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Abstract - Modernizing legacy computer programs is challenging. This paper introduces a generalized framework for language transformation with three main elements. First, target languages are shielded from the transformation process by a collection of interfaces such as "create an if statement. " Transforming from Delphi is the same whether the target is Python, Java, C# or some other language that implements the interfaces. Second, the framework ensures synchronization between source language grammars and transformation tools, so changes to a grammar cannot be made without adjusting the impacted tools. This allows large scale transformation projects where both the grammars and the tools are under concurrent development. Third, source code generation is accomplished by adding output formatting annotations to the target language grammar.
Keywords: Legacy modernization, programming language transformation.
1 Introduction
By some estimates, the global number of computer programming languages is about 565 [1], or about 1,500 including variations [2]. Sources that list the most popular programming languages, such as [3], do not include the most pervasive business programming language, COBOL.
Many of these programming languages have been in use for many decades, such as COBOL, Fortran, Natural, RPG, PL/I and others. They suffer from a shortage of skilled software developers, and many applications were built without internet security in mind, potentially exposing vulnerabilities.
New languages are introduced on a regular basis and existing languages continue to evolve, but legacy languages rarely become extinct. This proliferation of languages and their variations is not handled well by existing tools, such as [4] that tend to focus on a few specific language pairs, such as COBOL to Java [5].
"There are still hundreds of billions of lines of COBOL code in use today by banks, insurance companies and other organizations, and COBOL is still used somewhere in a large proportion of all business transactions." [6]
"Some 23 of the world's top 25 retailers, 92 of the top 100 banks, and the 10 largest insurers all entrust core operations to Cobol programs running on IBM mainframes." [7]
This paper deals with three issues, and introduces a new framework to facilitate more efficient, effective software modernization. The first issue is choosing a target language. We recognize that transformation does not have to utilize all the features of each target...