Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: code transformation; Java programming language; compilers. Includes bibliographical references (p. 65-67).

Code transformation is widely used in programming. Most developers are familiar with using a preprocessor to perform syntactic transformations (symbol substitution and macro expansion). However, it is often necessary to perform more complex transformations using semantic information contained in the source code. In this thesis, we developed EXTRACT; a general-purpose code transformation language. Using EXTRACT, it is possible to specify, in a modular and extensible manner, a variety of transformations on Java code such as insertion, removal, and restructuring. In support of this, we also developed JPath, a path language for identifying portions of Java source code. Combined, these two technologies make it possible to identify source code that is to be transformed and then specify how that code is to be transformed. We evaluate our technology using three case studies: a type name qualifier which transforms Java class names into fully-qualified class names; a contract checker which enforces pre- and post-conditions across behavioral subtypes; and a code obfuscator which mangles the names of a class's methods and fields such that they cannot be understood by a human, without breaking the semantic content of the class.