107 lines
3.1 KiB
Scheme
107 lines
3.1 KiB
Scheme
;;; nyacc/import.scm
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;;;
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;;; Copyright (C) 2015 Matthew R. Wette
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;;;
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;;; This library is free software; you can redistribute it and/or
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;;; modify it under the terms of the GNU Lesser General Public
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;;; License as published by the Free Software Foundation; either
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;;; version 3 of the License, or (at your option) any later version.
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;;;
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;;; This library is distributed in the hope that it will be useful,
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;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;;; Lesser General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU Lesser General Public
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;;; License along with this library; if not, write to the Free Software
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;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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;; Convert guile lalr grammar to nyacc grammar.
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;; What is *eoi* for?
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(define-module (nyacc import)
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#:export-syntax (lalr-parser)
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#:export (guile-lalr->nyacc-lalr)
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#:use-module ((srfi srfi-1) #:select (fold-right))
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)
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(define (convert-tree spec0)
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(let* ((terms (cons '*eoi* (car spec0)))
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(start (caadr spec0))
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(wrap-symb
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(lambda (s) (cons (if (memq s terms) 'terminal 'non-terminal) s))))
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(let iter ((prl1 '()) ; new production rules
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(prl0 (cdr spec0)) ; old production rules
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(lhs #f) ; LHS
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(rhs1-l #f) ; new RHS list
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(rhs0-l #f)) ; old RHS list
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(cond
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((pair? rhs0-l) ;; convert RHS
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(iter prl1 prl0 lhs
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(cons
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(fold-right ;; s1 ... : a => (('terminal . s) ... ('$$ . a))
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(lambda (symb seed) (cons (wrap-symb symb) seed))
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(list (list '$$ (cdar rhs0-l)))
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(caar rhs0-l))
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rhs1-l)
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(cdr rhs0-l)))
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((null? rhs0-l) ;; roll up LHS+RHSs to new rule
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(iter (cons (cons lhs (reverse rhs1-l)) prl1) prl0 #f #f #f))
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((pair? prl0) ;; next production rule
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(iter prl1 (cdr prl0) (caar prl0) '() (cdar prl0)))
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(else ;; return spec in preliminary form
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(list
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'lalr-spec
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`(start ,start)
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`(grammar ,(reverse prl1))))))))
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(define-syntax parse-rhs-list
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(syntax-rules (:)
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((_ (<rhs0sym> ...) : <rhs0act> <rhs1> ...)
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(cons (cons '(<rhs0sym> ...) '<rhs0act>)
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(parse-rhs-list <rhs1> ...)))
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((_) (list))))
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(define-syntax parse-prod-list
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(syntax-rules ()
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((_ (<lhs> <rhs> ...) <prod1> ...)
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(cons (cons '<lhs> (parse-rhs-list <rhs> ...))
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(parse-prod-list <prod1> ...)))
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((_) (list))))
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(define-syntax lalr-parser
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(syntax-rules ()
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((_ <tokens> <prod0> ...)
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(convert-tree
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(cons '<tokens> (parse-prod-list <prod0> ...))))))
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(define (guile-lalr->nyacc-lalr match-table spec)
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(letrec
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((mark (lambda (s) (if (symbol? s) `(quote ,s) s)))
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(rmt (map (lambda (p) (cons (cdr p) (mark (car p)))) match-table))
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(clean
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(lambda (dt)
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(cond
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((null? dt) '())
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((pair? dt)
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(case (car dt)
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((non-terminal) (cdr dt))
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((terminal)
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(cond
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((assq-ref rmt (cdr dt)))
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((symbol? (cdr dt)) (simple-format #f "~A" (cdr dt)))
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(else (cdr dt))))
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((start) dt)
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(else
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(cons (clean (car dt)) (clean (cdr dt))))))
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(else
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dt))))
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)
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(clean spec)))
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;;; --- last line ---
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