Implement proximity filter ~=

Signed-off-by: Moritz Kobel <moritz.kobel@qube.ag>

core/src/main/java/org/springframework/ldap/filter/ProximityFilter.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2005-2025 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.ldap.filter;
+
+import org.springframework.ldap.support.LdapEncoder;
+
+/**
+ * A filter for 'proximity'. The following code:
+ *
+ * <pre>
+ * ProximityFilter filter = new ProximityFilter(&quot;cn&quot;, &quot;Some CN&quot;);
+ * System.out.println(filter.encode());
+ * </pre>
+ *
+ * would result in:
+ *
+ * <pre>
+ * (cn~=Some CN)
+ * </pre>
+ *
+ * @author Moritz Kobel
+ * @since 3.3
+ */
+public final class ProximityFilter extends CompareFilter {
+
+	private static final String PROXIMITY_SIGN = "~=";
+
+	public ProximityFilter(String attribute, String value) {
+		super(attribute, PROXIMITY_SIGN, value, LdapEncoder.filterEncode(value));
+	}
+
+}

core/src/main/java/org/springframework/ldap/query/ConditionCriteria.java

@@ -105,4 +105,17 @@ public interface ConditionCriteria {
 	 */
 	ConditionCriteria not();
 
+	/**
+	 * Appends an {@link org.springframework.ldap.filter.ProximityFilter}.
+	 * @param value the value to compare with.
+	 * @return an ContainerCriteria instance that can be used to continue append more
+	 * criteria or as the LdapQuery instance to be used as instance to e.g.
+	 * {@link org.springframework.ldap.core.LdapOperations#search(LdapQuery, org.springframework.ldap.core.ContextMapper)}.
+	 * @since 3.3
+	 * @see org.springframework.ldap.filter.EqualsFilter
+	 */
+	default ContainerCriteria near(String value) {
+		throw new UnsupportedOperationException();
+	}
+
 }

core/src/main/java/org/springframework/ldap/query/DefaultConditionCriteria.java

@@ -23,6 +23,7 @@ import org.springframework.ldap.filter.LessThanOrEqualsFilter;
 import org.springframework.ldap.filter.LikeFilter;
 import org.springframework.ldap.filter.NotFilter;
 import org.springframework.ldap.filter.PresentFilter;
+import org.springframework.ldap.filter.ProximityFilter;
 import org.springframework.ldap.filter.WhitespaceWildcardsFilter;
 
 /**
@@ -72,6 +73,11 @@ class DefaultConditionCriteria implements ConditionCriteria {
 		return appendToParent(new PresentFilter(this.attribute));
 	}
 
+	@Override
+	public ContainerCriteria near(String value) {
+		return appendToParent(new ProximityFilter(this.attribute, value));
+	}
+
 	private ContainerCriteria appendToParent(Filter filter) {
 		return this.parent.append(negateIfApplicable(filter));
 	}

core/src/test/java/org/springframework/ldap/filter/ProximityFilterTests.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2005-2025 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.ldap.filter;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Moritz Kobel
+ */
+public class ProximityFilterTests {
+
+	@Test
+	public void testEncode() {
+
+		CompareFilter eqq = new ProximityFilter("foo", "*bar(fie)");
+
+		StringBuffer buff = new StringBuffer();
+		eqq.encode(buff);
+
+		assertThat(buff.toString()).isEqualTo("(foo~=\\2abar\\28fie\\29)");
+
+	}
+
+}

core/src/test/java/org/springframework/ldap/query/LdapQueryBuilderTests.java

@@ -73,6 +73,13 @@ public class LdapQueryBuilderTests {
 		assertThat(result.filter().encode()).isEqualTo("(cn=*)");
 	}
 
+	@Test
+	public void buildProximity() {
+		LdapQuery result = LdapQueryBuilder.query().where("cn").near("John Doe");
+
+		assertThat(result.filter().encode()).isEqualTo("(cn~=John Doe)");
+	}
+
 	@Test
 	public void buildHardcodedFilter() {
 		LdapQuery result = LdapQueryBuilder.query().filter("(cn=Person*)");