A program transformation is any operation that takes a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer program ...

and generates another program. In many cases the transformed program is required to be

semantically equivalent {{about, semantic equivalence of metadata, the concept in mathematical logic, Logical equivalence In computer metadata, semantic equivalence is a declaration that two data elements from different vocabularies contain data that has similar meaning. ...

to the original, relative to a particular formal semantics and in fewer cases the transformations result in programs that semantically differ from the original in predictable ways. While the transformations can be performed manually, it is often more practical to use a program transformation system that applies specifications of the required transformations. Program transformations may be specified as automated procedures that modify compiler data structures (e.g.

abstract syntax tree In computer science, an abstract syntax tree (AST), or just syntax tree, is a tree representation of the abstract syntactic structure of text (often source code) written in a formal language. Each node of the tree denotes a construct occurring ...

s) representing the program text, or may be specified more conveniently using patterns or templates representing parameterized source code fragments. A practical requirement for

source code In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the wo ...

transformation systems is that they be able to effectively process programs written in a

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...

. This usually requires integration of a full front-end for the programming language of interest, including source code

parsing Parsing, syntax analysis, or syntactic analysis is the process of analyzing a string of symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar. The term ''parsing'' comes from L ...

, building internal program representations of code structures, the meaning of program symbols, useful static analyses, and regeneration of valid source code from transformed program representations. The problem of building and integrating adequate front ends for conventional languages (

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...

C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...

PHP PHP is a general-purpose scripting language geared toward web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995. The PHP reference implementation is now produced by The PHP Group. ...

etc.) may be of equal difficulty as building the program transformation system itself because of the complexity of such languages. To be widely useful, a transformation system must be able to handle many target programming languages, and must provide some means of specifying such front ends. A generalisation of semantic equivalence is the notion of program refinement: one program is a refinement of another if it terminates on all the initial states for which the original program terminates, and for each such state it is guaranteed to terminate in a possible final state for the original program. In other words, a refinement of a program is ''more defined'' and ''more deterministic'' than the original program. If two programs are refinements of each other, then the programs are equivalent.

References

External links

The Program transformation Wiki

Papers on program transformation theory and practice

Transformation Technology Bibliography
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DMS Software Reengineering Toolkit The DMS Software Reengineering Toolkit is a proprietary set of program transformation tools available for automating custom source program analysis, modification, translation or generation of software systems for arbitrary mixtures of source langu ...

: A Program Transformation System for DSLs and modern (C++, Java, ...) and legacy (COBOL, RPG) computer languages
Spoon
A library to analyze, transform, rewrite, and transpile Java source code. It parses source files to build a well-designed AST with powerful analysis and transformation API.
JavaParser
The JavaParser library provides you with an Abstract Syntax Tree of your Java code. The AST structure then allows you to work with your Java code in an easy programmatic way.. Metaprogramming {{prog-lang-stub

See also

References

External links