Pluggable checking and inferencing of nonnull types for Java
Torbjörn Ekman, Computing Laboratory, Oxford University, United Kingdom
Görel Hedin, Department of Computer Science, Lund University, Sweden
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Abstract
We have implemented a non-null type checker for Java and a new non-null inferencing
algorithm for analyzing legacy code. The tools are modular extensions to the JastAdd
extensible Java compiler, illustrating how pluggable type systems can be achieved. The
resulting implementation is compact, less than 230 lines of code for the non-null checker
and 460 for the inferencer. Non-null checking is a local analysis with little effect on compilation
time. The inferencing algorithm is a whole-program analysis, yet it runs sufficiently
fast for practical use, less than 10 seconds for 100.000 lines of code. We ran our inferencer
on a large part of the JDK library, and could detect that around 70% of the dereferences,
and around 24% of the method return values, were guaranteed to be non-null.
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About the authors
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Torbjörn Ekman is a Research Fellow at the Computing Laboratory
at Oxford University, United Kingdom. He received a PhD from Lund
University in 2006. His research interests include extensible compilers,
scriptable refactorings, domain-specific languages, and aspect oriented
programming. He can be reached at torbjorn@comlab.ox.ac.uk |
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Görel Hedin is an Associate Professor of computer science at Lund
University, Sweden. She received a PhD from Lund University in 1992.
Her research interests include object-oriented languages and systems,
compilation technology, domain-specific languages, and agile methodologies.
She has served on the program committees of many international
workshops and conferences including ECOOP, CC, and LDTA.
She can be reached at gorel@cs.lth.se. |
Cite this document as follows: Torbjörn Ekman, Görel Hedin "Pluggable checking and inferencing
of non-null types for Java", in Journal of Object Technology, vol. 6, no. 9, Special Issue: TOOLS
EUROPE 2007, October 2007, pages 455–475, http://www.jot.fm/issues/issue_2007_10/paper23/
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