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Language Processing Language, Read Function Definition

IP.com Disclosure Number: IPCOM000108247D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Related People

Hidalgo, DS: AUTHOR

Abstract

Disclosed is a feature of the LANGUAGE PROCESSING LANGUAGE (LPL) that supports the interfacing of a Lexical Scanner mechanically generated from an LDF (Language Definition File) with manually written code to form a translator for a formal language. In order to provide maximum flexibility, LPL allows the formal language designer to provide the name of a manually written input routine that can be called by the mechanically generated Lexical Scanner, therefore providing an abstract interface mechanism for character input to the formal language translator.

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Language Processing Language, Read Function Definition

       Disclosed is a feature of the LANGUAGE PROCESSING
LANGUAGE (LPL) that supports the interfacing of a Lexical Scanner
mechanically generated from an LDF (Language Definition File) with
manually written code to form a translator for a formal language. In
order to provide maximum flexibility, LPL allows the formal language
designer to provide the name of a manually written input routine that
can be called by the mechanically generated Lexical Scanner,
therefore providing an abstract interface mechanism for character
input to the formal language translator.

      Since the LPL default input routines expect their input source
to be a file handle, the LPL user must be given the means by which
the default input source can be replaced by a manually written input
source that may, instead, read input characters from a main memory
buffer. When the LPL user provides a manually written input routine,
the name of that routine must be made known to the an LPL translator
through the Language Definition File, so that the rest of the
mechanically generated code can reference the user-supplied name
instead of the default one.

      The syntactic construct described in this article provides the
means by which the LPL user specifies the name of the manually
written Read Function in the Lexical Section of the LDF. By using the
syntactic facility shown in the figure, the formal language designer
can interface a customized...