;;; cl-indent.el --- enhanced lisp-indent mode

;; Copyright (C) 1987, 2000, 2001 Free Software Foundation, Inc.

;; Author: Richard Mlynarik <mly@eddie.mit.edu>
;; Created: July 1987
;; Maintainer: FSF
;; Keywords: lisp, tools

;; This file is part of GNU Emacs.

;; GNU Emacs 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 2, or (at your option)
;; any later version.

;; GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; This package supplies a single entry point, common-lisp-indent-function,
;; which performs indentation in the preferred style for Common Lisp code.
;; To enable it:
;;
;; (setq lisp-indent-function 'common-lisp-indent-function)

;;>> TODO
;; :foo
;;   bar
;; :baz
;;   zap
;; &key (like &body)??

;; &rest 1 in lambda-lists doesn't work
;;  -- really want (foo bar
;;                  baz)
;;     not (foo bar
;;              baz)
;;  Need something better than &rest for such cases

;;; Code:

(defgroup lisp-indent nil
  "Indentation in Lisp"
  :group 'lisp)


(defcustom lisp-indent-maximum-backtracking 3
  "*Maximum depth to backtrack out from a sublist for structured indentation.
If this variable is  0, no backtracking will occur and forms such as flet
may not be correctly indented."
  :type 'integer
  :group 'lisp-indent)

(defcustom lisp-tag-indentation 1
  "*Indentation of tags relative to containing list.
This variable is used by the function `lisp-indent-tagbody'."
  :type 'integer
  :group 'lisp-indent)

(defcustom lisp-tag-body-indentation 3
  "*Indentation of non-tagged lines relative to containing list.
This variable is used by the function `lisp-indent-tagbody' to indent normal
lines (lines without tags).
The indentation is relative to the indentation of the parenthesis enclosing
the special form.  If the value is t, the body of tags will be indented
as a block at the same indentation as the first s-expression following
the tag.  In this case, any forms before the first tag are indented
by `lisp-body-indent'."
  :type 'integer
  :group 'lisp-indent)


(defvar lisp-indent-error-function)
(defvar lisp-indent-defun-method '(4 &lambda &body))

;;;###autoload
(defun common-lisp-indent-function (indent-point state)
  (let ((normal-indent (current-column)))
    ;; Walk up list levels until we see something
    ;;  which does special things with subforms.
    (let ((depth 0)
          ;; Path describes the position of point in terms of
          ;;  list-structure with respect to containing lists.
          ;; `foo' has a path of (0 4 1) in `((a b c (d foo) f) g)'
          (path ())
          ;; set non-nil when somebody works out the indentation to use
          calculated
          (last-point indent-point)
          ;; the position of the open-paren of the innermost containing list
          (containing-form-start (elt state 1))
          ;; the column of the above
          sexp-column)
      ;; Move to start of innermost containing list
      (goto-char containing-form-start)
      (setq sexp-column (current-column))
      ;; Look over successively less-deep containing forms
      (while (and (not calculated)
                  (< depth lisp-indent-maximum-backtracking))
        (let ((containing-sexp (point)))
          (forward-char 1)
          (parse-partial-sexp (point) indent-point 1 t)
          ;; Move to the car of the relevant containing form
          (let (tem function method)
            (if (not (looking-at "\\sw\\|\\s_"))
                ;; This form doesn't seem to start with a symbol
                (setq function nil method nil)
              (setq tem (point))
              (forward-sexp 1)
              (setq function (downcase (buffer-substring-no-properties
                                        tem (point))))
              (goto-char tem)
              (setq tem (intern-soft function)
                    method (get tem 'common-lisp-indent-function))
              (cond ((and (null method)
                          (string-match ":[^:]+" function))
                     ;; The pleblisp package feature
                     (setq function (substring function
                                               (1+ (match-beginning 0)))
                           method (get (intern-soft function)
                                       'common-lisp-indent-function)))
                    ((and (null method))
                     ;; backwards compatibility
                     (setq method (get tem 'lisp-indent-function)))))
            (let ((n 0))
              ;; How far into the containing form is the current form?
              (if (< (point) indent-point)
                  (while (condition-case ()
                             (progn
                               (forward-sexp 1)
                               (if (>= (point) indent-point)
                                   nil
                                 (parse-partial-sexp (point)
                                                     indent-point 1 t)
                                 (setq n (1+ n))
                                 t))
                           (error nil))))
              (setq path (cons n path)))

            ;; backwards compatibility.
            (cond ((null function))
                  ((null method)
                   (when (null (cdr path))
                       ;; (package prefix was stripped off above)
                       (setq method (cond ((string-match "\\`def"
                                                         function)
                                         lisp-indent-defun-method)
                                          ((string-match "\\`\\(with\\|do\\)-"
                                                         function)
                                         '(&lambda &body))))))
                  ;; backwards compatibility.  Bletch.
                  ((eq method 'defun)
                   (setq method lisp-indent-defun-method)))

            (cond ((and (memq (char-after (1- containing-sexp)) '(?\' ?\`))
                        (not (eq (char-after (- containing-sexp 2)) ?\#)))
                   ;; No indentation for "'(...)" elements
                   (setq calculated (1+ sexp-column)))
                  ((or (eq (char-after (1- containing-sexp)) ?\,)
                       (and (eq (char-after (1- containing-sexp)) ?\@)
                            (eq (char-after (- containing-sexp 2)) ?\,)))
                   ;; ",(...)" or ",@(...)"
                   (setq calculated normal-indent))
                  ((eq (char-after (1- containing-sexp)) ?\#)
                   ;; "#(...)"
                   (setq calculated (1+ sexp-column)))
                  ((null method))
                  ((integerp method)
                   ;; convenient top-level hack.
                   ;;  (also compatible with lisp-indent-function)
                   ;; The number specifies how many `distinguished'
                   ;;  forms there are before the body starts
                   ;; Equivalent to (4 4 ... &body)
                   (setq calculated (cond ((cdr path)
                                           normal-indent)
                                          ((<= (car path) method)
                                           ;; `distinguished' form
                                           (list (+ sexp-column 4)
                                                 containing-form-start))
                                          ((= (car path) (1+ method))
                                           ;; first body form.
                                           (+ sexp-column lisp-body-indent))
                                          (t
                                           ;; other body form
                                           normal-indent))))
                  ((symbolp method)
                   (let ((lisp-indent-error-function function))
                     (setq calculated (funcall method
                                               path state indent-point
                                               sexp-column normal-indent))))
                  (t
                   (let ((lisp-indent-error-function function))
                     (setq calculated (lisp-indent-259
                                       method path state indent-point
                                       sexp-column normal-indent))))))
          (goto-char containing-sexp)
          (setq last-point containing-sexp)
          (unless calculated
              (condition-case ()
                   (progn (backward-up-list 1)
                          (setq depth (1+ depth)))
                (error (setq depth lisp-indent-maximum-backtracking))))))
      calculated)))


(defun lisp-indent-report-bad-format (m)
  (error "%s has a badly-formed %s property: %s"
         ;; Love those free variable references!!
         lisp-indent-error-function 'common-lisp-indent-function m))

;; Blame the crufty control structure on dynamic scoping
;;  -- not on me!
(defun lisp-indent-259 (method path state indent-point
                        sexp-column normal-indent)
  (catch 'exit
    (let ((p path)
          (containing-form-start (elt state 1))
          n tem tail)
      ;; Isn't tail-recursion wonderful?
      (while p
        ;; This while loop is for destructuring.
        ;; p is set to (cdr p) each iteration.
        (if (not (consp method)) (lisp-indent-report-bad-format method))
        (setq n (1- (car p))
              p (cdr p)
              tail nil)
        (while n
          ;; This while loop is for advancing along a method
          ;; until the relevant (possibly &rest/&body) pattern
          ;; is reached.
          ;; n is set to (1- n) and method to (cdr method)
          ;; each iteration.
          (setq tem (car method))

          (or (eq tem 'nil)             ;default indentation
              (eq tem '&lambda)         ;lambda list
              (and (eq tem '&body) (null (cdr method)))
              (and (eq tem '&rest)
                   (consp (cdr method))
                   (null (cddr method)))
              (integerp tem)            ;explicit indentation specified
              (and (consp tem)          ;destructuring
                   (eq (car tem) '&whole)
                   (or (symbolp (cadr tem))
                       (integerp (cadr tem))))
              (and (symbolp tem)        ;a function to call to do the work.
                   (null (cdr method)))
              (lisp-indent-report-bad-format method))

          (cond ((and tail (not (consp tem)))
                 ;; indent tail of &rest in same way as first elt of rest
                 (throw 'exit normal-indent))
                ((eq tem '&body)
                 ;; &body means (&rest <lisp-body-indent>)
                 (throw 'exit
                   (if (and (= n 0)     ;first body form
                            (null p))   ;not in subforms
                       (+ sexp-column
                          lisp-body-indent)
                       normal-indent)))
                ((eq tem '&rest)
                 ;; this pattern holds for all remaining forms
                 (setq tail (> n 0)
                       n 0
                       method (cdr method)))
                ((> n 0)
                 ;; try next element of pattern
                 (setq n (1- n)
                       method (cdr method))
                 (if (< n 0)
                     ;; Too few elements in pattern.
                     (throw 'exit normal-indent)))
                ((eq tem 'nil)
                 (throw 'exit (list normal-indent containing-form-start)))
          ((eq tem '&lambda)
           (throw 'exit
             (cond ((null p)
                    (list (+ sexp-column 4) containing-form-start))
                   ((null (cdr p))
                    (+ sexp-column 1))
                   (t normal-indent))))
                ((integerp tem)
                 (throw 'exit
                   (if (null p)         ;not in subforms
                       (list (+ sexp-column tem) containing-form-start)
                       normal-indent)))
                ((symbolp tem)          ;a function to call
                 (throw 'exit
                   (funcall tem path state indent-point
                            sexp-column normal-indent)))
                (t
                 ;; must be a destructing frob
                 (if (not (null p))
                     ;; descend
               (setq method (cddr tem)
                           n nil)
               (setq tem (cadr tem))
                   (throw 'exit
                     (cond (tail
                            normal-indent)
                           ((eq tem 'nil)
                            (list normal-indent
                                  containing-form-start))
                           ((integerp tem)
                            (list (+ sexp-column tem)
                                  containing-form-start))
                           (t
                            (funcall tem path state indent-point
                                     sexp-column normal-indent))))))))))))

(defun lisp-indent-tagbody (path state indent-point sexp-column normal-indent)
  (if (not (null (cdr path)))
      normal-indent
    (save-excursion
      (goto-char indent-point)
      (beginning-of-line)
      (skip-chars-forward " \t")
      (list (cond ((looking-at "\\sw\\|\\s_")
                   ;; a tagbody tag
                   (+ sexp-column lisp-tag-indentation))
                  ((integerp lisp-tag-body-indentation)
                   (+ sexp-column lisp-tag-body-indentation))
                  ((eq lisp-tag-body-indentation 't)
                   (condition-case ()
                       (progn (backward-sexp 1) (current-column))
                     (error (1+ sexp-column))))
                  (t (+ sexp-column lisp-body-indent)))
;            (cond ((integerp lisp-tag-body-indentation)
;                   (+ sexp-column lisp-tag-body-indentation))
;                  ((eq lisp-tag-body-indentation 't)
;                   normal-indent)
;                  (t
;                   (+ sexp-column lisp-body-indent)))
            (elt state 1)
            ))))

(defun lisp-indent-do (path state indent-point sexp-column normal-indent)
  (if (>= (car path) 3)
      (let ((lisp-tag-body-indentation lisp-body-indent))
        (funcall (function lisp-indent-tagbody)
                 path state indent-point sexp-column normal-indent))
    (funcall (function lisp-indent-259)
             '((&whole nil &rest
                ;; the following causes weird indentation
                ;;(&whole 1 1 2 nil)
                )
               (&whole nil &rest 1))
             path state indent-point sexp-column normal-indent)))

(defun lisp-indent-defmethod (path state indent-point sexp-column 
				   normal-indent)
  "Indentation function defmethod."
  (lisp-indent-259 (if (save-excursion (goto-char (elt state 1))
				       (forward-char 1)
				       (forward-sexp 2)
				       (looking-at "\\s-+:"))
		       '(4 4 (&whole 4 &rest 4) &body)
		     (get 'defun 'common-lisp-indent-function))
		   path state indent-point sexp-column normal-indent))


(defun lisp-indent-function-lambda-hack (path state indent-point
                                         sexp-column normal-indent)
  ;; indent (function (lambda () <newline> <body-forms>)) kludgily.
  (if (or (cdr path) ; wtf?
          (> (car path) 3))
      ;; line up under previous body form
      normal-indent
    ;; line up under function rather than under lambda in order to
    ;;  conserve horizontal space.  (Which is what #' is for.)
    (condition-case ()
        (save-excursion
          (backward-up-list 2)
          (forward-char 1)
          (if (looking-at "\\(lisp:+\\)?function\\(\\Sw\\|\\S_\\)")
              (+ lisp-body-indent -1 (current-column))
              (+ sexp-column lisp-body-indent)))
       (error (+ sexp-column lisp-body-indent)))))


(let ((l '((block 1)
           (case        (4 &rest (&whole 2 &rest 1)))
           (ccase . case) (ecase . case)
           (typecase . case) (etypecase . case) (ctypecase . case)
           (catch 1)
           (cond        (&rest (&whole 2 &rest 1)))
           (defvar      (4 2 2))
           (defclass    (6 4 (&whole 2 &rest 1) (&whole 2 &rest 1)))
           (defconstant . defvar)
           (defcustom   (4 2 2 2))
           (defparameter . defvar)
           (defconst     . defcustom)
           (define-condition  . defclass)
           (define-modify-macro (4 &body))
           (defsetf     (4 &lambda 4 &body))
           (defun       (4 &lambda &body))
           (define-setf-method . defun)
           (define-setf-expander . defun)
           (defmacro . defun) (defsubst . defun) (deftype . defun)
	   (defmethod	lisp-indent-defmethod)
           (defpackage  (4 2))
           (defstruct   ((&whole 4 &rest (&whole 2 &rest 1))
                         &rest (&whole 2 &rest 1)))
           (destructuring-bind
                        ((&whole 6 &rest 1) 4 &body))
           (do          lisp-indent-do)
           (do* . do)
           (dolist      ((&whole 4 2 1) &body))
           (dotimes . dolist)
           (eval-when   1)
           (flet        ((&whole 4 &rest (&whole 1 &lambda &body)) &body))
           (labels . flet)
           (macrolet . flet)
           (handler-case (4 &rest (&whole 2 &lambda &body)))
           (restart-case . handler-case)
           ;; `else-body' style
           (if          (nil nil &body))
           ;; single-else style (then and else equally indented)
           (if          (&rest nil))
           (lambda      (&lambda &rest lisp-indent-function-lambda-hack))
           (let         ((&whole 4 &rest (&whole 1 1 2)) &body))
           (let* . let)
           (compiler-let . let) ;barf
           (handler-bind . let) (restart-bind . let)
           (locally 1)
           ;(loop ...)
           (:method (&lambda &body)) ; in `defgeneric'
           (multiple-value-bind ((&whole 6 &rest 1) 4 &body))
           (multiple-value-call (4 &body))
           (multiple-value-prog1 1)
           (multiple-value-setq (4 2))
           (multiple-value-setf . multiple-value-setq)
           (pprint-logical-block (4 2))
           (print-unreadable-object ((&whole 4 1 &rest 1) &body))
           ;; Combines the worst features of BLOCK, LET and TAGBODY
           (prog        (&lambda &rest lisp-indent-tagbody))
           (prog* . prog)
           (prog1 1)
           (prog2 2)
           (progn 0)
           (progv       (4 4 &body))
           (return 0)
           (return-from (nil &body))
           (symbol-macrolet . multiple-value-bind)
           (tagbody     lisp-indent-tagbody)
           (throw 1)
           (unless 1)
           (unwind-protect (5 &body))
           (when 1)
           (with-output-to-string (4 2))
           (with-slots . multiple-value-bind)
           (with-standard-io-syntax (2)))))
  (while l
    (put (caar l) 'common-lisp-indent-function
         (if (symbolp (cdar l))
             (get (cdar l) 'common-lisp-indent-function)
             (car (cdar l))))
    (setq l (cdr l))))


;(defun foo (x)
;  (tagbody
;   foo
;     (bar)
;   baz
;     (when (losing)
;       (with-big-loser
;           (yow)
;         ((lambda ()
;            foo)
;          big)))
;     (flet ((foo (bar baz zap)
;              (zip))
;            (zot ()
;              quux))
;       (do ()
;           ((lose)
;            (foo 1))
;         (quux)
;        foo
;         (lose))
;       (cond ((x)
;              (win 1 2
;                   (foo)))
;             (t
;              (lose
;                3))))))


;(put 'while    'common-lisp-indent-function 1)
;(put 'defwrapper'common-lisp-indent-function ...)
;(put 'def 'common-lisp-indent-function ...)
;(put 'defflavor        'common-lisp-indent-function ...)
;(put 'defsubst 'common-lisp-indent-function ...)

;(put 'with-restart 'common-lisp-indent-function '((1 4 ((* 1))) (2 &body)))
;(put 'restart-case 'common-lisp-indent-function '((1 4) (* 2 ((0 1) (* 1)))))
;(put 'define-condition 'common-lisp-indent-function '((1 6) (2 6 ((&whole 1))) (3 4 ((&whole 1))) (4 &body)))
;(put 'with-condition-handler 'common-lisp-indent-function '((1 4 ((* 1))) (2 &body)))
;(put 'condition-case 'common-lisp-indent-function '((1 4) (* 2 ((0 1) (1 3) (2 &body)))))
;(put 'defclass 'common-lisp-indent-function '((&whole 2 &rest (&whole 2 &rest 1) &rest (&whole 2 &rest 1)))
;(put 'defgeneric 'common-lisp-indent-function 'defun)

;;; cl-indent.el ends here
