;;; find-paths.el --- setup various XEmacs paths

;; Copyright (C) 1985-1986, 1990, 1992-1997 Free Software Foundation, Inc.
;; Copyright (c) 1993, 1994 Sun Microsystems, Inc.
;; Copyright (C) 1995 Board of Trustees, University of Illinois
;; Copyright (C) 2003 Ben Wing.

;; Author: Mike Sperber <mike@xemacs.org>
;; Maintainer: XEmacs Development Team
;; Keywords: internal, dumped

;; This file is part of XEmacs.

;; XEmacs 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.

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

;;; Synched up with: Not in FSF.

;;; Commentary:

;; This file is dumped with XEmacs.

;; This file contains basic library functionality for manipulating paths
;; and path lists and finding paths in the XEmacs hierarchy.


;;; Code:

(defvar paths-version-control-filename-regexp
  "^\\(RCS\\|CVS\\|SCCS\\)$"
  "File bases associated with version control.")

(defvar paths-lisp-filename-regexp
  "^\\(.*\\.elc?\\)$"
  "File bases that name Emacs Lisp files.")

(defvar paths-no-lisp-directory-regexp
  (concat "\\(" paths-version-control-filename-regexp "\\)"
	  "\\|"
	  "\\(" paths-lisp-filename-regexp "\\)")
  "File bases that may not be directories containing Lisp code.")

(defun paths-find-recursive-path (directories &optional max-depth exclude-regexp)
  "Return a list of the directory hierarchy underneath DIRECTORIES.
The returned list is sorted by pre-order and lexicographically.
MAX-DEPTH limits the depth of the search to MAX-DEPTH level,
if it is a number.  If MAX-DEPTH is NIL, the search depth is unlimited.
EXCLUDE-REGEXP is a regexp that matches directory names to exclude
from the search."
  (let ((path '()))
    (while directories
      (let ((directory (file-name-as-directory
			(expand-file-name
			 (car directories)))))
	(if (paths-file-readable-directory-p directory)
	    (let ((raw-entries
		   (if (equal 0 max-depth)
		       '()
		     (directory-files directory nil "^[^.-]")))
		  (reverse-dirs '()))
	      (while raw-entries
		(if (not (and exclude-regexp
			      (string-match exclude-regexp (car raw-entries))))
		    (setq reverse-dirs
			  (cons (expand-file-name (car raw-entries) directory)
				reverse-dirs)))
		(setq raw-entries (cdr raw-entries)))

	      (let ((sub-path
		     (paths-find-recursive-path (reverse reverse-dirs)
						(if (numberp max-depth)
						    (- max-depth 1)
						  max-depth)
						exclude-regexp)))
		(setq path (nconc path
				  (list directory)
				  sub-path))))))
      (setq directories (cdr directories)))
    path))

(defun paths-file-readable-directory-p (filename)
  "Check if filename is a readable directory."
  (and (file-directory-p filename)
       (file-readable-p filename)))

(defun paths-find-recursive-load-path (directories &optional max-depth)
  "Construct a recursive load path underneath DIRECTORIES."
  (paths-find-recursive-path directories
			     max-depth paths-no-lisp-directory-regexp))

(defun paths-chase-symlink (file-name)
  "Chase a symlink until the bitter end."
      (let ((maybe-symlink (file-symlink-p file-name)))
	(if maybe-symlink
	    (let* ((directory (file-name-directory file-name))
		   (destination (expand-file-name maybe-symlink directory)))
	      (paths-chase-symlink destination))
	  file-name)))

(defun paths-construct-path (components &optional expand-directory)
  "Convert list of path components COMPONENTS into a path.
If EXPAND-DIRECTORY is non-NIL, use it as a directory to feed
to EXPAND-FILE-NAME."
  (let* ((reverse-components (reverse components))
	 (last-component (car reverse-components))
	 (first-components (reverse (cdr reverse-components)))
	 (path
	  (apply #'concat
		 (append (mapcar #'file-name-as-directory first-components)
			 (list last-component)))))
    (if expand-directory
	(expand-file-name path expand-directory)
      path)))

(defun paths-construct-emacs-directory (root suffix base)
  "Construct a directory name within the XEmacs hierarchy.
ROOT must be a an installation root.
SUFFIX is the subdirectory from there.
BASE is the base to look for."
  (file-name-as-directory
   (expand-file-name
    (concat
     (file-name-as-directory root)
     suffix
     base))))


(defun paths-for-each-emacs-directory (func
				       roots suffix base
				       &optional envvar default keep-suffix)
  "Iterate over directories in the XEmacs hierarchy.
FUNC is a function that called for each directory, with the directory
as the only argument.
ROOTS must be a list of installation roots.
SUFFIX is the subdirectory from there.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value.
If KEEP-SUFFIX is non-nil, the suffix must be respected in searching
the directory."
  (let ((preferred-value (or (and envvar (getenv envvar))
			     default)))
    (if (and preferred-value
	     (paths-file-readable-directory-p preferred-value))
	(file-name-as-directory preferred-value)
      (while roots
	(let* ((root (car roots))
	       ;; installed
	       (path (paths-construct-emacs-directory root suffix base)))
	  (if (paths-file-readable-directory-p path)
	      (funcall func path)
	    ;; in-place
	    (if (null keep-suffix)
		(let ((path (paths-construct-emacs-directory root "" base)))
		  (if (paths-file-readable-directory-p path)
		      (funcall func path))))))
	(setq roots (cdr roots))))))

(defun paths-find-emacs-directories (roots
				     suffix base
				     &optional envvar default keep-suffix)
  "Find a list of directories in the XEmacs hierarchy.
ROOTS must be a list of installation roots.
SUFFIX is the subdirectory from there.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value.
If KEEP-SUFFIX is non-nil, the suffix must be respected in searching
the directory."
  (let ((l '()))
    (paths-for-each-emacs-directory #'(lambda (dir)
					(setq l (cons dir l)))
				    roots
				    suffix base
				    envvar default keep-suffix)
    (reverse l)))

(defun paths-find-emacs-directory (roots suffix base
				   &optional envvar default keep-suffix)
  "Find a directory in the XEmacs hierarchy.
ROOTS must be a list of installation roots.
SUFFIX is the subdirectory from there.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value.
If KEEP-SUFFIX is non-nil, the suffix must be respected in searching
the directory."
  (catch 'gotcha
    (paths-for-each-emacs-directory #'(lambda (dir)
					(throw 'gotcha dir))
				    roots
				    suffix base
				    envvar default keep-suffix)))

(defun paths-for-each-site-directory (func roots base &optional envvar default)
  "Iterate over the site-specific directories in the XEmacs hierarchy.
FUNC is a function that called for each directory, with the directory
as the only argument.
ROOT must be a an installation root.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value."
  (paths-for-each-emacs-directory func
				  roots
				  (file-name-as-directory
				   (paths-construct-path (list
							  "lib"
							  emacs-program-name)))
				  base
				  envvar default))

(defun paths-find-site-directory (roots base &optional envvar default)
  "Find a site-specific directory in the XEmacs hierarchy.
ROOT must be a an installation root.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value."
  (catch 'gotcha
    (paths-for-each-site-directory #'(lambda (dir)
				       (throw 'gotcha dir))
				   roots base
				   envvar default)))

(defun paths-find-site-directories (roots base &optional envvar default)
  "Find a list of site-specific directories in the XEmacs hierarchy.
ROOT must be a an installation root.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value."
  (let ((l '()))
    (paths-for-each-site-directory #'(lambda (dir)
					(setq l (cons dir l)))
				   roots base
				   envvar default)
    (reverse l)))

(defun paths-for-each-version-directory (func roots base
					 &optional envvar default enforce-version)
  "Iterate over version-specific directories in the XEmacs hierarchy.
FUNC is a function that called for each directory, with the directory
as the only argument.
ROOT must be a an installation root.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value.
If ENFORCE-VERSION is non-nil, the directory must contain the XEmacs version."
  (paths-for-each-emacs-directory func
				  roots
				  (file-name-as-directory
				   (paths-construct-path
				    (list "lib"
					  (construct-emacs-version-name))))
				  base
				  envvar default))

(defun paths-find-version-directory (roots base
				     &optional envvar default enforce-version)
  "Find a version-specific directory in the XEmacs hierarchy.
ROOT must be a an installation root.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value.
If ENFORCE-VERSION is non-nil, the directory must contain the XEmacs version."
  (catch 'gotcha
    (paths-for-each-version-directory #'(lambda (dir)
					  (throw 'gotcha dir))
				      roots base
				      envvar default)))

(defun paths-find-version-directories (roots base
				       &optional envvar default enforce-version)
  "Find a list of version-specific directories in the XEmacs hierarchy.
ROOT must be a an installation root.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value.
If ENFORCE-VERSION is non-nil, the directory must contain the XEmacs version."
  (let ((l '()))
    (paths-for-each-site-directory #'(lambda (dir)
				       (setq l (cons dir l)))
				   roots base
				   envvar default)
    (reverse l)))

(defun paths-find-architecture-directory (roots base &optional envvar default)
  "Find an architecture-specific directory in the XEmacs hierarchy.
ROOT must be a an installation root.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value."
  (or
   ;; from more to less specific
   (paths-find-version-directory roots
				 (paths-construct-path
				  (list system-configuration base))
				 envvar default)
   (paths-find-version-directory roots
				 base
				 envvar)
   (paths-find-version-directory roots
				 system-configuration
				 envvar)))

(defun construct-emacs-version-name ()
  "Construct a string from the raw XEmacs version number."
  (concat emacs-program-name "-" emacs-program-version))

(defun paths-directories-which-exist (directories)
  "Return the directories among DIRECTORIES.
DIRECTORIES is a list of strings."
  (let ((reverse-directories '()))
    (while directories
      (if (paths-file-readable-directory-p (car directories))
	  (setq reverse-directories
		(cons (car directories)
		      reverse-directories)))
      (setq directories (cdr directories)))
    (reverse reverse-directories)))

(defun paths-uniq-append (list-1 list-2)
  "Append LIST-1 and LIST-2, omitting EQUAL duplicates."
  (let ((reverse-survivors '()))
    (while list-2
      (if (null (member (car list-2) list-1))
	  (setq reverse-survivors (cons (car list-2) reverse-survivors)))
      (setq list-2 (cdr list-2)))
    (append list-1
	    (reverse reverse-survivors))))

(defun paths-filter (predicate list)
  "Delete all matches of PREDICATE from LIST."
  (let ((reverse-result '()))
    (while list
      (if (funcall predicate (car list))
	  (setq reverse-result (cons (car list) reverse-result)))
      (setq list (cdr list)))
    (nreverse reverse-result)))

(defun paths-decode-directory-path (string &optional drop-empties)
  "Split STRING at path separators into a directory list.
Non-\"\" components are converted into directory form.
If DROP-EMPTIES is non-NIL, \"\" components are dropped from the output.
Otherwise, they are left alone."
  (let* ((components (split-path string))
	 (directories
	  (mapcar #'(lambda (component)
		      (if (string-equal "" component)
			  component
			(file-name-as-directory component)))
		  components)))
    (if drop-empties
	(paths-filter #'(lambda (component)
			  (null (string-equal "" component)))
		      directories)
      directories)))

;;; find-paths.el ends here