com.ibm.icu.impl.locale.LocaleDistance Maven / Gradle / Ivy
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// © 2017 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
package com.ibm.icu.impl.locale;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.Set;
import java.util.TreeMap;
import com.ibm.icu.impl.ICUData;
import com.ibm.icu.impl.ICUResourceBundle;
import com.ibm.icu.impl.UResource;
import com.ibm.icu.util.BytesTrie;
import com.ibm.icu.util.LocaleMatcher.FavorSubtag;
import com.ibm.icu.util.ULocale;
/**
* Offline-built data for LocaleMatcher.
* Mostly but not only the data for mapping locales to their maximized forms.
*/
public class LocaleDistance {
/**
* Bit flag used on the last character of a subtag in the trie.
* Must be set consistently by the builder and the lookup code.
*/
public static final int END_OF_SUBTAG = 0x80;
/** Distance value bit flag, set by the builder. */
public static final int DISTANCE_SKIP_SCRIPT = 0x80;
/** Distance value bit flag, set by trieNext(). */
private static final int DISTANCE_IS_FINAL = 0x100;
private static final int DISTANCE_IS_FINAL_OR_SKIP_SCRIPT =
DISTANCE_IS_FINAL | DISTANCE_SKIP_SCRIPT;
// Indexes into array of distances.
public static final int IX_DEF_LANG_DISTANCE = 0;
public static final int IX_DEF_SCRIPT_DISTANCE = 1;
public static final int IX_DEF_REGION_DISTANCE = 2;
public static final int IX_MIN_REGION_DISTANCE = 3;
public static final int IX_LIMIT = 4;
private static final int ABOVE_THRESHOLD = 100;
private static final boolean DEBUG_OUTPUT = LSR.DEBUG_OUTPUT;
// 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"/"".
private final BytesTrie trie;
/**
* Maps each region to zero or more single-character partitions.
*/
private final byte[] regionToPartitionsIndex;
private final String[] partitionArrays;
/**
* Used to get the paradigm region for a cluster, if there is one.
*/
private final Set paradigmLSRs;
private final int defaultLanguageDistance;
private final int defaultScriptDistance;
private final int defaultRegionDistance;
private final int minRegionDistance;
private final int defaultDemotionPerDesiredLocale;
// VisibleForTesting
public static final class Data {
public byte[] trie;
public byte[] regionToPartitionsIndex;
public String[] partitionArrays;
public Set paradigmLSRs;
public int[] distances;
public Data(byte[] trie,
byte[] regionToPartitionsIndex, String[] partitionArrays,
Set paradigmLSRs, int[] distances) {
this.trie = trie;
this.regionToPartitionsIndex = regionToPartitionsIndex;
this.partitionArrays = partitionArrays;
this.paradigmLSRs = paradigmLSRs;
this.distances = distances;
}
private static UResource.Value getValue(UResource.Table table,
String key, UResource.Value value) {
if (!table.findValue(key, value)) {
throw new MissingResourceException(
"langInfo.res missing data", "", "match/" + key);
}
return value;
}
// VisibleForTesting
public static Data load() throws MissingResourceException {
ICUResourceBundle langInfo = ICUResourceBundle.getBundleInstance(
ICUData.ICU_BASE_NAME, "langInfo",
ICUResourceBundle.ICU_DATA_CLASS_LOADER, ICUResourceBundle.OpenType.DIRECT);
UResource.Value value = langInfo.getValueWithFallback("match");
UResource.Table matchTable = value.getTable();
ByteBuffer buffer = getValue(matchTable, "trie", value).getBinary();
byte[] trie = new byte[buffer.remaining()];
buffer.get(trie);
buffer = getValue(matchTable, "regionToPartitions", value).getBinary();
byte[] regionToPartitions = new byte[buffer.remaining()];
buffer.get(regionToPartitions);
if (regionToPartitions.length < LSR.REGION_INDEX_LIMIT) {
throw new MissingResourceException(
"langInfo.res binary data too short", "", "match/regionToPartitions");
}
String[] partitions = getValue(matchTable, "partitions", value).getStringArray();
Set paradigmLSRs;
if (matchTable.findValue("paradigms", value)) {
String[] paradigms = value.getStringArray();
paradigmLSRs = new HashSet<>(paradigms.length / 3);
for (int i = 0; i < paradigms.length; i += 3) {
paradigmLSRs.add(new LSR(paradigms[i], paradigms[i + 1], paradigms[i + 2]));
}
} else {
paradigmLSRs = Collections.emptySet();
}
int[] distances = getValue(matchTable, "distances", value).getIntVector();
if (distances.length < IX_LIMIT) {
throw new MissingResourceException(
"langInfo.res intvector too short", "", "match/distances");
}
return new Data(trie, regionToPartitions, partitions, paradigmLSRs, distances);
}
@Override
public boolean equals(Object other) {
if (this == other) { return true; }
if (!getClass().equals(other.getClass())) { return false; }
Data od = (Data)other;
return Arrays.equals(trie, od.trie) &&
Arrays.equals(regionToPartitionsIndex, od.regionToPartitionsIndex) &&
Arrays.equals(partitionArrays, od.partitionArrays) &&
paradigmLSRs.equals(od.paradigmLSRs) &&
Arrays.equals(distances, od.distances);
}
}
// VisibleForTesting
public static final LocaleDistance INSTANCE = new LocaleDistance(Data.load());
private LocaleDistance(Data data) {
trie = new BytesTrie(data.trie, 0);
regionToPartitionsIndex = data.regionToPartitionsIndex;
partitionArrays = data.partitionArrays;
paradigmLSRs = data.paradigmLSRs;
defaultLanguageDistance = data.distances[IX_DEF_LANG_DISTANCE];
defaultScriptDistance = data.distances[IX_DEF_SCRIPT_DISTANCE];
defaultRegionDistance = data.distances[IX_DEF_REGION_DISTANCE];
minRegionDistance = data.distances[IX_MIN_REGION_DISTANCE];
// For the default demotion value, use the
// default region distance between unrelated Englishes.
// Thus, unless demotion is turned off,
// a mere region difference for one desired locale
// is as good as a perfect match for the next following desired locale.
// As of CLDR 36, we have Returns the index of the lowest-distance supported LSR in bits 31..8
* (negative if none has a distance below the threshold),
* and its distance (0..ABOVE_THRESHOLD) in bits 7..0.
*/
public int getBestIndexAndDistance(LSR desired, LSR[] supportedLSRs,
int threshold, FavorSubtag favorSubtag) {
BytesTrie iter = new BytesTrie(trie);
// Look up the desired language only once for all supported LSRs.
// Its "distance" is either a match point value of 0, or a non-match negative value.
// Note: The data builder verifies that there are no <*, supported> or rules.
int desLangDistance = trieNext(iter, desired.language, false);
long desLangState = desLangDistance >= 0 && supportedLSRs.length > 1 ? iter.getState64() : 0;
// Index of the supported LSR with the lowest distance.
int bestIndex = -1;
for (int slIndex = 0; slIndex < supportedLSRs.length; ++slIndex) {
LSR supported = supportedLSRs[slIndex];
boolean star = false;
int distance = desLangDistance;
if (distance >= 0) {
assert (distance & DISTANCE_IS_FINAL) == 0;
if (slIndex != 0) {
iter.resetToState64(desLangState);
}
distance = trieNext(iter, supported.language, true);
}
// Note: The data builder verifies that there are no rules with "any" (*) language and
// real (non *) script or region subtags.
// This means that if the lookup for either language fails we can use
// the default distances without further lookups.
int flags;
if (distance >= 0) {
flags = distance & DISTANCE_IS_FINAL_OR_SKIP_SCRIPT;
distance &= ~DISTANCE_IS_FINAL_OR_SKIP_SCRIPT;
} else { // <*, *>
if (desired.language.equals(supported.language)) {
distance = 0;
} else {
distance = defaultLanguageDistance;
}
flags = 0;
star = true;
}
assert 0 <= distance && distance <= 100;
// We implement "favor subtag" by reducing the language subtag distance
// (unscientifically reducing it to a quarter of the normal value),
// so that the script distance is relatively more important.
// For example, given a default language distance of 80, we reduce it to 20,
// which is below the default threshold of 50, which is the default script distance.
if (favorSubtag == FavorSubtag.SCRIPT) {
distance >>= 2;
}
if (distance >= threshold) {
continue;
}
int scriptDistance;
if (star || flags != 0) {
if (desired.script.equals(supported.script)) {
scriptDistance = 0;
} else {
scriptDistance = defaultScriptDistance;
}
} else {
scriptDistance = getDesSuppScriptDistance(iter, iter.getState64(),
desired.script, supported.script);
flags = scriptDistance & DISTANCE_IS_FINAL;
scriptDistance &= ~DISTANCE_IS_FINAL;
}
distance += scriptDistance;
if (distance >= threshold) {
continue;
}
if (desired.region.equals(supported.region)) {
// regionDistance = 0
} else if (star || (flags & DISTANCE_IS_FINAL) != 0) {
distance += defaultRegionDistance;
} else {
int remainingThreshold = threshold - distance;
if (minRegionDistance >= remainingThreshold) {
continue;
}
// From here on we know the regions are not equal.
// Map each region to zero or more partitions. (zero = one non-matching string)
// (Each array of single-character partition strings is encoded as one string.)
// If either side has more than one, then we find the maximum distance.
// This could be optimized by adding some more structure, but probably not worth it.
distance += getRegionPartitionsDistance(
iter, iter.getState64(),
partitionsForRegion(desired),
partitionsForRegion(supported),
remainingThreshold);
}
if (distance < threshold) {
if (distance == 0) {
return slIndex << 8;
}
bestIndex = slIndex;
threshold = distance;
}
}
return bestIndex >= 0 ? (bestIndex << 8) | threshold : 0xffffff00 | ABOVE_THRESHOLD;
}
private static final int getDesSuppScriptDistance(BytesTrie iter, long startState,
String desired, String supported) {
// Note: The data builder verifies that there are no <*, supported> or rules.
int distance = trieNext(iter, desired, false);
if (distance >= 0) {
distance = trieNext(iter, supported, true);
}
if (distance < 0) {
BytesTrie.Result result = iter.resetToState64(startState).next('*'); // <*, *>
assert result.hasValue();
if (desired.equals(supported)) {
distance = 0; // same script
} else {
distance = iter.getValue();
assert distance >= 0;
}
if (result == BytesTrie.Result.FINAL_VALUE) {
distance |= DISTANCE_IS_FINAL;
}
}
return distance;
}
private static final int getRegionPartitionsDistance(BytesTrie iter, long startState,
String desiredPartitions, String supportedPartitions, int threshold) {
int desLength = desiredPartitions.length();
int suppLength = supportedPartitions.length();
if (desLength == 1 && suppLength == 1) {
// Fastpath for single desired/supported partitions.
BytesTrie.Result result = iter.next(desiredPartitions.charAt(0) | END_OF_SUBTAG);
if (result.hasNext()) {
result = iter.next(supportedPartitions.charAt(0) | END_OF_SUBTAG);
if (result.hasValue()) {
return iter.getValue();
}
}
return getFallbackRegionDistance(iter, startState);
}
int regionDistance = 0;
// Fall back to * only once, not for each pair of partition strings.
boolean star = false;
for (int di = 0;;) {
// Look up each desired-partition string only once,
// not for each (desired, supported) pair.
BytesTrie.Result result = iter.next(desiredPartitions.charAt(di++) | END_OF_SUBTAG);
if (result.hasNext()) {
long desState = suppLength > 1 ? iter.getState64() : 0;
for (int si = 0;;) {
result = iter.next(supportedPartitions.charAt(si++) | END_OF_SUBTAG);
int d;
if (result.hasValue()) {
d = iter.getValue();
} else if (star) {
d = 0;
} else {
d = getFallbackRegionDistance(iter, startState);
star = true;
}
if (d >= threshold) {
return d;
} else if (regionDistance < d) {
regionDistance = d;
}
if (si < suppLength) {
iter.resetToState64(desState);
} else {
break;
}
}
} else if (!star) {
int d = getFallbackRegionDistance(iter, startState);
if (d >= threshold) {
return d;
} else if (regionDistance < d) {
regionDistance = d;
}
star = true;
}
if (di < desLength) {
iter.resetToState64(startState);
} else {
break;
}
}
return regionDistance;
}
private static final int getFallbackRegionDistance(BytesTrie iter, long startState) {
BytesTrie.Result result = iter.resetToState64(startState).next('*'); // <*, *>
assert result.hasValue();
int distance = iter.getValue();
assert distance >= 0;
return distance;
}
private static final int trieNext(BytesTrie iter, String s, boolean wantValue) {
if (s.isEmpty()) {
return -1; // no empty subtags in the distance data
}
for (int i = 0, end = s.length() - 1;; ++i) {
int c = s.charAt(i);
if (i < end) {
if (!iter.next(c).hasNext()) {
return -1;
}
} else {
// last character of this subtag
BytesTrie.Result result = iter.next(c | END_OF_SUBTAG);
if (wantValue) {
if (result.hasValue()) {
int value = iter.getValue();
if (result == BytesTrie.Result.FINAL_VALUE) {
value |= DISTANCE_IS_FINAL;
}
return value;
}
} else {
if (result.hasNext()) {
return 0;
}
}
return -1;
}
}
}
@Override
public String toString() {
return testOnlyGetDistanceTable().toString();
}
private String partitionsForRegion(LSR lsr) {
// ill-formed region -> one non-matching string
int pIndex = regionToPartitionsIndex[lsr.regionIndex];
return partitionArrays[pIndex];
}
public boolean isParadigmLSR(LSR lsr) {
return paradigmLSRs.contains(lsr);
}
// VisibleForTesting
public int getDefaultScriptDistance() {
return defaultScriptDistance;
}
int getDefaultRegionDistance() {
return defaultRegionDistance;
}
public int getDefaultDemotionPerDesiredLocale() {
return defaultDemotionPerDesiredLocale;
}
// TODO: When we build data offline,
// write test code to compare the loaded table with the builder output.
// Fail if different, with instructions for how to update the data file.
// VisibleForTesting
public Map testOnlyGetDistanceTable() {
Map map = new TreeMap<>();
StringBuilder sb = new StringBuilder();
for (BytesTrie.Entry entry : trie) {
sb.setLength(0);
int length = entry.bytesLength();
for (int i = 0; i < length; ++i) {
byte b = entry.byteAt(i);
if (b == '*') {
// One * represents a (desired, supported) = (ANY, ANY) pair.
sb.append("*-*-");
} else {
if (b >= 0) {
sb.append((char) b);
} else { // end of subtag
sb.append((char) (b & 0x7f)).append('-');
}
}
}
assert sb.length() > 0 && sb.charAt(sb.length() - 1) == '-';
sb.setLength(sb.length() - 1);
map.put(sb.toString(), entry.value);
}
return map;
}
// VisibleForTesting
public void testOnlyPrintDistanceTable() {
for (Map.Entry mapping : testOnlyGetDistanceTable().entrySet()) {
String suffix = "";
int value = mapping.getValue();
if ((value & DISTANCE_SKIP_SCRIPT) != 0) {
value &= ~DISTANCE_SKIP_SCRIPT;
suffix = " skip script";
}
System.out.println(mapping.getKey() + '=' + value + suffix);
}
}
}