From 9ab946738614c15df64136c8867964f97e2c726d Mon Sep 17 00:00:00 2001
From: Thomas Darimont <tdarimont@gopivotal.com>
Date: Mon, 7 Jul 2014 14:49:20 +0200
Subject: [PATCH] DATACMNS-533 - Discover declared functions on
 EvaluationContextExtension.

We new automatically register public static methods declared on classes extending EvaluationContextExtensionSupport as functions to be used within SpEL expressions.

Related pull request: spring-projects/spring-data-jpa#101
Related ticket: DATAJPA-564
---
 ...tensionAwareEvaluationContextProvider.java |  6 ++--
 .../EvaluationContextExtensionSupport.java    | 32 ++++++++++++++++++-
 ...bleEvaluationContextProviderUnitTests.java | 12 +++++--
 3 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/src/main/java/org/springframework/data/repository/query/ExtensionAwareEvaluationContextProvider.java b/src/main/java/org/springframework/data/repository/query/ExtensionAwareEvaluationContextProvider.java
index b2f421d66..fe7078399 100644
--- a/src/main/java/org/springframework/data/repository/query/ExtensionAwareEvaluationContextProvider.java
+++ b/src/main/java/org/springframework/data/repository/query/ExtensionAwareEvaluationContextProvider.java
@@ -168,11 +168,13 @@ public class ExtensionAwareEvaluationContextProvider implements EvaluationContex
 
 			for (EvaluationContextExtension ext : extensions) {
 
+				Map<String, Method> extFunctions = ext.getFunctions();
+
 				if (ext.getExtensionId() != null) {
-					functions.put(ext.getExtensionId(), ext.getFunctions());
+					functions.put(ext.getExtensionId(), extFunctions);
 				}
 
-				functions.putAll(ext.getFunctions());
+				functions.putAll(extFunctions);
 			}
 
 			this.functions = functions;
diff --git a/src/main/java/org/springframework/data/repository/query/spi/EvaluationContextExtensionSupport.java b/src/main/java/org/springframework/data/repository/query/spi/EvaluationContextExtensionSupport.java
index c4032d8f1..c80620a64 100644
--- a/src/main/java/org/springframework/data/repository/query/spi/EvaluationContextExtensionSupport.java
+++ b/src/main/java/org/springframework/data/repository/query/spi/EvaluationContextExtensionSupport.java
@@ -16,9 +16,14 @@
 package org.springframework.data.repository.query.spi;
 
 import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 
+import org.springframework.util.ReflectionUtils;
+import org.springframework.util.ReflectionUtils.MethodCallback;
+
 /**
  * A base class for {@link EvaluationContextExtension}s.
  * 
@@ -28,6 +33,31 @@ import java.util.Map;
  */
 public abstract class EvaluationContextExtensionSupport implements EvaluationContextExtension {
 
+	private final Map<String, Method> declaredFunctions;
+
+	public EvaluationContextExtensionSupport() {
+
+		this.declaredFunctions = discoverDeclaredFunctions();
+	}
+
+	private Map<String, Method> discoverDeclaredFunctions() {
+
+		final Map<String, Method> map = new HashMap<String, Method>();
+
+		ReflectionUtils.doWithMethods(getClass(), new MethodCallback() {
+
+			@Override
+			public void doWith(Method method) throws IllegalArgumentException, IllegalAccessException {
+
+				if (Modifier.isPublic(method.getModifiers()) && Modifier.isStatic(method.getModifiers())) {
+					map.put(method.getName(), method);
+				}
+			}
+		});
+
+		return map.isEmpty() ? Collections.<String, Method> emptyMap() : Collections.unmodifiableMap(map);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.query.EvaluationContextExtension#getProperties()
@@ -43,6 +73,6 @@ public abstract class EvaluationContextExtensionSupport implements EvaluationCon
 	 */
 	@Override
 	public Map<String, Method> getFunctions() {
-		return Collections.emptyMap();
+		return this.declaredFunctions;
 	}
 }
diff --git a/src/test/java/org/springframework/data/repository/query/ExtensibleEvaluationContextProviderUnitTests.java b/src/test/java/org/springframework/data/repository/query/ExtensibleEvaluationContextProviderUnitTests.java
index 667ad9c34..47dc537fb 100644
--- a/src/test/java/org/springframework/data/repository/query/ExtensibleEvaluationContextProviderUnitTests.java
+++ b/src/test/java/org/springframework/data/repository/query/ExtensibleEvaluationContextProviderUnitTests.java
@@ -21,6 +21,7 @@ import static org.junit.Assert.*;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -36,7 +37,7 @@ import org.springframework.expression.spel.standard.SpelExpressionParser;
  * 
  * @author Oliver Gierke
  */
-public class ExtensibleEvaluationContextProviderUnitTests<T extends Parameters<T, ? extends Parameter>> {
+public class ExtensibleEvaluationContextProviderUnitTests {
 
 	DefaultParameters parameters;
 
@@ -110,7 +111,9 @@ public class ExtensibleEvaluationContextProviderUnitTests<T extends Parameters<T
 		extensions.add(new DummyExtension("_first", "first"));
 
 		EvaluationContextProvider provider = new ExtensionAwareEvaluationContextProvider(extensions);
-		assertThat(evaluateExpression("method()", provider), is((Object) "methodResult"));
+
+		assertThat(evaluateExpression("aliasedMethod()", provider), is((Object) "methodResult"));
+		assertThat(evaluateExpression("extensionMethod()", provider), is((Object) "methodResult"));
 	}
 
 	static class DummyExtension extends EvaluationContextExtensionSupport {
@@ -152,8 +155,11 @@ public class ExtensibleEvaluationContextProviderUnitTests<T extends Parameters<T
 		@Override
 		public Map<String, Method> getFunctions() {
 
+			Map<String, Method> functions = new HashMap<String, Method>(super.getFunctions());
+
 			try {
-				return Collections.singletonMap("method", getClass().getMethod("extensionMethod"));
+				functions.put("aliasedMethod", getClass().getMethod("extensionMethod"));
+				return functions;
 			} catch (Exception o_O) {
 				throw new RuntimeException(o_O);
 			}