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beautiful-racket/beautiful-racket-ragg/br/ragg/rules/runtime.rkt

35 lines
1.4 KiB
Racket

9 years ago
#lang racket/base
(require parser-tools/lex)
(provide (all-defined-out))
;; During parsing, we should define the source of the input.
(define current-source (make-parameter #f))
;; When bad things happen, we need to emit errors with source location.
(struct exn:fail:parse-grammar exn:fail (srclocs)
#:transparent
#:property prop:exn:srclocs (lambda (instance)
(exn:fail:parse-grammar-srclocs instance)))
(define current-parser-error-handler
(make-parameter
(lambda (tok-ok? tok-name tok-value start-pos end-pos)
(raise (exn:fail:parse-grammar
(format "Error while parsing grammar near: ~e [line=~a, column~a, position=~a]"
tok-value
(position-line start-pos)
(position-col start-pos)
(position-offset start-pos))
(current-continuation-marks)
(list (srcloc (current-source)
(position-line start-pos)
(position-col start-pos)
(position-offset start-pos)
(if (and (number? (position-offset end-pos))
(number? (position-offset start-pos)))
(- (position-offset end-pos)
(position-offset start-pos))
#f))))))))