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Abstract : |
Yacc is well established in the compiler-compiler eld, but is beginning to show its age. Issues which were important when hardware resources were more scarce are now less critical. Precc is a new compiler-compiler tool that is much more versatile than yacc, whilst retaining e ciency of operation on modern computers. It copes with the context-dependent BNF grammar descriptions and higher order meta constructions that are naturally encountered in semi-formal concrete syntax speci cations, building fast and e cient in nite-lookahead tools in the form of ANSI-compliant C code. This paper provides a demonstration of this state-of-the-art compiler-compiler technology using the programming language occam as an example. The parsing of occam is particularly di cult compared to some programming languages since the indentation is an integral part of the language. However the precc tool allows a natural implementation of an occam parser that follows the syntax very closely. Keywords: Compiler-compiler, parsing, language grammars, occam, in nite lookahead, software tools., |
