% extras.red Copyright Codemist Ltd 2004-2007
%
% Additional useful functions to have in a Lisp environment.
%
%
% This code may be used and modified, and redistributed in binary
% or source form, subject to the "CCL Public License", which should
% accompany it. This license is a variant on the BSD license, and thus
% permits use of code derived from this in either open and commercial
% projects: but it does require that updates to this code be made
% available back to the originators of the package.
% Before merging other code in with this or linking this code
% with other packages or libraries please check that the license terms
% of the other material are compatible with those of this.
%
% The following small function is just used for testing the CSL OEM
% interface code...
symbolic procedure oem!-supervisor();
print eval read();
%
% If you go (setq !*break!-loop!* 'break!-loop) then errors will get this
% function called - and it is rather desirable that it does not itself fail.
% The argument is what was passed to (ERROR ...) if the Lisp-level error
% function was called. When this function exits the system will unwind back
% to the next enclosing ERRORSET. (enable!-backtrace <fg>) can be used to
% switch backtrace display on or off.
%
symbolic procedure break!-loop a;
begin
scalar prompt, ifile, ofile, u, v;
% I use wrs/rds so I am compatible between Standard and Common Lisp here
ifile := rds !*debug!-io!*;
ofile := wrs !*debug!-io!*;
prompt := setpchar "Break loop (:X exits)> ";
top:u := read();
if u = '!:x then go to exit
else if u = '!:q then <<
enable!-backtrace nil;
princ "Backtrace now disabled";
terpri() >>
else if u = '!:v then <<
enable!-backtrace t;
princ "Backtrace now enabled";
terpri() >>
else <<
if null u then v := nil
else v := errorset(u, nil, nil);
if atom v then <<
princ ":Q quietens backtrace"; terpri();
princ ":V enables backtrace"; terpri();
princ ":X exits from break loop"; terpri();
princ "else form for evaluation"; terpri();
>>
else <<
prin "=> ";
prinl car v;
terpri() >> >>;
go to top;
exit:
rds ifile;
wrs ofile;
setpchar prompt;
return nil
end;
% dated!-name manufactures a symbol that is expected to be unique - but
% there will in fact be no strict guarantee of that. The name is made up out
% of a base part provided by the caller, then a chunk that encodes the
% date and time of day that the function was called (accurate to around
% a second, typically). Finally a serial number that starts off as 1 when
% the "extras" module is loaded into a copy of Lisp. Two copies of Lisp
% running at the same time could lead to clashes here. But names of this
% sort seem to be needed for inclusion in files and other places where
% re-readability is vital.
global '(s!:gensym!-serial);
s!:gensym!-serial := 0;
symbolic procedure s!:stamp n;
% Converts an integer (which will in fact be a timestamp, an about
% 2^29 or 2^30 in value) into a sequence of letters and digits by
% converting to base 36 (with the digits ending up in the "wrong"
% order). Used only when generating probably-unique-identifiers to
% use as names for internally generated functions.
if n < 0 then append(s!:stamp(-n), '(!-))
else if n = 0 then nil
else schar("0123456789abcdefghijklmnopqrstuvwxyz", remainder(n, 36)) .
s!:stamp truncate(n ,36);
symbolic procedure dated!-name base;
intern list!-to!-string
append(explodec base,
'!_ . append(reverse s!:stamp datestamp(),
'!_ . explodec(s!:gensym!-serial := s!:gensym!-serial + 1)));
% hashtagged!-name(base, value) manufactures a name based on the
% base together with a hash-value computed from the "value". This
% is expected to be a reliable signature (but clashes are of course
% possible). Eg base may be the name of a function and value its
% definition, then this will invent a name suitable for a parallel
% version of the function where the new name ought not to conflict with
% ones used later if this function gets defined with a different
% definition.
symbolic procedure hashtagged!-name(base, value);
intern list!-to!-string
append(explodec base, '!_ . s!:stamp md60 value);
%
% Sorting
%
remflag('(sort sortip), 'lose);
symbolic procedure sort(l, pred);
% Sort the list l according to the given predicate. If l is a list
% of numbers then the predicate "lessp" will sort the list into
% ascending order. The predicate should be a strict inequality, i.e.
% it should return NIL if the two items compared are equal.
% As implemented here SORT just calls STABLE-SORT, but as a matter of
% style any use where the ordering of incomparable items in the output
% matters ought to use STABLE!-SORT directly, thereby allowing the
% replacement of this code with a faster non-stable method.
% (Note: the previous REDUCE sort function also happened to be stable, so
% this code should give exactly the same results for all calls where
% the predicate is self-consistent and never has both pred(a,b) and
% pred(b,a) true. A previous CSL sort was not stable, but was perhaps
% very slightly faster than this)
stable!-sortip(append(l, nil), pred);
symbolic procedure stable!-sort(l, pred);
% Sorts a list, as SORT, but if two items x and y in the input list
% satisfy neither pred(x,y) nor pred(y,x) [i.e. they are equal so far
% as the given ordering predicate is concerned] this function guarantees
% that they will appear in the output list in the same order that they
% were in the input.
stable!-sortip(append(l, nil), pred);
symbolic procedure sortip(l, pred);
stable!-sortip(l, pred);
symbolic procedure stable!-sortip(l, pred);
% As stable!-sort, but over-writes the input list to make the output.
% It is not intended that people should call this function directly: it
% is present just as the implementation of the main sort procedures defined
% above.
begin
scalar l1, l2, w;
if null l then return l; % Input list of length 0
l1 := l;
l2 := cdr l;
if null l2 then return l; % Input list of length 1
% Now I have dealt with the essential special cases of lists of length 0
% and 1 (which do not need sorting at all). Since it possibly speeds things
% up just a little I will now have some fairly ugly code that makes special
% cases of lists of length 2. I could easily have special code for length
% 3 lists here (and include it, but commented out), but at present my
% measurements suggest that the speed improvement that it gives is minimal
% and the increase in code bulk is large enough to give some pain.
l := cdr l2;
if null l then << % Input list of length 2
if apply2(pred, car l2, car l1) then <<
l := car l1;
rplaca(l1, car l2);
rplaca(l2, l) >>;
return l1 >>;
% Now I will check to see if the list is in fact in order already
% Doing so will have a cost - but sometimes that cost will be repaid
% when I am able to exit especially early. The result of all this
% is that I will have a best case behaviour with linear cost growth for
% inputs that are initially in the correct order, while my average and
% worst-case costs will increase by a constant factor.
l := l1;
while l2 and not apply2(pred, car l2, car l) do <<
% In the input list is NOT already in order then I expect that this
% loop will exit fairly early, and so will not contribute much to the
% total cost. If it exits very late then probably in the next recursion
% down the first half of the list will be found to be already sorted, and
% again I have a chance to win.
l := l2; l2 := cdr l2 >>;
if null l2 then return l1;
l2 := l1;
l := cddr l2;
while l and cdr l do << l2 := cdr l2; l := cddr l >>;
l := l2;
l2 := cdr l2;
rplacd(l, nil);
% The two sub-lists are then sorted.
l1 := stable!-sortip(l1, pred);
l2 := stable!-sortip(l2, pred);
% Now I merge the sorted fragments, giving priority to item from the
% earlier part of the original list.
l := w := list nil;
while l1 and l2 do <<
if apply2(pred, car l2, car l1) then <<
rplacd(w, l2); w := l2; l2 := cdr l2 >>
else << rplacd(w, l1); w := l1; l1 := cdr l1 >> >>;
if l1 then l2 := l1;
rplacd(w, l2);
return cdr l
end;
%
% Code to print potentially re-entrant lists
%
fluid '(!*prinl!-visited!-nodes!* !*prinl!-index!*
!*prinl!-fn!* !*loop!-print!* !*print!-array!*
!*print!-length!* !*print!-level!*);
!*print!-length!* := !*print!-level!* := nil;
!*prinl!-visited!-nodes!* := mkhash(10, 0, 1.5)$
symbolic procedure s!:prinl0(x,!*prinl!-fn!*);
% print x even if it has loops in it
begin
scalar !*prinl!-index!*;
!*prinl!-index!*:=0;
% Clear the hash table AFTER use, so that the junk that goes into it does
% not gobble memory between calls to prinl. This relies on unwind!-protect
% to make sure that it is indeed always cleared. Errors (eg ^C) during the
% clean-up operation could lead to curious displays in the next use of
% prinl. Also of course bugs in the implementation of unwind!-protect...
% clrhash !*prinl!-visited!-nodes!*;
unwind!-protect(<< s!:prinl1(x, 0); s!:prinl2(x, 0) >>,
clrhash !*prinl!-visited!-nodes!*);
return x
end;
symbolic procedure s!:prinl1(x, depth);
% Find all the nodes in x and record them in the hash table.
% The first time a node is met it is inserted with associated value 0.
% If a node is met a second time then it is assigned an unique positive
% integer code that will later be used in its label.
begin
scalar w, length;
if fixp !*print!-level!* and depth > !*print!-level!* then return nil;
length := 0;
top:
if atom x and not simple!-vector!-p x and not gensymp x then return nil
else if w := gethash(x,!*prinl!-visited!-nodes!*) then <<
if w = 0 then <<
!*prinl!-index!* := !*prinl!-index!* + 1;
puthash(x,!*prinl!-visited!-nodes!*, !*prinl!-index!*) >>;
return nil >>
else <<
puthash(x, !*prinl!-visited!-nodes!*, 0);
if simple!-vector!-p x then <<
if !*print!-array!* then <<
length := upbv x;
if fixp !*print!-length!* and !*print!-length!* < length then
length := !*print!-length!*;
for i:=0:length do s!:prinl1(getv(x,i), depth+1) >> >>
else if not atom x then <<
s!:prinl1(car x, depth+1);
if fixp !*print!-length!* and
(length := length+1) > !*print!-length!* then return nil;
x := cdr x;
go to top >> >>
end;
symbolic procedure s!:prinl2(x, depth);
% Scan a structure that was previously processed by s!:prinl1. Thus all
% nodes in x are already in the hash table. Those with value zero
% are only present once in x, while those with strictly positive values
% occur at least twice. After printing a label for such value this resets the
% value negative so that the printing can tell when the visit is for
% a second rather than first time. The output format is intended to
% bear some resemblance to the expectations of Common Lisp.
if fixp !*print!-level!* and depth > !*print!-level!* then
princ "#"
else if atom x and not simple!-vector!-p x and not gensymp x then <<
!#if common!-lisp!-mode
if complex!-arrayp x and not !*print!-array!* then princ "[Array]"
else if structp x and not !*print!-array!* then princ "[Struct]"
else
!#endif
funcall(!*prinl!-fn!*, x) >>
else begin scalar w, length;
w := gethash(x,!*prinl!-visited!-nodes!*);
% w has better be a number here, following s!:prinl1
if not zerop w then <<
if w < 0 then <<
princ "#";
princ (-w);
princ "#";
return nil >>
else <<
puthash(x,!*prinl!-visited!-nodes!*, -w);
princ "#";
princ w;
princ "=" >> >>;
if simple!-vector!-p x then <<
princ "%(";
if !*print!-array!* then <<
length := upbv x;
if fixp !*print!-length!* and !*print!-length!* < length then
length := !*print!-length!*;
for i:=0:length do << s!:prinl2(getv(x,i), depth+1);
if not i=upbv x then princ " " >> >>
else princ "...";
princ ")";
return nil >>
else if atom x then return funcall(!*prinl!-fn!*, x);
princ "(";
length := 0;
loop:
s!:prinl2(car x, depth+1);
x:=cdr x;
if atom x then <<
if simple!-vector!-p x then <<
princ " . %(";
if !*print!-array!* then <<
length := upbv x;
if fixp !*print!-length!* and !*print!-length!* < length then
length := !*print!-length!*;
for i:=0:length do <<s!:prinl2(getv(x,i), depth+1);
if not i=upbv x then princ " ">> >>
else princ "...";
princ ")" >>
else if x then <<
princ " . ";
funcall(!*prinl!-fn!*, x) >>;
return princ ")" >>;
if fixp !*print!-length!* and
(length := length + 1) > !*print!-length!* then
return princ " ...)";
w := gethash(x, !*prinl!-visited!-nodes!*);
if not (w = 0) then if w < 0 then <<
princ " . #";
princ (-w);
return princ "#)" >>
else <<
princ " . ";
s!:prinl2(x, depth+1); % This will set the label
return princ ")" >>
else princ " ";
go to loop
end;
symbolic procedure printl x;
<< prinl x;
terpri();
x >>;
symbolic procedure printcl x;
<< princl x;
terpri();
x >>;
symbolic procedure princl x;
s!:prinl0(x,function princ);
symbolic procedure prinl x;
s!:prinl0(x,function prin);
%
% A small subset of the facilities of the unreasonably baroque Common
% Lisp FORMAT function may be useful.
%
!#if (not common!-lisp!-mode)
% If I am in COMMON Lisp mode then a more complete version of this
% will be installed from elsewhere.
symbolic procedure s!:format(dest, fmt, args);
begin
scalar len, c, a, res, o;
if not null dest then <<
if dest = 't then o := wrs nil
else o := wrs dest >>;
len := upbv fmt;
for i := 0:len do <<
c := schar(fmt, i);
if c = '!~ then <<
i := i + 1;
c := char!-downcase schar(fmt, i);
if c = '!% then
if null dest then res := !$eol!$ . res
else terpri()
else if c = '!~ then
if null dest then res := '!~ . res
else princ '!~
else <<
if null args then a := nil
else <<
a := car args;
args := cdr args >>;
if c = '!a then
if null dest then for each k in explode2 a do res := k . res
else princ a
else if c = '!s then
if null dest then for each k in explode a do res := k . res
else prin a
else
if null dest then for each k in explode a do res := k . res
else prin list('!?!?!?, c, a) >> >>
else <<
if null dest then res := c . res
else princ c >> >>;
if null dest then return list!-to!-string reversip res
else << wrs o; return nil >>
end;
symbolic macro procedure format(u, !&optional, env);
list('s!:format, cadr u, caddr u, 'list . cdddr u);
!#endif
fluid '(bn
bufferi
buffero
indblanks
indentlevel
initialblanks
lmar
pendingrpars
rmar
rparcount
stack);
global '(!*quotes !*pretty!-symmetric thin!*);
!*pretty!-symmetric := t;
!*quotes := t;
thin!* := 5;
% This package prints list structures in an indented format that
% is intended to make them legible. There are a number of special
% cases recognized, but in general the intent of the algorithm
% is that given a list (R1 R2 R3 ...), SUPERPRINT checks if
% the list will fit directly on the current line and if so
% prints it as:
% (R1 R2 R3 ...)
% if not it prints it as:
% (R1
% R2
% R3
% ... )
% where each sublist is similarly treated.
%
% Functions:
% SUPERPRINTM(X,M) print expression X with left margin M
% PRETTYPRINT(X) = <<superprintm(x,posn()); terpri(); terpri()>>;
%
% Flag:
% !*SYMMETRIC If TRUE, print with escape characters,
% otherwise do not (as PRIN1/PRIN2
% distinction). defaults to TRUE;
% !*QUOTES If TRUE, (QUOTE x) gets displayed as 'x.
% default is TRUE;
%
% Variable:
% THIN!* if THIN!* expressions can be fitted onto
% a single line they will be printed that way.
% this is a parameter used to control the
% formatting of long thin lists. default
% value is 5;
symbolic procedure prettyprint x;
<< superprinm(x,posn()); % What REDUCE seems to want. Looks a bit odd to me!
terpri();
nil>>;
symbolic procedure superprintm(x,lmar);
<< superprinm(x,lmar); terpri(); x >>;
% From here down the functions are not intended for direct use.
symbolic procedure superprinm(x,lmar);
begin
scalar stack,bufferi,buffero,bn,initialblanks,rmar,
pendingrpars,indentlevel,indblanks,rparcount,w;
bufferi:=buffero:=list nil; %fifo buffer.
initialblanks:=0;
rparcount:=0;
indblanks:=0;
rmar:=linelength(nil); % right margin.
linelength 500; % To try to be extra cautious
if rmar<25 then error(0,list(rmar,
"Linelength too short for superprinting"));
bn:=0; %characters in buffer.
indentlevel:=0; %no indentation needed, yet.
if lmar+20>=rmar then lmar:=rmar - 21; %no room for specified margin
w:=posn();
if w>lmar then << terpri(); w:=0 >>;
if w<lmar then initialblanks:=lmar - w;
s!:prindent(x,lmar+3); %main recursive print routine.
% traverse routine finished - now tidy up buffers.
s!:overflow 'none; %flush out the buffer.
linelength rmar;
return x
end;
% Access functions for a stack entry.
symbolic macro procedure s!:top(u,!&optional,v);
'(car stack);
symbolic macro procedure s!:depth(u,!&optional,v);
list('car, cadr u);
symbolic macro procedure s!:indenting(u,!&optional,v);
list('cadr, cadr u);
symbolic macro procedure s!:blankcount(u,!&optional,v);
list('caddr, cadr u);
symbolic macro procedure s!:blanklist(u,!&optional,v);
list('cdddr, cadr u);
symbolic macro procedure s!:setindenting(u,!&optional,v);
list('rplaca, list('cdr, cadr u), caddr u);
symbolic macro procedure s!:setblankcount(u,!&optional,v);
list('rplaca, list('cddr, cadr u), caddr u);
symbolic macro procedure s!:setblanklist(u,!&optional,v);
list('rplacd, list('cddr, cadr u), caddr u);
symbolic macro procedure s!:newframe(u,!&optional,v);
list('list, cadr u, nil, 0);
symbolic macro procedure s!:blankp(u,!&optional,v);
list('numberp, list('car, cadr u));
symbolic procedure s!:prindent(x,n);
% Print list x with indentation level n.
if atom x then if simple!-vector!-p x then s!:prvector(x,n)
else for each c in
(if !*pretty!-symmetric
then if stringp x then s!:explodes x else explode x
else explode2 x) do s!:putch c
else if s!:quotep x then <<
s!:putch '!';
s!:prindent(cadr x,n+1) >>
else begin
scalar cx;
if 4*n>3*rmar then << %list is too deep for sanity.
s!:overflow 'all;
n:=truncate(n, 8);
if initialblanks>n then <<
lmar:=lmar - initialblanks+n;
initialblanks:=n >> >>;
stack := (s!:newframe n) . stack;
s!:putch ('lpar . s!:top());
cx:=car x;
s!:prindent(cx,n+1);
if idp cx and not atom cdr x then
cx:=get(cx,'s!:ppformat) else cx:=nil;
if cx=2 and atom cddr x then cx:=nil;
if cx='prog then <<
s!:putch '! ;
s!:prindent(car (x:=cdr x),n+3) >>;
% CX now controls the formatting of what follows:
% nil default action
% <number> first few blanks are non-indenting
% prog display atoms as labels.
x:=cdr x;
scan: if atom x then go to outt;
s!:finishpending(); %about to print a blank.
if cx='prog then <<
s!:putblank();
s!:overflow bufferi; %force format for prog.
if atom car x then << % a label.
lmar:=initialblanks:=max(lmar - 6,0);
s!:prindent(car x,n - 3); % print the label.
x:=cdr x;
if not atom x and atom car x then go to scan;
if lmar+bn>n then s!:putblank()
else for i:=lmar+bn:n - 1 do s!:putch '! ;
if atom x then go to outt>> >>
else if numberp cx then <<
cx:=cx - 1;
if cx=0 then cx:=nil;
s!:putch '! >>
else s!:putblank();
s!:prindent(car x,n+3);
x:=cdr x;
go to scan;
outt: if not null x then <<
s!:finishpending();
s!:putblank();
s!:putch '!.;
s!:putch '! ;
s!:prindent(x,n+5) >>;
s!:putch ('rpar . (n - 3));
if s!:indenting s!:top()='indent and not null s!:blanklist s!:top() then
s!:overflow car s!:blanklist s!:top()
else s!:endlist s!:top();
stack:=cdr stack
end;
symbolic procedure s!:explodes x;
%dummy function just in case another format is needed.
explode x;
symbolic procedure s!:prvector(x,n);
begin
scalar bound;
bound:=upbv x; % length of the vector.
stack:=(s!:newframe n) . stack;
s!:putch ('lsquare . s!:top());
s!:prindent(getv(x,0),n+3);
for i:=1:bound do <<
s!:putch '!,;
s!:putblank();
s!:prindent(getv(x,i),n+3) >>;
s!:putch('rsquare . (n - 3));
s!:endlist s!:top();
stack:=cdr stack
end;
symbolic procedure s!:putblank();
begin
s!:putch s!:top(); %represents a blank character.
s!:setblankcount(s!:top(),s!:blankcount s!:top()+1);
s!:setblanklist(s!:top(),bufferi . s!:blanklist s!:top());
%remember where I was.
indblanks:=indblanks+1
end;
symbolic procedure s!:endlist l;
%Fix up the blanks in a complete list so that they
%will not be turned into indentations.
pendingrpars:=l . pendingrpars;
% When I have printed a ')' I want to mark all of the blanks
% within the parentheses as being unindented, ordinary blank
% characters. It is however possible that I may get a buffer
% overflow while printing a string of )))))))))), and so this
% marking should be delayed until I get round to printing
% a further blank (which will be a candidate for a place to
% split lines). This delay is dealt with by the list
% pendingrpars which holds a list of levels that, when
% convenient, can be tidied up and closed out.
symbolic procedure s!:finishpending();
<< for each stackframe in pendingrpars do <<
if s!:indenting stackframe neq 'indent then
for each b in s!:blanklist stackframe do
<< rplaca(b,'! ); indblanks:=indblanks - 1>>;
% s!:blanklist of stackframe must be non-nil so that overflow
% will not treat the '(' specially.
s!:setblanklist(stackframe,t) >>;
pendingrpars:=nil >>;
symbolic procedure s!:quotep x;
!*quotes and
not atom x and
car x='quote and
not atom cdr x and
null cddr x;
% property s!:ppformat drives the prettyprinter -
% prog : special for prog only
% 1 : (fn a1
% a2
% ... )
% 2 : (fn a1 a2
% a3
% ... ) ;
put('prog,'s!:ppformat,'prog);
put('lambda,'s!:ppformat,1);
put('lambdaq,'s!:ppformat,1);
put('setq,'s!:ppformat,1);
put('set,'s!:ppformat,1);
put('while,'s!:ppformat,1);
put('t,'s!:ppformat,1);
put('de,'s!:ppformat,2);
put('df,'s!:ppformat,2);
put('dm,'s!:ppformat,2);
put('defun,'s!:ppformat,2);
put('defmacro,'s!:ppformat,2);
put('foreach,'s!:ppformat,4); % (foreach x in y do ...) etc.
% Now for the routines that buffer things on a character by character
% basis, and deal with buffer overflow.
symbolic procedure s!:putch c;
begin
if atom c then rparcount:=0
else if s!:blankp c then << rparcount:=0; go to nocheck >>
else if car c='rpar then <<
rparcount:=rparcount+1;
% format for a long string of rpars is:
% )))) ))) ))) ))) ))) ;
if rparcount>4 then << s!:putch '! ; rparcount:=2 >> >>
else rparcount:=0;
while lmar+bn>=rmar do s!:overflow 'more;
nocheck:
bufferi:=cdr rplacd(bufferi,list c);
bn:=bn+1
end;
symbolic procedure s!:overflow flg;
begin
scalar c,blankstoskip;
% The current buffer holds so much information that it will
% not all fit on a line. try to do something about it.
% flg is one of:
% 'none do not force more indentation
% 'more force one level more indentation
% <a pointer into the buffer>
% prints up to and including that character, which
% should be a blank.
if indblanks=0 and initialblanks>3 and flg='more then <<
initialblanks:=initialblanks - 3;
lmar:=lmar - 3;
return 'moved!-left >>;
fblank:
if bn=0 then <<
% No blank found - can do no more for now.
% If flg='more I am in trouble and so have to print
% a continuation mark. in the other cases I can just exit.
if not(flg = 'more) then return 'empty;
if atom car buffero then
% continuation mark not needed if last char printed was
% special (e.g. lpar or rpar).
prin2 "%+"; %continuation marker.
terpri();
lmar:=0;
return 'continued >>
else <<
spaces initialblanks;
initialblanks:=0 >>;
buffero:=cdr buffero;
bn:=bn - 1;
lmar:=lmar+1;
c:=car buffero;
if atom c then <<
prin2 c;
go to fblank >>
else if s!:blankp c then if not atom blankstoskip then <<
prin2 '! ;
indblanks:=indblanks - 1;
% blankstoskip = (stack-frame . skip-count).
if c eq car blankstoskip then <<
rplacd(blankstoskip,cdr blankstoskip - 1);
if cdr blankstoskip=0 then blankstoskip:=t >>;
go to fblank >>
else go to blankfound
else if car c='lpar or car c='lsquare then <<
prin2 get(car c,'s!:ppchar);
if flg='none then go to fblank;
% now I want to flag this level for indentation.
c:=cdr c; %the stack frame.
if not null s!:blanklist c then go to fblank;
if s!:depth c>indentlevel then << %new indentation.
% this level has not emitted any blanks yet.
indentlevel:=s!:depth c;
s!:setindenting(c,'indent) >>;
go to fblank >>
else if car c='rpar or car c='rsquare then <<
if cdr c<indentlevel then indentlevel:=cdr c;
prin2 get(car c,'s!:ppchar);
go to fblank >>
else error(0,list(c,"UNKNOWN TAG IN OVERFLOW"));
blankfound:
if eqcar(s!:blanklist c,buffero) then
s!:setblanklist(c,nil);
% at least one entry on blanklist ought to be valid, so if I
% print the last blank I must kill blanklist totally.
indblanks:=indblanks - 1;
% check if next level represents new indentation.
if s!:depth c>indentlevel then <<
if flg='none then << %just print an ordinary blank.
prin2 '! ;
go to fblank >>;
% here I increase the indentation level by one.
if blankstoskip then blankstoskip:=nil
else <<
indentlevel:=s!:depth c;
s!:setindenting(c,'indent) >> >>;
%otherwise I was indenting at that level anyway.
if s!:blankcount c>(thin!* - 1) then << %long thin list fix-up here.
blankstoskip:=c . ((s!:blankcount c) - 2);
s!:setindenting(c,'thin);
s!:setblankcount(c,1);
indentlevel:=(s!:depth c) - 1;
prin2 '! ;
go to fblank >>;
s!:setblankcount(c,(s!:blankcount c) - 1);
terpri();
lmar:=initialblanks:=s!:depth c;
if buffero eq flg then return 'to!-flg;
if blankstoskip or not (flg='more) then go to fblank;
% keep going unless call was of type 'more'.
return 'more; %try some more.
end;
put('lpar,'s!:ppchar,'!();
put('lsquare,'s!:ppchar,'![);
put('rpar,'s!:ppchar,'!));
put('rsquare,'s!:ppchar,'!]);
% Now some (experimental) support for network access
symbolic procedure fetch!-url(url, !&optional, dest);
begin
scalar a, b, c, d, e, w;
a := open!-url url;
if null a then return nil;
if dest then <<
d := open(dest, 'output);
if null d then <<
close a;
return error(0, "unable to open destination file") >>;
d := wrs d >>;
b := rds a;
w := linelength 500;
while not ((c := readch()) = !$eof!$) do princ c;
linelength e;
rds b;
close a;
if dest then close wrs d
end;
end;
% end of extras.red