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The open-source lexical analyzer "flex"
and the open-source parser-generator "bison" were chosen to generate
a table-driven interpreter for the test command language, rather than
hard-code an ad-hoc parser.
The textual specification for the test command language was analyzed
and re-expressed in a formal Backus-Naur Form (BNF) notation, with small modifications
to insure that it was a context-free grammar.
This BNF grammar was used to configure flex and bison
to generate the table-driven interpreter. Action routines and
flex/bison coding were done in the C language. This flexible approach allowed
for easy changes to the language as the initial specification evolved.
Because portable, open-source tools were used, it was possible to perform
the development and initial testing in a Linux environment, and later move
to the target MS Windows platform for integration with no code changes.
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