Voting
Category
real language
Bookmarking
Language VAX SCAN
| Date: | 03/22/09 |
| Author: | Gerardo Cacciari |
| URL: | http://decnet.ipv7.net |
| Comments: | 0 |
| Info: | See source comments |
| Score: |  (2.91 in 11 votes) |
!++
!
! "VAX SCAN is a block-structured programming language in the VAX/VMS
! environment that is designed to build tools to manipulate text strings and
! text files. The primary applications for VAX SCAN are filters, translators,
! extractors/analyzers, and preprocessors. VAX SCAN is a compiled programming
! language that includes string operators for searching, comparing, extracting,
! and assigning character strings. A significant strength of VAX SCAN is in the
! pattern-matching constructs that permit matching of one or more complex
! patterns of text in the input data. VAX SCAN can then create replacement text
! for the original patterns that were found in the input."
!
! The above text was taken from "Guide to VAX SCAN", order number AA-FU79C-TE
! Copyright (C) 1985, 1986, 1989 Digital Equipment Corporation.
!
! VAX SCAN is a hybrid language, being both procedural and pattern-driven. Every
! program executes in a classic imperative fashion up until a START SCAN
! statement is encountered. On such occurence, the program turns into a
! pattern-driven engine and tries to match whichever START SCAN input it
! receives to the pattern specified on trigger MACRO declarations. Matching
! macro code can then replace or even drop matched input by means of the ANSWER
! statement which in turn can optionally trigger other macros, either nested or
! not. The matching process stops whenever a STOP SCAN statement or the end of
! input stream is reached. Then the program continues in procedural mode.
!
! To better demonstrate VAX SCAN pattern-matching capabilities and syntax, this
! sample uses a START SCAN input procedure providing always the same sentence,
! plus some macros for numbering, formatting, and overall control. Nevertheless
! it could have been designed as a simple procedural program.
!
! VAX SCAN adheres to the common calling standard of the VAX/VMS operating
! system. An object created by the VAX SCAN compiler can be successfully linked
! and used in a multilanguage environment, thus allowing for projects written in
! other languages to take advantage of the particular VAX SCAN capabilities.
!
! VAX SCAN was retired as a product in 1994 and was submitted to the DECUS
! Library in 1995. It can be found in the [.VAXSCAN] directory of Freeware V4.0.
!
! Made on a VAX, 22-MAR-2009
!
!--
MODULE ninetynine_beers IDENT 'V1.0';
CONSTANT SS$_NORMAL EXTERNAL INTEGER;
CONSTANT SCN$_ENDINPSTM EXTERNAL INTEGER;
DECLARE thats_all: BOOLEAN;
SET digit ( '0'..'9' );
TOKEN how_many { ['-'] digit... };
TOKEN bottles { [' '...] 'bottle' ['s'] };
TOKEN placeholder { '<' digit '>' };
TOKEN end_of_line { '/' };
MACRO take_one_beer TRIGGER { which,where: placeholder };
IF which = '<3>' THEN
ANSWER TRIGGER STRING ( 99 - where );
ELSE
ANSWER TRIGGER STRING ( 100 - where );
END IF;
END MACRO;
MACRO no_more_beer TRIGGER { count: how_many bottles };
CASE INTEGER ( count ) FROM 1 TO 99;
[ 1 ]: ANSWER count, ' bottle';
[ INRANGE ]: ANSWER count, ' bottles';
[ OUTRANGE ]: ANSWER 'no more bottles';
thats_all = TRUE;
END CASE;
END MACRO;
MACRO insert_carriage_returns TRIGGER { end_of_line };
ANSWER S'EOL';
END MACRO;
PROCEDURE generate_song ( len: REFERENCE INTEGER,
buf: REFERENCE POINTER TO
FIXED STRING (132) )
OF INTEGER;
DECLARE song_line: DYNAMIC STRING;
song_line = '<1> bottles of beer on the wall, ' &
'<2> bottles of beer./' &
'Take one down and pass it around, ' &
'<3> bottles of beer on the wall./';
len = LENGTH ( song_line );
buf-> = song_line;
IF thats_all THEN
RETURN SCN$_ENDINPSTM;
ELSE
RETURN SS$_NORMAL;
END IF;
END PROCEDURE;
PROCEDURE end_song ( );
WRITE 'No more bottles of beer on the wall, ' &
'no more bottles of beer.';
WRITE 'Go to the store and buy some more, ' &
'99 bottles of beer on the wall.';
END PROCEDURE;
PROCEDURE beer_song MAIN ( );
START SCAN
INPUT PROCEDURE generate_song
OUTPUT FILE 'SYS$OUTPUT';
CALL end_song;
END PROCEDURE;
END MODULE;
Download Source | Write Comment
Download Source | Write Comment
Add Comment
Please provide a value for the fields Name,
Comment and Security Code.
This is a gravatar-friendly website.
E-mail addresses will never be shown.
Enter your e-mail address to use your gravatar.
Please don't post large portions of code here! Use the form to submit new examples or updates instead!
Comments