I'm trying to develop a program to manipulate and edit a zipper whose nodes are text editors (objects in the text% class). More precisely, a node is an instance of a class derived from text%, which can include additional information (name of the node, etc.) and methods for changing its state. The interface contains two elements: a canvas for viewing the zipper and manipulating it (moving around in the zipper, changing the name of the node in focus, deleting it, adding a new one, moving the sub-tree in focus, etc.) and another canvas associated with the editor of the node in focus, enabling you to edit its contents. This program works, but I can't manage to save the zipper in a file so that I can open it later in a new editing session. I have a simple solution that allows this, but only for plain text. Schematically, I proceed as follows (I'm simplifying here by considering a tree rather than a zipper and by assuming that a node is a plain text editor):
; Simple structure for a labeled tree.
(serializable-struct tree (label subtrees)#:transparent #:mutable)
(define (tree-map fun tree)
(tree (fun (tree-label tree)) (map tree-map (tree-subtree tree))
(define (string->text-editor string)
(define editor (new text%))
(send editor insert string)
editor)
(define (text-editor->string editor)
(send editor get-text 0 'eof #t #f)))
; define function for saving data to a rkdt file
(define (save-rktd data path)
(if (serializable? data)
(with-output-to-file path
(lambda () (write (serialize data)))
#:exists 'replace)
(error "Data is not serializable")))
; define function for reading data from a rkdt file
(define (read-rktd path)
(with-input-from-file path
(lambda () (deserialize (read)))))
(define (tree-write tree path)
(save-rktd (tree-map text-editor->string tree) path)
(define (tree-read path)
(tree-map string->text-editor (read-rktd path)))
To solve this problem I concentrated on the problem of serializing and deserializing a text editor and tried the following :
(require racket/serialize)
(require racket/gui/base)
(provide (all-defined-out))
(require (except-in racket/gui/base make-color make-pen))
(define (serialize-text text)
(define editor-stream-out-bytes-base (new editor-stream-out-bytes-base%))
(define editor-stream-out (make-object editor-stream-out% editor-stream-out-bytes-base))
(send text write-to-file editor-stream-out)
(send editor-stream-out-bytes-base get-bytes))
(define (deserialize-text byte-stream)
(define editor (new text% [auto-wrap #t]))
(define editor-stream-in-bytes-base (make-object editor-stream-in-bytes-base% byte-stream))
(define editor-stream-in (make-object editor-stream-in% editor-stream-in-bytes-base))
(send editor read-from-file editor-stream-in)
editor)
(define text-editor-frame%
(class frame%
(init-field (text (new text% [auto-wrap #t])))
(define editor text)
(super-new [min-height 800] [min-width 500])
(define CANVAS (new editor-canvas%
[parent this]
[editor editor]
[min-height 800]
[min-width 500]))
;; Creation of the menu bar
(define menu-bar (new menu-bar% [parent this]))
;; edit & font menus
(define menu-edit (new menu% [label "Edit"] [parent menu-bar]))
(append-editor-operation-menu-items menu-edit #f)
(define menu-font (new menu% [label "Font"] [parent menu-bar]))
(append-editor-font-menu-items menu-font)
;; Get a serialization of the current content of the editor
(define/public (serialize) (serialize-text editor))
))
(define (make-a-text-editor-frame title (text (new text% [auto-wrap #t])))
(let ([FRAME (new text-editor-frame% [label title] [text text])])
(send FRAME show #t)
FRAME))
;; TEST
; (define frame (make-a-text-editor-frame "Original"))
;; edit a text in the editor canvas using the keyboard and menus
; (define byte-stream (send frame serialize))
; byte-stream ;; to see how it looks!
; (define new-text (deserialize-text byte-stream)) ;; PROBLEM HERE !
; (define new-frame (make-a-text-editor-frame "Copy" new-text))
;; Both text-editor-frames should display the same content but the copy is empty !
I can't identify the problem. Can any of you point me in the right direction? Thank you
