418 lines
8.9 KiB
Groff
418 lines
8.9 KiB
Groff
.TH A68S 1 "Version 2.2a Jul 15 1987"
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.SH NAME
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a68s, indent68 \- ALGOL 68S compiler
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.SH SYNOPSIS
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.B a68s
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.IR arguments
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.PP
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.BR ack (etc)
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.IR arguments
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.PP
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.B indent68
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.IR filename
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.SH DESCRIPTION
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ALGOL68S source files should have the extension `.8'.
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.LP
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.I a68s
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accepts the same flags and conventions as
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.I ack
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(q.v.). Thus 'a68s -o
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.I prog
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.IR prog .8'
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will compile the source in file
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.IR prog .8,
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producing executable binary in
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.IR prog
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and a program listing in
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.IR prog .8.lst.
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.IP
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WARNING. Although the
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.I ack
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system will have produced the usual intermediate files with suffices .k, .m and .o
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(and you may even stop the compilation at these intermediate stages if you wish),
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do not try to include other files (whether ending in .8 or in .anything else)
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as the present compiler has no facilities for separate or
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mixed-language compilation. Hopefully, this will be rectified some day.
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.IP
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If the source file starts with a digit, it will be assumed that every line
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starts with a line number (but the sequencing is not checked). These line
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numbers will then appear on the .lst file,
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and will be used in diagnostic messages.
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.LP
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`indent68'
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will read the given
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.IR filename
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which is expected to be an ALGOL 68 program.
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A correctly indented form of the same program is sent to the standard output.
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Note that, unlike more elaborate prettyprinters, it confines itself to
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inserting or removing blanks at the beginnings of lines (although it does
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insist upon a space after each
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.BR go-on-symbol
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.RI ( ; )
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and after a starting
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.BR brief-comment-symbol
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.RI ( # ).
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It is particularly intended for indenting programs that place their
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.BR go-on-symbols
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at the start of the line (i.e. before the next
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.BR statement
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rather than after the last one), but it will produce an acceptable
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indentation of any program.
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.SH LANGUAGE
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The language implemented is the official sublanguage of ALGOL 68 (usually
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known as ALGOL 68S), as defined in [1] (see also Appendix 4 of [2]). The only
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features of ALGOL 68S not implemented are binary transput and
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.IR "stand back channel" .
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On the other hand, in addition to the official features of ALGOL 68S, the
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.B heap-generator
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(but not the
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.BR sample-heap-generator )
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is implemented. WARNING. The garbage collector is of the "access count"
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variety, and it will therefore not collect circular lists which may become
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inaccessible (however, circular lists constructed from
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.BR local-generators
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are collected correctly on range exit).
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.PP
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The hardware representation is the official one ([3]), except for the absence
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of reserved-word stropping.
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.PP
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The principal limitations with respect to full ALGOL 68 are therefore as
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follows.
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.TP
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1.
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All defining occurences must precede their applied occurrences (except for
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.BR labels ).
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.TP
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2.
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No
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.IR UNION s
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or
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.BR conformity-clauses
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or
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.IR EMPTY .
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.TP
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3.
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No
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.IR FLEX
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(but
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.IR STRING
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is OK) and no
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.BR vacuums .
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.TP
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4.
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Structures may not contain arrays, and
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.B 'row-of-row-of'
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modes are not permitted (as opposed to
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.B 'row-row-of'
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modes which are OK).
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.TP
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5.
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No
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.BR parallel-clauses
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or
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.BR void-collateral-clauses
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(but
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.BR displays
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are OK).
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.TP
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6.
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No formatted transput.
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.TP
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7.
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.IR GOTO
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(or
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.IR GO
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.IR TO )
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may not be omitted in a
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.BR jump .
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.TP
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8.
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No procedured jumps.
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.TP
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9.
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Existing
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.BR operators
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(notably the
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.BR standard-prelude
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ones) may not be redefined (nor may their priorities be altered).
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.TP
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10.
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Restricted
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.BR standard-prelude .
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The following is a complete list of the standard
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.BR indicators
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available.
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.IP
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.IR "maxint, maxreal, smallreal, pi, maxabschar"
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.br
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.IR "sqrt, exp, ln, nextrandom, random"
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.br
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.IR "cos, arccos, sin, arcsin, tan, arctan"
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.br
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.IR "bitspack, bytespack"
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.br
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.IR "standin channel, standout channel, "
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.IR "standin, standout"
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.br
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.IR "open, establish, associate, close"
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.br
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.IR "put, print, write, get, read"
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.br
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.IR "space, newline, newpage, set, reset"
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.br
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.IR "on logical file end, "
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.IR "on physical file end, on page end"
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.br
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.IR "on line end, maketerm"
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.br
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.IR "chan, char number, line number, page number"
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.br
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.IR "whole, fixed, float"
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.br
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.IR "stop"
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.br
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.IR "REPR, BIN, ENTIER, ROUND, ODD, SIGN, ABS, "
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.IR "LWB, UPB"
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.br
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.IR "RE, IM, ARG, CONJ"
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.br
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.IR "NOT, AND, OR, OVER, MOD, SHL, SHR, I"
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.br
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.IR "+ , - , * , / , % , %* , ^ , ** , +*"
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.br
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.IR "EQ, NE, GE, GT, LE, LT"
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.br
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.IR "= , /= , >= , > , <= , <"
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.br
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.IR "PLUSAB, MINUSAB, TIMESAB, DIVAB, OVERAB, "
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.IR "MODAB, PLUSTO"
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.br
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.IR "+:= , -:= , *:= , /:= , %:= , %*:= , +=:"
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.PP
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.SH PRAGMATS
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The following
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.BR pragmats
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are provided:
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.PD 0
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.IP
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.TP 17
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.IR "PR UPPER PR"
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(enable upper-case stropping)
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.TP
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.IR "PR POINT PR"
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(disable upper-case stropping)
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.br
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Note that point stropping always works (with either case of word).
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The essential difference with upper-case stropping is that upper-case words are
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assumed to be stropped whether a point is present or not. Thus it is always
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possible to write
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.IR ".PR UPPER .PR" ,
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which will be recognised whatever the previous stropping regime.
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.TP
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.IR "PR LIST PR"
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(turn listing on)
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.TP
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.IR "PR NOLIST PR"
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(turn listing off)
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.br
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listings are sent to the .lst file.
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.TP
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.IR "PR PAGE PR"
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(start a new page on the .lst file)
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.TP
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.IR "PR WARN PR"
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(include compile-time warning messages)
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.TP
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.IR "PR NOWARN PR"
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(omit compile-time warning messages)
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.PD
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.PP
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The words within a
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.BR pragmat
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may be in either upper or lower case, and one
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.BR pragmat
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may contain several such words, separated by commas, as in the following
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example which shows the default states.
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.IP
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.IR "PR UPPER, LIST, WARN PR"
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.SH DIAGNOSTICS
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The compile-time error messages are self-explanatory.
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They can be divided into 3 categories:
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.RS
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.br
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Lexcical errors (the offending lexeme is simply ignored)
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.br
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Syntactic errors (text up to the next
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.RI ' ; '
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or
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.RI ' ) ',
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etc. is ignored)
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.br
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Semantic errors.
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.RE
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.br
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After the first syntactic error, further checking for semantic errors is
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inhibited.
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.LP
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On the .lst file,
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a row of "=" indicates parts of the text that have been ignored.
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A "1" under a particular symbol indicates the point where an error was detected
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(a "2" indicates that 2 errors were found there). An "S" ("C", "P") is printed
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in the margin wherever a new line of source text starts within a
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.BR string-denotation
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.RB ( comment ,
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.BR pragmat ).
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Thus mismatched delimiters for these things will readily stand out.
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.LP
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A run-time error message is followed by a print out of the stack, giving the
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line number in each active procedure. For each procedure, the active
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.BR ranges
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are printed, starting from the innermost and finishing with the outermost.
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Within each range, the values ascribed to all identifiers and operators
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(apart from some manifest values) are listed in the order in which they were
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declared in the
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.BR range .
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Names are printed as a "#" followed by a number. Not much significance should
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be attached to these numbers except to note that the same name will always be
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printed as the same number. At the end of each range, the value of any active
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loop counter
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.RI ( .FOR )
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together with its increment and target
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.RI ( .BY
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and
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.IR .TO )
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will be printed.
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.SH ENVIRONMENT ENQUIRIES
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The following figures apply primarily to machines with a wordsize of 32 bits.
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Figures for 16-bit machines are given in parentheses where appropriate.
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.DS
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.IP
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.IR "max int"
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= 2147483647 (32767)
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.br
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.IR "max real"
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= 1.701411733192600E+38 (on the VAX)
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.br
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.IR "small real"
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= 3.469446951953614E-18 (on the VAX)
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.br
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.IR "bits width"
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= 32 (16)
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.br
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.IR "bytes width"
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= 4 (2)
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.br
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.IR "max abs char"
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= 127
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.br
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.IR "null character"
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= NULL
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.RI ( REPR(0) )
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.br
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.IR "int lengths" ,
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.IR "int shorths" ,
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.IR "real lengths" ,
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.IR "real shorths" ,
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.br
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.IR "bits lengths" ,
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.IR "bits shorths" ,
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.br
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.IR "bytes lengths" ,
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.IR "bytes shorths"
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.br
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all = 1
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.br
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.IR "int width"
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= 10 (5)
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.br
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.IR "real width"
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= 16
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.br
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.IR "exp width"
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= 3
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.br
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.IR "error character"
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= *
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.br
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.IR "flip"
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= T
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.br
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.IR "flop"
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= F
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.br
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On
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.IR "stand in channel" :
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.RS
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.br
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.RS
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.IR "get possible" ,
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.IR "reset possible"
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.RE
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.br
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On
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.IR "stand out channel" :
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.br
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.RS
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.IR "put possible" ,
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.IR "reset possible" ,
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.IR "compressible" ,
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.br
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.IR "estab possible"
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.RE
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.br
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On associated files:
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.br
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.RS
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.IR "get possible" ,
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.IR "put possiblle" ,
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.IR "set possible" ,
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.br
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.IR "reset possible"
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.DE
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.SH FILES
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.ta \w'/EMDISTR/lib/a68/a68s.out 'u
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.PD 0
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~em/bin/a68s
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.br
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~em/bin/indent68
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.br
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~em/lib/em_a68s?? - the compiler
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.br
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~em/lib/em_a68s_init?? - compiler initialization
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.br
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~em/mach/lib/MACH/tail_a68s - runtime library
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.br
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~em/lang/a68s/a68s.1 - this manual
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.SH BUGS
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There is no
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.IR REAL
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arithmetic on the SUNs.
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.LP
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Excessive static nesting (especially with
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.IR ELIF s
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or
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.IR CASE s
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with many alternatives) can exceed certain stack spaces in the compiler.
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.LP
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Dimensions of arrays are limited to 8.
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.LP
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.SH SEE ALSO
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.TP
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ack(I)
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.SH REFERENCES
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.TP
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[1]
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P. G. Hibbard,
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.IR "A Sublanguage of ALGOL 68" ,
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SIGPLAN Notices Vol. 12, No. 5, May 1977.
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.TP
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[2]
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C. H. Lindsey and S. G. van der Meulen,
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.IR "Informal Introduction to ALGOL 68" ,
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North Holland.
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.TP
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[3]
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Wilfred J. Hansen and Hendrik Boom,
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.IR "The Report on the Standard Hardware"
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.IR "Representation for ALGOL 68" ,
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SIGPLAN Notices Vol. 12, No. 5, May 1977.
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