1999-01-30 01:19:00 +00:00
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;;; The contents of this file are subject to the Netscape Public License
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;;; Version 1.0 (the "NPL"); you may not use this file except in
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;;; compliance with the NPL. You may obtain a copy of the NPL at
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;;; http://www.mozilla.org/NPL/
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;;;
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;;; Software distributed under the NPL is distributed on an "AS IS" basis,
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;;; WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
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;;; for the specific language governing rights and limitations under the
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;;; NPL.
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;;;
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;;; The Initial Developer of this code under the NPL is Netscape
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;;; Communications Corporation. Portions created by Netscape are
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;;; Copyright (C) 1998 Netscape Communications Corporation. All Rights
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;;; Reserved.
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;;;
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;;; LALR(1) and LR(1) grammar generator
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;;;
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;;; Waldemar Horwat (waldemar@netscape.com)
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;;;
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;;; ------------------------------------------------------------------------------------------------------
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; kernel-item-alist is a list of pairs (item . prev), where item is a kernel item
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; and prev is either nil or a laitem. kernel is a list of the kernel items in a canonical order.
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; Return a new state with the given list of kernel items and state number.
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1999-05-17 05:05:10 +00:00
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; If update-propagates is true, for each non-null prev in kernel-item-alist, update
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; (laitem-propagates prev) to include the corresponding laitem in the new state. Do this anyway
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; for internal lookaheads, regardless of update-propagates.
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(defun make-state (grammar kernel kernel-item-alist update-propagates number initial-lookaheads)
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1999-01-30 01:19:00 +00:00
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(let ((laitems nil)
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(laitems-hash (make-hash-table :test #'eq)))
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(labels
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;Create a laitem for this item and add the association item->laitem to the laitems-hash
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;hash table if it's not there already. Regardless of whether a new laitem was created,
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;update the laitem's lookaheads to also include the given lookaheads.
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1999-06-03 20:52:04 +00:00
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;forbidden is a terminalset of terminals that must not occur immediately after the dot in this
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;laitem. The forbidden set is inherited from constraints in parent laitems in the same state.
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;If prev is non-null, update (laitem-propagates prev) to include the laitem and the given
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;passthrough terminalset if it's not already included there.
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1999-01-30 01:19:00 +00:00
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;If a new laitem was created and its first symbol after the dot exists and is a
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;nonterminal A, recursively close items A->.rhs corresponding to all rhs's in the
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;grammar's rule for A.
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1999-06-03 20:52:04 +00:00
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((close-item (item forbidden lookaheads prev passthroughs)
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(let ((production (item-production item))
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(laitem (gethash item laitems-hash)))
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(unless (terminalset-empty? forbidden)
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(multiple-value-bind (dot-lookaheads dot-passthroughs)
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(string-initial-terminals grammar (item-unseen item) (production-constraints production) (item-dot item))
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(let ((dot-initial (terminalset-union dot-lookaheads dot-passthroughs)))
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;Check whether any terminal can start this item. If not, skip this item altogether.
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(when (terminalset-empty? (terminalset-difference dot-initial forbidden))
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;Mark skipped items in the laitems-hash table.
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(when (and laitem (not (eq laitem 'forbidden)))
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(error "Two laitems in the same state differing only in forbidden initial terminal constraints: ~S" laitem))
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(setf (gethash item laitems-hash) 'forbidden)
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(return-from close-item))
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;Convert forbidden into a canonical format by removing terminals that cannot begin this item's expansion anyway.
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(terminalset-intersection-f forbidden dot-initial))))
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1999-01-30 01:19:00 +00:00
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(if laitem
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1999-06-03 20:52:04 +00:00
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(progn
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(unless (terminalset-= forbidden (laitem-forbidden laitem))
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(error "Two laitems in the same state differing only in forbidden initial terminal constraints: ~S" laitem))
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(terminalset-union-f (laitem-lookaheads laitem) lookaheads))
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1999-01-30 01:19:00 +00:00
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(let ((item-next-symbol (item-next-symbol item)))
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1999-06-03 20:52:04 +00:00
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(setq laitem (allocate-laitem grammar item forbidden lookaheads))
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1999-01-30 01:19:00 +00:00
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(push laitem laitems)
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(setf (gethash item laitems-hash) laitem)
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(when (nonterminal? item-next-symbol)
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1999-06-03 20:52:04 +00:00
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(let* ((dot (item-dot item))
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(next-forbidden (terminalset-union forbidden
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(terminalset-complement (general-production-lookahead-constraint production dot)))))
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(multiple-value-bind (next-lookaheads next-passthroughs)
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(string-initial-terminals grammar (rest (item-unseen item)) (production-constraints production) (1+ dot))
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(let ((next-prev (and (not (terminalset-empty? next-passthroughs)) laitem)))
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(dolist (production (rule-productions (grammar-rule grammar item-next-symbol)))
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(close-item (make-item grammar production 0) next-forbidden next-lookaheads next-prev next-passthroughs))))))))
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1999-01-30 01:19:00 +00:00
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(when prev
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1999-06-03 20:52:04 +00:00
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(laitem-add-propagation prev laitem passthroughs)))))
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1999-01-30 01:19:00 +00:00
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1999-05-17 05:05:10 +00:00
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(dolist (acons kernel-item-alist)
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1999-06-03 20:52:04 +00:00
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(close-item (car acons)
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*empty-terminalset*
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initial-lookaheads
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(and update-propagates (cdr acons))
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*full-terminalset*))
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1999-01-30 01:19:00 +00:00
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(allocate-state number kernel (nreverse laitems)))))
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1999-06-03 20:52:04 +00:00
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; f is a function that takes three arguments:
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; a grammar symbol;
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; a list of kernel items in order of increasing item number;
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; a list of pairs (item . prev), where item is a kernel item and prev is a laitem.
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1999-01-30 01:19:00 +00:00
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; For each possible symbol X that can be shifted while in the given state S, call
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; f giving it S and the list of items that constitute the kernel of that shift's destination
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; state. The prev's are the sources of the corresponding shifted items.
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(defun state-each-shift-item-alist (f state)
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(let ((shift-symbols-hash (make-hash-table :test *grammar-symbol-=*)))
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(dolist (source-laitem (state-laitems state))
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(let* ((source-item (laitem-item source-laitem))
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(shift-symbol (item-next-symbol source-item)))
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(when shift-symbol
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(push (cons (item-next source-item) source-laitem)
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(gethash shift-symbol shift-symbols-hash)))))
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;Use dolist/gethash instead of maphash to make state assignments deterministic.
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(dolist (shift-symbol (sorted-hash-table-keys shift-symbols-hash))
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(let ((kernel-item-alist (gethash shift-symbol shift-symbols-hash)))
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(funcall f shift-symbol (sort (mapcar #'car kernel-item-alist) #'< :key #'item-number) kernel-item-alist)))))
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;;; ------------------------------------------------------------------------------------------------------
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;;; LR(1)
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; kernel-item-alist should have the same kernel items as state.
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; Return true if the prev lookaheads in kernel-item-alist are the same as or subsets of
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; the corresponding lookaheads in the state's kernel laitems.
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(defun state-subsumes-lookaheads (state kernel-item-alist)
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(every
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#'(lambda (acons)
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(terminalset-<= (laitem-lookaheads (cdr acons))
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(laitem-lookaheads (state-laitem state (car acons)))))
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kernel-item-alist))
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; kernel-item-alist should have the same kernel items as state.
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; Return true if the prev lookaheads in kernel-item-alist are weakly compatible
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; with the lookaheads in the state's kernel laitems.
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(defun state-weakly-compatible (state kernel-item-alist)
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(labels
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((lookahead-weakly-compatible (lookahead1a lookahead1b lookahead2a lookahead2b)
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(or (and (terminalsets-disjoint lookahead1a lookahead2b)
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(terminalsets-disjoint lookahead1b lookahead2a))
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(not (terminalsets-disjoint lookahead1a lookahead1b))
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(not (terminalsets-disjoint lookahead2a lookahead2b))))
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(lookahead-list-weakly-compatible (lookahead1a lookaheads1 lookahead2a lookaheads2)
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(or (endp lookaheads1)
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(and (lookahead-weakly-compatible lookahead1a (first lookaheads1) lookahead2a (first lookaheads2))
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(lookahead-list-weakly-compatible lookahead1a (rest lookaheads1) lookahead2a (rest lookaheads2)))))
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(lookahead-lists-weakly-compatible (lookaheads1 lookaheads2)
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(or (endp lookaheads1)
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(and (lookahead-list-weakly-compatible (first lookaheads1) (rest lookaheads1) (first lookaheads2) (rest lookaheads2))
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(lookahead-lists-weakly-compatible (rest lookaheads1) (rest lookaheads2))))))
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(or (= (length kernel-item-alist) 1)
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(lookahead-lists-weakly-compatible
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(mapcar #'(lambda (acons) (laitem-lookaheads (state-laitem state (car acons)))) kernel-item-alist)
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(mapcar #'(lambda (acons) (laitem-lookaheads (cdr acons))) kernel-item-alist)))))
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1999-05-17 05:05:10 +00:00
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1999-01-30 01:19:00 +00:00
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; Propagate all lookaheads in the state.
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(defun propagate-internal-lookaheads (state)
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(dolist (src-laitem (state-laitems state))
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(let ((src-lookaheads (laitem-lookaheads src-laitem)))
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1999-06-03 20:52:04 +00:00
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(dolist (propagation (laitem-propagates src-laitem))
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(let ((dst-laitem (car propagation))
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(mask (cdr propagation)))
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(terminalset-union-f (laitem-lookaheads dst-laitem) (terminalset-intersection src-lookaheads mask)))))))
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1999-01-30 01:19:00 +00:00
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; Propagate all lookaheads in kernel-item-alist, which must target destination-state.
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; Mark destination-state as dirty in the dirty-states hash table.
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(defun propagate-external-lookaheads (kernel-item-alist destination-state dirty-states)
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(dolist (acons kernel-item-alist)
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(let ((dest-laitem (state-laitem destination-state (car acons)))
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(src-laitem (cdr acons)))
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1999-06-03 20:52:04 +00:00
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(terminalset-union-f (laitem-lookaheads dest-laitem) (laitem-lookaheads src-laitem))))
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1999-01-30 01:19:00 +00:00
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(setf (gethash destination-state dirty-states) t))
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; Make all states in the grammar and return the initial state.
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; Initialize the grammar's list of states.
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; Set up the laitems' propagate lists but do not propagate lookaheads yet.
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; Initialize the states' gotos lists.
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; Initialize the states' shift (but not reduce or accept) transitions in the transitions lists.
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(defun add-all-lr-states (grammar)
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(let* ((initial-item (make-item grammar (grammar-start-production grammar) 0))
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(lr-states-hash (make-hash-table :test #'equal)) ;kernel -> list of states with that kernel
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(initial-kernel (list initial-item))
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1999-05-17 05:05:10 +00:00
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(initial-state (make-state grammar initial-kernel (list (cons initial-item nil)) nil 0 (make-terminalset grammar *end-marker*)))
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1999-01-30 01:19:00 +00:00
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(states (list initial-state))
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(next-state-number 1))
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(setf (gethash initial-kernel lr-states-hash) (list initial-state))
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(do ((source-states (list initial-state))
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(dirty-states (make-hash-table :test #'eq))) ;Set of states whose kernel lookaheads changed and haven't been propagated yet
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((and (endp source-states) (zerop (hash-table-count dirty-states))))
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(labels
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((make-destination-state (kernel kernel-item-alist)
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(let* ((possible-destination-states (gethash kernel lr-states-hash))
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(destination-state (find-if #'(lambda (possible-destination-state)
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(state-subsumes-lookaheads possible-destination-state kernel-item-alist))
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possible-destination-states)))
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(cond
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(destination-state)
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((setq destination-state (find-if #'(lambda (possible-destination-state)
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(state-weakly-compatible possible-destination-state kernel-item-alist))
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possible-destination-states))
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(propagate-external-lookaheads kernel-item-alist destination-state dirty-states))
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(t
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1999-05-17 05:05:10 +00:00
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(setq destination-state (make-state grammar kernel kernel-item-alist nil next-state-number *empty-terminalset*))
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1999-01-30 01:19:00 +00:00
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(propagate-external-lookaheads kernel-item-alist destination-state dirty-states)
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(push destination-state (gethash kernel lr-states-hash))
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(incf next-state-number)
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(push destination-state states)
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(push destination-state source-states)))
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destination-state))
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(update-destination-state (destination-state kernel-item-alist)
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(cond
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((state-subsumes-lookaheads destination-state kernel-item-alist)
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destination-state)
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((state-weakly-compatible destination-state kernel-item-alist)
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(propagate-external-lookaheads kernel-item-alist destination-state dirty-states)
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destination-state)
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(t (make-destination-state (state-kernel destination-state) kernel-item-alist)))))
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(if source-states
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(let ((source-state (pop source-states)))
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(remhash source-state dirty-states)
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(propagate-internal-lookaheads source-state)
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(state-each-shift-item-alist
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#'(lambda (shift-symbol kernel kernel-item-alist)
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(let ((destination-state (make-destination-state kernel kernel-item-alist)))
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(if (nonterminal? shift-symbol)
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(push (cons shift-symbol destination-state)
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(state-gotos source-state))
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(push (cons shift-symbol (make-shift-transition destination-state))
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(state-transitions source-state)))))
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source-state))
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(dolist (dirty-state (sort (hash-table-keys dirty-states) #'< :key #'state-number))
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(when (remhash dirty-state dirty-states)
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(propagate-internal-lookaheads dirty-state)
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(state-each-shift-item-alist
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#'(lambda (shift-symbol kernel kernel-item-alist)
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(declare (ignore kernel))
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(if (nonterminal? shift-symbol)
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(let* ((destination-binding (assoc shift-symbol (state-gotos dirty-state) :test *grammar-symbol-=*))
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(destination-state (assert-non-null (cdr destination-binding))))
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(setf (cdr destination-binding) (update-destination-state destination-state kernel-item-alist)))
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(let* ((destination-transition (cdr (assoc shift-symbol (state-transitions dirty-state) :test *grammar-symbol-=*)))
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(destination-state (assert-non-null (transition-state destination-transition))))
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(setf (transition-state destination-transition)
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(update-destination-state destination-state kernel-item-alist)))))
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dirty-state))))))
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(setf (grammar-states grammar) (nreverse states))
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initial-state))
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;;; ------------------------------------------------------------------------------------------------------
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;;; LALR(1)
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; Make all states in the grammar and return the initial state.
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; Initialize the grammar's list of states.
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; Set up the laitems' propagate lists but do not propagate lookaheads yet.
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; Initialize the states' gotos lists.
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; Initialize the states' shift (but not reduce or accept) transitions in the transitions lists.
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(defun add-all-lalr-states (grammar)
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(let* ((initial-item (make-item grammar (grammar-start-production grammar) 0))
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(lalr-states-hash (make-hash-table :test #'equal)) ;kernel -> state
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(initial-kernel (list initial-item))
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1999-05-17 05:05:10 +00:00
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(initial-state (make-state grammar initial-kernel (list (cons initial-item nil)) t 0 (make-terminalset grammar *end-marker*)))
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1999-01-30 01:19:00 +00:00
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(states (list initial-state))
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(next-state-number 1))
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(setf (gethash initial-kernel lalr-states-hash) initial-state)
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(do ((source-states (list initial-state)))
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((endp source-states))
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(let ((source-state (pop source-states)))
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(state-each-shift-item-alist
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#'(lambda (shift-symbol kernel kernel-item-alist)
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(let ((destination-state (gethash kernel lalr-states-hash)))
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(if destination-state
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(dolist (acons kernel-item-alist)
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1999-06-03 20:52:04 +00:00
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(laitem-add-propagation (cdr acons) (state-laitem destination-state (car acons)) *full-terminalset*))
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1999-01-30 01:19:00 +00:00
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(progn
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1999-05-17 05:05:10 +00:00
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(setq destination-state (make-state grammar kernel kernel-item-alist t next-state-number *empty-terminalset*))
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1999-01-30 01:19:00 +00:00
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(setf (gethash kernel lalr-states-hash) destination-state)
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(incf next-state-number)
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(push destination-state states)
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(push destination-state source-states)))
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(if (nonterminal? shift-symbol)
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(push (cons shift-symbol destination-state)
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(state-gotos source-state))
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(push (cons shift-symbol (make-shift-transition destination-state))
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(state-transitions source-state)))))
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source-state)))
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(setf (grammar-states grammar) (nreverse states))
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initial-state))
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; Propagate the lookaheads in the LALR(1) grammar.
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(defun propagate-lalr-lookaheads (grammar)
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(let ((dirty-laitems (make-hash-table :test #'eq)))
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(dolist (state (grammar-states grammar))
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(dolist (laitem (state-laitems state))
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(when (and (laitem-propagates laitem) (not (terminalset-empty? (laitem-lookaheads laitem))))
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(setf (gethash laitem dirty-laitems) t))))
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(do ()
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((zerop (hash-table-count dirty-laitems)))
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(dolist (dirty-laitem (hash-table-keys dirty-laitems))
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(remhash dirty-laitem dirty-laitems)
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(let ((src-lookaheads (laitem-lookaheads dirty-laitem)))
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1999-06-03 20:52:04 +00:00
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(dolist (propagation (laitem-propagates dirty-laitem))
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(let ((dst-laitem (car propagation))
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(mask (cdr propagation)))
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(let* ((old-dst-lookaheads (laitem-lookaheads dst-laitem))
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(new-dst-lookaheads (terminalset-union old-dst-lookaheads (terminalset-intersection src-lookaheads mask))))
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(unless (terminalset-= old-dst-lookaheads new-dst-lookaheads)
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(setf (laitem-lookaheads dst-laitem) new-dst-lookaheads)
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(setf (gethash dst-laitem dirty-laitems) t))))))))
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1999-01-30 01:19:00 +00:00
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;Erase the propagates chains in all laitems.
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(dolist (state (grammar-states grammar))
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(dolist (laitem (state-laitems state))
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(setf (laitem-propagates laitem) nil)))))
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;;; ------------------------------------------------------------------------------------------------------
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; Calculate the reduce and accept transitions in the grammar.
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; Also sort all transitions by their terminal numbers and gotos by their nonterminal numbers.
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; Conflicting transitions are sorted as follows:
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; shifts come before reduces and accepts
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; accepts come before reduces
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; reduces with lower production numbers come before reduces with higher production numbers
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; Disambiguation will choose the first member of a sorted list of conflicting transitions.
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(defun finish-transitions (grammar)
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(dolist (state (grammar-states grammar))
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(dolist (laitem (state-laitems state))
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(let ((item (laitem-item laitem)))
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(unless (item-next-symbol item)
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1999-06-03 20:52:04 +00:00
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(let ((lookaheads (terminalset-difference
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(terminalset-intersection
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(laitem-lookaheads laitem)
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(general-production-lookahead-constraint (item-production item) (item-dot item)))
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(laitem-forbidden laitem))))
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(if (grammar-symbol-= (item-lhs item) *start-nonterminal*)
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(when (terminal-in-terminalset grammar *end-marker* lookaheads)
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(push (cons *end-marker* (make-accept-transition))
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(state-transitions state)))
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(map-terminalset-reverse
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#'(lambda (lookahead)
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(push (cons lookahead (make-reduce-transition (item-production item)))
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(state-transitions state)))
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grammar
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lookaheads))))))
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1999-01-30 01:19:00 +00:00
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(setf (state-gotos state)
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(sort (state-gotos state) #'< :key #'(lambda (goto-cons) (state-number (cdr goto-cons)))))
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(setf (state-transitions state)
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(sort (state-transitions state)
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#'(lambda (transition-cons-1 transition-cons-2)
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(let ((terminal-number-1 (terminal-number grammar (car transition-cons-1)))
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(terminal-number-2 (terminal-number grammar (car transition-cons-2))))
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(cond
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((< terminal-number-1 terminal-number-2) t)
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((> terminal-number-1 terminal-number-2) nil)
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(t (let* ((transition1 (cdr transition-cons-1))
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(transition2 (cdr transition-cons-2))
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(transition-kind-1 (transition-kind transition1))
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(transition-kind-2 (transition-kind transition2)))
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(cond
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((eq transition-kind-2 :shift) nil)
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((eq transition-kind-1 :shift) t)
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((eq transition-kind-2 :accept) nil)
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((eq transition-kind-1 :accept) t)
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(t (let ((production-number-1 (production-number (transition-production transition1)))
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(production-number-2 (production-number (transition-production transition2))))
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(< production-number-1 production-number-2)))))))))))))
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; Find ambiguities, if any, in the grammar. Report them on the given stream.
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; Fix all ambiguities in favor of the first transition listed
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; (the transitions were ordered by finish-transitions).
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(defun report-and-fix-ambiguities (grammar stream)
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(let ((found-ambiguities nil))
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(pprint-logical-block (stream nil)
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(dolist (state (grammar-states grammar))
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(labels
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((report-ambiguity (transition-cons other-transition-conses)
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(unless found-ambiguities
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(setq found-ambiguities t)
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(format stream "~&Ambiguities:")
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(pprint-indent :block 2 stream))
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(pprint-newline :mandatory stream)
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(pprint-logical-block (stream nil)
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(format stream "S~D: ~W ~:_=> ~:_" (state-number state) (car transition-cons))
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(pprint-logical-block (stream nil)
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(dolist (a (cons transition-cons other-transition-conses))
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(print-transition (cdr a) stream)
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(format stream " ~:_")))))
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; Check the list of transition-conses and report ambiguities.
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; start is the start of a possibly larger list of transition-conses whose tail
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; is the given list. If ambiguities exist, return a copy of start up to the
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; position of list in it followed by list with ambiguities removed. If not,
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; return start unchanged.
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(check (transition-conses start)
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(if transition-conses
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(let* ((transition-cons (first transition-conses))
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(transition-terminal (car transition-cons))
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(transition-conses-rest (rest transition-conses)))
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(if transition-conses-rest
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(if (grammar-symbol-= transition-terminal (car (first transition-conses-rest)))
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(let ((unrelated-transitions
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(member-if #'(lambda (a) (not (grammar-symbol-= transition-terminal (car a))))
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transition-conses-rest)))
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(report-ambiguity transition-cons (ldiff transition-conses-rest unrelated-transitions))
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(check unrelated-transitions (append (ldiff start transition-conses-rest) unrelated-transitions)))
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(check transition-conses-rest start))
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start))
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start)))
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(let ((transition-conses (state-transitions state)))
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(setf (state-transitions state) (check transition-conses transition-conses))))))
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(when found-ambiguities
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(pprint-newline :mandatory stream))))
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; Erase the existing parser, if any, for the given grammar.
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(defun clear-parser (grammar)
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(clrhash (grammar-items-hash grammar))
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(setf (grammar-states grammar) nil))
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; Construct a LR or LALR parser in the given grammar. kind should be either :lalr-1 or :lr-1.
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; Return the grammar.
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(defun compile-parser (grammar kind)
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(clear-parser grammar)
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(ecase kind
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(:lalr-1
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(add-all-lalr-states grammar)
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(propagate-lalr-lookaheads grammar))
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(:lr-1
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(add-all-lr-states grammar)))
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(finish-transitions grammar)
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(report-and-fix-ambiguities grammar *error-output*)
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grammar)
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; Make the grammar and compile its parser. kind should be either :lalr-1 or :lr-1.
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1999-02-10 06:39:58 +00:00
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(defun make-and-compile-grammar (kind parametrization start-symbol grammar-source &optional excluded-nonterminals-source)
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(compile-parser (make-grammar parametrization start-symbol grammar-source excluded-nonterminals-source)
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1999-01-30 01:19:00 +00:00
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kind))
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;;; ------------------------------------------------------------------------------------------------------
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; Parse the input list of tokens to produce a parse tree.
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; token-terminal is a function that returns a terminal symbol when given an input token.
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(defun parse (grammar token-terminal input)
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(labels
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(;Continue the parse with the given parser stack and remainder of input.
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(parse-step (stack input)
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(if (endp input)
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(parse-step-1 stack *end-marker* nil nil)
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(let ((token (first input)))
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(parse-step-1 stack (funcall token-terminal token) token (rest input)))))
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;Same as parse-step except that the next input terminal has been determined already.
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;input-rest contains the input tokens after the next token.
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(parse-step-1 (stack terminal token input-rest)
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(let* ((state (caar stack))
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(transition (cdr (assoc terminal (state-transitions state) :test *grammar-symbol-=*))))
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(if transition
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(case (transition-kind transition)
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(:shift (parse-step (acons (transition-state transition) token stack) input-rest))
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(:reduce (let ((production (transition-production transition))
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(expansion nil))
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(dotimes (i (production-rhs-length production))
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(push (cdr (pop stack)) expansion))
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(let* ((state (caar stack))
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(dst-state (assert-non-null
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(cdr (assoc (production-lhs production) (state-gotos state) :test *grammar-symbol-=*))))
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(named-expansion (cons (production-name production) expansion)))
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(parse-step-1 (acons dst-state named-expansion stack) terminal token input-rest))))
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(:accept (cdar stack))
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(t (error "Bad transition: ~S" transition)))
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(error "Parse error on ~S followed by ~S ..." token (ldiff input-rest (nthcdr 10 input-rest)))))))
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(parse-step (list (cons (grammar-start-state grammar) nil)) input)))
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;;; ------------------------------------------------------------------------------------------------------
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;;; ACTIONS
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; Initialize the action-signatures hash table, setting each grammar symbol's signature
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; to null for now. Also clear all production actions in the grammar.
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(defun clear-actions (grammar)
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(let ((action-signatures (make-hash-table :test *grammar-symbol-=*))
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(terminals (grammar-terminals grammar))
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(nonterminals (grammar-nonterminals grammar)))
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(dotimes (i (length terminals))
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(setf (gethash (svref terminals i) action-signatures) nil))
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(dotimes (i (length nonterminals))
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(setf (gethash (svref nonterminals i) action-signatures) nil))
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(setf (grammar-action-signatures grammar) action-signatures)
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(each-grammar-production
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grammar
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#'(lambda (production)
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(setf (production-actions production) nil)
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(setf (production-n-action-args production) nil)
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(setf (production-evaluator-code production) nil)
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(setf (production-evaluator production) nil)))
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(clrhash (grammar-terminal-actions grammar))))
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; Declare the type of action action-symbol, when called on general-grammar-symbol, to be type-expr.
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; Signal an error on duplicate actions.
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; It's OK if some of the symbol instances don't exist, as long as at least one does.
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(defun declare-action (grammar general-grammar-symbol action-symbol type-expr)
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(unless (and action-symbol (symbolp action-symbol))
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(error "Bad action name ~S" action-symbol))
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(let ((action-signatures (grammar-action-signatures grammar))
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(grammar-symbols (general-grammar-symbol-instances grammar general-grammar-symbol))
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(symbol-exists nil))
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(dolist (grammar-symbol grammar-symbols)
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(let ((signature (gethash grammar-symbol action-signatures :undefined)))
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(unless (eq signature :undefined)
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(setq symbol-exists t)
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(when (assoc action-symbol signature :test #'eq)
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(error "Attempt to redefine the type of action ~S on ~S" action-symbol grammar-symbol))
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(setf (gethash grammar-symbol action-signatures)
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(nconc signature (list (cons action-symbol type-expr))))
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(if (nonterminal? grammar-symbol)
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(dolist (production (rule-productions (grammar-rule grammar grammar-symbol)))
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(setf (production-actions production)
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(nconc (production-actions production) (list (cons action-symbol nil)))))
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(let ((terminal-actions (grammar-terminal-actions grammar)))
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(assert-type grammar-symbol terminal)
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(setf (gethash grammar-symbol terminal-actions)
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(nconc (gethash grammar-symbol terminal-actions) (list (cons action-symbol nil)))))))))
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(unless symbol-exists
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(error "Bad action grammar symbol ~S" grammar-symbols))))
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; Return the list of pairs (action-symbol . type-or-type-expr) for this grammar-symbol.
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; The pairs are in order from oldest to newest action-symbols added to this grammar-symbol.
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(declaim (inline grammar-symbol-signature))
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(defun grammar-symbol-signature (grammar grammar-symbol)
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(gethash grammar-symbol (grammar-action-signatures grammar)))
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; Return the list of action types of the grammar's user start-symbol.
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(defun grammar-user-start-action-types (grammar)
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(mapcar #'cdr (grammar-symbol-signature grammar (gramar-user-start-symbol grammar))))
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; If action action-symbol is declared on grammar-symbol, return two values:
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; t, and
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; the action's type-expr;
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; If not, return nil.
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(defun action-declaration (grammar grammar-symbol action-symbol)
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(let ((declaration (assoc action-symbol (grammar-symbol-signature grammar grammar-symbol) :test #'eq)))
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(and declaration
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(values t (cdr declaration)))))
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; Call f on every action declaration, passing it two arguments:
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; the grammar-symbol;
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; a pair (action-symbol . type-expr).
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; f may modify the action's type-expr.
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(defun each-action-declaration (grammar f)
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(maphash #'(lambda (grammar-symbol signature)
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(dolist (action-declaration signature)
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(funcall f grammar-symbol action-declaration)))
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(grammar-action-signatures grammar)))
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; Define action action-symbol, when called on the production with the given name,
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|
; to be action-expr. The action should have been declared already.
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|
(defun define-action (grammar production-name action-symbol action-expr)
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|
(dolist (production (general-production-productions (grammar-general-production grammar production-name)))
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|
(let ((definition (assoc action-symbol (production-actions production) :test #'eq)))
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|
(cond
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((null definition)
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|
(error "Attempt to define action ~S on ~S, which hasn't been declared yet" action-symbol production-name))
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|
((cdr definition)
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|
(error "Duplicate definition of action ~S on ~S" action-symbol production-name))
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|
(t (setf (cdr definition) (make-action action-expr)))))))
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; Define action action-symbol, when called on the given terminal,
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|
; to execute the given function, which should take a token as an input and
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|
; produce a value of the proper type as output.
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|
; The action should have been declared already.
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|
(defun define-terminal-action (grammar terminal action-symbol action-function)
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|
|
(assert-type action-function function)
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|
|
(let ((definition (assoc action-symbol (gethash terminal (grammar-terminal-actions grammar)) :test #'eq)))
|
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|
|
(cond
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|
((null definition)
|
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|
|
(error "Attempt to define action ~S on ~S, which hasn't been declared yet" action-symbol terminal))
|
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|
|
((cdr definition)
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|
|
(error "Duplicate definition of action ~S on ~S" action-symbol terminal))
|
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|
|
(t (setf (cdr definition) action-function)))))
|
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|
; Parse the input list of tokens to produce a list of action results.
|
|
|
|
|
; token-terminal is a function that returns a terminal symbol when given an input token.
|
|
|
|
|
; If trace is:
|
|
|
|
|
; nil, don't print trace information
|
|
|
|
|
; :code, print trace information, including action code
|
|
|
|
|
; other print trace information
|
|
|
|
|
; Return two values:
|
|
|
|
|
; the list of action results;
|
|
|
|
|
; the list of action results' types.
|
|
|
|
|
(defun action-parse (grammar token-terminal input &key trace)
|
|
|
|
|
(labels
|
|
|
|
|
(;Continue the parse with the given stacks and remainder of input.
|
|
|
|
|
(parse-step (state-stack value-stack input)
|
|
|
|
|
(if (endp input)
|
|
|
|
|
(parse-step-1 state-stack value-stack *end-marker* nil nil)
|
|
|
|
|
(let ((token (first input)))
|
|
|
|
|
(parse-step-1 state-stack value-stack (funcall token-terminal token) token (rest input)))))
|
|
|
|
|
|
|
|
|
|
;Same as parse-step except that the next input terminal has been determined already.
|
|
|
|
|
;input-rest contains the input tokens after the next token.
|
|
|
|
|
(parse-step-1 (state-stack value-stack terminal token input-rest)
|
|
|
|
|
(let* ((state (car state-stack))
|
|
|
|
|
(transition (cdr (assoc terminal (state-transitions state) :test *grammar-symbol-=*))))
|
|
|
|
|
(if transition
|
|
|
|
|
(case (transition-kind transition)
|
|
|
|
|
(:shift
|
|
|
|
|
(dolist (action-function-binding (gethash terminal (grammar-terminal-actions grammar)))
|
|
|
|
|
(push (funcall (cdr action-function-binding) token) value-stack))
|
|
|
|
|
(parse-step (cons (transition-state transition) state-stack) value-stack input-rest))
|
|
|
|
|
(:reduce
|
|
|
|
|
(let* ((production (transition-production transition))
|
|
|
|
|
(state-stack (nthcdr (production-rhs-length production) state-stack))
|
|
|
|
|
(state (car state-stack))
|
|
|
|
|
(dst-state (assert-non-null
|
|
|
|
|
(cdr (assoc (production-lhs production) (state-gotos state) :test *grammar-symbol-=*))))
|
|
|
|
|
(value-stack (funcall (production-evaluator production) value-stack)))
|
|
|
|
|
(parse-step-1 (cons dst-state state-stack) value-stack terminal token input-rest)))
|
|
|
|
|
(:accept (values (nreverse value-stack) (grammar-user-start-action-types grammar)))
|
|
|
|
|
(t (error "Bad transition: ~S" transition)))
|
|
|
|
|
(error "Parse error on ~S followed by ~S ..." token (ldiff input-rest (nthcdr 10 input-rest)))))))
|
|
|
|
|
|
|
|
|
|
(if trace
|
|
|
|
|
(trace-action-parse grammar token-terminal input trace)
|
|
|
|
|
(parse-step (list (grammar-start-state grammar)) nil input))))
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
; Same as action-parse, but with tracing information
|
|
|
|
|
; If trace is:
|
|
|
|
|
; :code, print trace information, including action code
|
|
|
|
|
; other print trace information
|
|
|
|
|
; Return two values:
|
|
|
|
|
; the list of action results;
|
|
|
|
|
; the list of action results' types.
|
|
|
|
|
(defun trace-action-parse (grammar token-terminal input trace)
|
|
|
|
|
(labels
|
|
|
|
|
(;Continue the parse with the given stacks and remainder of input.
|
|
|
|
|
;type-stack contains the types of corresponding value-stack entries.
|
|
|
|
|
(parse-step (state-stack value-stack type-stack input)
|
|
|
|
|
(if (endp input)
|
|
|
|
|
(parse-step-1 state-stack value-stack type-stack *end-marker* nil nil)
|
|
|
|
|
(let ((token (first input)))
|
|
|
|
|
(parse-step-1 state-stack value-stack type-stack (funcall token-terminal token) token (rest input)))))
|
|
|
|
|
|
|
|
|
|
;Same as parse-step except that the next input terminal has been determined already.
|
|
|
|
|
;input-rest contains the input tokens after the next token.
|
|
|
|
|
(parse-step-1 (state-stack value-stack type-stack terminal token input-rest)
|
|
|
|
|
(let* ((state (car state-stack))
|
|
|
|
|
(transition (cdr (assoc terminal (state-transitions state) :test *grammar-symbol-=*))))
|
|
|
|
|
(format *trace-output* "S~D: ~@_" (state-number state))
|
|
|
|
|
(print-values (reverse value-stack) (reverse type-stack) *trace-output*)
|
|
|
|
|
(pprint-newline :mandatory *trace-output*)
|
|
|
|
|
(if transition
|
|
|
|
|
(case (transition-kind transition)
|
|
|
|
|
(:shift
|
|
|
|
|
(format *trace-output* " shift ~W~:@_" terminal)
|
|
|
|
|
(dolist (action-function-binding (gethash terminal (grammar-terminal-actions grammar)))
|
|
|
|
|
(push (funcall (cdr action-function-binding) token) value-stack))
|
|
|
|
|
(dolist (action-signature (grammar-symbol-signature grammar terminal))
|
|
|
|
|
(push (cdr action-signature) type-stack))
|
|
|
|
|
(parse-step (cons (transition-state transition) state-stack) value-stack type-stack input-rest))
|
|
|
|
|
(:reduce
|
|
|
|
|
(let ((production (transition-production transition)))
|
|
|
|
|
(write-string " reduce " *trace-output*)
|
|
|
|
|
(if (eq trace :code)
|
|
|
|
|
(write production :stream *trace-output* :pretty t)
|
|
|
|
|
(print-production production *trace-output*))
|
|
|
|
|
(pprint-newline :mandatory *trace-output*)
|
|
|
|
|
(let* ((state-stack (nthcdr (production-rhs-length production) state-stack))
|
|
|
|
|
(state (car state-stack))
|
|
|
|
|
(dst-state (assert-non-null
|
|
|
|
|
(cdr (assoc (production-lhs production) (state-gotos state) :test *grammar-symbol-=*))))
|
|
|
|
|
(value-stack (funcall (production-evaluator production) value-stack))
|
|
|
|
|
(type-stack (nthcdr (production-n-action-args production) type-stack)))
|
|
|
|
|
(dolist (action-signature (grammar-symbol-signature grammar (production-lhs production)))
|
|
|
|
|
(push (cdr action-signature) type-stack))
|
|
|
|
|
(parse-step-1 (cons dst-state state-stack) value-stack type-stack terminal token input-rest))))
|
|
|
|
|
(:accept
|
|
|
|
|
(format *trace-output* " accept~:@_")
|
|
|
|
|
(values (nreverse value-stack) (nreverse type-stack)))
|
|
|
|
|
(t (error "Bad transition: ~S" transition)))
|
|
|
|
|
(error "Parse error on ~S followed by ~S ..." token (ldiff input-rest (nthcdr 10 input-rest)))))))
|
|
|
|
|
|
|
|
|
|
(parse-step (list (grammar-start-state grammar)) nil nil input)))
|
|
|
|
|
|
