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APAREL-A PARSE-REQUEST LANGUAGE
RAND CORP SANTA MONICA CA
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The report describes APAREL, an extension to an algorithmic language PLI that provides the pattern-matching capabilities normally found only in such special-purpose languages as SNOBOL4 and TMG. This capability is provided through parse-requests stated in a BNF-like format. These parse-requests form their own programming language with special sequencing rules. Upon successfully completing a parse-request, an associated piece of PLI code is executed. This code has available for use, as normal PLI strings, the various pieces at all levels of the parse. It also has available as normal PLI variables, the information concerning which of the various alternatives were successful. Convenient facilities for multiple input-output streams, the initiation of sequences of parse-requests as a subroutine, and parse-time semantic checks are also included. APAREL has proven convenient not only as a general string manipulator but also in building a powerful SYNTAX and FUNCTION macro system, an algebraic language preprocessor debugging system, an on-line command parser, and a translator for Dataless Programming.
APPROVED FOR PUBLIC RELEASE