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;; Pieces themselves: the buffer is a reference to the buffer they take their
;; data from.
;; Start and end are numbers.
;; The type defines how they should be rendered, it makes
;; possible to account for hyperlinks or stuff like that in the future with
;; ease.
(define-record-type <piece>
(make-piece buffer start length type)
piece?
(buffer piece-buffer set-piece-buffer!)
(start piece-start set-piece-start!)
(length piece-length set-piece-length!)
(type piece-type set-piece-type!))
;; The piece table itself;
;; original and add are strings and pieces is a list of pieces
(define-record-type <piece-table>
(%make-piece-table original add pieces)
piece-table?
(original piece-table-original set-piece-table-original!)
(add piece-table-add set-piece-table-add!)
(pieces piece-table-pieces set-piece-table-pieces!))
(define %DEFAULT-ADD-BUFFER-LENGTH 1024)
(define (make-piece-table original)
(%make-piece-table
original
(make-string %DEFAULT-ADD-BUFFER-LENGTH)
(list (make-piece original 0 (string-length original) 'normal))))
(define (add-piece-table-piece! piece-table piece)
(append (piece-table-pieces piece-table) (list piece)))
(define (piece-table-index piece-table pos)
(let loop ((pieces (piece-table-pieces piece-table))
(start 0))
(let* ((piece (car pieces))
(end (piece-length piece)))
(if (<= start pos (- end 1))
(string-ref (piece-buffer piece) (+ start pos))
(if (not (null? (cdr pieces)))
(loop (cdr pieces) (+ start end))
(eof-object))))))
(define (piece-table-insert! piece-table pos char)
#f)
(define (piece-table-delete! piece-table pos)
#f)
;; Serialization - Deserialization
(define (piece-table-write port)
"Write a piece table to port"
#f)
(define (piece-table-read port)
"Read a piece table stored in port"
#f)
;; From/to string
(define string->piece-table make-piece-table)
(define (piece-table->string piece-table)
#f)
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