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original commit: ea6305faf60d9adc3868cab1789827ba67cb4e67
tokens
Scott Owens 22 years ago
parent a015a446e0
commit 9b439ae7a6
5 changed files with 341 additions and 204 deletions
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43
collects/parser-tools/private-yacc/grammar.ss
Unescape Escape View File

@ -15,7 +15,7 @@
;; Things that work on items
start-item? item-prod item->string
sym-at-dot move-dot-right item<? nullable-after-dot?
sym-at-dot move-dot-right move-dot-right! item<? nullable-after-dot?
;; Things that operate on grammar symbols
gram-sym-symbol gram-sym-index term-prec gram-sym->string
@ -72,28 +72,39 @@
(else (make-item (item-prod i)
(add1 (item-dot-pos i))
(item-n i)))))
;; move-dot-right!: LR-item -> LR-item | #f
;; moves the dot to the right in the item, unless it is at its
;; rightmost, then it returns false
(define (move-dot-right! i)
(cond
((= (item-dot-pos i) (vector-length (prod-rhs (item-prod i)))) #f)
(else (set-item-dot-pos! i (add1 (item-dot-pos i)))
i)))
;; sym-at-dot: LR-item -> gram-sym | #f
;; returns the symbol after the dot in the item or #f if there is none
(define (sym-at-dot i)
(cond
((= (item-dot-pos i) (vector-length (prod-rhs (item-prod i)))) #f)
(else (vector-ref (prod-rhs (item-prod i)) (item-dot-pos i)))))
(let ((dp (item-dot-pos i)))
(cond
((= dp (vector-length (prod-rhs (item-prod i)))) #f)
(else (vector-ref (prod-rhs (item-prod i)) dp)))))
;; nullable-after-dot?: LR1-iten * grammar -> bool
;; determines if the string after the dot is nullable
(define (nullable-after-dot? i g)
(cond
((item-n i) => (lambda (x) (>= (item-dot-pos i) x)))
(else
(let ((str (prod-rhs (item-prod i))))
(let loop ((c (sub1 (vector-length str))))
(cond
((= c -1) (set-item-n! i 0))
((term? (vector-ref str c)) (set-item-n! i (add1 c)))
((nullable? g (vector-ref str c)) (loop (sub1 c)))
(else (set-item-n! i (add1 c))))))
(>= (item-dot-pos i) (item-n i)))))
(let ((i-n (item-n i)))
(cond
(i-n (>= (item-dot-pos i) i-n))
(else
(let ((str (prod-rhs (item-prod i))))
(let loop ((c (sub1 (vector-length str))))
(cond
((= c -1) (set-item-n! i 0))
((term? (vector-ref str c)) (set-item-n! i (add1 c)))
((nullable? g (vector-ref str c)) (loop (sub1 c)))
(else (set-item-n! i (add1 c))))))
(>= (item-dot-pos i) (item-n i))))))
;; print-item: LR-item ->

38
collects/parser-tools/private-yacc/graph.ss
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@ -11,38 +11,27 @@
;; DeRemer and Pennello 1982
;; Computes (f x) = (f- x) union Union{(f y) | y in (edges x)}
;; We use a hash-table to represent the result function 'a -> 'b set, so
;; the values of type 'a must be comparable with equal?.
;; the values of type 'a must be comparable with eq?.
(define (digraph nodes edges f- union fail)
(letrec (
;; Will map elements of 'a to 'b sets
(results (make-hash-table 'equal))
(results (make-hash-table))
(f (lambda (x) (hash-table-get results x fail)))
;; Maps elements of 'a to integers.
(N (make-hash-table 'equal))
(N (make-hash-table))
(get-N (lambda (x) (hash-table-get N x zero-thunk)))
(set-N (lambda (x d) (hash-table-put! N x d)))
(stack null)
(push (lambda (x)
(set! stack (cons x stack))))
(pop (lambda ()
(begin0
(car stack)
(set! stack (cdr stack)))))
(depth (lambda () (length stack)))
; (stack null)
; (push (lambda (x)
; (set! stack (cons x stack))))
; (pop (lambda ()
; (begin0
; (car stack)
; (set! stack (cdr stack)))))
; (depth (lambda () (length stack)))
(stack (make-vector 1000 #f))
(stack-pointer 0)
(push (lambda (x)
(vector-set! stack stack-pointer x)
(set! stack-pointer (add1 stack-pointer))))
(pop (lambda ()
(set! stack-pointer (sub1 stack-pointer))
(vector-ref stack stack-pointer)))
(depth (lambda () stack-pointer))
;; traverse: 'a ->
(traverse
(lambda (x)
@ -62,13 +51,14 @@
(let loop ((p (pop)))
(set-N p +inf.0)
(hash-table-put! results p (f x))
(if (not (equal? x p))
(if (not (eq? x p))
(loop (pop)))))))))
(for-each (lambda (x)
(if (= 0 (get-N x))
(traverse x)))
nodes)
f))
)

130
collects/parser-tools/private-yacc/lalr.ss
Unescape Escape View File

@ -7,7 +7,8 @@
"grammar.ss"
"graph.ss"
"array2d.ss"
(lib "list.ss"))
(lib "list.ss")
(lib "class.ss"))
(provide compute-LA)
@ -16,33 +17,34 @@
;; which can transition out of the resulting state
(define (compute-DR a g)
(lambda (tk)
(let ((r (run-automaton (trans-key-st tk) (trans-key-gs tk) a)))
(let ((r (send a run-automaton (trans-key-st tk) (trans-key-gs tk))))
(term-list->bit-vector
(filter
(lambda (term)
(run-automaton r term a))
(send a run-automaton r term))
(grammar-terms g))))))
;; compute-reads:
;; LR0-automaton * grammar -> (trans-key -> trans-key list)
(define (compute-reads a g)
(lambda (tk)
(let ((r (run-automaton (trans-key-st tk) (trans-key-gs tk) a)))
(let ((r (send a run-automaton (trans-key-st tk) (trans-key-gs tk))))
(map (lambda (x) (make-trans-key r x))
(filter (lambda (non-term)
(and (nullable? g non-term)
(run-automaton r non-term a)))
(send a run-automaton r non-term)))
(grammar-non-terms g))))))
;; compute-read: LR0-automaton * grammar -> (trans-key -> term list)
(define (compute-read a g)
(let* ((dr (compute-DR a g))
(reads (compute-reads a g)))
(digraph (get-mapped-lr0-non-term-keys a)
reads
dr
bitwise-ior
(lambda () 0))))
(digraph-tk->terml (send a get-mapped-non-term-keys)
reads
dr
(vector-length (send a get-states))
(length (grammar-terms g))
(length (grammar-non-terms g)))))
;; comput-includes-and-lookback:
@ -50,13 +52,13 @@
;; (kernel * prod -> trans-key list))
(define (compute-includes-and-lookback a g)
(let* ((non-terms (grammar-non-terms g))
(num-states (vector-length (lr0-states a)))
(num-states (vector-length (send a get-states)))
(num-non-terms (length non-terms))
(includes (make-array2d num-states num-non-terms null))
(lookback (make-array2d num-states
(grammar-num-prods g)
null)))
(for-each-state
(send a for-each-state
(lambda (state)
(for-each
(lambda (non-term)
@ -65,8 +67,8 @@
(let loop ((i (make-item prod 0))
(p state))
(if (and p i)
(let ((new-i (move-dot-right i))
(next-sym (sym-at-dot i)))
(let* ((next-sym (sym-at-dot i))
(new-i (move-dot-right i)))
(if (and (non-term? next-sym)
(nullable-after-dot? new-i g))
(array2d-add! includes
@ -80,10 +82,10 @@
(make-trans-key state non-term)))
(if next-sym
(loop new-i
(run-automaton p next-sym a)))))))
(send a run-automaton p next-sym)))))))
(get-nt-prods g non-term)))
non-terms))
a)
non-terms)))
(values (lambda (tk)
(array2d-ref includes
(kernel-index (trans-key-st tk))
@ -93,15 +95,15 @@
(kernel-index state)
(prod-index prod))))))
;; compute-follow: LR0-automaton * grammar -> (trans-key -> term list)
(define (compute-follow a g includes)
(let ((read (compute-read a g)))
(digraph (get-mapped-lr0-non-term-keys a)
includes
read
bitwise-ior
(lambda () 0))))
(digraph-tk->terml (send a get-mapped-non-term-keys)
includes
read
(vector-length (send a get-states))
(length (grammar-terms g))
(length (grammar-non-terms g)))))
;; compute-LA: LR0-automaton * grammar -> (kernel * prod -> term list)
(define (compute-LA a g)
@ -128,7 +130,7 @@
(define (print-input-st-sym f name a g print-output)
(printf "~a:~n" name)
(for-each-state
(send a for-each-state
(lambda (state)
(for-each
(lambda (non-term)
@ -139,13 +141,12 @@
state
(gram-sym-symbol non-term)
(print-output res)))))
(grammar-non-terms g)))
a)
(grammar-non-terms g))))
(newline))
(define (print-input-st-prod f name a g print-output)
(printf "~a:~n" name)
(for-each-state
(send a for-each-state
(lambda (state)
(for-each
(lambda (non-term)
@ -159,8 +160,7 @@
(prod-index prod)
(print-output res)))))
(get-nt-prods g non-term)))
(grammar-non-terms g)))
a))
(grammar-non-terms g)))))
(define (print-output-terms r)
(map
@ -176,7 +176,77 @@
(gram-sym-symbol (trans-key-gs p))))
r))
;; digraph-tk->terml:
;; (trans-key list) * (trans-key -> trans-key list) * (trans-key -> term list) * int * int * int
;; -> (trans-key -> term list)
;; DeRemer and Pennello 1982
;; Computes (f x) = (f- x) union Union{(f y) | y in (edges x)}
;; A specialization of digraph in the file graph.ss
(define (digraph-tk->terml nodes edges f- num-states num-terms num-non-terms)
(letrec (
;; Will map elements of trans-key to term sets represented as bit vectors
(results-terms (make-array2d num-states num-terms 0))
(results-non-terms (make-array2d num-states num-non-terms 0))
;; Maps elements of trans-keys to integers.
(N-terms (make-array2d num-states num-terms 0))
(N-non-terms (make-array2d num-states num-non-terms 0))
(lookup-tk-map
(lambda (map-term map-non-term)
(lambda (tk)
(let ((st (trans-key-st tk))
(gs (trans-key-gs tk)))
(if (term? gs)
(array2d-ref map-term (kernel-index st) (term-index gs))
(array2d-ref map-non-term (kernel-index st) (non-term-index gs)))))))
(add-tk-map
(lambda (map-term map-non-term)
(lambda (tk v)
(let ((st (trans-key-st tk))
(gs (trans-key-gs tk)))
(if (term? gs)
(array2d-set! map-term (kernel-index st) (term-index gs) v)
(array2d-set! map-non-term (kernel-index st) (non-term-index gs) v))))))
(get-N (lookup-tk-map N-terms N-non-terms))
(set-N (add-tk-map N-terms N-non-terms))
(get-f (lookup-tk-map results-terms results-non-terms))
(set-f (add-tk-map results-terms results-non-terms))
(stack null)
(push (lambda (x)
(set! stack (cons x stack))))
(pop (lambda ()
(begin0
(car stack)
(set! stack (cdr stack)))))
(depth (lambda () (length stack)))
;; traverse: 'a ->
(traverse
(lambda (x)
(push x)
(let ((d (depth)))
(set-N x d)
(set-f x (f- x))
(for-each (lambda (y)
(if (= 0 (get-N y))
(traverse y))
(set-f x (bitwise-ior (get-f x) (get-f y)))
(set-N x (min (get-N x) (get-N y))))
(edges x))
(if (= d (get-N x))
(let loop ((p (pop)))
(set-N p +inf.0)
(set-f p (get-f x))
(if (not (equal? x p))
(loop (pop)))))))))
(for-each (lambda (x)
(if (= 0 (get-N x))
(traverse x)))
nodes)
get-f))
)

165
collects/parser-tools/private-yacc/lr0.ss
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@ -6,12 +6,117 @@
(require "grammar.ss"
"graph.ss"
"array2d.ss"
(lib "list.ss"))
(lib "list.ss")
(lib "class.ss"))
(provide build-lr0-automaton run-automaton (struct trans-key (st gs))
get-mapped-lr0-non-term-keys lr0-states lr0-epsilon-trans
kernel-items kernel-index for-each-state)
(provide build-lr0-automaton lr0%
(struct trans-key (st gs))
kernel-items kernel-index kernel-list-remove-duplicates)
;; kernel = (make-kernel (LR1-item list) index)
;; the list must be kept sorted according to item<? so that equal? can
;; be used to compare kernels
;; trans-key = (make-trans-key kernel gram-sym)
(define-struct kernel (items index) (make-inspector))
(define-struct trans-key (st gs) (make-inspector))
(define (kernel-list-remove-duplicates k num-states)
(let ((v (make-vector num-states #f)))
(for-each
(lambda (k)
(vector-set! v (kernel-index k) k))
k)
(let loop ((i 0))
(cond
((< i num-states)
(let ((k (vector-ref v i)))
(if k
(cons k (loop (add1 i)))
(loop (add1 i)))))
(else null)))))
;; LR0-automaton = object of class lr0%
(define lr0%
(class object%
(super-instantiate ())
(init term-hash non-term-hash)
(init-field states epsilons num-terms num-non-terms)
(define term-transitions (make-lr0-table term-hash (vector-length states) num-terms))
(define non-term-transitions (make-lr0-table non-term-hash (vector-length states) num-non-terms))
(define reverse-term-hash (reverse-hash term-hash))
(define reverse-non-term-hash (reverse-hash non-term-hash))
(define reverse-term-transitions (make-lr0-table reverse-term-hash (vector-length states) num-terms))
(define reverse-non-term-transitions (make-lr0-table reverse-non-term-hash (vector-length states) num-non-terms))
(define mapped-non-terms
(hash-table-map non-term-hash (lambda (k v) k)))
(define reverse-mapped-non-terms
(hash-table-map reverse-non-term-hash (lambda (k v) k)))
(define/public (get-mapped-non-term-keys)
mapped-non-terms)
(define/public (get-states)
states)
(define/public (get-epsilon-trans)
epsilons)
;; Iteration over the states in an automaton
(define/public (for-each-state f)
(let ((num-states (vector-length states)))
(let loop ((i 0))
(if (< i num-states)
(begin
(f (vector-ref states i))
(loop (add1 i)))))))
;; run-automaton: kernel * gram-sym -> kernel | #f
;; returns the state that the transition trans-key provides or #f
;; if there is no such state
(define/public (run-automaton k s)
(if (term? s)
(array2d-ref term-transitions (kernel-index k) (term-index s))
(array2d-ref non-term-transitions (kernel-index k) (non-term-index s))))
(define/public (run-automaton-back k s)
(apply append
(if (term? s)
(map (lambda (k)
(array2d-ref reverse-term-transitions (kernel-index k) (term-index s)))
k)
(map (lambda (k)
(array2d-ref reverse-non-term-transitions (kernel-index k) (non-term-index s)))
k))))))
(define (make-lr0-table auto-hash states syms)
(let ((t (make-array2d states syms #f)))
(hash-table-map auto-hash
(lambda (k v)
(array2d-set! t
(kernel-index (trans-key-st k))
(gram-sym-index (trans-key-gs k))
v)))
t))
(define (reverse-hash hash)
(let ((reverse-hash (make-hash-table 'equal))
(hash-table-add!
(lambda (ht k v)
(hash-table-put! ht k (cons v (hash-table-get ht k (lambda () null)))))))
(hash-table-for-each hash
(lambda (k v)
(hash-table-add! reverse-hash
(make-trans-key v (trans-key-gs k))
(trans-key-st k))))
reverse-hash))
(define (union comp<?)
(letrec ((union
(lambda (l1 l2)
@ -28,26 +133,7 @@
(else (union (cdr l1) l2)))))))))
union))
;; kernel = (make-kernel (LR1-item list) index)
;; the list must be kept sorted according to item<? so that equal? can
;; be used to compare kernels
;; LR0-automaton = (make-lr0 (kernel array2d) (kernel array2d) (trans-key list) (kernel vector) (kernel item hashtable))
;; trans-key = (make-trans-key kernel gram-sym)
(define-struct kernel (items index) (make-inspector))
(define-struct trans-key (st gs) (make-inspector))
(define-struct lr0 (term-transitions non-term-transitions mapped-non-terms states epsilon-trans) (make-inspector))
;; Iteration over the states in an automaton
(define (for-each-state f a)
(let* ((states (lr0-states a))
(num-states (vector-length states)))
(let loop ((i 0))
(if (< i num-states)
(begin
(f (vector-ref states i))
(loop (add1 i)))))))
;; The kernels in the automaton are represented cannonically.
;; That is (equal? a b) <=> (eq? a b)
(define (kernel->string k)
@ -56,16 +142,7 @@
(kernel-items k))
"}")))
;; run-automaton: kernel * gram-sym * LR0-automaton -> kernel | #f
;; returns the state that the transition trans-key provides or #f
;; if there is no such state
(define (run-automaton k s a)
(if (term? s)
(array2d-ref (lr0-term-transitions a) (kernel-index k) (term-index s))
(array2d-ref (lr0-non-term-transitions a) (kernel-index k) (non-term-index s))))
(define get-mapped-lr0-non-term-keys lr0-mapped-non-terms)
(define (add-lr0-transition! ttable nttable key value)
(hash-table-put!
(if (term? (trans-key-gs key))
@ -73,17 +150,7 @@
nttable)
key
value))
(define (make-lr0-table auto-hash states syms)
(let ((t (make-array2d states syms #f)))
(hash-table-map auto-hash
(lambda (k v)
(array2d-set! t
(kernel-index (trans-key-st k))
(gram-sym-index (trans-key-gs k))
v)))
t))
;; build-LR0-automaton: grammar -> LR0-automaton
;; Constructs the kernels of the sets of LR(0) items of g
@ -263,11 +330,13 @@
(seen-kernels null))
(cond
((and (empty-queue? new-kernels) (null? old-kernels))
(make-lr0 (make-lr0-table automaton-term (length seen-kernels) (vector-length terms))
(make-lr0-table automaton-non-term (length seen-kernels) (vector-length non-terms))
(hash-table-map automaton-non-term (lambda (k v) k))
(list->vector (reverse! seen-kernels))
epsilons))
(make-object lr0%
automaton-term
automaton-non-term
(list->vector (reverse! seen-kernels))
epsilons
(vector-length terms)
num-non-terms))
((null? old-kernels)
(loop (deq! new-kernels) seen-kernels))
(else

169
collects/parser-tools/private-yacc/table.ss
Unescape Escape View File

@ -8,7 +8,8 @@
"array2d.ss"
"lalr.ss"
"parser-actions.ss"
(lib "list.ss"))
(lib "list.ss")
(lib "class.ss"))
(provide build-table)
@ -65,7 +66,7 @@
(gram-sym-symbol (prod-lhs prod))
(map gram-sym-symbol (vector->list (prod-rhs prod)))))
prods)
(for-each-state
(send a for-each-state
(lambda (state)
(fprintf port "State ~a~n" (kernel-index state))
(for-each (lambda (item)
@ -112,8 +113,7 @@
port)))
(loop (add1 j)))))
(newline port))
a)
(newline port)))
(if (> SR-conflicts 0)
(fprintf port "~a shift/reduce conflicts~n" SR-conflicts))
@ -141,7 +141,7 @@
(loop (car rest) (cdr rest)))
(else (loop current-guess (cdr rest))))))
(else entry)))))
(for-each-state
(send a for-each-state
(lambda (state)
(let loop ((term 0))
(if (< term num-terms)
@ -151,8 +151,7 @@
(array2d-ref table
(kernel-index state)
(+ num-non-terms term))))
(loop (add1 term))))))
a)
(loop (add1 term)))))))
(if (not suppress)
(begin
(if (> SR-conflicts 0)
@ -168,7 +167,7 @@
(define (resolve-prec-conflicts a table get-term get-prod
num-terms num-non-terms)
(for-each-state
(send a for-each-state
(lambda (state)
(let loop ((term 0))
(if (< term num-terms)
@ -210,102 +209,100 @@
((eq? 'right (prec-assoc s-prec))
shift)
(else #f)))))))
(loop (add1 term))))))
a))
(loop (add1 term))))))))
;; In the result table the first index is the state and the second is the
;; term/non-term index (with the non-terms coming first)
;; buile-table: grammar * string -> action2d-array
(define (build-table g file suppress)
(let* ((a (time (build-lr0-automaton g)))
(terms (grammar-terms g))
(non-terms (grammar-non-terms g))
(get-term (list->vector terms))
(get-non-term (list->vector non-terms))
(get-prod (list->vector (grammar-prods g)))
(num-terms (vector-length get-term))
(num-non-terms (vector-length get-non-term))
(terms (grammar-terms g))
(non-terms (grammar-non-terms g))
(get-term (list->vector terms))
(get-non-term (list->vector non-terms))
(get-prod (list->vector (grammar-prods g)))
(num-terms (vector-length get-term))
(num-non-terms (vector-length get-non-term))
(end-term-indexes
(map
(lambda (term)
(+ num-non-terms (gram-sym-index term)))
(grammar-end-terms g)))
(num-gram-syms (+ num-terms num-non-terms))
(table (make-array2d (vector-length (lr0-states a)) num-gram-syms #f))
(array2d-add!
(lambda (v i1 i2 a)
(let ((old (array2d-ref v i1 i2)))
(cond
((not old) (array2d-set! v i1 i2 a))
((list? old) (if (not (member a old))
(array2d-set! v i1 i2 (cons a old))))
(else (if (not (equal? a old))
(array2d-set! v i1 i2 (list a old))))))))
(get-lookahead (compute-LA a g)))
(num-gram-syms (+ num-terms num-non-terms))
(table (make-array2d (vector-length (send a get-states)) num-gram-syms #f))
(array2d-add!
(lambda (v i1 i2 a)
(let ((old (array2d-ref v i1 i2)))
(cond
((not old) (array2d-set! v i1 i2 a))
((list? old) (if (not (member a old))
(array2d-set! v i1 i2 (cons a old))))
(else (if (not (equal? a old))
(array2d-set! v i1 i2 (list a old))))))))
(get-lookahead (compute-LA a g)))
(time
(for-each-state
(lambda (state)
(let loop ((i 0))
(if (< i num-gram-syms)
(begin
(let* ((s (if (< i num-non-terms)
(vector-ref get-non-term i)
(vector-ref get-term (- i num-non-terms))))
(goto
(run-automaton state s a)))
(if goto
(array2d-set! table
(kernel-index state)
i
(send a for-each-state
(lambda (state)
(let loop ((i 0))
(if (< i num-gram-syms)
(begin
(let* ((s (if (< i num-non-terms)
(vector-ref get-non-term i)
(vector-ref get-term (- i num-non-terms))))
(goto
(send a run-automaton state s)))
(if goto
(array2d-set! table
(kernel-index state)
i
(cond
((< i num-non-terms)
(kernel-index goto))
((member i end-term-indexes)
(make-accept))
(else
(make-shift
(kernel-index goto)))))))
(loop (add1 i)))))
(for-each
(lambda (item)
(let ((item-prod (item-prod item)))
(bit-vector-for-each
(lambda (term-index)
(array2d-add! table
(kernel-index state)
(+ num-non-terms term-index)
(cond
((< i num-non-terms)
(kernel-index goto))
((member i end-term-indexes)
(make-accept))
(else
(make-shift
(kernel-index goto)))))))
(loop (add1 i)))))
(for-each
(lambda (item)
(let ((item-prod (item-prod item)))
(bit-vector-for-each
(lambda (term-index)
(array2d-add! table
(kernel-index state)
(+ num-non-terms term-index)
(cond
((not (start-item? item))
(make-reduce
(prod-index item-prod)
(gram-sym-index (prod-lhs item-prod))
(vector-length (prod-rhs item-prod)))))))
(get-lookahead state item-prod))))
(append (hash-table-get (lr0-epsilon-trans a) state (lambda () null))
(filter (lambda (item)
(not (move-dot-right item)))
(kernel-items state)))))
a))
((not (start-item? item))
(make-reduce
(prod-index item-prod)
(gram-sym-index (prod-lhs item-prod))
(vector-length (prod-rhs item-prod)))))))
(get-lookahead state item-prod))))
(append (hash-table-get (send a get-epsilon-trans) state (lambda () null))
(filter (lambda (item)
(not (move-dot-right item)))
(kernel-items state)))))))
(resolve-prec-conflicts a table get-term get-prod num-terms
num-non-terms)
(if (not (string=? file ""))
(with-handlers [(exn:i/o:filesystem?
(lambda (e)
(fprintf
(current-error-port)
"Cannot write debug output to file \"~a\". ~a~n"
(exn:i/o:filesystem-pathname e)
(exn:i/o:filesystem-detail e))))]
(call-with-output-file file
(lambda (port)
(display-parser a table get-term get-non-term (grammar-prods g)
(with-handlers [(exn:i/o:filesystem?
(lambda (e)
(fprintf
(current-error-port)
"Cannot write debug output to file \"~a\". ~a~n"
(exn:i/o:filesystem-pathname e)
(exn:i/o:filesystem-detail e))))]
(call-with-output-file file
(lambda (port)
(display-parser a table get-term get-non-term (grammar-prods g)
port)))))
(resolve-conflicts a table num-terms num-non-terms suppress)
table))
)

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