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Polish SpEL operator examples in reference docs
Closes gh-36367 Signed-off-by: Tran Ngoc Nhan <ngocnhan.tran1996@gmail.com>
1 parent 7299ff9 commit 057633e

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Lines changed: 89 additions & 33 deletions

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  • framework-docs
    • modules/ROOT/pages/core/expressions/language-ref
    • src/main
      • java/org/springframework/docs/core/expressions/languageref/expressionsoperatorsoverloaded
      • kotlin/org/springframework/docs/core/expressions/languageref/expressionsoperatorsoverloaded

‎framework-docs/modules/ROOT/pages/core/expressions/language-ref/operators.adoc‎

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@@ -53,7 +53,7 @@ Kotlin::
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val trueValue = parser.parseExpression("'black' < 'block'").getValue(Boolean::class.java)
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// uses CustomValue:::compareTo
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val trueValue = parser.parseExpression("new CustomValue(1) < new CustomValue(2)").getValue(Boolean::class.java);
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val trueValue = parser.parseExpression("new CustomValue(1) < new CustomValue(2)").getValue(Boolean::class.java)
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----
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======
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@@ -167,7 +167,7 @@ Kotlin::
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[CAUTION]
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====
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The syntax for the `between` operator is `<input> between {<range_begin>, <range_end>}`,
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which is effectively a shortcut for `<input> >= <range_begin> && <input> \<= <range_end>}`.
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which is effectively a shortcut for `<input> >= <range_begin> && <input> \<= <range_end>`.
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Consequently, `1 between {1, 5}` evaluates to `true`, while `1 between {5, 1}` evaluates
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to `false`.
@@ -312,13 +312,13 @@ Kotlin::
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// evaluates to 'a'
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val ch = parser.parseExpression("'d' - 3")
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.getValue(Character::class.java);
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.getValue(Char::class.java)
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// -- Repeat --
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// evaluates to "abcabc"
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val repeated = parser.parseExpression("'abc' * 2")
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.getValue(String::class.java);
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.getValue(String::class.java)
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----
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======
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@@ -485,7 +485,7 @@ Kotlin::
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// -- Operator precedence --
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val minusTwentyOne = parser.parseExpression("1+2-3*8").getValue(Int::class.java) // -21
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val minusTwentyOne = parser.parseExpression("1+2-3*8").getValue(Int::class.java) // -21
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----
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======
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@@ -541,32 +541,7 @@ For example, if we want to overload the `ADD` operator to allow two lists to be
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concatenated using the `+` sign, we can implement a custom `OperatorOverloader` as
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follows.
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[source,java,indent=0,subs="verbatim,quotes"]
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----
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pubic class ListConcatenation implements OperatorOverloader {
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@Override
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public boolean overridesOperation(Operation operation, Object left, Object right) {
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return (operation == Operation.ADD &&
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left instanceof List && right instanceof List);
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}
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@Override
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@SuppressWarnings("unchecked")
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public Object operate(Operation operation, Object left, Object right) {
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if (operation == Operation.ADD &&
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left instanceof List list1 && right instanceof List list2) {
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List result = new ArrayList(list1);
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result.addAll(list2);
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return result;
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}
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throw new UnsupportedOperationException(
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"No overload for operation %s and operands [%s] and [%s]"
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.formatted(operation, left, right));
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}
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}
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----
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include-code::./ListConcatenation[]
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If we register `ListConcatenation` as the `OperatorOverloader` in a
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`StandardEvaluationContext`, we can then evaluate expressions like `{1, 2, 3} + {4, 5}`
@@ -589,8 +564,8 @@ Kotlin::
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+
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[source,kotlin,indent=0,subs="verbatim,quotes"]
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----
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StandardEvaluationContext context = StandardEvaluationContext()
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context.setOperatorOverloader(ListConcatenation())
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val context = StandardEvaluationContext()
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context.operatorOverloader = ListConcatenation()
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// evaluates to a new list: [1, 2, 3, 4, 5]
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parser.parseExpression("{1, 2, 3} + {2 + 2, 5}").getValue(context, List::class.java)

‎framework-docs/src/main/java/org/springframework/docs/core/expressions/languageref/expressionsoperatorsoverloaded/ListConcatenation.java‎

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@@ -0,0 +1,46 @@
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/*
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* Copyright 2026-present the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.expressions.languageref.expressionsoperatorsoverloaded;
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import org.springframework.expression.Operation;
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import org.springframework.expression.OperatorOverloader;
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import java.util.ArrayList;
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import java.util.List;
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public class ListConcatenation implements OperatorOverloader {
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@Override
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public boolean overridesOperation(Operation operation, Object left, Object right) {
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return operation == Operation.ADD && left instanceof List && right instanceof List;
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}
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@Override
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@SuppressWarnings({"rawtypes", "unchecked"})
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public Object operate(Operation operation, Object left, Object right) {
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if (operation == Operation.ADD &&
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left instanceof List list1 && right instanceof List list2) {
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List result = new ArrayList(list1);
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result.addAll(list2);
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return result;
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}
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throw new UnsupportedOperationException(
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"No overload for operation %s and operands [%s] and [%s]"
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.formatted(operation, left, right));
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}
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}

‎framework-docs/src/main/kotlin/org/springframework/docs/core/expressions/languageref/expressionsoperatorsoverloaded/ListConcatenation.kt‎

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/*
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* Copyright 2026-present the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.docs.core.expressions.languageref.expressionsoperatorsoverloaded
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import org.springframework.expression.Operation
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import org.springframework.expression.OperatorOverloader
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class ListConcatenation: OperatorOverloader {
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override fun overridesOperation(operation: Operation, left: Any?, right: Any?): Boolean {
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return operation == Operation.ADD && left is List<*> && right is List<*>
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}
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override fun operate(operation: Operation, left: Any?, right: Any?): Any {
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if (operation == Operation.ADD && left is List<*> && right is List<*>) {
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return left + right
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}
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throw UnsupportedOperationException("No overload for operation $operation and operands [$left] and [$right]")
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}
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}

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