A Simple Sexp Structure Editor

This is a simple sexp structure editor to demonstrate how we can edit lisp sources directly instead of going thru the deserialization and serialization (converting the sexps into a textual representation and using a text editor such as emacs).

This editor manipulates directly the sexp data structure.

• sedit.lisp

It is invoked as (sedit sexp), and returns the modified sexp. (The sexp is modified destructively).

 (sedit (copy-tree '(an example)))
  

At each interaction loop, it prints the whole sexp, showing the selected sub-sexp, and query a command. The list of commands are:

• q quit to return the modified sexp from sedit.
• i in to enter inside the selected list.
• o out to select the list containing the selection.
• f forward n next to select the sexp following the selection (or out).
• b backward p previous to select the sexp preceding the selection (or out).
• s insert to insert a new sexp before the selection.
• r replace to replace the selection with a new sexp.
• a add to add a new sexp after the selection.
• x cut to cut the selection into a *clipboard*.
• c copy to copy the selection into a *clipboard*.
• y paste to paste the *clipboard* replacing the selection.

Example:

C/IBCL-USER[4]> (sedit '())

Sexp Editor:
【NIL】
> r
replacement sexp: (let ((*package #.*package*)) (print 'hello))
【(LET ((*PACKAGE #<PACKAGE IMAGE-BASED-COMMON-LISP-USER>)) (PRINT (QUOTE HELLO)))】
> i
(【LET】 ((*PACKAGE #<PACKAGE IMAGE-BASED-COMMON-LISP-USER>)) (PRINT (QUOTE HELLO)))
> n
(LET 【((*PACKAGE #<PACKAGE IMAGE-BASED-COMMON-LISP-USER>))】 (PRINT (QUOTE HELLO)))
> i
(LET (【(*PACKAGE #<PACKAGE IMAGE-BASED-COMMON-LISP-USER>)】) (PRINT (QUOTE HELLO)))
> i
(LET ((【*PACKAGE】 #<PACKAGE IMAGE-BASED-COMMON-LISP-USER>)) (PRINT (QUOTE HELLO)))
> r
replacement sexp: *package*
(LET ((【*PACKAGE*】 #<PACKAGE IMAGE-BASED-COMMON-LISP-USER>)) (PRINT (QUOTE HELLO)))
> q
(LET ((*PACKAGE* #<PACKAGE IMAGE-BASED-COMMON-LISP-USER>)) (PRINT 'HELLO))
C/IBCL-USER[5]> (eval *)

HELLO
HELLO
C/IBCL-USER[6]>