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parser-generator-ll.el
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parser-generator-ll.el
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;;; parser-generator-ll.el --- LL(k) Parser Generator -*- lexical-binding: t -*-
;; Copyright (C) 2020-2024 Free Software Foundation, Inc.
;;; Commentary:
;;; Code:
(require 'parser-generator)
(require 'parser-generator-lex-analyzer)
;;; Variables:
(defvar
parser-generator-ll--table
nil
"Table for grammar.")
;;; Functions
(defun parser-generator-ll-generate-table ()
"Generate table for grammar."
(let ((list-parsing-table)
(hash-parsing-table (make-hash-table :test 'equal)))
(if (> parser-generator--look-ahead-number 1)
(progn
(message "\n;; Starting generation of LL(k) tables..\n")
(unless (parser-generator-ll--valid-grammar-k-gt-1-p)
(error "Invalid LL(k) grammar specified!"))
(setq
list-parsing-table
(parser-generator-ll--generate-action-table-k-gt-1
(parser-generator-ll--generate-goto-table))))
(message "\n;; Starting generation of LL(1) tables..\n")
(unless (parser-generator-ll--valid-grammar-k-eq-1-p)
(error "Invalid LL(1) grammar specified!"))
(setq
list-parsing-table
(parser-generator-ll--generate-action-table-k-eq-1
(parser-generator-ll--generate-goto-table))))
;; Convert list-structure to hash-map
(dolist (state-list list-parsing-table)
(let ((state-key (nth 0 state-list))
(state-look-aheads (nth 1 state-list))
(state-hash-table (make-hash-table :test 'equal)))
(dolist (state-look-ahead-list state-look-aheads)
(let ((state-look-ahead-string (nth 0 state-look-ahead-list))
(state-look-ahead-action (nth 1 state-look-ahead-list)))
(if (equal state-look-ahead-action 'reduce)
(let ((state-look-ahead-reduction
(nth 2 state-look-ahead-list))
(state-look-ahead-production-number
(nth 3 state-look-ahead-list)))
(puthash
(format "%S" state-look-ahead-string)
(list
state-look-ahead-action
state-look-ahead-reduction
state-look-ahead-production-number)
state-hash-table))
(puthash
(format "%S" state-look-ahead-string)
state-look-ahead-action
state-hash-table))))
(puthash
(format "%S" state-key)
state-hash-table
hash-parsing-table)))
(setq
parser-generator-ll--table
hash-parsing-table)
(if (> parser-generator--look-ahead-number 1)
(message "\n;; Completed generation of LL(k) tables.\n")
(message "\n;; Completed generation of LL(1) tables.\n"))))
(defun parser-generator-ll-parse ()
(let ((parse (parser-generator-ll--parse)))
(car parse)))
(defun parser-generator-ll-translate ()
(let ((parse (parser-generator-ll--parse t)))
(car (cdr parse))))
;; Generally described at .p 339
(defun parser-generator-ll--parse (&optional translate-p)
"Parse input via lex-analyzer and return parse trail."
(let ((accept)
(stack
(if (> parser-generator--look-ahead-number 1)
(list
(list
(list
(parser-generator--get-grammar-start))
(parser-generator--generate-list-of-symbol
parser-generator--look-ahead-number
parser-generator--eof-identifier))
parser-generator--eof-identifier)
(list
(parser-generator--get-grammar-start)
parser-generator--eof-identifier)))
(output)
(eof-look-ahead
(parser-generator--generate-list-of-symbol
parser-generator--look-ahead-number
parser-generator--eof-identifier))
(e-reduction
(list parser-generator--e-identifier))
(translation)
(translation-stack)
(translation-symbol-table
(make-hash-table :test 'equal))
(terminal-stack '()))
(parser-generator-lex-analyzer--reset)
(while (not accept)
(let* ((state (car stack))
(state-action-table
(gethash
(format "%S" state)
parser-generator-ll--table))
(look-ahead-list
(parser-generator-lex-analyzer--peek-next-look-ahead))
(look-ahead))
(parser-generator--debug
(message "\nstack: %S" stack)
(message "translation-stack: %S" translation-stack)
(message "output: %S" output)
(message "state: %S" state)
(message "state-action-table: %S" state-action-table))
(unless state-action-table
(signal
'error
(list
(format
"State action table lacks actions for state: '%S'!"
state)
state)))
(if look-ahead-list
(progn
(parser-generator--debug
(message "look-ahead-list: %S" look-ahead-list))
(dolist (look-ahead-list-item look-ahead-list)
(push (car look-ahead-list-item) look-ahead))
(setq look-ahead (reverse look-ahead)))
(setq
look-ahead
eof-look-ahead))
(parser-generator--debug
(message "look-ahead: %S" look-ahead))
(unless (gethash
(format "%S" look-ahead)
state-action-table)
(let ((possible-look-aheads))
(maphash
(lambda (k _v) (push k possible-look-aheads))
state-action-table)
(signal
'error
(list
(format
"Invalid look-ahead '%S' in state: '%S', valid look-aheads: '%S'"
look-ahead
state
possible-look-aheads)
look-ahead
state
possible-look-aheads))))
(let* ((action
(gethash
(format "%S" look-ahead)
state-action-table))
(action-type action))
(parser-generator--debug
(message "action: %S" action))
(when (listp action)
(setq action-type (car action)))
(parser-generator--debug
(message "action-type: %S" action-type))
(cond
((equal action-type 'pop)
(parser-generator--debug
(message "popped: %S" look-ahead))
(let ((popped-tokens
(parser-generator-lex-analyzer--pop-token)))
;; Is it time for SDT?
(when (and
translate-p
translation-stack
(string=
(car (car translation-stack))
(format "%S" stack)))
(let* ((translation-item (pop translation-stack))
(partial-translation
(parser-generator-ll--perform-translation
(nth 1 translation-item)
translation-symbol-table
(reverse (pop terminal-stack)))))
(setq
translation
partial-translation)))
(pop stack)
(when translate-p
(let ((token-data)
(old-terminal-stack (car terminal-stack)))
(dolist (popped-token popped-tokens)
(push
popped-token
token-data))
(push
token-data
old-terminal-stack)
(setf
(car terminal-stack)
old-terminal-stack)))
;; Is it time for SDT?
(when (and
translate-p
translation-stack
(string=
(car (car translation-stack))
(format "%S" stack)))
(let* ((translation-item (pop translation-stack))
(partial-translation
(parser-generator-ll--perform-translation
(nth 1 translation-item)
translation-symbol-table
(reverse (pop terminal-stack)))))
(setq
translation
partial-translation)))
))
((equal action-type 'reduce)
(parser-generator--debug
(message "reduced: %S -> %S" state (nth 1 action)))
;; Is it time for SDT?
(when (and
translate-p
translation-stack
(string=
(car (car translation-stack))
(format "%S" stack)))
(let* ((translation-item (pop translation-stack))
(partial-translation
(parser-generator-ll--perform-translation
(nth 1 translation-item)
translation-symbol-table
(reverse (pop terminal-stack)))))
(setq
translation
partial-translation)))
(pop stack)
;; Is it time for SDT?
(when (and
translate-p
translation-stack
(string=
(car (car translation-stack))
(format "%S" stack)))
(let* ((translation-item (pop translation-stack))
(partial-translation
(parser-generator-ll--perform-translation
(nth 1 translation-item)
translation-symbol-table
(reverse (pop terminal-stack)))))
(setq
translation
partial-translation)))
(when translate-p
(push
(list
(format "%S" stack)
(nth 2 action))
translation-stack)
(push
'()
terminal-stack))
(unless (equal (nth 1 action) e-reduction)
(dolist (reduce-item (reverse (nth 1 action)))
(push reduce-item stack)))
(push
(nth 2 action)
output))
((equal action-type 'accept)
(setq accept t))))))
(list
(reverse output)
translation)))
(defun parser-generator-ll--perform-translation (production-number symbol-table terminals)
"Perform translation by PRODUCTION-NUMBER, with SYMBOL-TABLE and TERMINALS."
(let* ((production
(parser-generator--get-grammar-production-by-number
production-number))
(production-lhs
(car (nth 0 production)))
(production-rhs
(nth 1 production))
(translation)
(args-1)
(args-2))
(parser-generator--debug
(message
"Perform translation %S %S %S = %S"
production-number
symbol-table
terminals
production-rhs))
;; Collect arguments for translation
(let ((terminal-index 0))
(dolist (rhs-item production-rhs)
(cond
((parser-generator--valid-non-terminal-p
rhs-item)
(let* ((non-terminal-value-list
(gethash rhs-item symbol-table))
(non-terminal-value
(pop non-terminal-value-list)))
(push
(car non-terminal-value)
args-1)
(push
(car (cdr non-terminal-value))
args-2)
(puthash
rhs-item
non-terminal-value-list
symbol-table)))
((parser-generator--valid-terminal-p
rhs-item)
(push
(parser-generator-lex-analyzer--get-function
(nth terminal-index terminals))
args-1)
(push
(nth terminal-index terminals)
args-2)
(setq
terminal-index
(1+ terminal-index))))))
(setq
args-1
(reverse args-1))
(setq
args-2
(reverse args-2))
(parser-generator--debug
(message
"Perform translation %d: %S -> %S via args-1: %S and args-2: %S"
production-number
production-lhs
production-rhs
args-1
args-2))
(if (parser-generator--get-grammar-translation-by-number
production-number)
(let ((partial-translation
(funcall
(parser-generator--get-grammar-translation-by-number
production-number)
args-1
args-2))
(old-symbol-value
(gethash production-lhs symbol-table)))
(parser-generator--debug
(message
"\ntranslation-symbol-table: %S = %S (processed)\n"
production-lhs
partial-translation))
(push
(list
partial-translation
args-2)
old-symbol-value)
(puthash
production-lhs
old-symbol-value
symbol-table)
(setq
translation
partial-translation))
;; When no translation is specified just use popped contents as translation
(let ((partial-translation
(list
args-1
args-2))
(old-symbol-value
(gethash production-lhs symbol-table)))
(parser-generator--debug
(message
"\ntranslation-symbol-table: %S = %S (generic)\n"
production-lhs
partial-translation))
(push
partial-translation
old-symbol-value)
(puthash
production-lhs
old-symbol-value
symbol-table)
(setq
translation
(car partial-translation))))
translation))
;;; Algorithms
(defun parser-generator-ll--generate-action-table-k-eq-1 (goto-table)
"Generate action-table for LL(1) grammar using GOTO-TABLE."
(let ((parsing-table))
;; Iterate all possible look-aheads
;; Add EOF symbol look-ahead
(let ((eof-look-ahead
(parser-generator--generate-list-of-symbol
parser-generator--look-ahead-number
parser-generator--eof-identifier))
(terminal-mutations
(parser-generator--get-grammar-look-aheads))
(terminal-buffer)
(last-terminal))
(dolist (terminal-mutation terminal-mutations)
(if (equal terminal-mutation eof-look-ahead)
(push
(list
parser-generator--eof-identifier
(list
(list
eof-look-ahead
'accept)))
parsing-table)
(let ((stack-item (nth 0 terminal-mutation)))
(when (and
last-terminal
(not (equal last-terminal stack-item)))
(push
(list
last-terminal
terminal-buffer)
parsing-table)
(setq
terminal-buffer
nil))
(push
(list terminal-mutation 'pop)
terminal-buffer)
(setq
last-terminal
stack-item))))
(when (and
last-terminal
terminal-buffer)
(push
(list
last-terminal
terminal-buffer)
parsing-table)))
;; Add non-terminal -> FIRST(non-terminal) -> reduce RHS, production-number
(let ((non-terminal-look-ahead-p (make-hash-table :test 'equal))
(non-terminal-look-ahead-list (make-hash-table :test 'equal)))
(dolist (goto-row goto-table)
(let* ((stack (nth 0 goto-row))
(non-terminal (car (nth 0 stack)))
(local-follows (nth 1 stack))
(look-aheads (nth 1 goto-row)))
(parser-generator--debug
(message "\nnon-terminal: %S" non-terminal)
(message "local-follows: %S" local-follows)
(message "look-aheads: %S" look-aheads))
(dolist (look-ahead look-aheads)
(let* ((rhs
(nth 1 look-ahead))
(production
(list (list non-terminal) rhs))
(production-number
(parser-generator--get-grammar-production-number
production))
(look-ahead-terminal
(nth 0 look-ahead))
(hashmap-key
(format "%S-%S" non-terminal look-ahead-terminal)))
(parser-generator--debug
(message "\nrhs: %S" rhs)
(message "production: %S" production)
(message "production-number: %S" production-number)
(message "hashmap-key: %S" hashmap-key))
(unless (gethash hashmap-key non-terminal-look-ahead-p)
(let ((old-non-terminal-look-aheads
(gethash
non-terminal
non-terminal-look-ahead-list)))
(push
(list
look-ahead-terminal
'reduce
rhs
production-number)
old-non-terminal-look-aheads)
(puthash
non-terminal
old-non-terminal-look-aheads
non-terminal-look-ahead-list)
(puthash
hashmap-key
t
non-terminal-look-ahead-p)))))))
(maphash
(lambda (non-terminal look-ahead)
(push
(list
non-terminal
look-ahead)
parsing-table))
non-terminal-look-ahead-list))
parsing-table))
;; Algorithm 5.2 p. 350
(defun parser-generator-ll--generate-goto-table ()
"Construction of LL(k) GOTO-table.
Output the set of LL(k) tables needed to
construct a action table for the grammar G."
(let ((tables (make-hash-table :test 'equal))
(distinct-item-p (make-hash-table :test 'equal))
(stack)
(distinct-stack-item-p (make-hash-table :test 'equal))
(stack-item))
;; (1) Construct T_0, the LL(k) table associated with S {e}
(let* ((start (parser-generator--get-grammar-start))
(start-rhss (parser-generator--get-grammar-rhs start)))
(dolist (start-rhs start-rhss)
(let* ((initial-stack-item
(list
(list start)
start-rhs
(parser-generator--generate-list-of-symbol
parser-generator--look-ahead-number
parser-generator--eof-identifier))))
(puthash
initial-stack-item
t
distinct-stack-item-p)
(push
initial-stack-item
stack))))
(setq stack (nreverse stack))
(parser-generator--debug
(message "stack: %S" stack))
(while stack
(setq stack-item (pop stack))
(let* ((production-lhs
(nth 0 stack-item))
(production-rhs
(nth 1 stack-item))
(parent-follow
(nth 2 stack-item))
(concatenated-follow
(append production-rhs parent-follow))
(first-concatenated-follow
(parser-generator--first concatenated-follow nil t t))
(look-aheads
(parser-generator--merge-max-terminal-sets
first-concatenated-follow))
(sets))
(parser-generator--debug
(message "\nproduction-lhs: %S" production-lhs)
(message "production-rhs: %S" production-rhs)
(message "parent-follow: %S" parent-follow)
(message "concatenated-follow: %S" concatenated-follow)
(message "first-concatenated-follow: %S" first-concatenated-follow)
(message "look-aheads: %S" look-aheads))
;; For each non-terminal in the production right-hand side
;; push a new item to stack with a local-follow
;; and a new left-hand-side
(let ((sub-symbol-index 0)
(sub-symbol-length (length production-rhs)))
(while (< sub-symbol-index sub-symbol-length)
(let ((sub-symbol (nth sub-symbol-index production-rhs)))
(when (parser-generator--valid-non-terminal-p
sub-symbol)
(let* ((follow-set
(nthcdr (1+ sub-symbol-index) production-rhs))
(concatenated-follow-set
(append follow-set parent-follow))
(first-concatenated-follow-set
(parser-generator--first concatenated-follow-set nil t t))
(local-follow-set
(parser-generator--merge-max-terminal-sets
first-concatenated-follow-set
nil
t))
(sub-symbol-rhss
(parser-generator--get-grammar-rhs
sub-symbol)))
(parser-generator--debug
(message
"\nnon-terminal sub-symbol: %S" sub-symbol)
(message
"follow-set: %S for %S in %S"
follow-set
(nth sub-symbol-index production-rhs)
production-rhs)
(message
"concatenated-follow-set: %S"
concatenated-follow-set)
(message
"first-concatenated-follow-set: %S"
first-concatenated-follow-set)
(message
"local-follow-set: %S"
local-follow-set)
(message
"sub-symbol-rhss: %S"
sub-symbol-rhss))
(unless local-follow-set
(setq local-follow-set '(nil)))
(push
local-follow-set
sets)
(parser-generator--debug
(message
"pushed local follow set to sets: %S"
local-follow-set))
(dolist (local-follow local-follow-set)
(dolist (sub-symbol-rhs sub-symbol-rhss)
(let* ((new-stack-item
(list
(list sub-symbol)
sub-symbol-rhs
local-follow)))
(unless (gethash
new-stack-item
distinct-stack-item-p)
(parser-generator--debug
(message
"new-stack-item: %S"
new-stack-item))
(puthash
new-stack-item
t
distinct-stack-item-p)
(push
new-stack-item
stack))))))))
(setq
sub-symbol-index
(1+ sub-symbol-index))))
(setq sets (reverse sets))
(parser-generator--debug
(message
"\nsets: %S"
sets))
;; Add all distinct combinations of left-hand-side,
;; look-aheads and parent-follow to tables list here
(when look-aheads
(dolist (look-ahead look-aheads)
(let ((table
(list
look-ahead
production-rhs
sets))
(item-hash-key
(format
"%S-%S-%S"
production-lhs
parent-follow
look-ahead))
(table-hash-key
(list
production-lhs
parent-follow)))
;; Only add distinct items
(unless (gethash item-hash-key distinct-item-p)
(puthash
item-hash-key
t
distinct-item-p)
(parser-generator--debug
(message "\nnew table: %S" table))
(if (gethash
table-hash-key
tables)
(puthash
table-hash-key
(push
table
(gethash
table-hash-key
tables))
tables)
(puthash
table-hash-key
(list table)
tables))))))))
(let ((sorted-tables))
(maphash
(lambda (k v)
(push
(list k (sort v 'parser-generator--sort-list))
sorted-tables))
tables)
sorted-tables)))
;; Algorithm 5.3 p. 351
(defun parser-generator-ll--generate-action-table-k-gt-1 (tables)
"Generate a action table for an LL(k)
grammar G and TABLES.
Output M, a valid parsing table for G."
(let ((parsing-table))
;; (3) M($, e) = accept
;; (2) M(a, av) = pop for all v in E where |E| = k-1
(let ((eof-look-ahead
(parser-generator--generate-list-of-symbol
parser-generator--look-ahead-number
parser-generator--eof-identifier))
(terminal-mutations
(parser-generator--get-grammar-look-aheads))
(terminal-buffer)
(last-terminal))
(dolist (terminal-mutation terminal-mutations)
(if (equal terminal-mutation eof-look-ahead)
(push
(list
parser-generator--eof-identifier
(list
(list
eof-look-ahead
'accept)))
parsing-table)
(let ((stack-item (nth 0 terminal-mutation)))
(when (and
last-terminal
(not (equal last-terminal stack-item)))
(push
(list
last-terminal
terminal-buffer)
parsing-table)
(setq
terminal-buffer
nil))
(push
(list terminal-mutation 'pop)
terminal-buffer)
(setq
last-terminal
stack-item))))
(when (and
last-terminal
terminal-buffer)
(push
(list
last-terminal
terminal-buffer)
parsing-table)))
(dolist (table tables)
(let* ((key (nth 0 table))
(value (nth 1 table))
(left-hand-side (nth 0 key))
(parse-table))
(dolist (look-ahead-row value)
(let* ((look-ahead (nth 0 look-ahead-row))
(right-hand-side (nth 1 look-ahead-row))
(local-follow-sets (nth 2 look-ahead-row))
(non-terminal-index 0)
(sub-symbol-index 0)
(sub-symbol-length (length right-hand-side))
(production (list left-hand-side right-hand-side))
(production-number
(parser-generator--get-grammar-production-number
production))
(modified-right-hand-side))
(while (< sub-symbol-index sub-symbol-length)
(let ((sub-symbol (nth sub-symbol-index right-hand-side)))
(if (parser-generator--valid-non-terminal-p
sub-symbol)
(let ((local-follow
(car (nth non-terminal-index local-follow-sets))))
(push
(list
(list sub-symbol)
local-follow)
modified-right-hand-side)
(setq
non-terminal-index
(1+ non-terminal-index)))
(push
sub-symbol
modified-right-hand-side)))
(setq
sub-symbol-index
(1+ sub-symbol-index)))
(setq
modified-right-hand-side
(reverse modified-right-hand-side))
(push
(list
look-ahead
'reduce
modified-right-hand-side
production-number)
parse-table)))
(push
(list
key
parse-table)
parsing-table)))
parsing-table))
(defun parser-generator-ll--valid-grammar-k-eq-1-p ()
"Test for LL(1)-ness. Output t if grammar is LL(1), nil otherwise."
(let* ((non-terminals (parser-generator--get-grammar-non-terminals))
(non-terminal-length (length non-terminals))
(non-terminal-index 0)
(non-terminal)
(valid t))
(while (and
valid
(< non-terminal-index non-terminal-length))
(setq non-terminal (nth non-terminal-index non-terminals))
(let* ((rhss (parser-generator--get-grammar-rhs non-terminal))
(rhss-length (length rhss))
(rhss-index 0)
(rhs)
(look-aheads (make-hash-table :test 'equal)))
(while (and
valid
(< rhss-index rhss-length))
(setq rhs (nth rhss-index rhss))
(let* ((firsts-rhs (parser-generator--first rhs))
(firsts-rhs-length (length firsts-rhs))
(firsts-index 0)
(first-rhs))
(while (and
valid
(< firsts-index firsts-rhs-length))
(setq first-rhs (nth firsts-index firsts-rhs))
(let ((first-rhs-hash (format "%S" first-rhs)))
(if (gethash first-rhs-hash look-aheads)
(setq valid nil)
(puthash first-rhs-hash t look-aheads)))
(setq firsts-index (1+ firsts-index))))
(setq rhss-index (1+ rhss-index))))
(setq non-terminal-index (1+ non-terminal-index)))
valid))
;; Algorithm 5.4 p. 357
(defun parser-generator-ll--valid-grammar-k-gt-1-p ()
"Test for LL(k)-ness. Output t if grammar is LL(k), nil otherwise."
(let ((stack)
(stack-item)
(distinct-production-p (make-hash-table :test 'equal))
(valid t))
;; (1) Construct T_0, the LL(k) table associated with S {e}
(let* ((start (parser-generator--get-grammar-start))
(start-rhss (parser-generator--get-grammar-rhs start)))
(dolist (start-rhs start-rhss)
(let* ((production (list (list start) start-rhs)))
(push
production
stack)
(puthash
production
t
distinct-production-p))))
(setq stack (nreverse stack))
(parser-generator--debug
(message "stack: %S" stack))
(while (and
stack
valid)
(setq stack-item (pop stack))
(let ((production-rhs
(nth 1 stack-item)))
;; For each non-terminal in the production right-hand side
;; push a new item to stack with a local-follow
;; and a new left-hand-side
(let ((sub-symbol-index 0)
(sub-symbol-length (length production-rhs)))
(while (< sub-symbol-index sub-symbol-length)
(let ((sub-symbol (nth sub-symbol-index production-rhs)))
(when (parser-generator--valid-non-terminal-p
sub-symbol)
(let* ((local-follow
(nthcdr (1+ sub-symbol-index) production-rhs))
(first-local-follow-sets
(parser-generator--first local-follow nil t t))
(sub-symbol-rhss
(parser-generator--get-grammar-rhs sub-symbol))
(distinct-item-p
(make-hash-table :test 'equal)))
(parser-generator--debug
(message "\nsub-symbol: %S" sub-symbol)
(message "local-follow: %S" local-follow)
(message "first-local-follow-sets: %S" first-local-follow-sets)
(message "sub-symbol-rhss: %S" sub-symbol-rhss))
;; Calculate following terminals to see if there is a conflict
(dolist (sub-symbol-rhs sub-symbol-rhss)
(let ((first-sub-symbol-rhs
(parser-generator--first sub-symbol-rhs nil t t)))
(let ((merged-terminal-sets
(parser-generator--merge-max-terminal-sets
first-sub-symbol-rhs
first-local-follow-sets)))
(parser-generator--debug
(message "sub-symbol-rhs: %S" sub-symbol-rhs)
(message "first-sub-symbol-rhs: %S" first-sub-symbol-rhs)
(message "merged-terminal-sets: %S" merged-terminal-sets))
(dolist (merged-terminal-set merged-terminal-sets)
(if (gethash
merged-terminal-set
distinct-item-p)
(progn
(setq valid nil)
(parser-generator--debug
(message
"merged-terminal-set: %S was not distinct"
merged-terminal-set)))
(puthash
merged-terminal-set
t
distinct-item-p)))))
;; Add production to stack if it has not been added already
(let ((production
(list
(list sub-symbol)
sub-symbol-rhs)))
(unless
(gethash
production
distinct-production-p)
(push
production
stack)
(puthash
production
t
distinct-production-p)))))))
(setq