package opalj
OPAL is a Scala-based framework for the static analysis, manipulation and creation of Java bytecode. OPAL is designed with performance, scalability and adaptability in mind.
Its main components are:
- a library (
Common
) which provides generally useful data-structures and algorithms for static analyses. - a framework for implementing lattice based static analyses (
Static Analysis Infrastructure
) - a framework for parsing Java bytecode (Bytecode Infrastructure
) that can be used to create arbitrary representations.
- a library to create a one-to-one in-memory representation of Java bytecode
(
Bytecode Disassembler
). - a library to create a representation of Java bytecode that facilitates writing
simple static analyses (
Bytecode Representation
- org.opalj.br). - a scalable, easily customizable framework for the abstract interpretation of
Java bytecode (
Abstract Interpretation Framework
- org.opalj.ai). - a library to extract dependencies between code elements and to facilitate checking architecture definitions.
- a library for the lightweight manipulation and creation of Java bytecode (Bytecode Assembler).
General Design Decisions
Thread Safety
Unless explicitly noted, OPAL is thread safe. I.e., the classes defined by OPAL can be considered to be thread safe unless otherwise stated. (For example, it is possible to read and process class files concurrently without explicit synchronization on the client side.)
No null
Values
Unless explicitly noted, OPAL does not null
values
I.e., fields that are accessible will never contain null
values and methods will
never return null
. If a method accepts null
as a value for a parameter or
returns a null
value it is always explicitly documented.
In general, the behavior of methods that are passed null
values is undefined unless
explicitly documented.
No Typecasts for Collections
For efficiency reasons, OPAL sometimes uses mutable data-structures internally.
After construction time, these data-structures are generally represented using
their generic interfaces (e.g., scala.collection.{Set,Map}
). However, a downcast
(e.g., to add/remove elements) is always forbidden as it would effectively prevent
thread-safety.
Assertions
OPAL makes heavy use of Scala's Assertion Facility to facilitate writing correct
code. Hence, for production builds (after thorough testing(!)) it is
highly recommend to build OPAL again using -Xdisable-assertions
.
- Source
- package.scala
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Package Members
- package ai
Implementation of an abstract interpretation (ai) framework – also referred to as OPAL.
Implementation of an abstract interpretation (ai) framework – also referred to as OPAL.
Please note that OPAL/the abstract interpreter just refers to the classes and traits defined in this package (
ai
). The classes and traits defined in the sub-packages (in particular indomain
) are not considered to be part of the core of OPAL/the abstract interpreter.- Note
This framework assumes that the analyzed bytecode is valid; i.e., the JVM's bytecode verifier would be able to verify the code. Furthermore, load-time errors (e.g.,
LinkageErrors
) are – by default – completely ignored to facilitate the analysis of parts of a project. In general, if the presented bytecode is not valid, the result is undefined (i.e., OPAL may report meaningless results, crash or run indefinitely).- See also
org.opalj.ai.AI - Implements the abstract interpreter that processes a methods code and uses an analysis-specific domain to perform the abstract computations.
org.opalj.ai.Domain - The core interface between the abstract interpretation framework and the abstract domain that is responsible for performing the abstract computations.
- package av
- package ba
Implementation of an eDSL for creating Java bytecode.
Implementation of an eDSL for creating Java bytecode. The eDSL is designed to facilitate the creation of correct class files; i.e., whenever possible it tries to fill wholes. For example, when an interface is specified the library automatically ensures that the super class type is (initially) set to
java.lang.Object
as required by the JVM specification.This package in particular provides functionality to convert org.opalj.br classes to org.opalj.da classes.
- package bc
- package bi
Implementation of a library for parsing Java bytecode and creating arbitrary representations.
Implementation of a library for parsing Java bytecode and creating arbitrary representations.
OPAL's primary representation of Java byte code is the org.opalj.br representation which is defined in the respective package. A second representation that represents bytecode one-by-one is found in the org.opalj.da package.
This Package
Common constants and type definitions used across OPAL.
- package br
In this representation of Java bytecode references to a Java class file's constant pool and to attributes are replaced by direct references to the corresponding constant pool entries.
In this representation of Java bytecode references to a Java class file's constant pool and to attributes are replaced by direct references to the corresponding constant pool entries. This facilitates developing analyses and fosters comprehension.
Based on the fact that indirect references to constant pool entries are resolved and replaced by direct references this representation is called the resolved representation.
This representation of Java bytecode is considered as OPAL's standard representation for writing Scala based analyses. This representation is engineered such that it facilitates writing analyses that use pattern matching.
- package bytecode
Defines functionality commonly useful when processing Java bytecode.
- package collection
OPAL's collection library is primarily designed with high performance in mind.
Design Goals
OPAL's collection library is primarily designed with high performance in mind. I.e., all methods provided by the collection library are reasonably optimized. However, providing a very large number of methods is a non-goal. Overall, OPAL's collection library provides:
- collection classes that are manually specialized for primitive data-types.
- collection classes that are optimized for particularly small collections of values.
- collection classes that target special use cases such as using a collection as a workset/worklist.
- collection classes that offer special methods that minimize the number of steps when compared to general purpose methods.
Integration With Scala's Collection Library
Hence, OPAL's collection library complements Scala's default collection library and is not intended to replace it. Integration with Scala's collection library is primarily provided by means of iterators (OPAL's
Iterator
s inherit from Scala'sIterator
s). Furthermore the companion object of each of OPAL's collection classes generally provides factory methods that facilitate the conversion from Scala collection classes to OPAL collection classes.Status
The collection library is growing. Nevertheless, the existing classes are production ready.
- package concurrent
Common constants, factory methods and objects used throughout OPAL when performing concurrent computations.
- package constraints
Defines helper values and methods related to modeling constraints.
- package control
Defines common control abstractions.
- package da
Defines convenience methods related to representing certain class file elements.
- package de
Functionality to extract dependencies between class files.
- package fpcf
The fixpoint computations framework (
fpcf
) is a general framework to perform fixpoint computations of properties ordered by a lattice.The fixpoint computations framework (
fpcf
) is a general framework to perform fixpoint computations of properties ordered by a lattice. The framework in particular supports the development of static analyses.In this case, the fixpoint computations/static analyses are generally operating on the code and need to be executed until the computations have reached their (implicit) fixpoint. The fixpoint framework explicitly supports resolving cyclic dependencies/computations. A prime use case of the fixpoint framework are all those analyses that may interact with the results of other analyses.
For example, an analysis that analyzes all field write accesses to determine if we can refine a field's type (for the purpose of the analysis) can (reuse) the information about the return types of methods, which however may depend on the refined field types.
The framework is generic enough to facilitate the implementation of anytime algorithms.
- Note
This framework assumes that all data-structures (e.g., dependee lists and properties) that are passed to the framework are effectively immutable! (Effectively immutable means that a data structure is never updated after it was passed to the framework.)
,The dependency relation is as follows: “A depends on B”
,===
“A is the depender, B is the dependee”.===
“B is depended on by A”The very core of the framework is described in: Lattice Based Modularization of Static Analyses
- package graphs
This package defines graph algorithms as well as factory methods to describe and compute graphs and trees.
This package defines graph algorithms as well as factory methods to describe and compute graphs and trees.
This package supports the following types of graphs:
- graphs based on explicitly connected nodes (org.opalj.graphs.Node),
- graphs where the relationship between the nodes are encoded externally (org.opalj.graphs.Graph).
- package io
Various io-related helper methods and classes.
Various io-related helper methods and classes.
- Note
The implementations of the methods rely on Java NIO(2).
- package issues
Defines implicit conversions to wrap some types of analyses such that they generate results of type org.opalj.br.analyses.ReportableAnalysisResult.
- package log
- package tac
Common definitions related to the definition and processing of three address code.
- package util
Utility methods.
- package value
Provides a general query interface for querying a value's properties.
Type Members
- sealed trait Answer extends AnyRef
- final type BinaryArithmeticOperator = opalj.BinaryArithmeticOperators.Value
The type of the predefined binary arithmetic operators.
The type of the predefined binary arithmetic operators.
See org.opalj.BinaryArithmeticOperators for the list of all defined operators.
- sealed trait NoResult extends Result[Nothing]
- final type RelationalOperator = opalj.RelationalOperators.Value
The type of the predefined relational operators.
The type of the predefined relational operators.
See org.opalj.RelationalOperators for the list of all defined operators.
- sealed trait Result[+T] extends Serializable
Represents the result of some expression that either (a) succeeded and encapsulates some value, or (b) finished, but has no value - because it was not possible to compute a value using the given/available information - or (c) that failed.
Represents the result of some expression that either (a) succeeded and encapsulates some value, or (b) finished, but has no value - because it was not possible to compute a value using the given/available information - or (c) that failed.
- Note
Depending on the context, it may be useful to distinguish between a success that returns an empty collection and a success that has no further information.
- case class Success[+T](value: T) extends Result[T] with Product with Serializable
The computation succeeded and produced a result.
The computation succeeded and produced a result. In general
- final type UByte = Int
A simple type alias that can be used to communicate that the respective value will/should only take values in the range of unsigned byte values.
- final type UShort = Int
A simple type alias that can be used to communicate that the respective value will/should only take values in the range of unsigned short values.
- final type UnaryArithmeticOperator = opalj.UnaryArithmeticOperators.Value
The type of the predefined unary arithmetic operators.
The type of the predefined unary arithmetic operators.
See org.opalj.UnaryArithmeticOperators for the list of all defined operators.
Value Members
- final val BaseConfig: Config
- final val NotRequired: (Any) => Nothing
A method that takes an arbitrary parameter and throws an
UnknownError
that states that an implementation was not required. - final val WEBPAGE: String("https://www.opal-project.de")
The URL of the webpage of the opal project.
- def check(condition: Boolean, message: => String): Unit
Non-elidable version of
assert
; only to be used in a guarded context. - def check(condition: Boolean): Unit
Non-elidable version of
assert
; only to be used in a guarded context. - final def i2lBitMask(value: Int): Long
Converts a given bit mask using an
Int
value into a bit mask using aLong
value.Converts a given bit mask using an
Int
value into a bit mask using aLong
value.- Annotations
- @inline()
- Note
This is not the same as a type conversion as the "sign-bit" is not treated as such. I.e., after conversion of the
Int
value -1, theLong
value will be4294967295
(both have the same bit mask:11111111111111111111111111111111
); in other words, the long's sign bit will still be0
.
- final def notRequired(): Nothing
- def partitionByType[T <: AnyRef, X <: AnyRef](data: ArraySeq[T], clazz: Class[X]): (ArraySeq[X], ArraySeq[T])
- object Answer
Factory for
Answer
s. - object BinaryArithmeticOperators extends Enumeration
All standard binary arithmetic operators defined in the Java Virtual Machine/Java Language Specification.
All standard binary arithmetic operators defined in the Java Virtual Machine/Java Language Specification.
- Note
The type of a value of this enumeration is org.opalj.BinaryArithmeticOperator.
- case object Empty extends NoResult with Product with Serializable
The computation finished, but did no produce any results or the result was filtered.
The computation finished, but did no produce any results or the result was filtered.
- Note
The precise semantics of succeeded without results is dependent on the semantics of the concrete computation and needs to be defined per use case.
- case object Failure extends NoResult with Product with Serializable
The computation failed because of missing/incomplete information.
The computation failed because of missing/incomplete information.
- Note
The precise semantics of the computation failed is dependent on the semantics of the concrete computation and needs to be defined per use case.
- case object No extends Answer with Product with Serializable
Represents the answer to a question where the answer is
No
. - object NoResult extends Serializable
- object RelationalOperators extends Enumeration
The standard relational operators defined in the Java Virtual Machine Specification/ Java Language Specification.
- object Result extends Serializable
Defines factory methods for Result objects.
- object UByte
Properties of unsigned byte values.
- object UShort
Properties of unsigned short values.
- object UnaryArithmeticOperators extends Enumeration
All standard unary arithmetic operators defined in the Java Virtual Machine/Java Language Specification.
All standard unary arithmetic operators defined in the Java Virtual Machine/Java Language Specification.
- Note
The type of a value of this enumeration is org.opalj.UnaryArithmeticOperator.
- case object Unknown extends Answer with Product with Serializable
Represents the answer to a question where the answer is either
Unknown
or is actually both; that is,Yes
andNo
. - case object Yes extends Answer with Product with Serializable
Represents the answer to a question where the answer is
Yes
.