;; introspection.scm -- name says it all

;; Copyright (C) 2009 Jose Antonio Ortega Ruiz

;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
;; Start date: Sun Feb 08, 2009 18:44

;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 3 of the License, or
;; (at your option) any later version.

;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Comentary:

;; Procedures introspecting on scheme objects and their properties.

;;; Code:

(define-module (geiser introspection)
  #:export (arguments completions symbol-location docstring)
  #:use-module (system vm program)
  #:use-module (ice-9 session)
  #:use-module (ice-9 documentation)
  #:use-module (srfi srfi-1))

(define (arguments sym . syms)
  (let loop ((sym sym) (syms syms))
    (cond ((obj-args (symbol->obj sym)) => (lambda (args)
                                             (cons sym (apply args-alist args))))
          ((null? syms) #f)
          (else (loop (car syms) (cdr syms))))))

(define (args-alist args opt module)
  (list (cons 'required args)
        (cons 'optional (or opt '()))
        (cons 'module (cond ((module? module) (module-name module))
                            ((list? module) module)
                            (else '())))))

(define (symbol->obj sym)
  (and (symbol? sym)
       (module-defined? (current-module) sym)
       (module-ref (current-module) sym)))

(define (obj-args obj)
  (cond ((not obj) #f)
        ((program? obj) (program-args obj))
        ((procedure? obj) (procedure-args obj))
        ((macro? obj) (macro-args obj))
        (else #f)))

(define (symbol-module sym)
  (call/cc
   (lambda (k)
     (apropos-fold (lambda (module name var init)
                     (if (eq? name sym) (k (module-name module)) init))
                   #f
                   (symbol->string sym)
                   (apropos-fold-accessible (current-module))))))

(define (program-args program)
  (let* ((arity (program-arity program))
         (arg-no (first arity))
         (opt (> (second arity) 0))
         (args (map first (take (program-bindings program) arg-no))))
    (list (if opt (drop-right args 1) args)
          (and opt (last args))
          (program-module program))))

(define (procedure-args proc)
  (let ((name (procedure-name proc)))
    (cond ((procedure-source proc) => (lambda (src)
                                        (procedure-args-from-source name src)))
          (else (let* ((arity (procedure-property proc 'arity))
                       (req (first arity))
                       (opt (third arity)))
                  (list (map (lambda (n)
                               (string->symbol (format "arg~A" (+ 1 n))))
                             (iota req))
                        (and opt 'rest)
                        (and name (symbol-module name))))))))

(define (procedure-args-from-source name src)
  (let ((formals (cadr src)))
    (cond ((list? formals) (list formals #f (symbol-module name)))
          ((pair? formals) (let ((req (car formals))
                                 (opt (cdr formals)))
                             (list (if (list? req) req (list req))
                                   opt
                                   (symbol-module name))))
          (else #f))))

(define (macro-args macro)
  (let ((prog (macro-transformer macro)))
    (if prog
        (obj-args prog)
        (list '(...) #f #f))))

(define (completions prefix)
  (sort! (map symbol->string
              (apropos-internal (string-append "^" prefix)))
         string<?))

(define (symbol-location sym)
  (cond ((symbol-module sym) => make-location-from-module-name)
        (else '())))

(define (make-location file line)
  (list (cons 'file (if (string? file) file '()))
        (cons 'line (if (number? line) (+ 1 line) '()))))

(define module-filename (@@ (ice-9 session) module-filename))

(define (make-location-from-module-name name)
  (make-location (module-filename name) #f))

(define (display-docstring sym)
  (let ((obj (symbol->obj sym)))
    (if obj
        (let* ((args (obj-args obj))
               (req (and args (car args)))
               (opt (and args (cadr args)))
               (signature (if args (cond ((and (not req) (not opt)) (list sym))
                                         ((and (not opt) req) (cons sym req))
                                         ((and (not req) opt) (cons sym opt))
                                         (else `(,sym ,@req . ,opt)))
                              sym))
               (type (cond ((macro? obj) "A macro")
                           ((procedure? obj) "A  procedure")
                           ((program? obj) "A compiled program")
                           (else "An object")))
               (modname (symbol-module sym)))
          (display signature)
          (newline)
          (display type)
          (if modname (begin (display " in module ")
                             (display modname)))
          (newline)
          (display (or (object-documentation obj) ""))))))

(define (docstring sym)
  (with-output-to-string
    (lambda () (display-docstring sym))))

;;; introspection.scm ends here