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beautiful-racket/beautiful-racket/br/basic/expander.rkt

58 lines
1.6 KiB
Racket

#lang br
(provide (all-defined-out)
#%top-interaction
#%datum
(rename-out [basic-module-begin #%module-begin]))
(define #'(basic-module-begin PARSE-TREE ...)
#'(#%module-begin
PARSE-TREE ...))
(define #'(basic-program LINE ...)
#'(basic-run LINE ...))
(define (basic-run . lines)
(define program-lines (list->vector (filter (λ(x) x) lines)))
(for/fold ([line-idx 0])
([i (in-naturals)]
#:break (= line-idx (vector-length program-lines)))
(match-define (cons line-number proc)
(vector-ref program-lines line-idx))
(define maybe-jump-number (and proc (proc)))
(if (number? maybe-jump-number)
(let ([jump-number maybe-jump-number])
(for/or ([idx (in-range (vector-length program-lines))])
(and (= (car (vector-ref program-lines idx)) jump-number)
idx)))
(add1 line-idx))))
;; model each line as (cons line-number line-thunk)
(define-cases #'line
[#'(line 'end) #'#f]
[#'(_ NUMBER STATEMENT 'end) #'(cons NUMBER (λ _ STATEMENT))]
[#'(_ STATEMENT 'end) #'(cons #f (λ _ STATEMENT))])
(define #'(statement NAME ARG ...) #'(NAME ARG ...))
(define #'(expression ITEM) #'ITEM)
(define #'(unsignedexpr ITEM) #'ITEM)
(define #'(term ITEM) #'ITEM)
(define #'(factor ITEM) #'ITEM)
(define #'(number ITEM) #'ITEM)
(define #'(printitem EXPR-OR-STRING) #'EXPR-OR-STRING)
(define #'(printlist ITEM-OR-SEPARATOR ...) #'(list ITEM-OR-SEPARATOR ...))
(define (PRINT args)
(for-each display args)
(displayln ""))
(define (GOTO where)
where)
(define-cases #'expr-list
[#'(_ EXPR ...) #'(list EXPR ...)])