Abstract syntax trees are a very common data-structure in language related tools. For example compilers, interpreters, documentation generators, and syntax-directed editors use them extensively to extract, transform, store and produce information that is key to their functionality. We present a Java back-end for ApiGen, a tool that generates implementations of abstract syntax trees. The generated code is characterized by strong typing combined with a generic interface and maximal sub-term sharing for memory efficiency and fast equality checking. The goal of this tool is to obtain safe and more efficient programming interfaces for abstract syntax trees. The contribution of this work is the combination of generating a strongly typed data-structure with maximal sub-term sharing in Java. Practical experience shows that this approach is beneficial for extremely large as well as smaller data types.
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