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#lang racket
(provide full-parse)
; + - * / ^ ( ) [0-9]
; 5+3*x
(define (full-parse str)
(define (get-general expr operator next-operation)
(define (char->wanted c)
((if (char-numeric? c)
string->number string->symbol)
(string c)))
; used to add a completed part of the operation to the list of operations
; 5 is one of those in the addition iteration
; 3 and x are in the product iteration
(define (add-operation-to-list operation seq)
;(display (list operator "|" operation "|" seq))
;(newline)
(cons (if (= (length operation) 1)
(char->wanted (car operation))
(next-operation operation))
seq))
(define (contains value seq)
(memq value seq))
(define (inner cfac facts rexpr)
(cond
[(null? rexpr)
(reverse (add-operation-to-list cfac facts))]
[(eqv? (car rexpr) operator)
(inner '() (add-operation-to-list cfac facts) (cdr rexpr))]
[else
(inner (cons (car rexpr) cfac) facts (cdr rexpr))]))
(if (not (contains operator expr))
(next-operation expr)
(cons (char->wanted operator) (inner '() '() expr))))
(define (create-trace expr ops)
(lambda (expr)
(get-general expr (car ops)
(if (null? (cdr ops))
(lambda (x) x)
(create-trace expr (cdr ops))))))
(let ((expr (string->list str)))
((create-trace expr '(#\+ #\- #\* #\/)) expr)))
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