User defined pipe and redirection operators/ALGOL 68
Iterator_pipe_operators
File: Iterator_pipe_operators.a68 <lang algol68>MODE
PAGEIN = PAGE, PAGEAPPEND = REF PAGE, PAGEOUT = REF PAGE;
MODE
MOID = VOID, YIELDLINE = PROC(LINE)VOID, GENLINE = PROC(YIELDLINE)VOID, FILTER = PROC(GENLINE)GENLINE, # the classic shell filter # MANYTOONE = PROC([]GENLINE)GENLINE; # eg cat, as in con[cat]enate #
PRIO =: = 5, << = 5, >> = 5;
OP < = (FILTER filter, PAGEIN page)GENLINE: filter(READ page),
< = (MANYTOONE cmd, PAGEIN page)GENLINE: cmd(READ page), << = (FILTER filter, PAGEIN page)GENLINE: filter(READ page), > = (GENLINE gen, PAGEOUT page)VOID: gen(WRITE page), >> = (GENLINE gen, PAGEAPPEND page)VOID: gen(APPEND page), =: = (GENLINE gen, FILTER filter)GENLINE: filter(gen), =: = (GENLINE gen, MANYTOONE cmd)GENLINE: cmd(gen);</lang>
Iterator_pipe_utilities
File: Iterator_pipe_utilities.a68 <lang algol68>PROC cat yield line = ([]GENLINE argv, YIELDLINE yield)VOID:
FOR gen line FROM LWB argv TO UPB argv DO argv[gen line](yield) OD;
PROC cat = ([]GENLINE argv)GENLINE:
cat yield line(argv, );
PROC tee yield line = (GENLINE gen, []YIELDLINE args yield, YIELDLINE yield)VOID: (
# FOR LINE line IN # gen(#) DO #
## (LINE line)VOID: (
yield(line);
FOR outn FROM LWB args yield TO UPB args yield DO
args yield[outn](line)
OD
# OD #))
);
PROC tee filter = (GENLINE gen, []YIELDLINE args yield)GENLINE:
tee yield line(gen, args yield, );
PROC tee = ([]YIELDLINE args filter)FILTER:
tee filter(, args filter);
PROC grep yield line = (STRING pattern, []GENLINE argv, YIELDLINE yield)VOID:
- FOR LINE line IN # cat(argv)(
- (LINE line)VOID:
IF string in string(pattern, NIL, line) THEN yield(line) FI
- OD #);
PROC grep = (STRING pattern, []GENLINE argv)GENLINE:
grep yield line(pattern, cat(argv), );
PROC uniq yield line = (GENLINE arg, YIELDLINE yield)VOID:(
UNION(VOID, LINE)prev := EMPTY;
- FOR LINE this IN # arg(#) DO #
- (LINE this)VOID:
CASE prev IN
(LINE case prev): IF NOT(case prev=this) THEN prev := this; yield(this) FI,
(VOID): (prev := this; yield(this))
ESAC
- OD #)
);
PROC uniq = (GENLINE arg)GENLINE:
uniq yield line(arg, );
MODE SORTSTRUCT = LINE; PR READ "prelude/sort.a68" PR
PROC sort yield line = ([]GENLINE args, YIELDLINE yield)VOID:(
PAGE out; cat(args) > out; in place shell sort(out); FOR elem FROM LWB out TO UPB out DO yield(out[elem]) OD
);
PROC sort = (GENLINE arg)GENLINE:
sort yield line(arg, );
PROC head yield line= (INT n, []GENLINE args, YIELDLINE yield)VOID:
FOR argn FROM LWB args TO UPB args DO
GENLINE line gen = args[argn];
INT count := 0;
# FOR LINE line IN # cat(line gen)(#) DO #
## (LINE line)VOID:(
count+:=1;
yield(line);
IF count = n THEN done FI
# OD #));
done: SKIP
OD;
PROC head = (INT n, []GENLINE args)GENLINE:
head yield line(n, args, );
PROC tail yield line = (INT n, []GENLINE args, YIELDLINE yield)VOID:
FOR argn FROM LWB args TO UPB args DO
GENLINE gen line = args[argn];
[0:n-1]LINE window; INT window end := -1;
# FOR LINE line IN # gen line(#) DO #
## (LINE line)VOID:
window[(window end+:=1) MOD n]:= line
# OD #);
FOR line FROM window end-n+1 TO window end DO
IF line>=0 THEN
yield(window[line MOD n])
FI
OD
OD;
PROC tail = (INT n, []GENLINE args)GENLINE:
tail yield line(n, args, );
- Define an optional monadic OPerator #
OP TAIL = (INT n)MANYTOONE: tail(n, );</lang>
Iterator_pipe_page
File: Iterator_pipe_page.a68 <lang algol68># Define the required OPerators for pipes of user-defined type "PAGE" # OP +:= = (PAGEOUT page, LINE line)MOID:(
[LWB page:UPB page+1]LINE out; out[:UPB page]:=page; out[UPB out]:=line; page := out
);
PROC page read line = (PAGEIN page, YIELDLINE yield)VOID:
FOR elem FROM LWB page TO UPB page DO yield(page[elem]) OD;
OP READ = (PAGEIN page)GENLINE:
page read line(page, );
PROC page append line = (PAGEAPPEND page, LINE line)VOID:
page +:= line;
OP WRITE = (PAGEOUT page)YIELDLINE: (
page := LINE(); page append line(page, )
);
OP APPEND = (PAGEAPPEND page)YIELDLINE:
page append line(page, );</lang>
test_Iterator_pipe_page
File: test_Iterator_pipe_page.a68 <lang algol68>#!/usr/local/bin/a68g --script #
- First define what kind of record (aka LINE) we are piping and filtering #
FORMAT line fmt = $xg$; MODE
LINE = STRING, PAGE = FLEX[0]LINE, BOOK = FLEX[0]PAGE;
PR READ "Iterator_pipe_page.a68" PR PR READ "Iterator_pipe_operators.a68" PR PR READ "Iterator_pipe_utilities.a68" PR
PAGE list of computer scientists = (
"Wil van der Aalst - business process management, process mining, Petri nets", "Hal Abelson - intersection of computing and teaching", "Serge Abiteboul - database theory", "Samson Abramsky - game semantics", "Leonard Adleman - RSA, DNA computing", "Manindra Agrawal - polynomial-time primality testing", "Luis von Ahn - human-based computation", "Alfred Aho - compilers book, the 'a' in AWK", "Stephen R. Bourne - Bourne shell, portable ALGOL 68C compiler", "Kees Koster - ALGOL 68", "Lambert Meertens - ALGOL 68, ABC (programming language)", "Peter Naur - BNF, ALGOL 60", "Guido van Rossum - Python (programming language)", "Adriaan van Wijngaarden - Dutch pioneer; ARRA, ALGOL", "Dennis E. Wisnosky - Integrated Computer-Aided Manufacturing (ICAM), IDEF", "Stephen Wolfram - Mathematica", "William Wulf - compilers", "Edward Yourdon - Structured Systems Analysis and Design Method", "Lotfi Zadeh - fuzzy logic", "Arif Zaman - Pseudo-random number generator", "Albert Zomaya - Australian pioneer of scheduling in parallel and distributed systems", "Konrad Zuse - German pioneer of hardware and software"
);
PAGE algol pioneers list, the scientists list; PAGE aa;
- Now do a bit of plumbing: #
cat((
head(4, ) < list of computer scientists,
cat(READ list of computer scientists) =: grep("ALGOL", ) =: tee(WRITE algol pioneers list),
tail(4, READ list of computer scientists)
)) =: sort =: uniq =: tee(WRITE the scientists list) =: grep("aa", ) >> aa;
- Finally check the result: #
printf((
$"Pioneer: "$, line fmt, aa, $l$, $"Number of Algol pioneers: "g(-0)$, UPB algol pioneers list, $l$, $"Number of scientists: "g(-0)$, UPB the scientists list, $l$
))</lang> Output:
Pioneer: Adriaan van Wijngaarden - Dutch pioneer; ARRA, ALGOL Number of Algol pioneers: 6 Number of scientists: 15