52a93f69fa
Backed out changeset 3877f1fa62f5 (bug 1927706) Backed out changeset 233c6ebf84a2 (bug 1927706) Backed out changeset 07e5871d5fa3 (bug 1927706) Backed out changeset 84ef75087931 (bug 1927706) Backed out changeset f89b916619e1 (bug 1927706) Backed out changeset b82d9d622315 (bug 1927706) Backed out changeset b0d2c5711865 (bug 1927706) Backed out changeset 9529dda25bd9 (bug 1927706) Backed out changeset 40b7907d7fc8 (bug 1927706) Backed out changeset c549655dbd73 (bug 1927706) Backed out changeset c5cc289771b3 (bug 1927706) Backed out changeset 8ef66f7822c4 (bug 1927706) Backed out changeset dff6d37fb2fe (bug 1927706) Backed out changeset 083a0b3da643 (bug 1927706) Backed out changeset 06649ac72a19 (bug 1927706) Backed out changeset 019f7533abbc (bug 1927706) Backed out changeset f1539604c459 (bug 1927706) Backed out changeset 578667f1f0d4 (bug 1927706) Backed out changeset 8ed1e7e7d4ab (bug 1927706)
416 lines
17 KiB
C++
416 lines
17 KiB
C++
// © 2019 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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// locdistance.cpp
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// created: 2019may08 Markus W. Scherer
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#include "unicode/utypes.h"
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#include "unicode/bytestrie.h"
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#include "unicode/localematcher.h"
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#include "unicode/locid.h"
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#include "unicode/uobject.h"
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#include "unicode/ures.h"
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#include "cstring.h"
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#include "locdistance.h"
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#include "loclikelysubtags.h"
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#include "uassert.h"
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#include "ucln_cmn.h"
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#include "uinvchar.h"
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#include "umutex.h"
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U_NAMESPACE_BEGIN
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namespace {
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/**
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* Bit flag used on the last character of a subtag in the trie.
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* Must be set consistently by the builder and the lookup code.
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*/
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constexpr int32_t END_OF_SUBTAG = 0x80;
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/** Distance value bit flag, set by the builder. */
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constexpr int32_t DISTANCE_SKIP_SCRIPT = 0x80;
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/** Distance value bit flag, set by trieNext(). */
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constexpr int32_t DISTANCE_IS_FINAL = 0x100;
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constexpr int32_t DISTANCE_IS_FINAL_OR_SKIP_SCRIPT = DISTANCE_IS_FINAL | DISTANCE_SKIP_SCRIPT;
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constexpr int32_t ABOVE_THRESHOLD = 100;
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// Indexes into array of distances.
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enum {
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IX_DEF_LANG_DISTANCE,
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IX_DEF_SCRIPT_DISTANCE,
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IX_DEF_REGION_DISTANCE,
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IX_MIN_REGION_DISTANCE,
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IX_LIMIT
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};
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LocaleDistance *gLocaleDistance = nullptr;
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UInitOnce gInitOnce {};
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UBool U_CALLCONV cleanup() {
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delete gLocaleDistance;
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gLocaleDistance = nullptr;
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gInitOnce.reset();
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return true;
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}
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} // namespace
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void U_CALLCONV LocaleDistance::initLocaleDistance(UErrorCode &errorCode) {
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// This function is invoked only via umtx_initOnce().
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U_ASSERT(gLocaleDistance == nullptr);
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const XLikelySubtags &likely = *XLikelySubtags::getSingleton(errorCode);
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if (U_FAILURE(errorCode)) { return; }
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const LocaleDistanceData &data = likely.getDistanceData();
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if (data.distanceTrieBytes == nullptr ||
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data.regionToPartitions == nullptr || data.partitions == nullptr ||
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// ok if no paradigms
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data.distances == nullptr) {
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errorCode = U_MISSING_RESOURCE_ERROR;
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return;
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}
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gLocaleDistance = new LocaleDistance(data, likely);
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if (gLocaleDistance == nullptr) {
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errorCode = U_MEMORY_ALLOCATION_ERROR;
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return;
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}
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ucln_common_registerCleanup(UCLN_COMMON_LOCALE_DISTANCE, cleanup);
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}
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const LocaleDistance *LocaleDistance::getSingleton(UErrorCode &errorCode) {
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if (U_FAILURE(errorCode)) { return nullptr; }
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umtx_initOnce(gInitOnce, &LocaleDistance::initLocaleDistance, errorCode);
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return gLocaleDistance;
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}
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LocaleDistance::LocaleDistance(const LocaleDistanceData &data, const XLikelySubtags &likely) :
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likelySubtags(likely),
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trie(data.distanceTrieBytes),
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regionToPartitionsIndex(data.regionToPartitions), partitionArrays(data.partitions),
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paradigmLSRs(data.paradigms), paradigmLSRsLength(data.paradigmsLength),
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defaultLanguageDistance(data.distances[IX_DEF_LANG_DISTANCE]),
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defaultScriptDistance(data.distances[IX_DEF_SCRIPT_DISTANCE]),
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defaultRegionDistance(data.distances[IX_DEF_REGION_DISTANCE]),
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minRegionDistance(data.distances[IX_MIN_REGION_DISTANCE]) {
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// For the default demotion value, use the
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// default region distance between unrelated Englishes.
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// Thus, unless demotion is turned off,
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// a mere region difference for one desired locale
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// is as good as a perfect match for the next following desired locale.
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// As of CLDR 36, we have <languageMatch desired="en_*_*" supported="en_*_*" distance="5"/>.
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LSR en("en", "Latn", "US", LSR::EXPLICIT_LSR);
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LSR enGB("en", "Latn", "GB", LSR::EXPLICIT_LSR);
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const LSR *p_enGB = &enGB;
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int32_t indexAndDistance = getBestIndexAndDistance(en, &p_enGB, 1,
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shiftDistance(50), ULOCMATCH_FAVOR_LANGUAGE, ULOCMATCH_DIRECTION_WITH_ONE_WAY);
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defaultDemotionPerDesiredLocale = getDistanceFloor(indexAndDistance);
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}
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int32_t LocaleDistance::getBestIndexAndDistance(
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const LSR &desired,
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const LSR **supportedLSRs, int32_t supportedLSRsLength,
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int32_t shiftedThreshold,
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ULocMatchFavorSubtag favorSubtag, ULocMatchDirection direction) const {
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BytesTrie iter(trie);
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// Look up the desired language only once for all supported LSRs.
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// Its "distance" is either a match point value of 0, or a non-match negative value.
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// Note: The data builder verifies that there are no <*, supported> or <desired, *> rules.
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int32_t desLangDistance = trieNext(iter, desired.language, false);
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uint64_t desLangState = desLangDistance >= 0 && supportedLSRsLength > 1 ? iter.getState64() : 0;
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// Index of the supported LSR with the lowest distance.
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int32_t bestIndex = -1;
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// Cached lookup info from XLikelySubtags.compareLikely().
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int32_t bestLikelyInfo = -1;
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for (int32_t slIndex = 0; slIndex < supportedLSRsLength; ++slIndex) {
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const LSR &supported = *supportedLSRs[slIndex];
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bool star = false;
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int32_t distance = desLangDistance;
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if (distance >= 0) {
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U_ASSERT((distance & DISTANCE_IS_FINAL) == 0);
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if (slIndex != 0) {
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iter.resetToState64(desLangState);
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}
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distance = trieNext(iter, supported.language, true);
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}
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// Note: The data builder verifies that there are no rules with "any" (*) language and
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// real (non *) script or region subtags.
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// This means that if the lookup for either language fails we can use
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// the default distances without further lookups.
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int32_t flags;
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if (distance >= 0) {
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flags = distance & DISTANCE_IS_FINAL_OR_SKIP_SCRIPT;
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distance &= ~DISTANCE_IS_FINAL_OR_SKIP_SCRIPT;
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} else { // <*, *>
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if (uprv_strcmp(desired.language, supported.language) == 0) {
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distance = 0;
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} else {
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distance = defaultLanguageDistance;
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}
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flags = 0;
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star = true;
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}
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U_ASSERT(0 <= distance && distance <= 100);
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// Round up the shifted threshold (if fraction bits are not 0)
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// for comparison with un-shifted distances until we need fraction bits.
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// (If we simply shifted non-zero fraction bits away, then we might ignore a language
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// when it's really still a micro distance below the threshold.)
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int32_t roundedThreshold = (shiftedThreshold + DISTANCE_FRACTION_MASK) >> DISTANCE_SHIFT;
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// We implement "favor subtag" by reducing the language subtag distance
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// (unscientifically reducing it to a quarter of the normal value),
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// so that the script distance is relatively more important.
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// For example, given a default language distance of 80, we reduce it to 20,
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// which is below the default threshold of 50, which is the default script distance.
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if (favorSubtag == ULOCMATCH_FAVOR_SCRIPT) {
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distance >>= 2;
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}
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// Let distance == roundedThreshold pass until the tie-breaker logic
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// at the end of the loop.
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if (distance > roundedThreshold) {
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continue;
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}
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int32_t scriptDistance;
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if (star || flags != 0) {
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if (uprv_strcmp(desired.script, supported.script) == 0) {
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scriptDistance = 0;
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} else {
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scriptDistance = defaultScriptDistance;
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}
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} else {
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scriptDistance = getDesSuppScriptDistance(iter, iter.getState64(),
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desired.script, supported.script);
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flags = scriptDistance & DISTANCE_IS_FINAL;
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scriptDistance &= ~DISTANCE_IS_FINAL;
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}
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distance += scriptDistance;
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if (distance > roundedThreshold) {
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continue;
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}
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if (uprv_strcmp(desired.region, supported.region) == 0) {
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// regionDistance = 0
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} else if (star || (flags & DISTANCE_IS_FINAL) != 0) {
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distance += defaultRegionDistance;
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} else {
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int32_t remainingThreshold = roundedThreshold - distance;
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if (minRegionDistance > remainingThreshold) {
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continue;
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}
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// From here on we know the regions are not equal.
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// Map each region to zero or more partitions. (zero = one non-matching string)
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// (Each array of single-character partition strings is encoded as one string.)
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// If either side has more than one, then we find the maximum distance.
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// This could be optimized by adding some more structure, but probably not worth it.
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distance += getRegionPartitionsDistance(
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iter, iter.getState64(),
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partitionsForRegion(desired),
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partitionsForRegion(supported),
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remainingThreshold);
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}
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int32_t shiftedDistance = shiftDistance(distance);
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if (shiftedDistance == 0) {
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// Distinguish between equivalent but originally unequal locales via an
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// additional micro distance.
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shiftedDistance |= (desired.flags ^ supported.flags);
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if (shiftedDistance < shiftedThreshold) {
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if (direction != ULOCMATCH_DIRECTION_ONLY_TWO_WAY ||
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// Is there also a match when we swap desired/supported?
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isMatch(supported, desired, shiftedThreshold, favorSubtag)) {
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if (shiftedDistance == 0) {
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return slIndex << INDEX_SHIFT;
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}
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bestIndex = slIndex;
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shiftedThreshold = shiftedDistance;
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bestLikelyInfo = -1;
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}
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}
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} else {
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if (shiftedDistance < shiftedThreshold) {
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if (direction != ULOCMATCH_DIRECTION_ONLY_TWO_WAY ||
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// Is there also a match when we swap desired/supported?
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isMatch(supported, desired, shiftedThreshold, favorSubtag)) {
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bestIndex = slIndex;
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shiftedThreshold = shiftedDistance;
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bestLikelyInfo = -1;
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}
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} else if (shiftedDistance == shiftedThreshold && bestIndex >= 0) {
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if (direction != ULOCMATCH_DIRECTION_ONLY_TWO_WAY ||
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// Is there also a match when we swap desired/supported?
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isMatch(supported, desired, shiftedThreshold, favorSubtag)) {
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bestLikelyInfo = likelySubtags.compareLikely(
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supported, *supportedLSRs[bestIndex], bestLikelyInfo);
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if ((bestLikelyInfo & 1) != 0) {
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// This supported locale matches as well as the previous best match,
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// and neither matches perfectly,
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// but this one is "more likely" (has more-default subtags).
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bestIndex = slIndex;
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}
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}
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}
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}
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}
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return bestIndex >= 0 ?
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(bestIndex << INDEX_SHIFT) | shiftedThreshold :
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INDEX_NEG_1 | shiftDistance(ABOVE_THRESHOLD);
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}
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int32_t LocaleDistance::getDesSuppScriptDistance(
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BytesTrie &iter, uint64_t startState, const char *desired, const char *supported) {
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// Note: The data builder verifies that there are no <*, supported> or <desired, *> rules.
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int32_t distance = trieNext(iter, desired, false);
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if (distance >= 0) {
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distance = trieNext(iter, supported, true);
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}
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if (distance < 0) {
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UStringTrieResult result = iter.resetToState64(startState).next(u'*'); // <*, *>
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U_ASSERT(USTRINGTRIE_HAS_VALUE(result));
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if (uprv_strcmp(desired, supported) == 0) {
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distance = 0; // same script
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} else {
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distance = iter.getValue();
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U_ASSERT(distance >= 0);
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}
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if (result == USTRINGTRIE_FINAL_VALUE) {
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distance |= DISTANCE_IS_FINAL;
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}
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}
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return distance;
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}
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int32_t LocaleDistance::getRegionPartitionsDistance(
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BytesTrie &iter, uint64_t startState,
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const char *desiredPartitions, const char *supportedPartitions, int32_t threshold) {
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char desired = *desiredPartitions++;
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char supported = *supportedPartitions++;
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U_ASSERT(desired != 0 && supported != 0);
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// See if we have single desired/supported partitions, from NUL-terminated
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// partition strings without explicit length.
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bool suppLengthGt1 = *supportedPartitions != 0; // gt1: more than 1 character
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// equivalent to: if (desLength == 1 && suppLength == 1)
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if (*desiredPartitions == 0 && !suppLengthGt1) {
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// Fastpath for single desired/supported partitions.
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UStringTrieResult result = iter.next(uprv_invCharToAscii(desired) | END_OF_SUBTAG);
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if (USTRINGTRIE_HAS_NEXT(result)) {
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result = iter.next(uprv_invCharToAscii(supported) | END_OF_SUBTAG);
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if (USTRINGTRIE_HAS_VALUE(result)) {
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return iter.getValue();
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}
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}
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return getFallbackRegionDistance(iter, startState);
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}
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const char *supportedStart = supportedPartitions - 1; // for restart of inner loop
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int32_t regionDistance = 0;
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// Fall back to * only once, not for each pair of partition strings.
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bool star = false;
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for (;;) {
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// Look up each desired-partition string only once,
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// not for each (desired, supported) pair.
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UStringTrieResult result = iter.next(uprv_invCharToAscii(desired) | END_OF_SUBTAG);
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if (USTRINGTRIE_HAS_NEXT(result)) {
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uint64_t desState = suppLengthGt1 ? iter.getState64() : 0;
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for (;;) {
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result = iter.next(uprv_invCharToAscii(supported) | END_OF_SUBTAG);
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int32_t d;
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if (USTRINGTRIE_HAS_VALUE(result)) {
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d = iter.getValue();
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} else if (star) {
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d = 0;
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} else {
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d = getFallbackRegionDistance(iter, startState);
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star = true;
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}
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if (d > threshold) {
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return d;
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} else if (regionDistance < d) {
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regionDistance = d;
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}
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if ((supported = *supportedPartitions++) != 0) {
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iter.resetToState64(desState);
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} else {
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break;
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}
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}
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} else if (!star) {
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int32_t d = getFallbackRegionDistance(iter, startState);
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if (d > threshold) {
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return d;
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} else if (regionDistance < d) {
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regionDistance = d;
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}
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star = true;
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}
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if ((desired = *desiredPartitions++) != 0) {
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iter.resetToState64(startState);
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supportedPartitions = supportedStart;
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supported = *supportedPartitions++;
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} else {
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break;
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}
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}
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return regionDistance;
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}
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int32_t LocaleDistance::getFallbackRegionDistance(BytesTrie &iter, uint64_t startState) {
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#if U_DEBUG
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UStringTrieResult result =
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#endif
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iter.resetToState64(startState).next(u'*'); // <*, *>
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U_ASSERT(USTRINGTRIE_HAS_VALUE(result));
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int32_t distance = iter.getValue();
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U_ASSERT(distance >= 0);
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return distance;
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}
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int32_t LocaleDistance::trieNext(BytesTrie &iter, const char *s, bool wantValue) {
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uint8_t c;
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if ((c = *s) == 0) {
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return -1; // no empty subtags in the distance data
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}
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for (;;) {
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c = uprv_invCharToAscii(c);
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// EBCDIC: If *s is not an invariant character,
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// then c is now 0 and will simply not match anything, which is harmless.
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uint8_t next = *++s;
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if (next != 0) {
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if (!USTRINGTRIE_HAS_NEXT(iter.next(c))) {
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return -1;
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}
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} else {
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// last character of this subtag
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UStringTrieResult result = iter.next(c | END_OF_SUBTAG);
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if (wantValue) {
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if (USTRINGTRIE_HAS_VALUE(result)) {
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int32_t value = iter.getValue();
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if (result == USTRINGTRIE_FINAL_VALUE) {
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value |= DISTANCE_IS_FINAL;
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}
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return value;
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}
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} else {
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if (USTRINGTRIE_HAS_NEXT(result)) {
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return 0;
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}
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}
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return -1;
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}
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c = next;
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}
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}
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UBool LocaleDistance::isParadigmLSR(const LSR &lsr) const {
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// Linear search for a very short list (length 6 as of 2019),
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// because we look for equivalence not equality, and
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// because it's easy.
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// If there are many paradigm LSRs we should use a hash set
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// with custom comparator and hasher.
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U_ASSERT(paradigmLSRsLength <= 15);
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for (int32_t i = 0; i < paradigmLSRsLength; ++i) {
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if (lsr.isEquivalentTo(paradigmLSRs[i])) { return true; }
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}
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return false;
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}
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U_NAMESPACE_END
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