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|
letref FAIL_LIST = []:(string#string#string) list;;
letref FIRST_CHARS = []:string list;;
letref CHARS = []:string list;;
let pg_failwith symb prdn =
FAIL_LIST := append FAIL_LIST [(`*`,prdn,symb)]; fail;;
let push item lst = (item . lst);;
let pop lst =
if null lst then failwith `can't pop null list`
else (hd lst,tl lst);;
let write_string str file =
if file = `nil` then tty_write str else write(file,str);;
let read_char file =
if file = `nil` then tty_read() else (read file);;
let close_file file =
if file = `nil` then ()
else close file;;
let open_file direction filename =
if filename = `nil` then `nil`
else if mem direction [`in` ; `input` ; `i`] then
openi filename
else if mem direction [`out`; `output`; `o`] then
openw filename
else
failwith (concat `can't open `
(concat filename
(concat ` in direction ` direction)));;
letrec e_w_s file chr whitespace =
if mem chr whitespace then e_w_s file (read_char file) whitespace
else if chr = `nil` then failwith `unexpected eof`
else chr;;
letrec e_w_s_ok file chr whitespace =
if mem chr whitespace then e_w_s_ok file (read_char file) whitespace
else if chr = `nil` then `nil`
else chr;;
let determine_lst ch follow white =
if follow = white then
mem ch white
else
not (mem ch follow);;
letrec get_word2 ch lst file white seps =
if ch = `nil` then
(lst,`nil`)
else if can (assoc ch) seps then
(lst,ch)
else if mem ch white then
(lst,e_w_s_ok file (read_char file) white)
else
get_word2 (read_char file) (append lst [ch]) file white seps;;
letrec get_word1 ch lst file follow white =
if ch = `nil` then
(lst,`nil`)
else if not (mem ch follow) then
(lst,e_w_s_ok file ch white)
else
get_word1 (read_char file) (append lst [ch]) file follow white;;
let complete_separator thing file white seps =
if can (assoc thing) seps then
let follow = snd (assoc thing seps) in
if null follow then
(thing,e_w_s_ok file (read_char file) white)
else
let (wrd,sep) = get_word1 (read_char file) [thing] file
follow white in
(implode wrd,sep)
else
let (wrd,sep) = get_word2 (read_char file) [thing] file white seps in
(implode wrd,sep);;
let get_word file white last seps sep =
if mem last white then
failwith `Generated Parser Error, please report it.`
else if not (mem sep white) then
(last,sep)
else if last = `nil` then
(`nil`,`nil`)
else
complete_separator last file white seps;;
letrec read_input file lst white seps prev =
let (WORD,sep) = get_word file white prev seps (hd white) in
let lst = append lst [WORD] in
if WORD = `nil` then
(close_file file; lst)
else
read_input file lst white seps sep;;
let gnt lst white WORD =
if WORD = `nil` then
if null lst then
(`nil`,[])
else failwith `Unexpected end of term.`
else if WORD = white then
(hd lst,tl lst)
else
(WORD,lst);;
let eat_terminal token WORD lst prdn =
if WORD = token then
if WORD = `nil` then
if null lst then
(`nil`,[])
else failwith `Unexpected end of term.`
else
(hd lst,tl lst)
else
pg_failwith WORD prdn (concat `expected "`
(concat token `".`));;
letrec chop_off ctr pop_list result_list =
if ctr = 0 then (result_list,pop_list)
else chop_off (ctr-1) ((hd result_list) . pop_list) (tl result_list);;
let do_return_1 res_list white prdn thing lst expect =
if thing = white then
(FAIL_LIST := append FAIL_LIST [(`<`,prdn,``)];
(hd res_list, tl res_list, (hd lst), (tl lst)))
else if thing = expect then
(FAIL_LIST := append FAIL_LIST [(`<`,prdn,``)];
(hd res_list, tl res_list, thing, lst))
else
(FAIL_LIST := append FAIL_LIST [(`*`,prdn,thing)];
fail);;
let do_return res_list white prdn prev lst expect =
if expect = `nil` then
(FAIL_LIST := append FAIL_LIST [(`<`,prdn,``)];
(hd res_list, tl res_list, prev, lst))
else
do_return_1 res_list white prdn prev lst expect;;
letrec write_tabs tab =
if tab = 0 then ()
else (write_string ` ` `nil`;write_tabs (tab-1));;
letrec backtrace lst tab =
if null lst then
write_string `\L` `nil`
else
let (dir,prdn,symb) = hd lst in
if dir = `>` then
(write_tabs (tab+2);
write_string (`>> `^prdn^`: "`^symb^`"\L`) `nil`;
backtrace (tl lst) (tab+2))
else if dir = `<` then
(write_tabs tab;
write_string (`<< `^prdn^`\L`) `nil`;
backtrace (tl lst) (tab-2))
else
(write_tabs tab;
write_string (`** `^prdn^`: "`^symb^`" (FAIL)\L`) `nil`;
backtrace (tl lst) (tab-2));;
let evaluation_failed lst =
write_string `\L\LERROR: unrecognisable input.\L` `nil`;
write_string ` -- TRACE: \L` `nil`;
backtrace lst 3;
FAIL_LIST := [];
fail;;
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