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Spring Data Relational support
/*
* Copyright 2020-2023 the original author or authors.
*
* Licensed 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
*
* https://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.springframework.data.relational.core.dialect;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.springframework.lang.Nullable;
/**
* Helper class encapsulating an escape character for LIKE queries and the actually usage of it in escaping
* {@link String}s.
*
* @author Roman Chigvintsev
* @author Mark Paluch
* @since 2.0
*/
public class Escaper {
public static final Escaper DEFAULT = Escaper.of('\\');
private final char escapeCharacter;
private final List toReplace;
private Escaper(char escapeCharacter, List toReplace) {
if (toReplace.contains(Character.toString(escapeCharacter))) {
throw new IllegalArgumentException(
String.format("'%s' and cannot be used as escape character as it should be replaced", escapeCharacter));
}
this.escapeCharacter = escapeCharacter;
this.toReplace = toReplace;
}
/**
* Creates new instance of this class with the given escape character.
*
* @param escapeCharacter escape character
* @return new instance of {@link Escaper}.
* @throws IllegalArgumentException if escape character is one of special characters ('_' and '%')
*/
public static Escaper of(char escapeCharacter) {
return new Escaper(escapeCharacter, Arrays.asList("_", "%"));
}
/**
* Apply the {@link Escaper} to the given {@code chars}.
*
* @param chars characters/char sequences that should be escaped.
* @return
*/
public Escaper withRewriteFor(String... chars) {
List toReplace = new ArrayList<>(this.toReplace.size() + chars.length);
toReplace.addAll(this.toReplace);
toReplace.addAll(Arrays.asList(chars));
return new Escaper(this.escapeCharacter, toReplace);
}
/**
* Returns the escape character.
*
* @return the escape character to use.
*/
public char getEscapeCharacter() {
return escapeCharacter;
}
/**
* Escapes all special like characters ({@code _}, {@code %}) using the configured escape character.
*
* @param value value to be escaped
* @return escaped value
*/
@Nullable
public String escape(@Nullable String value) {
if (value == null) {
return null;
}
return toReplace.stream().reduce(value, (it, character) -> it.replace(character, escapeCharacter + character));
}
}