DATACMNS-533 - Infrastructure support for SpEL expressions in manually defined queries.

Extracted SPI build for DATAJPA-564 into Spring Data Commons. Simplified the configuration setup code and removed the ability to define a custom EvaluationContextProvider for now. We directly declare a bean definition which automatically picks up EvaluationContextExtensions.

RepositoryFactory(Bean)Support is now aware of the EvaluationContextProvider to hand it to the template method that creates the QueryLookupStrategy. Deprecated the previously existing template method in favor of an extended one.

Removed variable declarations from the extension interface for now as usually properties serve the same purposes as variables which makes the latter superfluous for now. Applied some JavaDoc and API signature polish. Added unit tests for ExtensionAwareEvaluationContextProvider.

Related pull request: spring-projects/spring-data-jpa#101
Related ticket: DATAJPA-564

src/test/java/org/springframework/data/repository/query/ExtensibleEvaluationContextProviderUnitTests.java

@@ -0,0 +1,177 @@
+/*
+ * Copyright 2014 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
+ *
+ *      http://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.repository.query;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.data.repository.query.spi.EvaluationContextExtension;
+import org.springframework.data.repository.query.spi.EvaluationContextExtensionSupport;
+import org.springframework.expression.EvaluationContext;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+
+/**
+ * Unit tests {@link ExtensionAwareEvaluationContextProvider}.
+ * 
+ * @author Oliver Gierke
+ */
+public class ExtensibleEvaluationContextProviderUnitTests<T extends Parameters<T, ? extends Parameter>> {
+
+	DefaultParameters parameters;
+
+	@Before
+	public void setUp() throws Exception {
+
+		Method method = SampleRepo.class.getMethod("findByFirstname", String.class);
+		this.parameters = new DefaultParameters(method);
+	}
+
+	/**
+	 * @see DATACMNS-533
+	 */
+	@Test
+	public void usesPropertyDefinedByExtension() {
+
+		List<EvaluationContextExtension> extensions = new ArrayList<EvaluationContextExtension>();
+		extensions.add(new DummyExtension("_first", "first"));
+
+		ExtensionAwareEvaluationContextProvider provider = new ExtensionAwareEvaluationContextProvider(extensions);
+		assertThat(evaluateExpression("key", provider), is((Object) "first"));
+	}
+
+	/**
+	 * @see DATACMNS-533
+	 */
+	@Test
+	public void secondExtensionOverridesFirstOne() {
+
+		List<EvaluationContextExtension> extensions = new ArrayList<EvaluationContextExtension>();
+		extensions.add(new DummyExtension("_first", "first"));
+		extensions.add(new DummyExtension("_second", "second"));
+
+		ExtensionAwareEvaluationContextProvider provider = new ExtensionAwareEvaluationContextProvider(extensions);
+		assertThat(evaluateExpression("key", provider), is((Object) "second"));
+	}
+
+	/**
+	 * @see DATACMNS-533
+	 */
+	@Test
+	public void allowsDirectAccessToExtensionViaKey() {
+
+		List<EvaluationContextExtension> extensions = new ArrayList<EvaluationContextExtension>();
+		extensions.add(new DummyExtension("_first", "first"));
+		extensions.add(new DummyExtension("_second", "second"));
+
+		EvaluationContextProvider provider = new ExtensionAwareEvaluationContextProvider(extensions);
+		assertThat(evaluateExpression("_first.key", provider), is((Object) "first"));
+	}
+
+	/**
+	 * @see DATACMNS-533
+	 */
+	@Test
+	public void exposesParametersAsVariables() {
+
+		ExtensionAwareEvaluationContextProvider provider = new ExtensionAwareEvaluationContextProvider(
+				Collections.<EvaluationContextExtension> emptyList());
+
+		assertThat(evaluateExpression("#firstname", provider), is((Object) "parameterValue"));
+	}
+
+	/**
+	 * @see DATACMNS-533
+	 */
+	@Test
+	public void exposesMethodDefinedByExtension() {
+
+		List<EvaluationContextExtension> extensions = new ArrayList<EvaluationContextExtension>();
+		extensions.add(new DummyExtension("_first", "first"));
+
+		EvaluationContextProvider provider = new ExtensionAwareEvaluationContextProvider(extensions);
+		assertThat(evaluateExpression("method()", provider), is((Object) "methodResult"));
+	}
+
+	static class DummyExtension extends EvaluationContextExtensionSupport {
+
+		private final String key;
+		private final String value;
+
+		/**
+		 * @param value
+		 */
+		public DummyExtension(String key, String value) {
+
+			this.key = key;
+			this.value = value;
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.repository.query.spi.EvaluationContextExtension#getExtensionId()
+		 */
+		@Override
+		public String getExtensionId() {
+			return key;
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.repository.query.EvaluationContextExtensionAdapter#getProperties()
+		 */
+		@Override
+		public Map<String, Object> getProperties() {
+			return Collections.<String, Object> singletonMap("key", value);
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.data.repository.query.spi.EvaluationContextExtensionSupport#getFunctions()
+		 */
+		@Override
+		public Map<String, Method> getFunctions() {
+
+			try {
+				return Collections.singletonMap("method", getClass().getMethod("extensionMethod"));
+			} catch (Exception o_O) {
+				throw new RuntimeException(o_O);
+			}
+		}
+
+		public static String extensionMethod() {
+			return "methodResult";
+		}
+	}
+
+	private Object evaluateExpression(String expression, EvaluationContextProvider provider) {
+
+		EvaluationContext evaluationContext = provider.getEvaluationContext(parameters, new Object[] { "parameterValue" });
+		return new SpelExpressionParser().parseExpression(expression).getValue(evaluationContext);
+	}
+
+	interface SampleRepo {
+
+		List<Object> findByFirstname(@Param("firstname") String firstname);
+	}
+}