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spelhelper
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Abhinav Sarkar 14 years ago
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8
.classpath
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<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="src" output="target/classes" path="src/main/java"/>
<classpathentry kind="src" output="target/test-classes" path="src/test/java"/>
<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER"/>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
<classpathentry kind="output" path="target/classes"/>
</classpath>

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.project
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<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
<name>SpelHelper</name>
<comment></comment>
<projects>
</projects>
<buildSpec>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.maven.ide.eclipse.maven2Builder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.jdt.core.javanature</nature>
<nature>org.maven.ide.eclipse.maven2Nature</nature>
</natures>
</projectDescription>

20
SpelHelper.iml
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<?xml version="1.0" encoding="UTF-8"?>
<module org.jetbrains.idea.maven.project.MavenProjectsManager.isMavenModule="true" type="JAVA_MODULE" version="4">
<component name="NewModuleRootManager" inherit-compiler-output="false">
<output url="file://$MODULE_DIR$/target/classes" />
<output-test url="file://$MODULE_DIR$/target/test-classes" />
<content url="file://$MODULE_DIR$">
<sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
<sourceFolder url="file://$MODULE_DIR$/src/test/java" isTestSource="true" />
<excludeFolder url="file://$MODULE_DIR$/target" />
</content>
<orderEntry type="inheritedJdk" />
<orderEntry type="sourceFolder" forTests="false" />
<orderEntry type="library" scope="TEST" name="Maven: junit:junit:3.8.1" level="project" />
<orderEntry type="library" exported="" name="Maven: org.springframework:spring-core:3.0.2.RELEASE" level="project" />
<orderEntry type="library" exported="" name="Maven: org.springframework:spring-asm:3.0.2.RELEASE" level="project" />
<orderEntry type="library" exported="" name="Maven: commons-logging:commons-logging:1.1.1" level="project" />
<orderEntry type="library" exported="" name="Maven: org.springframework:spring-expression:3.0.2.RELEASE" level="project" />
</component>
</module>

47
pom.xml
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>net.abhinavsarkar.spelhelper</groupId>
<artifactId>SpelHelper</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<name>SpelHelper</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.4</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>3.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>3.0.2.RELEASE</version>
</dependency>
</dependencies>
</project>

38
src/main/java/net/abhinavsarkar/spelhelper/ExtensionFunctions.java
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package net.abhinavsarkar.spelhelper;
import static java.util.Collections.unmodifiableList;
import static java.util.Collections.unmodifiableMap;
import static java.util.Collections.unmodifiableSet;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.springframework.util.Assert;
final class ExtensionFunctions {
public static <T> List<T> list(final T... args) {
return unmodifiableList(Arrays.asList(args));
}
public static <T> Set<T> set(final T... args) {
return unmodifiableSet(new HashSet<T>(list(args)));
}
public static <K,V> Map<K,V> map(final List<? extends K> keys,
final List<? extends V> values) {
Assert.isTrue(keys.size() == values.size(),
"There should equal number of keys and values");
Map<K,V> map = new HashMap<K,V>();
int length = keys.size();
for (int i = 0; i < length; i++) {
map.put(keys.get(i), values.get(i));
}
return unmodifiableMap(map);
}
}

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src/main/java/net/abhinavsarkar/spelhelper/ImplicitConstructorResolver.java
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/**
*
*/
package net.abhinavsarkar.spelhelper;
import java.lang.reflect.Constructor;
import java.util.Arrays;
import org.springframework.expression.AccessException;
import org.springframework.expression.ConstructorExecutor;
import org.springframework.expression.ConstructorResolver;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.spel.support.ReflectiveConstructorResolver;
final class ImplicitConstructorResolver implements
ConstructorResolver {
private final ReflectiveConstructorResolver delegate = new ReflectiveConstructorResolver();
public ConstructorExecutor resolve(final EvaluationContext context,
final String typeName, final Class<?>[] argumentTypes) throws AccessException {
try {
return delegate.resolve(context, typeName, argumentTypes);
} catch (AccessException ex) {
Object variable = ((SpelHelper) context.lookupVariable(SpelHelper.CONTEXT_LOOKUP_KEY))
.lookupImplicitConstructor(typeName + Arrays.toString(argumentTypes));
if (variable instanceof Constructor<?>) {
Constructor<?> constructor = (Constructor<?>) variable;
return delegate.resolve(context, constructor.getDeclaringClass().getName(), argumentTypes);
}
return null;
}
}
}

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src/main/java/net/abhinavsarkar/spelhelper/ImplicitMethodResolver.java
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/**
*
*/
package net.abhinavsarkar.spelhelper;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.concurrent.ConcurrentHashMap;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.MethodExecutor;
import org.springframework.expression.MethodResolver;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.support.ReflectiveMethodResolver;
public final class ImplicitMethodResolver implements MethodResolver {
private static final ConcurrentHashMap<String, MethodExecutor> cache =
new ConcurrentHashMap<String, MethodExecutor>();
private static final MethodExecutor NULL_ME = new MethodExecutor() {
public TypedValue execute(final EvaluationContext context, final Object target,
final Object... arguments) throws AccessException {
return null;
}
};
private static final class ImplicitMethodExecutor implements
MethodExecutor {
private final MethodExecutor executor;
private ImplicitMethodExecutor(final MethodExecutor executor) {
this.executor = executor;
}
public TypedValue execute(final EvaluationContext context, final Object target,
final Object... arguments) throws AccessException {
Object[] modifiedArguments = new Object[arguments.length + 1];
modifiedArguments[0] = target;
System.arraycopy(arguments, 0, modifiedArguments, 1, arguments.length);
return executor.execute(context, null, modifiedArguments);
}
}
public MethodExecutor resolve(final EvaluationContext context,
final Object targetObject, final String name, final Class<?>[] argumentTypes)
throws AccessException {
if (targetObject == null) {
return null;
}
Class<?> type = targetObject.getClass();
String cacheKey = type.getName() + "." + name;
if (cache.containsKey(cacheKey)) {
MethodExecutor executor = cache.get(cacheKey);
return executor == NULL_ME ? null : executor;
}
Method method = lookupMethod(context, type, name);
if (method != null) {
int modifiers = method.getModifiers();
if (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers)) {
Class<?>[] parameterTypes = method.getParameterTypes();
Class<?> firstParameterType = parameterTypes[0];
if (parameterTypes.length > 0
&& firstParameterType.isAssignableFrom(type)) {
Class<?>[] modifiedArgumentTypes = new Class[argumentTypes.length + 1];
modifiedArgumentTypes[0] = firstParameterType;
System.arraycopy(argumentTypes, 0, modifiedArgumentTypes,
1, argumentTypes.length);
MethodExecutor executor = new ReflectiveMethodResolver()
.resolve(context, method.getDeclaringClass(), name,
modifiedArgumentTypes);
MethodExecutor wrappedExecutor = executor == null ? null
: new ImplicitMethodExecutor(executor);
cache.putIfAbsent(cacheKey, wrappedExecutor);
return wrappedExecutor;
}
}
}
cache.putIfAbsent(cacheKey, NULL_ME);
return null;
}
private static Method lookupMethod(final EvaluationContext context,
final Class<?> type, final String name) {
for (Class<?> clazz : InheritenceUtil.getInheritance(type)) {
Object variable = ((SpelHelper) context.lookupVariable(SpelHelper.CONTEXT_LOOKUP_KEY))
.lookupImplicitMethod(clazz.getName() + "." + name);
if (variable instanceof Method) {
return (Method) variable;
}
}
return null;
}
}

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src/main/java/net/abhinavsarkar/spelhelper/ImplicitMethods.java
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package net.abhinavsarkar.spelhelper;
import static java.util.Collections.unmodifiableList;
import static java.util.Collections.unmodifiableSet;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
final class ImplicitMethods {
public static <T> Set<T> distinct(final List<? extends T> list) {
return unmodifiableSet(new HashSet<T>(list));
}
public static <T extends Comparable<? super T>> List<T> sorted(
final List<? extends T> list) {
List<T> temp = new ArrayList<T>(list);
Collections.sort(temp);
return unmodifiableList(temp);
}
public static <T> List<T> reversed(final List<? extends T> list) {
List<T> temp = new ArrayList<T>(list);
Collections.reverse(temp);
return unmodifiableList(temp);
}
public static <T> List<T> take(final List<T> list, final int n) {
return unmodifiableList(list.subList(0, n));
}
public static <T> List<T> drop(final List<T> list, final int n) {
return unmodifiableList(list.subList(n, list.size()));
}
}

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src/main/java/net/abhinavsarkar/spelhelper/ImplicitPropertyAccessor.java
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/**
*
*/
package net.abhinavsarkar.spelhelper;
import java.text.MessageFormat;
import java.util.concurrent.ConcurrentHashMap;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.MethodExecutor;
import org.springframework.expression.MethodResolver;
import org.springframework.expression.TypedValue;
import org.springframework.util.Assert;
public final class ImplicitPropertyAccessor extends ReadOnlyGenericPropertyAccessor {
private static final ConcurrentHashMap<String, MethodExecutor> cache =
new ConcurrentHashMap<String, MethodExecutor>();
public boolean canRead(final EvaluationContext context,
final Object target, final String name)
throws AccessException {
Assert.notNull(target, "target is null");
String cacheKey = target.getClass().getName() + "." + name;
if (cache.containsKey(cacheKey)) {
return cache.get(cacheKey) != null;
}
for (MethodResolver mr : context.getMethodResolvers()) {
MethodExecutor me = mr.resolve(context, target, name, new Class[0]);
if (me != null) {
cache.putIfAbsent(cacheKey, me);
return true;
}
}
cache.putIfAbsent(cacheKey, null);
return false;
}
public TypedValue read(final EvaluationContext context,
final Object target, final String name)
throws AccessException {
if (canRead(context, target, name)) {
String cacheKey = target.getClass().getName() + "." + name;
return cache.get(cacheKey).execute(context, target, new Object[0]);
}
throw new AccessException(MessageFormat.format(
"Cannot read property: {0} of target: {1}", name, target));
}
}

66
src/main/java/net/abhinavsarkar/spelhelper/InheritenceUtil.java
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package net.abhinavsarkar.spelhelper;
import java.util.LinkedHashSet;
import java.util.Set;
final class InheritenceUtil {
public static Set<Class<?>> getInheritance(final Class<?> in) {
LinkedHashSet<Class<?>> result = new LinkedHashSet<Class<?>>();
result.add(in);
getInheritance(in, result);
return result;
}
/**
* Get inheritance of type.
*
* @param in
* @param result
*/
private static void getInheritance(final Class<?> in, final Set<Class<?>> result) {
Class<?> superclass = getSuperclass(in);
if (superclass != null) {
result.add(superclass);
getInheritance(superclass, result);
}
getInterfaceInheritance(in, result);
}
/**
* Get interfaces that the type inherits from.
*
* @param in
* @param result
*/
private static void getInterfaceInheritance(final Class<?> in,
final Set<Class<?>> result) {
for (Class<?> c : in.getInterfaces()) {
result.add(c);
getInterfaceInheritance(c, result);
}
}
/**
* Get superclass of class.
*
* @param in
* @return
*/
private static Class<?> getSuperclass(final Class<?> in) {
if (in == null) {
return null;
}
if (in.isArray() && in != Object[].class) {
Class<?> type = in.getComponentType();
while (type.isArray()) {
type = type.getComponentType();
}
return type;
}
return in.getSuperclass();
}
}

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src/main/java/net/abhinavsarkar/spelhelper/ReadOnlyGenericPropertyAccessor.java
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package net.abhinavsarkar.spelhelper;
import java.text.MessageFormat;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.PropertyAccessor;
public abstract class ReadOnlyGenericPropertyAccessor implements
PropertyAccessor {
public final boolean canWrite(final EvaluationContext context,
final Object target, final String name) throws AccessException {
return false;
}
@SuppressWarnings("unchecked")
public final Class[] getSpecificTargetClasses() {
return null;
}
public final void write(final EvaluationContext context, final Object target,
final String name, final Object newValue) throws AccessException {
throw new AccessException(MessageFormat.format(
"Cannot write property: {0} of target: {1}", name, target));
}
}

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src/main/java/net/abhinavsarkar/spelhelper/SpelHelper.java
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package net.abhinavsarkar.spelhelper;
import static java.util.Arrays.asList;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.springframework.expression.ConstructorResolver;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.util.Assert;
public final class SpelHelper {
public static final String CONTEXT_LOOKUP_KEY = SpelHelper.class.getName();
private static final ExpressionParser PARSER = new SpelExpressionParser();
private static final ThreadLocal<EvaluationContext> currentContext =
new ThreadLocal<EvaluationContext>();
private volatile EvaluationContext context;
private final Set<Method> registeredFunctions = new HashSet<Method>();
private final Map<String,Method> registeredMethods =
new ConcurrentHashMap<String, Method>();
private final Map<String,Constructor<?>> registeredConstructors =
new ConcurrentHashMap<String, Constructor<?>>();
{
registerFunctionsFromClass(ExtensionFunctions.class);
registerImplicitMethodsFromClass(ImplicitMethods.class);
}
public SpelHelper registerImplicitMethodsFromClass(final Class<?> clazz) {
for (Method method : filterMethods(clazz)) {
registeredMethods.put(String.format(
"%s.%s", method.getParameterTypes()[0].getName(), method.getName()),
method);
}
return this;
}
public SpelHelper registerFunctionsFromClass(final Class<?> clazz) {
registeredFunctions.addAll(filterMethods(clazz));
context = null;
return this;
}
public SpelHelper registerImplicitConstructorsFromClass(final Class<?> clazz) {
for (Constructor<?> constructor : asList(clazz.getConstructors())) {
registeredConstructors.put(
constructor.getDeclaringClass().getSimpleName()
+ Arrays.toString(constructor.getParameterTypes()),
constructor);
}
return this;
}
public <T> T evalExpression(final String expressionString,
final Object rootElement, final Class<T> desiredType) {
EvaluationContext evaluationContext = getEvaluationContext(rootElement);
currentContext.set(evaluationContext);
T value = evalExpression(expressionString, evaluationContext, desiredType);
currentContext.set(null);
return value;
}
public <T> T evalExpression(final String expressionString,
final EvaluationContext evaluationContext, final Class<T> desiredType) {
return PARSER.parseExpression(expressionString)
.getValue(evaluationContext, desiredType);
}
public <T> T evalExpressions(final String[] expressionStrings,
final Object rootElement, final Class<T> desiredType) {
int length = expressionStrings.length;
Assert.isTrue(length > 0,
"expressionStrings should have length more than 0");
for (int i = 0; i < length - 1; i++) {
evalExpression(expressionStrings[i], rootElement, Object.class);
}
return evalExpression(expressionStrings[length - 1],
rootElement, desiredType);
}
private EvaluationContext getEvaluationContext(final Object rootObject) {
if (context == null) {
synchronized (PARSER) {
if (context == null) {
StandardEvaluationContext newContext = new StandardEvaluationContext(rootObject);
newContext.getMethodResolvers().add(new ImplicitMethodResolver());
newContext.getPropertyAccessors().add(new ImplicitPropertyAccessor());
newContext.setConstructorResolvers(
asList((ConstructorResolver) new ImplicitConstructorResolver()));
for (Method method : registeredFunctions) {
newContext.setVariable(method.getName(), method);
}
newContext.setVariable(CONTEXT_LOOKUP_KEY, this);
context = newContext;
}
}
}
return context;
}
public Method lookupImplicitMethod(final String lookup) {
Assert.notNull(lookup);
return registeredMethods.get(lookup);
}
public Constructor<?> lookupImplicitConstructor(final String lookup) {
Assert.notNull(lookup);
return registeredConstructors.get(lookup);
}
public static EvaluationContext getCurrentContext() {
return currentContext.get();
}
private static List<Method> filterMethods(final Class<?> clazz) {
List<Method> allowedMethods = new ArrayList<Method>();
for (Method method : clazz.getMethods()) {
int modifiers = method.getModifiers();
if (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers)
&& !method.getReturnType().equals(Void.TYPE)
&& method.getParameterTypes().length > 0) {
allowedMethods.add(method);
}
}
return allowedMethods;
}
}

43
src/test/java/net/abhinavsarkar/spelhelper/SpelHelperTest.java
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package net.abhinavsarkar.spelhelper;
import java.util.Arrays;
import java.util.List;
import org.junit.Assert;
import org.junit.Test;
public class SpelHelperTest {
@Test
public void testRegisteredFunction() {
Assert.assertEquals(
Arrays.asList("abhinav", "mini", "dan"),
new SpelHelper().evalExpression(
"#list('abhinav','mini','dan')", new Object(), List.class));
}
@Test
public void testImplicitMethod() {
Assert.assertEquals(
Arrays.asList("abhinav", "dan", "mini"),
new SpelHelper().evalExpression(
"#list('abhinav','mini','dan').sorted", new Object(), List.class));
}
public static final class ConstructorTest {
@Override
public boolean equals(final Object o) {
return o instanceof ConstructorTest;
}
}
@Test
public void testImplicitConstructor() {
Assert.assertEquals(
new ConstructorTest(),
new SpelHelper()
.registerImplicitConstructorsFromClass(ConstructorTest.class)
.evalExpression("new ConstructorTest()", new Object(), ConstructorTest.class));
}
}
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