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.
brag/base/derivation.rkt

187 lines
6.5 KiB
Racket

#lang racket/base
(require racket/contract/base)
(provide
(struct-out terminal-derivation)
(struct-out nonterminal-derivation)
(contract-out
[parser-derivation? predicate/c]
[parser-derivation-first-terminal (-> parser-derivation? any/c)]
[parser-derivation-last-terminal (-> parser-derivation? any/c)]
[parser-derivation
(case->
(-> any/c terminal-derivation?)
(-> any/c parser-derivation? #:rest (listof parser-derivation?) nonterminal-derivation?))]
[parser-derivation->syntax (-> parser-derivation? syntax?)]
[syntax-label? predicate/c]
[syntax-label (->* (any/c) (#:properties hash? #:expression-properties hash?) syntax-label?)]
[syntax-label-value (-> syntax-label? any/c)]
[syntax-label-properties (-> syntax-label? hash?)]
[syntax-label-expression-properties (-> syntax-label? hash?)]))
(require racket/match
racket/sequence
racket/struct
rebellion/collection/vector
rebellion/private/static-name
yaragg/base/token)
(module+ test
(require (submod "..")
rackunit))
;@----------------------------------------------------------------------------------------------------
(define (parser-derivation? v)
(or (terminal-derivation? v) (nonterminal-derivation? v)))
;; A (Terminal-Derivation V) represents a terminal that was matched by the grammar. It contains the
;; value V of the (Token T V) that was matched.
(struct terminal-derivation (value) #:transparent)
;; A (Nonterminal-Derivation V L) represents a nonterminal that was matched by the grammar. It
;; contains the label of type L of the production rule that matched, and an immutable vector of
;; subderivations
(struct nonterminal-derivation (label children)
#:guard
(let ([contract-guard (struct-guard/c any/c (sequence/c parser-derivation? #:min-count 1))])
(λ (label children name)
(let-values ([(label children) (contract-guard label children name)])
(values label (sequence->vector children)))))
#:transparent
#:property prop:custom-print-quotable 'never
#:methods gen:custom-write
[(define write-proc
(make-constructor-style-printer
(λ (_) 'nonterminal-derivation)
(λ (this)
(cons (nonterminal-derivation-label this)
(vector->list (nonterminal-derivation-children this))))))])
(define parser-derivation
(case-lambda
[(value) (terminal-derivation value)]
[(label first-child . children) (nonterminal-derivation label (cons first-child children))]))
(define (parser-derivation-first-terminal derivation)
(match derivation
[(terminal-derivation value) value]
[(nonterminal-derivation _ (vector first-child _ ...))
(parser-derivation-first-terminal first-child)]))
(define (parser-derivation-last-terminal derivation)
(match derivation
[(terminal-derivation value) value]
[(nonterminal-derivation _ (vector _ ... last-child))
(parser-derivation-last-terminal last-child)]))
(module+ test
(test-case (name-string parser-derivation-first-terminal)
(test-case "terminal"
(check-equal? (parser-derivation-first-terminal (terminal-derivation 1)) 1))
(test-case "nonterminal of terminals"
(define derivation
(parser-derivation
'a
(parser-derivation 1)
(parser-derivation 2)
(parser-derivation 3)))
(check-equal? (parser-derivation-first-terminal derivation) 1))
(test-case "nonterminal of nonterminals and terminals"
(define derivation
(parser-derivation
'a
(parser-derivation 'b (parser-derivation 1))
(parser-derivation 2)
(parser-derivation 3)))
(check-equal? (parser-derivation-first-terminal derivation) 1)))
(test-case (name-string parser-derivation-last-terminal)
(test-case "terminal"
(check-equal? (parser-derivation-last-terminal (terminal-derivation 1)) 1))
(test-case "nonterminal of terminals"
(define derivation
(parser-derivation
'a
(parser-derivation 1)
(parser-derivation 2)
(parser-derivation 3)))
(check-equal? (parser-derivation-last-terminal derivation) 3))
(test-case "nonterminal of nonterminals and terminals"
(define derivation
(parser-derivation
'a
(parser-derivation 1)
(parser-derivation 2)
(parser-derivation 'b (parser-derivation 3))))
(check-equal? (parser-derivation-last-terminal derivation) 3))))
(struct syntax-label (value expression-properties properties)
#:transparent
#:constructor-name constructor:syntax-label
#:omit-define-syntaxes
#:guard
(struct-guard/c any/c
(hash/c any/c any/c #:immutable #true #:flat? #true)
(hash/c any/c any/c #:immutable #true #:flat? #true)))
(define (syntax-label value
#:properties [properties (hash)]
#:expression-properties [expression-properties (hash)])
(constructor:syntax-label value properties expression-properties))
(define (parser-derivation->syntax derivation)
(match derivation
[(terminal-derivation t) (syntax-token->syntax t)]
[(nonterminal-derivation label children)
(define first-token (parser-derivation-first-terminal derivation))
(define label-location
(srcloc (syntax-token-source first-token)
(syntax-token-line first-token)
(syntax-token-column first-token)
(syntax-token-position first-token)
0))
(define label-stx
(for/fold ([stx (datum->syntax #false (syntax-label-value label) label-location #false)])
([(key value) (in-hash (syntax-label-properties label))])
(syntax-property stx key value)))
(define children-syntaxes
(for/list ([child (in-vector children)])
(parser-derivation->syntax child)))
(define last-token (parser-derivation-last-terminal derivation))
(define expression-location
(srcloc (syntax-token-source first-token)
(syntax-token-line first-token)
(syntax-token-column first-token)
(syntax-token-position first-token)
(- (syntax-token-end-position last-token) (syntax-token-position first-token))))
(define expression-stx
(datum->syntax #false (cons label-stx children-syntaxes) expression-location #false))
(for/fold ([expression-stx expression-stx])
([(key value) (in-hash (syntax-label-expression-properties label))])
(syntax-property expression-stx key value))]))