You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
142 lines
6.5 KiB
Scheme
142 lines
6.5 KiB
Scheme
#cs
|
|
(module parser-builder mzscheme
|
|
|
|
(require "input-file-parser.ss"
|
|
"table.ss"
|
|
"parser-actions.ss"
|
|
"grammar.ss")
|
|
|
|
(provide build-parser)
|
|
|
|
(define (build-parser filename error-expr input-terms start end assocs prods runtime src)
|
|
(let* ((grammar (parse-input start end input-terms assocs prods runtime))
|
|
(table (build-table grammar filename))
|
|
(table-code
|
|
(cons 'vector
|
|
(map (lambda (action)
|
|
(cond
|
|
((shift? action)
|
|
`(make-shift ,(shift-state action)))
|
|
((reduce? action)
|
|
`(make-reduce ,(reduce-prod-num action)
|
|
,(reduce-lhs-num action)
|
|
,(reduce-rhs-length action)))
|
|
((accept? action)
|
|
`(make-accept))
|
|
(else action)))
|
|
(vector->list table))))
|
|
|
|
(num-non-terms (length (grammar-non-terms grammar)))
|
|
|
|
(token-code
|
|
`(let ((ht (make-hash-table)))
|
|
(begin
|
|
,@(map (lambda (term)
|
|
`(hash-table-put! ht
|
|
',(gram-sym-symbol term)
|
|
,(+ num-non-terms (gram-sym-index term))))
|
|
(grammar-terms grammar))
|
|
ht)))
|
|
|
|
(actions-code
|
|
`(vector ,@(map prod-action (grammar-prods grammar))))
|
|
|
|
(parser-code
|
|
`(letrec ((err ,error-expr)
|
|
(err-state 0)
|
|
(table ,table-code)
|
|
(term-sym->index ,token-code)
|
|
(actions ,actions-code)
|
|
(reduce-stack
|
|
(lambda (s n v)
|
|
(if (> n 0)
|
|
(reduce-stack (cddr s) (sub1 n) (cons (cadr s) v))
|
|
(values s v))))
|
|
(fix-error
|
|
(lambda (stack ip get-token)
|
|
(let remove-states ()
|
|
(let ((a (find-action stack 'error)))
|
|
(cond
|
|
((shift? a)
|
|
(printf "shift:~a~n" (shift-state a))
|
|
(set! stack (cons (shift-state a) (cons #f stack))))
|
|
(else
|
|
(printf "discard-state:~a~n" (car stack))
|
|
(cond
|
|
((< (length stack) 3)
|
|
(printf "Unable to shift error token~n")
|
|
#f)
|
|
(else
|
|
(set! stack (cddr stack))
|
|
(remove-states)))))))
|
|
(let remove-input ()
|
|
(let ((a (find-action stack ip)))
|
|
(cond
|
|
((shift? a)
|
|
(printf "shift:~a~n" (shift-state a))
|
|
(cons (shift-state a)
|
|
(cons (if (token? ip)
|
|
(token-value ip)
|
|
#f)
|
|
stack)))
|
|
(else
|
|
(printf "discard-input:~a~n" (if (token? ip)
|
|
(token-name ip)
|
|
ip))
|
|
(set! ip (get-token))
|
|
(remove-input)))))))
|
|
|
|
(find-action
|
|
(lambda (stack tok)
|
|
(array2d-ref table
|
|
(car stack)
|
|
(hash-table-get term-sym->index
|
|
(if (token? tok)
|
|
(token-name tok)
|
|
tok)
|
|
err)))))
|
|
(lambda (get-token)
|
|
(let loop ((stack (list 0))
|
|
(ip (get-token)))
|
|
(display stack)
|
|
(newline)
|
|
(display (if (token? ip) (token-name ip) ip))
|
|
(newline)
|
|
(let ((action (find-action stack ip)))
|
|
(cond
|
|
((shift? action)
|
|
(printf "shift:~a~n" (shift-state action))
|
|
(let ((val (if (token? ip)
|
|
(token-value ip)
|
|
#f)))
|
|
(loop (cons (shift-state action) (cons val stack))
|
|
(get-token))))
|
|
((reduce? action)
|
|
(printf "reduce:~a~n" (reduce-prod-num action))
|
|
(let-values (((new-stack args)
|
|
(reduce-stack stack
|
|
(reduce-rhs-length action)
|
|
null)))
|
|
(let* ((A (reduce-lhs-num action))
|
|
(goto (array2d-ref table (car new-stack) A)))
|
|
(loop (cons goto
|
|
(cons (apply
|
|
(vector-ref actions
|
|
(reduce-prod-num action))
|
|
args)
|
|
new-stack))
|
|
ip))))
|
|
((accept? action)
|
|
(printf "accept~n")
|
|
(cadr stack))
|
|
(else
|
|
(err)
|
|
(let ((new-stack (fix-error stack ip get-token)))
|
|
(if new-stack
|
|
(loop new-stack (get-token))
|
|
(void)))))))))))
|
|
(datum->syntax-object
|
|
runtime
|
|
parser-code
|
|
src))))
|
|
|