Interface ClassHierarchyResolver

Functional Interface:: This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface public interface ClassHierarchyResolver

Provides class hierarchy information for stack maps generation and verification. A class hierarchy resolver must be able to process all classes and interfaces encountered during these workloads.

See Java Virtual Machine Specification:

4.10.1.2 Verification Type System

Since:

See Also:

Nested Class Summary

Modifier and Type	Interface	Description
`static interface`	`ClassHierarchyResolver.ClassHierarchyInfo`	Information about a resolved class.

Method Summary

Modifier and Type	Method	Description
`default ClassHierarchyResolver`	`cached()`	Returns a `ClassHierarchyResolver` that caches class hierarchy information from this resolver.
`default ClassHierarchyResolver`	`cached(Supplier<Map<ClassDesc, ClassHierarchyResolver.ClassHierarchyInfo>> cacheFactory)`	Returns a `ClassHierarchyResolver` that caches class hierarchy information from this resolver.
`static ClassHierarchyResolver`	`defaultResolver()`	Returns the default instance of `ClassHierarchyResolver` that gets `ClassHierarchyResolver.ClassHierarchyInfo` from system class loader with reflection.
`ClassHierarchyResolver.ClassHierarchyInfo`	`getClassInfo(ClassDesc classDesc)`	Returns the `ClassHierarchyInfo` for a given class name, or `null` if the name is unknown to the resolver.
`static ClassHierarchyResolver`	`of(Collection<ClassDesc> interfaces, Map<ClassDesc, ClassDesc> classToSuperClass)`	Returns a `ClassHierarchyResolver` that extracts class hierarchy information from collections of class hierarchy metadata.
`static ClassHierarchyResolver`	`ofClassLoading(ClassLoader loader)`	Returns a `ClassHierarchyResolver` that extracts class hierarchy information via classes loaded by a class loader with reflection.
`static ClassHierarchyResolver`	`ofClassLoading(MethodHandles.Lookup lookup)`	Returns a `ClassHierarchyResolver` that extracts class hierarchy information via classes accessible to a `MethodHandles.Lookup` with reflection.
`static ClassHierarchyResolver`	`ofResourceParsing(ClassLoader loader)`	Returns a `ClassHierarchyResolver` that extracts class hierarchy information from `class` files located by a class loader.
`static ClassHierarchyResolver`	`ofResourceParsing(Function<ClassDesc, InputStream> classStreamResolver)`	Returns a `ClassHierarchyResolver` that extracts class hierarchy information from `class` files returned by a mapping function.
`default ClassHierarchyResolver`	`orElse(ClassHierarchyResolver other)`	Chains this `ClassHierarchyResolver` with another to be consulted if this resolver does not know about the specified class.

Method Details

defaultResolver

static ClassHierarchyResolver defaultResolver()

Returns the default instance of ClassHierarchyResolver that gets ClassHierarchyResolver.ClassHierarchyInfo from system class loader with reflection. This default instance cannot load classes from other class loaders, such as the caller's class loader; it also loads the system classes if they are not yet loaded, which makes it unsuitable for instrumentation.

Returns:: the default instance of ClassHierarchyResolver that gets ClassHierarchyResolver.ClassHierarchyInfo from system class loader with reflection

getClassInfo

ClassHierarchyResolver.ClassHierarchyInfo getClassInfo(ClassDesc classDesc)

Returns the ClassHierarchyInfo for a given class name, or


null

if the name is unknown to the resolver.

This method is called by the Class-File API to obtain the hierarchy information of a class or interface; users should not call this method. The symbolic descriptor passed by the Class-File API always represents a class or interface.

Parameters:: classDesc - descriptor of the class
Returns:: the ClassHierarchyInfo for a given class name, or null if the name is unknown to the resolver
Throws:: IllegalArgumentException - if a class shouldn't be queried for hierarchy, such as when it is inaccessible

orElse

default ClassHierarchyResolver orElse(ClassHierarchyResolver other)

Chains this ClassHierarchyResolver with another to be consulted if this resolver does not know about the specified class.

Implementation Requirements:: The default implementation returns resolver implemented to query other resolver in case this resolver returns null.
Parameters:: other - the other resolver
Returns:: the chained resolver

cached

default ClassHierarchyResolver cached(Supplier<Map<ClassDesc, ClassHierarchyResolver.ClassHierarchyInfo>> cacheFactory)

Returns a ClassHierarchyResolver that caches class hierarchy information from this resolver. The returned resolver will not update if the query results from this resolver changed over time. The thread safety of the returned resolver depends on the thread safety of the map returned by the cacheFactory.

Implementation Requirements:: The default implementation returns a resolver holding an instance of the cache map provided by the cacheFactory. It looks up in the cache map, or if a class name has not yet been queried, queries this resolver and caches the result, including a null that indicates unknown class names. The cache map may refuse null keys and values.
Parameters:: cacheFactory - the factory for the cache
Returns:: a ClassHierarchyResolver that caches class hierarchy information from this resolver

cached

default ClassHierarchyResolver cached()

MethodHandles.Lookup lookup = ...;
ClassHierarchyResolver resolver = ClassHierarchyResolver.ofClassLoading(lookup).cached();

Implementation Requirements:: The default implementation calls cached(Supplier) with HashMap supplier as cacheFactory.
Returns:: a ClassHierarchyResolver that caches class hierarchy information from this resolver

ofResourceParsing

static ClassHierarchyResolver ofResourceParsing(Function<ClassDesc, InputStream> classStreamResolver)

Returns a ClassHierarchyResolver that extracts class hierarchy information from class files returned by a mapping function. The mapping function should return null if it cannot provide a class file for a class name. Any IOException from the provided input stream is rethrown as an UncheckedIOException in getClassInfo(ClassDesc).

Parameters:: classStreamResolver - maps class descriptors to class file input streams
Returns:: a ClassHierarchyResolver that extracts class hierarchy information from class files returned by a mapping function

ofResourceParsing

static ClassHierarchyResolver ofResourceParsing(ClassLoader loader)

Returns a ClassHierarchyResolver that extracts class hierarchy information from class files located by a class loader.

Parameters:: loader - the class loader, to find class files
Returns:: a ClassHierarchyResolver that extracts class hierarchy information from class files located by a class loader

of

static ClassHierarchyResolver of(Collection<ClassDesc> interfaces, Map<ClassDesc, ClassDesc> classToSuperClass)

Returns a ClassHierarchyResolver that extracts class hierarchy information from collections of class hierarchy metadata.

Parameters:: interfaces - a collection of classes known to be interfaces; classToSuperClass - a map from classes to their super classes
Returns:: a ClassHierarchyResolver that extracts class hierarchy information from collections of class hierarchy metadata

ofClassLoading

static ClassHierarchyResolver ofClassLoading(ClassLoader loader)

Returns a ClassHierarchyResolver that extracts class hierarchy information via classes loaded by a class loader with reflection.

Parameters:: loader - the class loader
Returns:: a ClassHierarchyResolver that extracts class hierarchy information via classes loaded by a class loader with reflection

ofClassLoading

static ClassHierarchyResolver ofClassLoading(MethodHandles.Lookup lookup)

Returns a ClassHierarchyResolver that extracts class hierarchy information via classes accessible to a MethodHandles.Lookup with reflection. If the class resolved is inaccessible to the given lookup, getClassInfo(ClassDesc) throws IllegalArgumentException instead of returning null.

Parameters:: lookup - the lookup, must be able to access classes to resolve
Returns:: a ClassHierarchyResolver that extracts class hierarchy information via classes accessible to a MethodHandles.Lookup with reflection

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