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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.common.unit;
import org.elasticsearch.ElasticsearchParseException;
import org.elasticsearch.Version;
import org.elasticsearch.common.ParseField;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.Writeable;
import org.elasticsearch.common.xcontent.ToXContentFragment;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import java.io.IOException;
import java.util.Locale;
import java.util.Objects;
/**
* A unit class that encapsulates all in-exact search
* parsing and conversion from similarities to edit distances
* etc.
*/
public final class Fuzziness implements ToXContentFragment, Writeable {
public static final String X_FIELD_NAME = "fuzziness";
public static final Fuzziness ZERO = new Fuzziness(0);
public static final Fuzziness ONE = new Fuzziness(1);
public static final Fuzziness TWO = new Fuzziness(2);
public static final Fuzziness AUTO = new Fuzziness("AUTO");
public static final ParseField FIELD = new ParseField(X_FIELD_NAME);
private static final int DEFAULT_LOW_DISTANCE = 3;
private static final int DEFAULT_HIGH_DISTANCE = 6;
private final String fuzziness;
private int lowDistance = DEFAULT_LOW_DISTANCE;
private int highDistance = DEFAULT_HIGH_DISTANCE;
private Fuzziness(int fuzziness) {
if (fuzziness != 0 && fuzziness != 1 && fuzziness != 2) {
throw new IllegalArgumentException("Valid edit distances are [0, 1, 2] but was [" + fuzziness + "]");
}
this.fuzziness = Integer.toString(fuzziness);
}
private Fuzziness(String fuzziness) {
if (fuzziness == null || fuzziness.isEmpty()) {
throw new IllegalArgumentException("fuzziness can't be null!");
}
this.fuzziness = fuzziness.toUpperCase(Locale.ROOT);
}
private Fuzziness(String fuzziness, int lowDistance, int highDistance) {
this(fuzziness);
if (lowDistance < 0 || highDistance < 0 || lowDistance > highDistance) {
throw new IllegalArgumentException("fuzziness wrongly configured, must be: lowDistance > 0, highDistance" +
" > 0 and lowDistance <= highDistance ");
}
this.lowDistance = lowDistance;
this.highDistance = highDistance;
}
/**
* Read from a stream.
*/
public Fuzziness(StreamInput in) throws IOException {
fuzziness = in.readString();
if (in.getVersion().onOrAfter(Version.V_6_1_0) && in.readBoolean()) {
lowDistance = in.readVInt();
highDistance = in.readVInt();
}
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeString(fuzziness);
if (out.getVersion().onOrAfter(Version.V_6_1_0)) {
// we cannot serialize the low/high bounds since the other node does not know about them.
// This is a best-effort to not fail queries in case the cluster is being upgraded and users
// start using features that are not available on all nodes.
if (isAutoWithCustomValues()) {
out.writeBoolean(true);
out.writeVInt(lowDistance);
out.writeVInt(highDistance);
} else {
out.writeBoolean(false);
}
}
}
/**
* Creates a {@link Fuzziness} instance from an edit distance. The value must be one of {@code [0, 1, 2]}
*
* Note: Using this method only makes sense if the field you are applying Fuzziness to is some sort of string.
*/
public static Fuzziness fromEdits(int edits) {
return new Fuzziness(edits);
}
public static Fuzziness build(Object fuzziness) {
if (fuzziness instanceof Fuzziness) {
return (Fuzziness) fuzziness;
}
String string = fuzziness.toString();
if (AUTO.asString().equalsIgnoreCase(string)) {
return AUTO;
} else if (string.toUpperCase(Locale.ROOT).startsWith(AUTO.asString() + ":")) {
return parseCustomAuto(string);
}
return new Fuzziness(string);
}
private static Fuzziness parseCustomAuto( final String string) {
assert string.toUpperCase(Locale.ROOT).startsWith(AUTO.asString() + ":");
String[] fuzzinessLimit = string.substring(AUTO.asString().length() + 1).split(",");
if (fuzzinessLimit.length == 2) {
try {
int lowerLimit = Integer.parseInt(fuzzinessLimit[0]);
int highLimit = Integer.parseInt(fuzzinessLimit[1]);
return new Fuzziness("AUTO", lowerLimit, highLimit);
} catch (NumberFormatException e) {
throw new ElasticsearchParseException("failed to parse [{}] as a \"auto:int,int\"", e,
string);
}
} else {
throw new ElasticsearchParseException("failed to find low and high distance values");
}
}
public static Fuzziness parse(XContentParser parser) throws IOException {
XContentParser.Token token = parser.currentToken();
switch (token) {
case VALUE_STRING:
case VALUE_NUMBER:
final String fuzziness = parser.text();
if (AUTO.asString().equalsIgnoreCase(fuzziness)) {
return AUTO;
} else if (fuzziness.toUpperCase(Locale.ROOT).startsWith(AUTO.asString() + ":")) {
return parseCustomAuto(fuzziness);
}
try {
final int minimumSimilarity = Integer.parseInt(fuzziness);
switch (minimumSimilarity) {
case 0:
return ZERO;
case 1:
return ONE;
case 2:
return TWO;
default:
return build(fuzziness);
}
} catch (NumberFormatException ex) {
return build(fuzziness);
}
default:
throw new IllegalArgumentException("Can't parse fuzziness on token: [" + token + "]");
}
}
@Override
public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
builder.field(X_FIELD_NAME, asString());
return builder;
}
public int asDistance() {
return asDistance(null);
}
public int asDistance(String text) {
if (this.equals(AUTO) || isAutoWithCustomValues()) { //AUTO
final int len = termLen(text);
if (len < lowDistance) {
return 0;
} else if (len < highDistance) {
return 1;
} else {
return 2;
}
}
return Math.min(2, (int) asFloat());
}
public float asFloat() {
if (this.equals(AUTO) || isAutoWithCustomValues()) {
return 1f;
}
return Float.parseFloat(fuzziness.toString());
}
private int termLen(String text) {
return text == null ? 5 : text.codePointCount(0, text.length()); // 5 avg term length in english
}
public String asString() {
if (isAutoWithCustomValues()) {
return fuzziness.toString() + ":" + lowDistance + "," + highDistance;
}
return fuzziness.toString();
}
private boolean isAutoWithCustomValues() {
return fuzziness.startsWith("AUTO") && (lowDistance != DEFAULT_LOW_DISTANCE ||
highDistance != DEFAULT_HIGH_DISTANCE);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
Fuzziness other = (Fuzziness) obj;
return Objects.equals(fuzziness, other.fuzziness) &&
lowDistance == other.lowDistance &&
highDistance == other.highDistance;
}
@Override
public int hashCode() {
return Objects.hash(fuzziness, lowDistance, highDistance);
}
}