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298 lines
12 KiB
Racket
298 lines
12 KiB
Racket
#lang racket/base
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(require "yacc-helper.rkt"
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"../private-lex/token-syntax.rkt"
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"grammar.rkt"
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racket/class
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racket/contract
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(for-template racket/base))
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;; routines for parsing the input to the parser generator and producing a
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;; grammar (See grammar.rkt)
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(define (is-a-grammar%? x) (is-a? x grammar%))
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(provide/contract
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[parse-input ((listof identifier?) (listof identifier?) (listof identifier?)
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(or/c #f syntax?) syntax? any/c . -> . is-a-grammar%?)]
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[get-term-list ((listof identifier?) . -> . (listof identifier?))])
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(define stx-for-original-property (read-syntax #f (open-input-string "original")))
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;; get-args: ??? -> (values (listof syntax) (or/c #f (cons integer? stx)))
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(define (get-args i rhs src-pos term-defs)
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(define empty-table (make-hasheq))
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(define biggest-pos #f)
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(hash-set! empty-table 'error #t)
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(for* ([td (in-list term-defs)]
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[v (in-value (syntax-local-value td))]
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#:when (e-terminals-def? v)
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[s (in-list (syntax->list (e-terminals-def-t v)))])
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(hash-set! empty-table (syntax->datum s) #t))
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(define args
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(let get-args ([i i][rhs rhs])
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(cond
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[(null? rhs) null]
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[else
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(define b (car rhs))
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(define name (if (hash-ref empty-table (syntax->datum (car rhs)) #f)
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(gensym)
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(string->symbol (format "$~a" i))))
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(cond
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[src-pos
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(define start-pos-id
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(datum->syntax b (string->symbol (format "$~a-start-pos" i)) b stx-for-original-property))
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(define end-pos-id
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(datum->syntax b (string->symbol (format "$~a-end-pos" i)) b stx-for-original-property))
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(set! biggest-pos (cons start-pos-id end-pos-id))
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(list* (datum->syntax b name b stx-for-original-property)
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start-pos-id
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end-pos-id
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(get-args (add1 i) (cdr rhs)))]
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[else
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(list* (datum->syntax b name b stx-for-original-property)
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(get-args (add1 i) (cdr rhs)))])])))
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(values args biggest-pos))
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;; Given the list of terminal symbols and the precedence/associativity definitions,
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;; builds terminal structures (See grammar.rkt)
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;; build-terms: symbol list * symbol list list -> term list
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(define (build-terms term-list precs)
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(define counter 0)
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;;(term-list (cons (gensym) term-list))
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;; Will map a terminal symbol to its precedence/associativity
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(define prec-table (make-hasheq))
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;; Fill the prec table
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(for ([p-decl (in-list precs)])
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(define assoc (car p-decl))
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(for ([term-sym (in-list (cdr p-decl))])
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(hash-set! prec-table term-sym (make-prec counter assoc)))
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(set! counter (add1 counter)))
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;; Build the terminal structures
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(for/list ([term-sym (in-list term-list)])
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(make-term term-sym
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#f
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(hash-ref prec-table term-sym (λ () #f)))))
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;; Retrieves the terminal symbols from a terminals-def (See terminal-syntax.rkt)
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;; get-terms-from-def: identifier? -> (listof identifier?)
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(define (get-terms-from-def term-syn)
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(define t (syntax-local-value term-syn #f))
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(cond
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[(terminals-def? t) (syntax->list (terminals-def-t t))]
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[(e-terminals-def? t) (syntax->list (e-terminals-def-t t))]
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[else
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(raise-syntax-error
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'parser-tokens
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"undefined token group"
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term-syn)]))
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(define (get-term-list term-group-names)
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(remove-duplicates
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(cons (datum->syntax #f 'error)
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(apply append (map get-terms-from-def term-group-names)))))
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(define (parse-input term-defs start ends prec-decls prods src-pos)
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(define start-syms (map syntax-e start))
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(define list-of-terms (map syntax-e (get-term-list term-defs)))
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(define end-terms
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(for/list ([end (in-list ends)])
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(unless (memq (syntax-e end) list-of-terms)
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(raise-syntax-error
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'parser-end-tokens
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(format "End token ~a not defined as a token"
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(syntax-e end))
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end))
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(syntax-e end)))
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;; Get the list of terminals out of input-terms
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(define list-of-non-terms
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(syntax-case prods ()
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[((NON-TERM PRODUCTION ...) ...)
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(begin
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(for ([nts (in-list (syntax->list #'(NON-TERM ...)))]
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#:when (memq (syntax->datum nts) list-of-terms))
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(raise-syntax-error
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'parser-non-terminals
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(format "~a used as both token and non-terminal" (syntax->datum nts))
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nts))
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(let ([dup (duplicate-list? (syntax->datum #'(NON-TERM ...)))])
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(when dup
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(raise-syntax-error
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'parser-non-terminals
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(format "non-terminal ~a defined multiple times" dup)
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prods)))
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(syntax->datum #'(NON-TERM ...)))]
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[_ (raise-syntax-error
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'parser-grammar
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"Grammar must be of the form (grammar (non-terminal productions ...) ...)"
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prods)]))
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;; Check the precedence declarations for errors and turn them into data
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(define precs
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(syntax-case prec-decls ()
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[((TYPE TERM ...) ...)
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(let ([p-terms (syntax->datum #'(TERM ... ...))])
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(cond
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[(duplicate-list? p-terms) =>
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(λ (d)
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(raise-syntax-error
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'parser-precedences
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(format "duplicate precedence declaration for token ~a" d)
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prec-decls))]
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[else (for ([t (in-list (syntax->list #'(TERM ... ...)))]
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#:when (not (memq (syntax->datum t) list-of-terms)))
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(raise-syntax-error
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'parser-precedences
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(format "Precedence declared for non-token ~a" (syntax->datum t))
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t))
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(for ([type (in-list (syntax->list #'(TYPE ...)))]
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#:unless (memq (syntax->datum type) `(left right nonassoc)))
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(raise-syntax-error
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'parser-precedences
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"Associativity must be left, right or nonassoc"
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type))
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(syntax->datum prec-decls)]))]
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[#f null]
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[_ (raise-syntax-error
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'parser-precedences
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"Precedence declaration must be of the form (precs (assoc term ...) ...) where assoc is left, right or nonassoc"
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prec-decls)]))
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(define terms (build-terms list-of-terms precs))
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(define non-terms (map (λ (non-term) (make-non-term non-term #f))
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list-of-non-terms))
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(define term-table (make-hasheq))
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(define non-term-table (make-hasheq))
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(for ([t (in-list terms)])
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(hash-set! term-table (gram-sym-symbol t) t))
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(for ([nt (in-list non-terms)])
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(hash-set! non-term-table (gram-sym-symbol nt) nt))
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;; parse-prod: syntax-object -> gram-sym vector
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(define (parse-prod prod-so)
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(syntax-case prod-so ()
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[(PROD-RHS-SYM ...)
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(andmap identifier? (syntax->list prod-so))
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(begin
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(for ([t (in-list (syntax->list prod-so))]
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#:when (memq (syntax->datum t) end-terms))
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(raise-syntax-error
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'parser-production-rhs
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(format "~a is an end token and cannot be used in a production" (syntax->datum t))
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t))
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(for/vector ([s (in-list (syntax->list prod-so))])
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(cond
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[(hash-ref term-table (syntax->datum s) #f)]
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[(hash-ref non-term-table (syntax->datum s) #f)]
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[else (raise-syntax-error
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'parser-production-rhs
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(format "~a is not declared as a terminal or non-terminal" (syntax->datum s))
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s)])))]
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[_ (raise-syntax-error
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'parser-production-rhs
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"production right-hand-side must have form (symbol ...)"
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prod-so)]))
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;; parse-action: syntax-object * syntax-object -> syntax-object
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(define (parse-action rhs act-in)
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(define-values (args biggest) (get-args 1 (syntax->list rhs) src-pos term-defs))
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(define act
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(if biggest
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(with-syntax ([(CAR-BIGGEST . CDR-BIGGEST) biggest]
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[$N-START-POS (datum->syntax (car biggest) '$n-start-pos)]
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[$N-END-POS (datum->syntax (cdr biggest) '$n-end-pos)]
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[ACT-IN act-in])
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#'(let ([$N-START-POS CAR-BIGGEST]
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[$N-END-POS CDR-BIGGEST])
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ACT-IN))
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act-in))
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(with-syntax ([ARGS args][ACT act])
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(syntax/loc #'ACT (λ ARGS ACT))))
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;; parse-prod+action: non-term * syntax-object -> production
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(define (parse-prod+action nt prod-so)
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(syntax-case prod-so ()
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[(PROD-RHS ACTION)
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(let ([p (parse-prod #'PROD-RHS)])
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(make-prod
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nt
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p
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#f
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(let loop ([i (sub1 (vector-length p))])
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(if (>= i 0)
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(let ([gs (vector-ref p i)])
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(if (term? gs)
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(term-prec gs)
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(loop (sub1 i))))
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#f))
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(parse-action #'PROD-RHS #'ACTION)))]
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[(PROD-RHS (PREC TERM) ACTION)
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(identifier? #'TERM)
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(let ([p (parse-prod #'PROD-RHS)])
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(make-prod
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nt
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p
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#f
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(term-prec
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(cond
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[(hash-ref term-table (syntax->datum #'TERM) #f)]
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[else (raise-syntax-error
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'parser-production-rhs
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(format
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"unrecognized terminal ~a in precedence declaration"
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(syntax->datum #'TERM))
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#'TERM)]))
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(parse-action #'PROD-RHS #'ACTION)))]
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[_ (raise-syntax-error
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'parser-production-rhs
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"production must have form [(symbol ...) expression] or [(symbol ...) (prec symbol) expression]"
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prod-so)]))
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;; parse-prod-for-nt: syntax-object -> production list
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(define (parse-prods-for-nt prods-so)
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(syntax-case prods-so ()
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[(NT PRODUCTIONS ...)
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(positive? (length (syntax->list #'(PRODUCTIONS ...))))
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(let ([nt (hash-ref non-term-table (syntax->datum #'NT))])
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(map (λ (p) (parse-prod+action nt p)) (syntax->list #'(PRODUCTIONS ...))))]
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[_ (raise-syntax-error
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'parser-productions
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"A production for a non-terminal must be (non-term right-hand-side ...) with at least 1 right hand side"
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prods-so)]))
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(for ([sstx (in-list start)]
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[ssym (in-list start-syms)]
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#:unless (memq ssym list-of-non-terms))
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(raise-syntax-error
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'parser-start
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(format "Start symbol ~a not defined as a non-terminal" ssym)
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sstx))
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(define starts (map (λ (x) (make-non-term (gensym) #f)) start-syms))
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(define end-non-terms (map (λ (x) (make-non-term (gensym) #f)) start-syms))
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(define parsed-prods (map parse-prods-for-nt (syntax->list prods)))
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(define start-prods (for/list ([start (in-list starts)]
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[end-non-term (in-list end-non-terms)])
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(list (make-prod start (vector end-non-term) #f #f #'values))))
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(define new-prods
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(append start-prods
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(for/list ([end-nt (in-list end-non-terms)]
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[start-sym (in-list start-syms)])
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(for/list ([end (in-list end-terms)])
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(make-prod end-nt
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(vector
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(hash-ref non-term-table start-sym)
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(hash-ref term-table end))
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#f
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#f
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#'values)))
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parsed-prods))
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(make-object grammar%
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new-prods
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(map car start-prods)
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terms
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(append starts (append end-non-terms non-terms))
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(map (λ (term-name) (hash-ref term-table term-name)) end-terms)))
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