Using Java Reflection to Automate Extension Language Parsing

An extension language is an interpreted programming language designed to be embedded in a domain-specific framework. The addition of domain-specific primitive operations to an embedded extension language transforms that vanilla extension language into a domain-specific language. The LUxWORKS processor simulator and debugger from Lucent uses Tcl as its extension language. After an overview of extension language embedding and LUxWORKS experience, this paper looks at using Java reflection and related mechanisms to solve three limitations in extension language - domain framework interaction. The three limitations are gradual accumulation of ad hoc interface code connecting an extension language to a domain framework, over-coupling of a domain framework to a specific extension language, and inefficient command interpretation.

Java reflection consists of a set of programming interfaces through which a software module in a Java system can discover the structure of classes, methods and their associations in the system. Java reflection and a naming convention for primitive domain operations eliminate ad hoc interface code by supporting recursive inspection of a domain command interface and translation of extension language objects into domain objects. Java reflection, name-based dynamic class loading, and a language-neutral extension language abstraction eliminate language over-coupling by transforming the specific extension language into a run-time parameter. Java reflection and command objects eliminate inefficiency by bypassing the extension language interpreter for stereotyped commands. Overall, Java reflection helps to eliminate these limitations by supporting reorganization and elimination of hand-written code, and by streamlining interpretation.