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ClassFinder.scala
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ClassFinder.scala
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/** This library provides methods for locating and filtering classes
* quickly--faster, in fact, than can be done with Java or Scala runtime
* reflection. Under the covers, it uses the ASM bytecode library, though
* it can easily be extended to use other bytecode libraries. ClassUtil
* loads and returns information about classes using an efficient lazy
* iterator approach, which offers minimal startup penalty and the ability
* to cut the traversal short.
*/
package org.clapper.classutil
import java.io.{File, InputStream}
import java.util.jar.{JarFile, Manifest => JarManifest}
import java.util.zip.{ZipEntry, ZipFile}
import org.clapper.classutil.ScalaCompat._
import scala.annotation.tailrec
import scala.language.reflectiveCalls
/** An enumerated high-level view of the modifiers that can be attached
* to a method, class or field.
*/
object Modifier {
abstract sealed class Modifier(val name: String, val id: Int)
extends Product with Serializable {
override def hashCode: Int = id.hashCode
}
case object Abstract extends Modifier(name = "abstract", id = 1)
case object Final extends Modifier(name = "final", id = 2)
case object Interface extends Modifier(name = "interface", id = 3)
case object Native extends Modifier(name = "native", id = 4)
case object Private extends Modifier(name = "private", id = 5)
case object Protected extends Modifier(name = "protected", id = 6)
case object Public extends Modifier(name = "public", id = 7)
case object Static extends Modifier(name = "static", id = 8)
case object Strict extends Modifier(name = "strict", id = 0)
case object Synchronized extends Modifier(name = "synchronized", id = 10)
case object Synthetic extends Modifier(name = "synthetic", id = 11)
case object Transient extends Modifier(name = "transient", id = 12)
case object Volatile extends Modifier(name = "volatile", id = 13)
}
/** Base trait for method, field and class info.
*/
private[classutil] trait BaseInfo {
/** The name of the entity.
*/
val name: String
/** The entity's modifiers.
*/
val modifiers: Set[Modifier.Modifier]
/** A printable version of the field. Currently, the string version is
* the entity name.
*/
override def toString = name
/** Convenience method that determines whether the class implements an
* interface. This method is just shorthand for:
* {{{
* modifiers contains Modifier.Interface
* }}}
*/
def isInterface = modifiers contains Modifier.Interface
/** Convenience method that determines whether the class is abstract
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Abstract
* }}}
*/
def isAbstract = modifiers contains Modifier.Abstract
/** Convenience method that determines whether the class is private.
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Private
* }}}
*/
def isPrivate = modifiers contains Modifier.Private
/** Convenience method that determines whether the class is protected.
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Protected
* }}}
*/
def isProtected = modifiers contains Modifier.Protected
/** Convenience methods that determines whether the class is public.
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Public
* }}}
*/
def isPublic = modifiers contains Modifier.Public
/** Convenience methods that determines whether the class is final.
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Final
* }}}
*/
def isFinal = modifiers contains Modifier.Final
/** Convenience methods that determines whether the class is static.
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Static
* }}}
*/
def isStatic = modifiers contains Modifier.Static
/** Convenience methods that determines whether the class is synchronized.
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Synchronized
* }}}
*/
def isSynchronized = modifiers contains Modifier.Synchronized
/** Convenience methods that determines whether the class is synthetic.
* This method is just shorthand for:
* {{{
* modifiers contains Modifier.Synthetic
* }}}
*/
def isSynthetic = modifiers contains Modifier.Synthetic
/** Convenience method to determine whether the class is concrete (i.e.,
* isn't abstract and isn't an interface).
*/
def isConcrete = !((modifiers contains Modifier.Abstract) ||
(modifiers contains Modifier.Interface))
}
/** Information about a method, as read from a class file.
*/
trait MethodInfo extends BaseInfo {
/** The method's JVM signature (only available with generics).
* Ex: java.util.List.iterator ()Ljava/util/Iterator<TE;>;
*/
val signature: String
/** The method's descriptor which describes it's arg types
* and return type.
* Ex: (ILjava/lang/String;)[I
*/
val descriptor: String
/** A list of the checked exceptions (as class names) that the method
* throws, or an empty list if it throws no known checked exceptions.
*/
val exceptions: List[String]
/** A printable version of the method. Currently, the string is
* the method name plus descriptor.
*/
override def toString = name + descriptor
override def hashCode = toString.hashCode
override def equals(o: Any) = o match {
case m: MethodInfo => m.toString == toString
case _ => false
}
}
/** Information about a field, as read from a class file.
*/
trait FieldInfo extends BaseInfo {
/** The field's JVM signature (only available with generics).
*/
val signature: String
/** The field's descriptor which describes it's type
* Ex: Ljava/lang/String;
*/
val descriptor: String
/** The field's default value, only available when the field
* is a static field that is a primitive or a String type.
*/
val value: Option[java.lang.Object]
override def hashCode = name.hashCode
override def equals(o: Any) = o match {
case m: FieldInfo => m.name == name
case _ => false
}
}
/** Information about a field, as read from a class file.
*/
trait AnnotationInfo {
/** The annotations's descriptor which describes it's type
* Ex: Lscala/reflect/ScalaSignature;
*/
val descriptor: String
val visible: Boolean
def params: Map[String, Any]
override def hashCode = (descriptor, params).hashCode
override def equals(o: Any) = o match {
case m: AnnotationInfo => m.descriptor == descriptor && m.params == params
case _ => false
}
}
/** Information about a class, as read from a class file.
*/
trait ClassInfo extends BaseInfo {
/** The parent class's fully qualified name.
*/
def superClassName: String
/** A list of the interfaces, as class names, that the class implements;
* or, an empty list if it implements no interfaces.
*/
def interfaces: List[String]
/** The class's JVM signature.
*/
def signature: String
/** Where the class was found (directory, jar file, or zip file).
*/
def location: File
/** A set of the methods in the class.
*/
def methods: Set[MethodInfo]
/** A set of the fields in the class.
*/
def fields: Set[FieldInfo]
/** A set of the runtime-retained annotations in the class.
*/
def annotations: Set[AnnotationInfo]
/** Convenience method to determine whether this class directly
* implements a specific interface. Since a `ClassInfo` object contains
* information about a single class, this method cannot determine
* whether a class indirectly implements an interface. That capability
* is a higher-order operation.
*
* @param interface the name of the interface
* @return whether the class implements the interface
*/
def implements(interface: String): Boolean = interfaces contains interface
}
/** A `ClassFinder` finds classes in a class path, returning the result in a
* lazy iterator. The iterator can then be filtered, mapped, or passed to
* the utility methods in the `ClassFinder` companion object.
*
* @param path a sequence of directories, jars and zips to
* search
* @param maybeOverrideAsmVersion the version of asm to be used. Defaults to v6.
* To override use one of the ASM-fields in
* `org.objectweb.asm.Opcodes` (e.g.,
* (`org.objectweb.asm.Opcodes.ASM5`).
*/
class ClassFinder(path: Seq[File], maybeOverrideAsmVersion: Option[Int]) {
val classpath: List[File] = path.toList
/** Find all classes in the specified path, which can contain directories,
* zip files and jar files. Returns metadata about each class in a
* `ClassInfo` object. The `ClassInfo` objects are returned lazily,
* rather than loaded all up-front.
*
* @return a `LazyList` of `ClassInfo` objects. When compiling against
* versions of Scala prior to 2.13.0, this result is really a
* `scala.Stream` object. (There's a compatibility type definition
* with the `classutil` library.)
*/
def getClasses(): LazyList[ClassInfo] = find(classpath)
/* ---------------------------------------------------------------------- *\
Private Methods
\* ---------------------------------------------------------------------- */
private def find(path: Seq[File]): LazyList[ClassInfo] = {
path match {
case Nil => LazyList.empty[ClassInfo]
case item :: Nil => findClassesIn(item)
case item :: tail => findClassesIn(item) ++ find(tail)
}
}
private def findClassesIn(f: File): LazyList[ClassInfo] = {
val name = f.getPath.toLowerCase
if (name.endsWith(".jar"))
processJar(f)
else if (name.endsWith(".zip"))
processZip(f)
else if (f.isDirectory)
processDirectory(f)
else
LazyList.empty[ClassInfo]
}
private def processJar(file: File): LazyList[ClassInfo] = {
val jar = new JarFile(file)
val list1 = processOpenZip(file, jar)
Option(jar.getManifest)
.map { manifest =>
val path = loadManifestPath(jar, file, manifest)
val list2 = find(path)
list1 ++ list2
}
.getOrElse(list1)
}
private def loadManifestPath(jar: JarFile,
jarFile: File,
manifest: JarManifest): List[File] = {
val attrs = manifest.getMainAttributes
val value = attrs.get("Class-Path").asInstanceOf[String]
if (value == null)
Nil
else {
val parent = jarFile.getParent
val tokens = value.split("""\s+""").toList
if (parent == null)
tokens.map(new File(_))
else
tokens.map(s => new File(parent + File.separator + s))
}
}
private def processZip(file: File): LazyList[ClassInfo] =
processOpenZip(file, new ZipFile(file))
private def processOpenZip(file: File,
zipFile: ZipFile): LazyList[ClassInfo] = {
import org.clapper.classutil.ScalaCompat.CollectionConverters._
val classInfoIterators =
zipFile
.entries
.asScala
.filter((e: ZipEntry) => isClass(e))
.map((e: ZipEntry) => classData(zipFile.getInputStream(e), file))
LazyList.from(
for {it <- classInfoIterators
data <- it}
yield data
)
}
// Structural type that matches both ZipEntry and File
private type FileEntry = {
def isDirectory(): Boolean
def getName(): String
}
private def isClass(e: FileEntry): Boolean =
(!e.isDirectory) && e.getName.toLowerCase.endsWith(".class")
private def processDirectory(dir: File): LazyList[ClassInfo] = {
import java.io.FileInputStream
import grizzled.file.Implicits._
val inputStreams = dir.listRecursively().filter(isClass).
map(f => new FileInputStream(f))
val iterators =
for (fis <- inputStreams) yield {
try {
classData(fis, dir)
}
finally {
fis.close()
}
}
for {it <- iterators
data <- it}
yield data
}
private def classData(is: InputStream,
location: File): Iterator[ClassInfo] = {
import org.clapper.classutil.asm.ClassFile
ClassFile.load(is, location, maybeOverrideAsmVersion.getOrElse(asm.DefaultAsmVersion))
}
}
/** The entrance to the factory floor, providing methods for finding and
* filtering classes.
*/
object ClassFinder {
/** Convenient method for getting the standard JVM classpath, into a
* variable suitable for use with the `find()` method.
*
* @return the classpath, as a list of `File` objects
*/
def classpath: List[File] = System
.getProperty("java.class.path")
.split(File.pathSeparator)
.map(s => if (s.trim.length == 0) "." else s)
.map(new File(_))
.toList
/** Instantiate a new `ClassFinder` that will search the specified
* classpath, or the default classpath, if no classpath is defined.
*
* @param path the classpath, which is a sequence of `File`
* objects representing directories, jars and zip files
* to search. Defaults to `classpath` if empty.
* @param maybeOverrideAsmVersion the version of asm to be used. Defaults to v6.
* To override use one of the ASM-fields in
* `org.objectweb.asm.Opcodes` (e.g.,
* (`org.objectweb.asm.Opcodes.ASM5`).
* @return a new `ClassFinder` object
*/
def apply(path: Seq[File] = Seq.empty[File], maybeOverrideAsmVersion: Option[Int] = None): ClassFinder =
new ClassFinder(if (path.nonEmpty) path else classpath, maybeOverrideAsmVersion)
/** Create a map from an Iterator of ClassInfo objects. The resulting
* map is indexed by class name.
*
* @return a map of (classname, `ClassInfo`) pairs
*/
def classInfoMap(iterator: Iterator[ClassInfo]): Map[String, ClassInfo] =
iterator.map(c => c.name -> c).toMap
/** Create a map from a Stream of ClassInfo objects. The resulting map is
* indexed by class name.
*
* @return a map of (classname, `ClassInfo`) pairs
*/
def classInfoMap(stream: LazyList[ClassInfo]): Map[String, ClassInfo] =
classInfoMap(stream.iterator)
/** Convenience method that scans the specified classes for all concrete
* classes that are subclasses of a superclass or trait. A subclass, in this
* definition, is a class that directly or indirectly (a) implements an
* interface (if the named class is an interface) or (b) extends a
* subclass (if the named class is a class). The class must be
* concrete, so intermediate abstract classes are not returned, though
* any children of such abstract classes will be.
*
* '''WARNINGS'''
*
* This method converts the stream to a map of classes, for easier
* lookup. Thus, upon its return, the stream will be empty. You can
* certainly recreate the stream, but at a cost. If you need to make
* multiple calls to this method with the same classpath, consider
* converting the stream to a map first, as shown below:
* {{{
* val finder = ClassFinder(myPath)
* val classes = finder.getClasses // classes is an Stream[ClassInfo]
* val classMap = ClassFinder.classInfoMap // runs the stream out, once
* val foos = ClassFinder.concreteSubclasses(classOf[org.example.Foo], classMap)
* val bars = ClassFinder.concreteSubclasses(classOf[Bar], classMap)
* }}}
*
* This method can chew up a lot of temporary heap space, if called
* with a large classpath.
*
* @param ancestor the `Class` object of the superclass or trait for which
* to find descendent concrete subclasses
* @param classes the `LazyList` of `ClassInfo` objects to search. (Note
* that in versions of Scala prior to 2.13.0, this lazy
* list should really be a `Stream`. A compatibility type
* definition within this library ensures that methods
* returning `LazyList` really return `Stream`, in that
* case.)
*
* @return an iterator of `ClassInfo` objects that are concrete subclasses
* of `ancestor`. The iterator will be empty if no matching classes
* could be found.
*/
def concreteSubclasses(ancestor: Class[_], classes: LazyList[ClassInfo]):
Iterator[ClassInfo] = {
findConcreteSubclasses(ancestor.getName, ClassFinder.classInfoMap(classes))
}
/** Variant of `concreteSubclasses()` that takes a string class name and
* a `Stream` of `ClassInfo` objects, rather than a `Class` and a `Stream`.
*
* @param ancestor the name of the class for which to find descendent
* concrete subclasses
* @param classes the `LazyList` of `ClassInfo` objects to search. (Note
* that in versions of Scala prior to 2.13.0, this lazy
* list should really be a `Stream`. A compatibility type
* definition within this library ensures that methods
* returning `LazyList` really return `Stream`, in that
* case.)
*
* @return an iterator of `ClassInfo` objects that are concrete subclasses
* of `ancestor`. The iterator will be empty if no matching classes
* could be found.
* @see `concreteSubclasses(Class[_], Stream[ClassInfo])`
*/
def concreteSubclasses(ancestor: String, classes: LazyList[ClassInfo]):
Iterator[ClassInfo] = {
findConcreteSubclasses(ancestor, ClassFinder.classInfoMap(classes))
}
/** Variant of `concreteSubclasses()` that takes a class and an `Iterator`
* of `ClassInfo` objects, rather than a `Class` and a `Stream`.
*
* @example
* {{{
* val finder = ClassFinder(myPath)
* val classes = finder.getClasses // classes is an Stream[ClassInfo]
* // Of course, it's easier just to call the version that takes a
* // Stream...
* ClassFinder.concreteSubclasses(classOf[Baz], classes.iterator)
* }}}
* @param ancestor the `Class` object of the superclass or trait for which
* to find descendent concrete subclasses
* @param classes the iterator of `ClassInfo` objects to search
* @return an iterator of `ClassInfo` objects that are concrete subclasses
* of `ancestor`. The iterator will be empty if no matching classes
* could be found.
* @see `concreteSubclasses(Class[_], Stream[ClassInfo])`
*/
def concreteSubclasses(ancestor: Class[_], classes: Iterator[ClassInfo]):
Iterator[ClassInfo] = {
findConcreteSubclasses(ancestor.getName, ClassFinder.classInfoMap(classes))
}
/** Variant of `concreteSubclasses()` that takes a string class name and
* an `Iterator` of `ClassInfo` objects, rather than a `Class` and an
* `Iterator`.
*
* @example
* {{{
* val finder = ClassFinder(myPath)
* val classes = finder.getClasses // classes is an Stream[ClassInfo]
* // Of course, it's easier just to call the version that takes a
* // Stream...
* ClassFinder.concreteSubclasses("org.example.Foo", classes.iterator)
* }}}
* @param ancestor the name of the class for which to find descendent
* concrete subclasses
* @param classes the stream of `ClassInfo` objects to search
* @return an iterator of `ClassInfo` objects that are concrete subclasses
* of `ancestor`. The iterator will be empty if no matching classes
* could be found.
* @see `concreteSubclasses(String, Stream[ClassInfo])`
* @see `concreteSubclasses(Class[_], Iterator[ClassInfo])`
*/
def concreteSubclasses(ancestor: String, classes: Iterator[ClassInfo]):
Iterator[ClassInfo] = {
findConcreteSubclasses(ancestor, ClassFinder.classInfoMap(classes))
}
/** Variant of `concreteSubclasses()` that takes a class and a `Map`
* `ClassInfo` objects.
*
* @param ancestor the `Class` object of the superclass or trait for which
* to find descendent concrete subclasses
* @param classes the iterator of `ClassInfo` objects to search
* @return an iterator of `ClassInfo` objects that are concrete subclasses
* of `ancestor`. The iterator will be empty if no matching classes
* could be found.
* @see `concreteSubclasses(Class[_], Stream[ClassInfo])`
* @see `concreteSubclasses(Class[_], Iterator[ClassInfo])`
*/
def concreteSubclasses(ancestor: Class[_], classes: Map[String, ClassInfo]):
Iterator[ClassInfo] = {
findConcreteSubclasses(ancestor.getName, classes)
}
/** Variant of `concreteSubclasses()` that takes a string class name and
* a map, rather than a `Class` and a map.
*
* @param ancestor the name of the class for which to find descendent
* concrete subclasses
* @param classes the iterator of `ClassInfo` objects to search
* @return an iterator of `ClassInfo` objects that are concrete subclasses
* of `ancestor`. The iterator will be empty if no matching classes
* could be found.
* @see `concreteSubclasses(Class[_], Map[String, ClassInfo])`
* @see `concreteSubclasses(String, Stream[ClassInfo])`
* @see `concreteSubclasses(String, Iterator[ClassInfo])`
*/
def concreteSubclasses(ancestor: String, classes: Map[String, ClassInfo]):
Iterator[ClassInfo] = {
findConcreteSubclasses(ancestor, classes)
}
// -------------------------------------------------------------------------
// Private methods
// -------------------------------------------------------------------------
private def findConcreteSubclasses(ancestor: String,
classes: Map[String, ClassInfo]):
Iterator[ClassInfo] = {
// Convert the set of classes to search into a map of ClassInfo objects
// indexed by class name.
@SuppressWarnings(Array("org.wartremover.warts.Option2Iterable"))
@tailrec
def classMatches(targetClassInfo: ClassInfo,
classesToCheck: Seq[ClassInfo]): Boolean = {
val targetName = targetClassInfo.name // could use ancestor, but, yuck.
val classNames = classesToCheck.map(_.name)
val interfaceNamesToCheck = classesToCheck.flatMap(_.interfaces)
if (classNames contains targetName) {
// The current classes we're checking match the target class. Done.
true
}
else if (interfaceNamesToCheck contains targetName) {
// At least one of current classes implements an interface that is
// the target class. Done.
true
}
else {
val superClasses = classesToCheck.flatMap { c =>
classes.get(c.superClassName)
}
val interfaces = interfaceNamesToCheck.flatMap { i =>
classes.get(i)
}
val newClassesToCheck = superClasses ++ interfaces
if (newClassesToCheck.isEmpty) {
// No matches. Done.
false
}
else {
// Dive deeper.
classMatches(targetClassInfo, newClassesToCheck)
}
}
}
// Find the ancestor class
classes
.get(ancestor)
.map { classInfo =>
classes
.values
.iterator
.filter(_.isConcrete)
.filter(c => classMatches(classInfo, Seq(c)))
}
.getOrElse(Iterator.empty)
}
}