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74 lines
3.0 KiB
Scheme
74 lines
3.0 KiB
Scheme
#cs
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(module parser-builder mzscheme
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(require "input-file-parser.ss"
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"table.ss"
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"parser-actions.ss"
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"grammar.ss")
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(provide build-parser)
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(define (build-parser start input-terms assocs prods filename runtime src)
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(let* ((grammar (parse-input start input-terms assocs prods))
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(table (build-table grammar ""))
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(table-code
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(cons 'vector
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(map (lambda (action)
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(cond
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((shift? action)
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`(make-shift ,(shift-state action)))
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((reduce? action)
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`(make-reduce ,(reduce-prod-num action)
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,(reduce-lhs-num action)
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,(reduce-rhs-length action)))
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((accept? action)
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`(make-accept))
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(else action)))
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(vector->list table))))
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(num-non-terms (length (grammar-non-terms grammar)))
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(token-code
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`(let ((ht (make-hash-table)))
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(begin
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,@(map (lambda (term)
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`(hash-table-put! ht
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',(gram-sym-symbol term)
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,(+ num-non-terms (gram-sym-index term))))
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(grammar-terms grammar))
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ht)))
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(parser-code
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`(letrec ((term-sym->index ,token-code)
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(table ,table-code)
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(pop-2x
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(lambda (s n)
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(if (> n 0)
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(pop-2x (cdr (cdr s)) (sub1 n))
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s))))
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(lambda (get-token)
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(let loop ((stack (list 0))
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(next (get-token)))
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(let* ((s (car stack))
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(a (hash-table-get term-sym->index
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(if (token? next)
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(token-name next)
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next)))
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(action (array2d-ref table s a)))
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(cond
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((shift? action)
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(loop (cons (shift-state action) (cons a stack)) (get-token)))
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((reduce? action)
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(printf "reduce:~a~n" (reduce-prod-num action))
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(let* ((A (reduce-lhs-num action))
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(new-stack (pop-2x stack (reduce-rhs-length action)))
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(goto (array2d-ref table (car new-stack) A)))
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(loop (cons goto (cons A new-stack)) next)))
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((accept? action)
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(printf "accept~n"))
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(else (error 'parser)))))))))
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(datum->syntax-object
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runtime
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parser-code
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src))))
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