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A library for fast runtime class-querying, and more
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/*
---------------------------------------------------------------------------
This software is released under a BSD license, adapted from
http://opensource.org/licenses/bsd-license.php
Copyright (c) 2010, Brian M. Clapper
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
* Neither the names "clapper.org", "ClassUtil", nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
---------------------------------------------------------------------------
*/
package org.clapper.classutil
import scala.reflect.Manifest
import grizzled.reflect
/** Some general-purpose class-related utility functions.
*/
object ClassUtil {
private lazy val JavaPrimitives = Set(
classOf[java.lang.Boolean]. asInstanceOf[Any],
java.lang.Boolean.TYPE. asInstanceOf[Any],
classOf[java.lang.Byte]. asInstanceOf[Any],
java.lang.Byte.TYPE. asInstanceOf[Any],
classOf[java.lang.Character]. asInstanceOf[Any],
java.lang.Character.TYPE. asInstanceOf[Any],
classOf[java.lang.Double]. asInstanceOf[Any],
java.lang.Double.TYPE. asInstanceOf[Any],
classOf[java.lang.Float]. asInstanceOf[Any],
java.lang.Float.TYPE. asInstanceOf[Any],
classOf[java.lang.Integer]. asInstanceOf[Any],
java.lang.Integer.TYPE. asInstanceOf[Any],
classOf[java.lang.Long]. asInstanceOf[Any],
java.lang.Long.TYPE. asInstanceOf[Any],
classOf[java.lang.Short]. asInstanceOf[Any],
java.lang.Short.TYPE. asInstanceOf[Any],
classOf[java.lang.Void]. asInstanceOf[Any],
java.lang.Void.TYPE. asInstanceOf[Any]
)
// For generating type signatures.
private[classutil] lazy val PrimitiveSigMap = Map(
classOf[Boolean].getName -> "Z",
classOf[Byte].getName -> "B",
classOf[Char].getName -> "C",
classOf[Short].getName -> "S",
classOf[Int].getName -> "I",
classOf[Long].getName -> "J",
classOf[Float].getName -> "F",
classOf[Double].getName -> "D",
classOf[Unit].getName -> "V",
"void" -> "V"
)
/** Determine whether an object is a primitive or not.
*
* @param obj the object
*
* @return `true` if its class is a primitive, `false` if not.
*/
def isPrimitive(obj: Any): Boolean =
isPrimitive(obj.asInstanceOf[AnyRef].getClass)
/** Determine whether a class represents an underlying primitive or not.
* For instance, `Int`, `Float` and `Unit` all represent underlying
* primitives. Note that Java classes are considered primitives if they
* *are*, in fact, primitives, or if they represent boxed forms of
* primitives.
*
* @param cls the class
*
* @return `true` if the class represents a primitive, `false` if not
*/
def isPrimitive[T](cls: Class[T])(implicit man: Manifest[T]): Boolean = {
import scala.reflect.ClassManifest
def scalaPrimitive = man match {
case ClassManifest.Boolean => true
case ClassManifest.Byte => true
case ClassManifest.Char => true
case ClassManifest.Double => true
case ClassManifest.Float => true
case ClassManifest.Int => true
case ClassManifest.Long => true
case ClassManifest.Short => true
case ClassManifest.Unit => true
case _ => false
}
def javaPrimitive = JavaPrimitives contains cls
scalaPrimitive || javaPrimitive
}
/** Determine if a value is of, or is assignable to, a specified type.
* Works with generics. Example of use:
*
* {{{
* val value: Any = ...
* assert(isOfType[Map[String,Int]](value))
* }}}
*
* @tparam T the type against which to check the value
* @param value the value to check
*
* @return whether or not `value` conforms to type `T`
*/
def isOfType[T](v: Any)(implicit man: Manifest[T]): Boolean =
reflect.isOfType[T](v)
/** Convenience method to load a class from an array of class bytes.
*
* @param classLoader the class loader to use
* @param className the name of the class
* @param classBytes the class's byte code
*
* @return the loaded class
*/
def loadClass(classLoader: ClassLoader,
className: String,
classBytes: Array[Byte]): Class[_] = {
val cls = Class.forName("java.lang.ClassLoader")
val method = cls.getDeclaredMethod("defineClass",
classOf[String],
classOf[Array[Byte]],
classOf[Int],
classOf[Int])
method.setAccessible(true)
method.invoke(classLoader, className, classBytes,
new java.lang.Integer(0),
new java.lang.Integer(classBytes.length)).
asInstanceOf[Class[_]]
}
/** Generate a runtime signature for a class (type). For instance:
*
* {{{
* java.lang.String -> Ljava/lang/String;
* int -> I
* }}}
*
* @param cls The class (type)
*
* @return its string signature
*/
def classSignature(cls: Class[_]): String = {
if (cls.isArray)
"[" + classSignature(cls.getComponentType)
else if (cls.isPrimitive) {
val s = PrimitiveSigMap.get(cls.getName)
if (s == None)
throw new Exception("Can't map class \"" + cls.getName + "\" " +
"to signature.")
s.get
}
else
"L" + binaryClassName(cls.getName) + ";"
}
/** Generate a runtime signature for a method. See, for instance:
* [[http://journals.ecs.soton.ac.uk/java/tutorial/native1.1/implementing/method.html]]
*
* @param returnType the method's return type
* @param paramTypes the methods parameter types. An empty array
* signifies a method that takes no parameters.
*
* @return its string signature
*/
def methodSignature(returnType: Class[_], paramTypes: Array[Class[_]]) = {
val paramSig =
if ((paramTypes == null) || (paramTypes.length == 0))
""
else
paramTypes.map(pt => classSignature(pt)).mkString("")
"(" + paramSig + ")" + classSignature(returnType)
}
/** Generate a runtime signature for a method. See, for instance:
* [[http://journals.ecs.soton.ac.uk/java/tutorial/native1.1/implementing/method.html]]
*
* @param method method, from java.lang.reflect
*
* @return its string signature
*/
def methodSignature(method: java.lang.reflect.Method): String =
methodSignature(method.getReturnType, method.getParameterTypes)
/** Convert a class name (e.g., "java.lang.String") into its binary
* form (e.g., "java/lang/String").
*
* @param className the internal class name
*
* @return the binary form
*/
private[classutil] def binaryClassName(className: String): String =
className.replaceAll("""\.""", "/")
}
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