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beautiful-racket/brag/brag/support.rkt

99 lines
3.4 KiB
Racket

#lang racket/base
(require parser-tools/lex
racket/string
racket/struct
(prefix-in : parser-tools/lex-sre)
(for-syntax racket/base))
(provide (all-from-out parser-tools/lex)
(all-from-out parser-tools/lex-sre)
[struct-out token-struct]
token
[struct-out exn:fail:parsing])
(define (token-print token port mode)
(write-string (format "~a"
(cons 'token-struct
(map (λ(proc) (format "~v" (proc token)))
(list
token-struct-type
token-struct-val
token-struct-line
token-struct-column
token-struct-offset
token-struct-span
token-struct-skip?)))) port))
(struct token-struct (type val offset line column span skip?)
#:auto-value #f
#:transparent)
;; Token constructor.
;; This is intended to be a general token structure constructor that's nice
;; to work with.
;; It should cooperate with the tokenizers constructed with make-permissive-tokenizer.
(define token
(lambda (type ;; (U symbol string)
[val #f] ;; any
#:position [position #f] ;; (U #f number)
#:line [line #f] ;; (U #f number)
#:column [column #f] ;; (U #f number)
#:span [span #f] ;; boolean
#:skip? [skip? #f])
(token-struct (if (string? type) (string->symbol type) type)
val
position line column span skip?)))
;; When bad things happen, we need to emit errors with source location.
(struct exn:fail:parsing exn:fail (srclocs)
#:transparent
#:property prop:exn:srclocs (lambda (instance)
(exn:fail:parsing-srclocs instance)))
(provide apply-tokenizer)
(define (apply-tokenizer tokenize in)
(define input-port (if (string? in)
(open-input-string in)
in))
(define token-producer (tokenize input-port))
(for/list ([token (in-producer token-producer (λ(tok)
;; position-tokens are produced by lexer-src-pos
(eq? eof (if (position-token? tok)
(position-token-token tok)
tok))))])
token))
(provide trim-ends)
(define (trim-ends left lexeme right)
(string-trim (string-trim lexeme left #:right? #f) right #:left? #f))
(provide from/to)
(define-lex-trans from/to
(λ(stx)
(syntax-case stx ()
[(_ OPEN CLOSE)
#'(:seq OPEN (complement (:seq any-string CLOSE any-string)) CLOSE)])))
;; change names of lexer abbreviations to be consistent with Racket srcloc conventions
(define-syntax-rule (dprt ID-IN ID-OUT)
(begin
(provide ID-IN)
(define-syntax ID-IN (make-rename-transformer (syntax ID-OUT)))))
(dprt lexeme-start start-pos)
(dprt lexeme-end end-pos)
(dprt line position-line)
(dprt col position-col)
(dprt pos position-offset)
(provide span)
(define (span lexeme-start lexeme-end)
(abs ; thus same result in reverse order
(- (pos lexeme-end)
(pos lexeme-start))))