The ASF+SDF Meta-Environment is an interactive language development environment whose main application areas are definition and implementation of domain-specific languages, generation of program analysis and transformation tools, and production of software renovation tools. It uses conditional rewrite rules to define the dynamic semantics and other tool-oriented aspects of languages, so the effectiveness of the generated tools is critically dependent on the quality of the rewrite rule implementation. The ASF+SDF rewrite rule compiler generates C code, thus taking advantage of C's portability and the sophisticated optimization capabilities of current C compilers as well as avoiding potential abstract machine interface bottlenecks. It can handle large (10,000+ rule) language definitions and uses an efficient run-time storage scheme capable of handling large (1,000,000+ node) terms. Term storage uses maximal subterm sharing (hash-consing), which turns out to be more effective in the case of ASF+SDF than in Lisp or SML. Extensive benchmarking has shown the time and space performance of the generated code to be as good as or better than that of the best current rewrite rule and functional language compilers.

How do distributed applications exchange tree-like data structures? We introduce the abstract data type of Annotated Terms (ATerms), and discuss their design, implementation and application. A comprehensive procedural interface enables the creation and manipulation of ATerms in C or Java. The ATerm implementation is based on maximal subterm sharing and automatic garbage collection. A binary exchange format for the concise representation of ATerms (sharing preserved) allows the fast exchange of ATerms between applications. In a typical application – parse trees which contain considerable redundant information – less than two bytes are needed to represent a node in memory, and less than two bits are needed to represent it in binary format. The implementation of ATerms scales up to the manipulation of ATerms in the giga-byte range. Copyright © 2000 John Wiley & Sons, Ltd.