#lang racket
(require "pasterack-utils.rkt")

;; parsing utility functions used by pasterack.org

(provide (all-defined-out))

;; lang regexp patterns
(define hashlang-pat #px"^\\#lang ([\\w/\\-\\+]+)\\s*(.*)")
(define weblang-pat #px"^web-server.*")
(define scribblelang-pat #px"^scribble/.*")
(define htdplang-pat #px"^htdp/(.*)")
(define TRlang-pat #px"^typed/racket.*")

(define (hashlang? code)
  (define in (open-input-string code))
  (begin0 (read-language in (lambda () #f)) (close-input-port in)))

;; ie maps htdp/bsl -> lang/htdp-beginner
(define (htdplang->modulename lang)
  (match (cadr (regexp-match htdplang-pat lang))
    ["bsl"  "lang/htdp-beginner"]
    ["bsl+" "lang/htdp-beginner-abbr"]
    ["isl"  "lang/htdp-intermediate"]
    ["isl+" "lang/htdp-intermediate-lambda"]
    ["asl"  "lang/htdp-advanced"]
    [_ "racket"]))

;; returns two string values, one for lang and one for the rest of the program
(define (hashlang-split code)
  (match (regexp-match hashlang-pat code)
    [(list _ lang rst) (values lang rst)]
    [_ (values "racket" code)]))

(define (scribble-lang? lang) (regexp-match scribblelang-pat lang))
(define (htdp-lang? lang) (regexp-match htdplang-pat lang))
(define (TR-lang? lang) (regexp-match TRlang-pat lang))
(define (web-lang? lang) (regexp-match weblang-pat lang))

;; htdp form patterns
(define provide-pat #px"^\\(provide (.*)\\)$")
(define require-pat #px"^\\(require (.*)\\)$")
(define define-pat #px"^\\(define(.*)\\)$")
(define check-pat #px"^\\(check-(.*)\\)$")

(define (require-datum? e) (get-require-spec e))
(define (provide-datum? e) (regexp-match provide-pat (to-string e)))
(define (define-datum? e) (regexp-match define-pat (to-string e)))
(define (check-datum? e) (regexp-match check-pat (to-string e)))
(define (get-require-spec e) (regexp-match require-pat (to-string e)))

(define (not-htdp-expr? e) (or (require-datum? e) (provide-datum? e)
                               (check-datum? e) (define-datum? e)))

;; wont work if s has a #lang line
;; returns list of datums
(define (string->datums s)
  (with-handlers ([exn:fail? (lambda () null)])
    (with-input-from-string s (lambda () (for/list ([e (in-port)]) e)))))