racket/collects/unstable/error.rkt
2012-08-22 11:55:11 -04:00

114 lines
4.6 KiB
Racket

#lang racket/base
(require racket/contract/base)
#|
TODO
- more options
- 'pretty : pretty-print, then use multi-line format as necessary
- need no-contracts version?
- document or remove #:details arg
|#
;; A DetailsTable is (listof (cons Field any))
;; A Field is one of
;; - string
;; - (cons string (listof FieldOption))
;; A FieldOption is one of
;; - 'multi
;; - 'value
;; - 'maybe
(define field-option/c (or/c 'multi 'value 'maybe))
(define field/c (or/c string? (cons/c string? (listof field-option/c))))
(define details-list/c
(recursive-contract
(or/c '() (cons/c field/c (cons/c any/c details-list/c)))))
(provide/contract
[raise-misc-error
(->* (symbol? string?)
(#:continued (or/c string? (listof string))
#:constructor (-> string? continuation-mark-set? exn?))
#:rest details-list/c
any)]
[compose-error-message
(->* (symbol? string?)
(#:continued (or/c string? (listof string)))
#:rest details-list/c
string?)])
;; ----
(define (raise-misc-error who message
#:details [detail-table null]
#:continued [continued-message null]
#:constructor [constructor exn:fail]
. field+detail-list)
(raise
(constructor
(compose* who message
continued-message
(field+detail-list->table 'raise-misc-error field+detail-list detail-table))
(current-continuation-marks))))
(define (compose-error-message who message
#:details [detail-table null]
#:continued [continued-message null]
. field+detail-list)
(let ([details
(field+detail-list->table 'compose-error-message field+detail-list detail-table)])
(compose* who message continued-message details)))
(define (compose* who message continued-message details)
(let* ([parts (let loop ([details details])
(cond [(null? details) null]
[else
(let* ([field+opts (car (car details))]
[options (if (pair? field+opts) (cdr field+opts) '())]
[value? (memq 'value options)]
[multi? (memq 'multi options)]
[maybe? (memq 'maybe options)]
[convert-value
(cond [value?
(lambda (v) ((error-value->string-handler) v (error-print-width)))]
[else
(lambda (v) (format "~a" v))])]
[field (if (pair? field+opts) (car field+opts) field+opts)]
[value (cdr (car details))])
(cond [(and (or maybe? multi? (not value?))
(not value))
(loop (cdr details))]
[multi?
(list* "\n " field ": "
(let value-loop ([value value])
(cond [(pair? value)
(list* "\n "
(convert-value (car value))
(value-loop (cdr value)))]
[(null? value)
(loop (cdr details))])))]
[else
(list* "\n " field ": "
(convert-value value)
(loop (cdr details)))]))]))]
[parts (let loop ([continued continued-message])
(cond [(pair? continued) (list* "\n " (car continued) (loop (cdr continued)))]
[(string? continued) (loop (list continued))]
[(null? continued) parts]))]
[parts (list* message (if (null? continued-message) "" ";") parts)]
[parts (if who
(list* (symbol->string who) ": " parts)
parts)])
(apply string-append parts)))
;; ----
(define (field+detail-list->table who lst onto)
(cond [(null? lst) onto]
[else
(let ([field (car lst)]
[value (cadr lst)])
(cons (cons field value)
(field+detail-list->table who (cddr lst) onto)))]))