Support prefix notation for SpEL increment/decrement in AST representation

Closes gh-32144

Author: sbrannen

Diff for: spring-expression/src/main/java/org/springframework/expression/spel/ast/OpDec.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -39,11 +39,13 @@
  */
 public class OpDec extends Operator {
 
+	private static final String DEC = "--";
+
 	private final boolean postfix;  // false means prefix
 
 
 	public OpDec(int startPos, int endPos, boolean postfix, SpelNodeImpl... operands) {
-		super("--", startPos, endPos, operands);
+		super(DEC, startPos, endPos, operands);
 		this.postfix = postfix;
 		Assert.notEmpty(operands, "Operands must not be empty");
 	}
@@ -133,7 +135,8 @@ else if (op1 instanceof Byte) {
 
 	@Override
 	public String toStringAST() {
-		return getLeftOperand().toStringAST() + "--";
+		String ast = getLeftOperand().toStringAST();
+		return (this.postfix ? ast + DEC : DEC + ast);
 	}
 
 	@Override

Diff for: spring-expression/src/main/java/org/springframework/expression/spel/ast/OpInc.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -39,11 +39,13 @@
  */
 public class OpInc extends Operator {
 
+	private static final String INC = "++";
+
 	private final boolean postfix;  // false means prefix
 
 
 	public OpInc(int startPos, int endPos, boolean postfix, SpelNodeImpl... operands) {
-		super("++", startPos, endPos, operands);
+		super(INC, startPos, endPos, operands);
 		this.postfix = postfix;
 		Assert.notEmpty(operands, "Operands must not be empty");
 	}
@@ -128,7 +130,8 @@ else if (op1 instanceof Byte) {
 
 	@Override
 	public String toStringAST() {
-		return getLeftOperand().toStringAST() + "++";
+		String ast = getLeftOperand().toStringAST();
+		return (this.postfix ? ast + INC : INC + ast);
 	}
 
 	@Override

Diff for: spring-expression/src/test/java/org/springframework/expression/spel/ParsingTests.java

@@ -16,7 +16,6 @@
 
 package org.springframework.expression.spel;
 
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
@@ -370,7 +369,6 @@ void mathOperatorModulus() {
 			parseCheck("7 % 4", "(7 % 4)");
 		}
 
-		@Disabled("Disabled due to a bug in OpInc.toStringAST()")
 		@Test
 		void mathOperatorIncrementPrefix() {
 			parseCheck("++7", "++7");
@@ -383,7 +381,6 @@ void mathOperatorIncrementPostfix() {
 			parseCheck("foo++", "foo++");
 		}
 
-		@Disabled("Disabled due to a bug in OpDec.toStringAST()")
 		@Test
 		void mathOperatorDecrementPrefix() {
 			parseCheck("--7", "--7");