desiredPartitions, const char *supportedPartitions,
int32_t threshold);
static int32_t getFallbackRegionDistance(BytesTrie &iter, uint64_t startState);
static int32_t trieNext(BytesTrie &iter, const char *s, bool wantValue);
const char *partitionsForRegion(const LSR &lsr) const {
// ill-formed region -> one non-matching string
int32_t pIndex = regionToPartitionsIndex[lsr.regionIndex];
return partitionArrays[pIndex];
int32_t getDefaultRegionDistance() const {
return defaultRegionDistance;
const XLikelySubtags &likelySubtags;
// The trie maps each dlang+slang+dscript+sscript+dregion+sregion
// (encoded in ASCII with bit 7 set on the last character of each subtag) to a distance.
// There is also a trie value for each subsequence of whole subtags.
// One '*' is used for a (desired, supported) pair of "und", "Zzzz"/"", or "ZZ"/"".
BytesTrie trie;
* Maps each region to zero or more single-character partitions.
const uint8_t *regionToPartitionsIndex;
const char **partitionArrays;
* Used to get the paradigm region for a cluster, if there is one.
const LSR *paradigmLSRs;
int32_t paradigmLSRsLength;
int32_t defaultLanguageDistance;
int32_t defaultScriptDistance;
int32_t defaultRegionDistance;
int32_t minRegionDistance;
int32_t defaultDemotionPerDesiredLocale;
#endif // __LOCDISTANCE_H__