lisp/tree-widget.el

   1 ;;; tree-widget.el --- Tree widget
   2
   3 ;; Copyright (C) 2004-2015 Free Software Foundation, Inc.
   4
   5 ;; Author: David Ponce <david@dponce.com>
   6 ;; Maintainer: David Ponce <david@dponce.com>
   7 ;; Created: 16 Feb 2001
   8 ;; Keywords: extensions
   9
  10 ;; This file is part of GNU Emacs
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26 ;;
  27 ;; This library provide a tree widget useful to display data
  28 ;; structures organized in a hierarchical order.
  29 ;;
  30 ;; The following properties are specific to the tree widget:
  31 ;;
  32 ;; :open
  33 ;;    Set to non-nil to expand the tree.  By default the tree is
  34 ;;    collapsed.
  35 ;;
  36 ;; :node
  37 ;;    Specify the widget used to represent the value of a tree node.
  38 ;;    By default this is an `item' widget which displays the
  39 ;;    tree-widget :tag property value if defined, or a string
  40 ;;    representation of the tree-widget value.
  41 ;;
  42 ;; :keep
  43 ;;    Specify a list of properties to keep when the tree is collapsed
  44 ;;    so they can be recovered when the tree is expanded.  This
  45 ;;    property can be used in child widgets too.
  46 ;;
  47 ;; :expander (obsoletes :dynargs)
  48 ;;    Specify a function to be called to dynamically provide the
  49 ;;    tree's children in response to an expand request.  This function
  50 ;;    will be passed the tree widget and must return a list of child
  51 ;;    widgets.  Child widgets returned by the :expander function are
  52 ;;    stored in the :args property of the tree widget.
  53 ;;
  54 ;; :expander-p
  55 ;;    Specify a predicate which must return non-nil to indicate that
  56 ;;    the :expander function above has to be called.  By default, to
  57 ;;    speed up successive expand requests, the :expander-p predicate
  58 ;;    return non-nil when the :args value is nil.  So, by default, to
  59 ;;    refresh child values, it is necessary to set the :args property
  60 ;;    to nil, then redraw the tree.
  61 ;;
  62 ;; :open-icon  (default `tree-widget-open-icon')
  63 ;; :close-icon (default `tree-widget-close-icon')
  64 ;; :empty-icon (default `tree-widget-empty-icon')
  65 ;; :leaf-icon  (default `tree-widget-leaf-icon')
  66 ;;    Those properties define the icon widgets associated to tree
  67 ;;    nodes.  Icon widgets must derive from the `tree-widget-icon'
  68 ;;    widget.  The :tag and :glyph-name property values are
  69 ;;    respectively used when drawing the text and graphic
  70 ;;    representation of the tree.  The :tag value must be a string
  71 ;;    that represent a node icon, like "[+]" for example.  The
  72 ;;    :glyph-name value must the name of an image found in the current
  73 ;;    theme, like "close" for example (see also the variable
  74 ;;    `tree-widget-theme').
  75 ;;
  76 ;; :guide      (default `tree-widget-guide')
  77 ;; :end-guide  (default `tree-widget-end-guide')
  78 ;; :no-guide   (default `tree-widget-no-guide')
  79 ;; :handle     (default `tree-widget-handle')
  80 ;; :no-handle  (default `tree-widget-no-handle')
  81 ;;    Those properties define `item'-like widgets used to draw the
  82 ;;    tree guide lines.  The :tag property value is used when drawing
  83 ;;    the text representation of the tree.  The graphic look and feel
  84 ;;    is given by the images named "guide", "no-guide", "end-guide",
  85 ;;    "handle", and "no-handle" found in the current theme (see also
  86 ;;    the variable `tree-widget-theme').
  87 ;;
  88 ;; These are the default :tag values for icons, and guide lines:
  89 ;;
  90 ;; open-icon    "[-]"
  91 ;; close-icon   "[+]"
  92 ;; empty-icon   "[X]"
  93 ;; leaf-icon    ""
  94 ;; guide        " |"
  95 ;; no-guide     "  "
  96 ;; end-guide    " `"
  97 ;; handle       "-"
  98 ;; no-handle    " "
  99 ;;
 100 ;; The text representation of a tree looks like this:
 101 ;;
 102 ;; [-] 1        (open-icon :node)
 103 ;;  |-[+] 1.0   (guide+handle+close-icon :node)
 104 ;;  |-[X] 1.1   (guide+handle+empty-icon :node)
 105 ;;  `-[-] 1.2   (end-guide+handle+open-icon :node)
 106 ;;     |- 1.2.1 (no-guide+no-handle+guide+handle+leaf-icon leaf)
 107 ;;     `- 1.2.2 (no-guide+no-handle+end-guide+handle+leaf-icon leaf)
 108 ;;
 109 ;; By default, images will be used instead of strings to draw a
 110 ;; nice-looking tree.  See the `tree-widget-image-enable',
 111 ;; `tree-widget-themes-directory', and `tree-widget-theme' options for
 112 ;; more details.
 113
 114 ;;; History:
 115 ;;
 116
 117 ;;; Code:
 118 (require 'wid-edit)
 119 \f
 120 ;;; Customization
 121 ;;
 122 (defgroup tree-widget nil
 123   "Customization support for the Tree Widget library."
 124   :version "22.1"
 125   :group 'widgets)
 126
 127 (defcustom tree-widget-image-enable (if (fboundp 'display-images-p)
 128                                         (display-images-p))
 129   "Non-nil means that tree-widget will try to use images."
 130   :type  'boolean
 131   :group 'tree-widget)
 132
 133 (defvar tree-widget-themes-load-path
 134   '(load-path
 135     (let ((dir (if (fboundp 'locate-data-directory)
 136                    (locate-data-directory "tree-widget") ;; XEmacs
 137                  data-directory)))
 138       (and dir (list dir (expand-file-name "images" dir))))
 139     )
 140   "List of locations in which to search for the themes sub-directory.
 141 Each element is an expression that will be recursively evaluated until
 142 it returns a single directory or a list of directories.
 143 The default is to search in the `load-path' first, then in the
 144 \"images\" sub directory in the data directory, then in the data
 145 directory.
 146 The data directory is the value of the variable `data-directory' on
 147 Emacs, and what `(locate-data-directory \"tree-widget\")' returns on
 148 XEmacs.")
 149
 150 (defcustom tree-widget-themes-directory "tree-widget"
 151   "Name of the directory in which to look for an image theme.
 152 When nil use the directory where the tree-widget library is located.
 153 When it is a relative name, search in all occurrences of that sub
 154 directory in the path specified by `tree-widget-themes-load-path'.
 155 The default is to use the \"tree-widget\" relative name."
 156   :type '(choice (const :tag "Default" "tree-widget")
 157                  (const :tag "Where is this library" nil)
 158                  (directory :format "%{%t%}:\n%v"))
 159   :group 'tree-widget)
 160
 161 (defcustom tree-widget-theme nil
 162   "Name of the theme in which to look for images.
 163 This is a sub directory of the themes directory specified by the
 164 `tree-widget-themes-directory' option.
 165 The default theme is \"default\".  When an image is not found in a
 166 theme, it is searched in its parent theme.
 167
 168 A complete theme must at least contain images with these file names
 169 with a supported extension (see also `tree-widget-image-formats'):
 170
 171 \"guide\"
 172   A vertical guide line.
 173 \"no-guide\"
 174   An invisible vertical guide line.
 175 \"end-guide\"
 176   End of a vertical guide line.
 177 \"handle\"
 178   Horizontal guide line that joins the vertical guide line to an icon.
 179 \"no-handle\"
 180   An invisible handle.
 181
 182 Plus images whose name is given by the :glyph-name property of the
 183 icon widgets used to draw the tree.  By default these images are used:
 184
 185 \"open\"
 186   Icon associated to an expanded tree.
 187 \"close\"
 188   Icon associated to a collapsed tree.
 189 \"empty\"
 190   Icon associated to an expanded tree with no child.
 191 \"leaf\"
 192   Icon associated to a leaf node."
 193   :type '(choice (const  :tag "Default" nil)
 194                  (string :tag "Name"))
 195   :group 'tree-widget)
 196
 197 (defcustom tree-widget-image-properties-emacs
 198   '(:ascent center :mask (heuristic t))
 199   "Default properties of Emacs images."
 200   :type 'plist
 201   :group 'tree-widget)
 202
 203 (defcustom tree-widget-image-properties-xemacs
 204   nil
 205   "Default properties of XEmacs images."
 206   :type 'plist
 207   :group 'tree-widget)
 208
 209 (defcustom tree-widget-space-width 0.5
 210   "Amount of space between an icon image and a node widget.
 211 Must be a valid space :width display property."
 212   :group 'tree-widget
 213   :type 'sexp)
 214 \f
 215 ;;; Image support
 216 ;;
 217 (eval-and-compile ;; Emacs/XEmacs compatibility stuff
 218   (cond
 219    ;; XEmacs
 220    ((featurep 'xemacs)
 221     (defsubst tree-widget-use-image-p ()
 222       "Return non-nil if image support is currently enabled."
 223       (and tree-widget-image-enable
 224            widget-glyph-enable
 225            (console-on-window-system-p)))
 226     (defsubst tree-widget-create-image (type file &optional props)
 227       "Create an image of type TYPE from FILE, and return it.
 228 Give the image the specified properties PROPS."
 229       (apply 'make-glyph `([,type :file ,file ,@props])))
 230     (defsubst tree-widget-image-formats ()
 231       "Return the alist of image formats/file name extensions.
 232 See also the option `widget-image-file-name-suffixes'."
 233       (delq nil
 234             (mapcar
 235              #'(lambda (fmt)
 236                  (and (valid-image-instantiator-format-p (car fmt)) fmt))
 237              widget-image-file-name-suffixes)))
 238     )
 239    ;; Emacs
 240    (t
 241     (defsubst tree-widget-use-image-p ()
 242       "Return non-nil if image support is currently enabled."
 243       (and tree-widget-image-enable
 244            widget-image-enable
 245            (display-images-p)))
 246     (defsubst tree-widget-create-image (type file &optional props)
 247       "Create an image of type TYPE from FILE, and return it.
 248 Give the image the specified properties PROPS."
 249       (apply 'create-image `(,file ,type nil ,@props)))
 250     (defsubst tree-widget-image-formats ()
 251       "Return the alist of image formats/file name extensions.
 252 See also the option `widget-image-conversion'."
 253       (delq nil
 254             (mapcar
 255              #'(lambda (fmt)
 256                  (and (image-type-available-p (car fmt)) fmt))
 257              widget-image-conversion)))
 258     ))
 259   )
 260
 261 ;; Buffer local cache of theme data.
 262 (defvar tree-widget--theme nil)
 263
 264 (defsubst tree-widget-theme-name ()
 265   "Return the current theme name, or nil if no theme is active."
 266   (and tree-widget--theme (car (aref tree-widget--theme 0))))
 267
 268 (defsubst tree-widget-set-parent-theme (name)
 269   "Set to NAME the parent theme of the current theme.
 270 The default parent theme is the \"default\" theme."
 271   (unless (member name (aref tree-widget--theme 0))
 272     (aset tree-widget--theme 0
 273           (append (aref tree-widget--theme 0) (list name)))
 274     ;; Load the theme setup from the first directory where the theme
 275     ;; is found.
 276     (catch 'found
 277       (dolist (dir (tree-widget-themes-path))
 278         (setq dir (expand-file-name name dir))
 279         (when (file-accessible-directory-p dir)
 280           (throw 'found
 281                  (load (expand-file-name
 282                         "tree-widget-theme-setup" dir) t)))))))
 283
 284 (defun tree-widget-set-theme (&optional name)
 285   "In the current buffer, set the theme to use for images.
 286 The current buffer must be where the tree widget is drawn.
 287 Optional argument NAME is the name of the theme to use.  It defaults
 288 to the value of the variable `tree-widget-theme'.
 289 Does nothing if NAME is already the current theme.
 290
 291 If there is a \"tree-widget-theme-setup\" library in the theme
 292 directory, load it to setup a parent theme or the images properties.
 293 Typically it should contain something like this:
 294
 295   (tree-widget-set-parent-theme \"my-parent-theme\")
 296   (tree-widget-set-image-properties
 297    (if (featurep 'xemacs)
 298        '(:ascent center)
 299      '(:ascent center :mask (heuristic t))
 300      ))"
 301   (or name (setq name (or tree-widget-theme "default")))
 302   (unless (string-equal name (tree-widget-theme-name))
 303     (set (make-local-variable 'tree-widget--theme)
 304          (make-vector 4 nil))
 305       (tree-widget-set-parent-theme name)
 306       (tree-widget-set-parent-theme "default")))
 307
 308 (defun tree-widget--locate-sub-directory (name path &optional found)
 309   "Locate all occurrences of the sub-directory NAME in PATH.
 310 Return a list of absolute directory names in reverse order, or nil if
 311 not found."
 312   (condition-case err
 313       (dolist (elt path)
 314         (setq elt (eval elt))
 315         (cond
 316          ((stringp elt)
 317           (and (file-accessible-directory-p
 318                 (setq elt (expand-file-name name elt)))
 319                (push elt found)))
 320          (elt
 321           (setq found (tree-widget--locate-sub-directory
 322                        name (if (atom elt) (list elt) elt) found)))))
 323     (error
 324      (message "In tree-widget--locate-sub-directory: %s"
 325               (error-message-string err))))
 326   found)
 327
 328 (defun tree-widget-themes-path ()
 329   "Return the path where to search for a theme.
 330 It is specified in variable `tree-widget-themes-directory'.
 331 Return a list of absolute directory names, or nil when no directory
 332 has been found accessible."
 333   (let ((path (aref tree-widget--theme 1)))
 334     (cond
 335      ;; No directory was found.
 336      ((eq path 'void) nil)
 337      ;; The list of directories is available in the cache.
 338      (path)
 339      ;; Use the directory where this library is located.
 340      ((null tree-widget-themes-directory)
 341       (when (setq path (locate-library "tree-widget"))
 342         (setq path (file-name-directory path))
 343         (setq path (and (file-accessible-directory-p path)
 344                         (list path)))
 345         ;; Store the result in the cache for later use.
 346         (aset tree-widget--theme 1 (or path 'void))
 347         path))
 348      ;; Check accessibility of absolute directory name.
 349      ((file-name-absolute-p tree-widget-themes-directory)
 350       (setq path (expand-file-name tree-widget-themes-directory))
 351       (setq path (and (file-accessible-directory-p path)
 352                       (list path)))
 353       ;; Store the result in the cache for later use.
 354       (aset tree-widget--theme 1 (or path 'void))
 355       path)
 356      ;; Locate a sub-directory in `tree-widget-themes-load-path'.
 357      (t
 358       (setq path (nreverse (tree-widget--locate-sub-directory
 359                             tree-widget-themes-directory
 360                             tree-widget-themes-load-path)))
 361       ;; Store the result in the cache for later use.
 362       (aset tree-widget--theme 1 (or path 'void))
 363       path))))
 364
 365 (defconst tree-widget--cursors
 366   ;; Pointer shapes when the mouse pointer is over inactive
 367   ;; tree-widget images.  This feature works since Emacs 22, and
 368   ;; ignored on older versions, and XEmacs.
 369   '(
 370     ("guide"     . arrow)
 371     ("no-guide"  . arrow)
 372     ("end-guide" . arrow)
 373     ("handle"    . arrow)
 374     ("no-handle" . arrow)
 375     ))
 376
 377 (defsubst tree-widget-set-image-properties (props)
 378   "In current theme, set images properties to PROPS.
 379 Does nothing if images properties have already been set for that
 380 theme."
 381   (or (aref tree-widget--theme 2)
 382       (aset tree-widget--theme 2 props)))
 383
 384 (defsubst tree-widget-image-properties (name)
 385   "Return the properties of image NAME in current theme.
 386 Default global properties are provided for respectively Emacs and
 387 XEmacs in the variables `tree-widget-image-properties-emacs', and
 388 `tree-widget-image-properties-xemacs'."
 389   ;; Add the pointer shape
 390   (cons :pointer
 391         (cons (or (cdr (assoc name tree-widget--cursors)) 'hand)
 392               (tree-widget-set-image-properties
 393                (if (featurep 'xemacs)
 394                    tree-widget-image-properties-xemacs
 395                  tree-widget-image-properties-emacs)))))
 396
 397 (defun tree-widget-lookup-image (name)
 398   "Look up in current theme for an image with NAME.
 399 Search first in current theme, then in parent themes (see also the
 400 function `tree-widget-set-parent-theme').
 401 Return the first image found having a supported format, or nil if not
 402 found."
 403   (let (file)
 404     (catch 'found
 405       (dolist (default-directory (tree-widget-themes-path))
 406         (dolist (dir (aref tree-widget--theme 0))
 407           (dolist (fmt (tree-widget-image-formats))
 408             (dolist (ext (cdr fmt))
 409               (setq file (expand-file-name (concat name ext) dir))
 410               (and (file-readable-p file)
 411                    (file-regular-p file)
 412                    (throw 'found
 413                           (tree-widget-create-image
 414                            (car fmt) file
 415                            (tree-widget-image-properties name))))))))
 416       nil)))
 417
 418 (defun tree-widget-find-image (name)
 419   "Find the image with NAME in current theme.
 420 NAME is an image file name sans extension.
 421 Return the image found, or nil if not found."
 422   (when (tree-widget-use-image-p)
 423     ;; Ensure there is an active theme.
 424     (tree-widget-set-theme (tree-widget-theme-name))
 425     (let ((image (assoc name (aref tree-widget--theme 3))))
 426       ;; The image NAME is found in the cache.
 427       (if image
 428           (cdr image)
 429         ;; Search the image in current, and default themes.
 430         (prog1
 431             (setq image (tree-widget-lookup-image name))
 432           ;; Store image reference in the cache for later use.
 433           (push (cons name image) (aref tree-widget--theme 3))))
 434       )))
 435 \f
 436 ;;; Widgets
 437 ;;
 438 (defun tree-widget-button-click (event)
 439   "Move to the position clicked on, and if it is a button, invoke it.
 440 EVENT is the mouse event received."
 441   (interactive "e")
 442   (mouse-set-point event)
 443   (let ((pos (widget-event-point event)))
 444     (if (get-char-property pos 'button)
 445         (widget-button-click event))))
 446
 447 (defvar tree-widget-button-keymap
 448   (let ((km (make-sparse-keymap)))
 449     (if (boundp 'widget-button-keymap)
 450         ;; XEmacs
 451         (progn
 452           (set-keymap-parent km widget-button-keymap)
 453           (define-key km [button1] 'tree-widget-button-click))
 454       ;; Emacs
 455       (set-keymap-parent km widget-keymap)
 456       (define-key km [down-mouse-1] 'tree-widget-button-click))
 457     km)
 458   "Keymap used inside node buttons.
 459 Handle mouse button 1 click on buttons.")
 460
 461 (define-widget 'tree-widget-icon 'push-button
 462   "Basic widget other tree-widget icons are derived from."
 463   :format        "%[%t%]"
 464   :button-keymap tree-widget-button-keymap ; XEmacs
 465   :keymap        tree-widget-button-keymap ; Emacs
 466   :create        'tree-widget-icon-create
 467   :action        'tree-widget-icon-action
 468   :help-echo     'tree-widget-icon-help-echo
 469   )
 470
 471 (define-widget 'tree-widget-open-icon 'tree-widget-icon
 472   "Icon for an expanded tree-widget node."
 473   :tag        "[-]"
 474   :glyph-name "open"
 475   )
 476
 477 (define-widget 'tree-widget-empty-icon 'tree-widget-icon
 478   "Icon for an expanded tree-widget node with no child."
 479   :tag        "[X]"
 480   :glyph-name "empty"
 481   )
 482
 483 (define-widget 'tree-widget-close-icon 'tree-widget-icon
 484   "Icon for a collapsed tree-widget node."
 485   :tag        "[+]"
 486   :glyph-name "close"
 487   )
 488
 489 (define-widget 'tree-widget-leaf-icon 'tree-widget-icon
 490   "Icon for a tree-widget leaf node."
 491   :tag        ""
 492   :glyph-name "leaf"
 493   :button-face 'default
 494   )
 495
 496 (define-widget 'tree-widget-guide 'item
 497   "Vertical guide line."
 498   :tag       " |"
 499   ;;:tag-glyph (tree-widget-find-image "guide")
 500   :format    "%t"
 501   )
 502
 503 (define-widget 'tree-widget-end-guide 'item
 504   "End of a vertical guide line."
 505   :tag       " `"
 506   ;;:tag-glyph (tree-widget-find-image "end-guide")
 507   :format    "%t"
 508   )
 509
 510 (define-widget 'tree-widget-no-guide 'item
 511   "Invisible vertical guide line."
 512   :tag       "  "
 513   ;;:tag-glyph (tree-widget-find-image "no-guide")
 514   :format    "%t"
 515   )
 516
 517 (define-widget 'tree-widget-handle 'item
 518   "Horizontal guide line that joins a vertical guide line to a node."
 519   :tag       "-"
 520   ;;:tag-glyph (tree-widget-find-image "handle")
 521   :format    "%t"
 522   )
 523
 524 (define-widget 'tree-widget-no-handle 'item
 525   "Invisible handle."
 526   :tag       " "
 527   ;;:tag-glyph (tree-widget-find-image "no-handle")
 528   :format    "%t"
 529   )
 530
 531 (define-widget 'tree-widget 'default
 532   "Tree widget."
 533   :format         "%v"
 534   :convert-widget 'tree-widget-convert-widget
 535   :value-get      'widget-value-value-get
 536   :value-delete   'widget-children-value-delete
 537   :value-create   'tree-widget-value-create
 538   :action         'tree-widget-action
 539   :help-echo      'tree-widget-help-echo
 540   :expander-p     'tree-widget-expander-p
 541   :open-icon      'tree-widget-open-icon
 542   :close-icon     'tree-widget-close-icon
 543   :empty-icon     'tree-widget-empty-icon
 544   :leaf-icon      'tree-widget-leaf-icon
 545   :guide          'tree-widget-guide
 546   :end-guide      'tree-widget-end-guide
 547   :no-guide       'tree-widget-no-guide
 548   :handle         'tree-widget-handle
 549   :no-handle      'tree-widget-no-handle
 550   )
 551 \f
 552 ;;; Widget support functions
 553 ;;
 554 (defun tree-widget-p (widget)
 555   "Return non-nil if WIDGET is a tree-widget."
 556   (let ((type (widget-type widget)))
 557     (while (and type (not (eq type 'tree-widget)))
 558       (setq type (widget-type (get type 'widget-type))))
 559     (eq type 'tree-widget)))
 560
 561 (defun tree-widget-node (widget)
 562   "Return WIDGET's :node child widget.
 563 If not found, setup an `item' widget as default.
 564 Signal an error if the :node widget is a tree-widget.
 565 WIDGET is, or derives from, a tree-widget."
 566   (let ((node (widget-get widget :node)))
 567     (if node
 568         ;; Check that the :node widget is not a tree-widget.
 569         (and (tree-widget-p node)
 570              (error "Invalid tree-widget :node %S" node))
 571       ;; Setup an item widget as default :node.
 572       (setq node `(item :tag ,(or (widget-get widget :tag)
 573                                   (widget-princ-to-string
 574                                    (widget-value widget)))))
 575       (widget-put widget :node node))
 576     node))
 577
 578 (defun tree-widget-keep (arg widget)
 579   "Save in ARG the WIDGET's properties specified by :keep."
 580   (dolist (prop (widget-get widget :keep))
 581     (widget-put arg prop (widget-get widget prop))))
 582
 583 (defun tree-widget-children-value-save (widget &optional args node)
 584   "Save WIDGET children values.
 585 WIDGET is, or derives from, a tree-widget.
 586 Children properties and values are saved in ARGS if non-nil, else in
 587 WIDGET's :args property value.  Properties and values of the
 588 WIDGET's :node sub-widget are saved in NODE if non-nil, else in
 589 WIDGET's :node sub-widget."
 590   (let ((args (cons (or node (widget-get widget :node))
 591                     (or args (widget-get widget :args))))
 592         (children (widget-get widget :children))
 593         arg child)
 594     (while (and args children)
 595       (setq arg      (car args)
 596             args     (cdr args)
 597             child    (car children)
 598             children (cdr children))
 599        (if (tree-widget-p child)
 600 ;;;; The child is a tree node.
 601            (progn
 602              ;; Backtrack :args and :node properties.
 603              (widget-put arg :args (widget-get child :args))
 604              (widget-put arg :node (widget-get child :node))
 605              ;; Save :open property.
 606              (widget-put arg :open (widget-get child :open))
 607              ;; The node is open.
 608              (when (widget-get child :open)
 609                ;; Save the widget value.
 610                (widget-put arg :value (widget-value child))
 611                ;; Save properties specified in :keep.
 612                (tree-widget-keep arg child)
 613                ;; Save children.
 614                (tree-widget-children-value-save
 615                 child (widget-get arg :args) (widget-get arg :node))))
 616 ;;;; Another non tree node.
 617          ;; Save the widget value.
 618          (widget-put arg :value (widget-value child))
 619          ;; Save properties specified in :keep.
 620          (tree-widget-keep arg child)))))
 621 \f
 622 ;;; Widget creation
 623 ;;
 624 (defvar tree-widget-before-create-icon-functions nil
 625   "Hooks run before to create a tree-widget icon.
 626 Each function is passed the icon widget not yet created.
 627 The value of the icon widget :node property is a tree :node widget or
 628 a leaf node widget, not yet created.
 629 This hook can be used to dynamically change properties of the icon and
 630 associated node widgets.  For example, to dynamically change the look
 631 and feel of the tree-widget by changing the values of the :tag
 632 and :glyph-name properties of the icon widget.
 633 This hook should be local in the buffer setup to display widgets.")
 634
 635 (defun tree-widget-icon-create (icon)
 636   "Create the ICON widget."
 637   (run-hook-with-args 'tree-widget-before-create-icon-functions icon)
 638   (widget-put icon :tag-glyph
 639               (tree-widget-find-image (widget-get icon :glyph-name)))
 640   ;; Ensure there is at least one char to display the image.
 641   (and (widget-get icon :tag-glyph)
 642        (equal "" (or (widget-get icon :tag) ""))
 643        (widget-put icon :tag " "))
 644   (widget-default-create icon)
 645   ;; Insert space between the icon and the node widget.
 646   (insert-char ?  1)
 647   (put-text-property
 648    (1- (point)) (point)
 649    'display (list 'space :width tree-widget-space-width)))
 650
 651 (defun tree-widget-convert-widget (widget)
 652   "Convert :args as widget types in WIDGET."
 653   (let ((tree (widget-types-convert-widget widget)))
 654     ;; Compatibility
 655     (widget-put tree :expander (or (widget-get tree :expander)
 656                                    (widget-get tree :dynargs)))
 657     tree))
 658
 659 (defvar widget-glyph-enable) ; XEmacs
 660
 661 (defun tree-widget-value-create (tree)
 662   "Create the TREE tree-widget."
 663   (let* ((node   (tree-widget-node tree))
 664          (flags  (widget-get tree :tree-widget--guide-flags))
 665          (indent (widget-get tree :indent))
 666          ;; Setup widget's image support.  Looking up for images, and
 667          ;; setting widgets' :tag-glyph is done here, to allow to
 668          ;; dynamically change the image theme.
 669          (widget-image-enable (tree-widget-use-image-p))     ; Emacs
 670          (widget-glyph-enable widget-image-enable)           ; XEmacs
 671          children buttons)
 672     (and indent (not (widget-get tree :parent))
 673          (insert-char ?\  indent))
 674     (if (widget-get tree :open)
 675 ;;;; Expanded node.
 676         (let ((args     (widget-get tree :args))
 677               (guide    (widget-get tree :guide))
 678               (noguide  (widget-get tree :no-guide))
 679               (endguide (widget-get tree :end-guide))
 680               (handle   (widget-get tree :handle))
 681               (nohandle (widget-get tree :no-handle))
 682               (guidi    (tree-widget-find-image "guide"))
 683               (noguidi  (tree-widget-find-image "no-guide"))
 684               (endguidi (tree-widget-find-image "end-guide"))
 685               (handli   (tree-widget-find-image "handle"))
 686               (nohandli (tree-widget-find-image "no-handle")))
 687           ;; Request children at run time, when requested.
 688           (when (and (widget-get tree :expander)
 689                      (widget-apply tree :expander-p))
 690             (setq args (mapcar 'widget-convert
 691                                (widget-apply tree :expander)))
 692             (widget-put tree :args args))
 693           ;; Defer the node widget creation after icon creation.
 694           (widget-put tree :node (widget-convert node))
 695           ;; Create the icon widget for the expanded tree.
 696           (push (widget-create-child-and-convert
 697                  tree (widget-get tree (if args :open-icon :empty-icon))
 698                  ;; Pass the node widget to child.
 699                  :node (widget-get tree :node))
 700                 buttons)
 701           ;; Create the tree node widget.
 702           (push (widget-create-child tree (widget-get tree :node))
 703                 children)
 704           ;; Update the icon :node with the created node widget.
 705           (widget-put (car buttons) :node (car children))
 706           ;; Create the tree children.
 707           (while args
 708             (setq node (car args)
 709                   args (cdr args))
 710             (and indent (insert-char ?\  indent))
 711             ;; Insert guide lines elements from previous levels.
 712             (dolist (f (reverse flags))
 713               (widget-create-child-and-convert
 714                tree (if f guide noguide)
 715                :tag-glyph (if f guidi noguidi))
 716               (widget-create-child-and-convert
 717                tree nohandle :tag-glyph nohandli))
 718             ;; Insert guide line element for this level.
 719             (widget-create-child-and-convert
 720              tree (if args guide endguide)
 721              :tag-glyph (if args guidi endguidi))
 722             ;; Insert the node handle line
 723             (widget-create-child-and-convert
 724              tree handle :tag-glyph handli)
 725             (if (tree-widget-p node)
 726                 ;; Create a sub-tree node.
 727                 (push (widget-create-child-and-convert
 728                        tree node :tree-widget--guide-flags
 729                        (cons (if args t) flags))
 730                       children)
 731               ;; Create the icon widget for a leaf node.
 732               (push (widget-create-child-and-convert
 733                      tree (widget-get tree :leaf-icon)
 734                      ;; At this point the node widget isn't yet created.
 735                      :node (setq node (widget-convert
 736                                        node :tree-widget--guide-flags
 737                                        (cons (if args t) flags)))
 738                      :tree-widget--leaf-flag t)
 739                     buttons)
 740               ;; Create the leaf node widget.
 741               (push (widget-create-child tree node) children)
 742               ;; Update the icon :node with the created node widget.
 743               (widget-put (car buttons) :node (car children)))))
 744 ;;;; Collapsed node.
 745       ;; Defer the node widget creation after icon creation.
 746       (widget-put tree :node (widget-convert node))
 747       ;; Create the icon widget for the collapsed tree.
 748       (push (widget-create-child-and-convert
 749              tree (widget-get tree :close-icon)
 750              ;; Pass the node widget to child.
 751              :node (widget-get tree :node))
 752             buttons)
 753       ;; Create the tree node widget.
 754       (push (widget-create-child tree (widget-get tree :node))
 755             children)
 756       ;; Update the icon :node with the created node widget.
 757       (widget-put (car buttons) :node (car children)))
 758     ;; Save widget children and buttons.  The tree-widget :node child
 759     ;; is the first element in :children.
 760     (widget-put tree :children (nreverse children))
 761     (widget-put tree :buttons  buttons)))
 762 \f
 763 ;;; Widget callbacks
 764 ;;
 765 (defsubst tree-widget-leaf-node-icon-p (icon)
 766   "Return non-nil if ICON is a leaf node icon.
 767 That is, if its :node property value is a leaf node widget."
 768   (widget-get icon :tree-widget--leaf-flag))
 769
 770 (defun tree-widget-icon-action (icon &optional event)
 771   "Handle the ICON widget :action.
 772 If ICON :node is a leaf node it handles the :action.  The tree-widget
 773 parent of ICON handles the :action otherwise.
 774 Pass the received EVENT to :action."
 775   (let ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
 776                                    :node :parent))))
 777     (widget-apply node :action event)))
 778
 779 (defun tree-widget-icon-help-echo (icon)
 780   "Return the help-echo string of ICON.
 781 If ICON :node is a leaf node it handles the :help-echo.  The tree-widget
 782 parent of ICON handles the :help-echo otherwise."
 783   (let* ((node (widget-get icon (if (tree-widget-leaf-node-icon-p icon)
 784                                     :node :parent)))
 785          (help-echo (widget-get node :help-echo)))
 786     (if (functionp help-echo)
 787         (funcall help-echo node)
 788       help-echo)))
 789
 790 (defvar tree-widget-after-toggle-functions nil
 791   "Hooks run after toggling a tree-widget expansion.
 792 Each function is passed a tree-widget.  If the value of the :open
 793 property is non-nil the tree has been expanded, else collapsed.
 794 This hook should be local in the buffer setup to display widgets.")
 795
 796 (defun tree-widget-action (tree &optional _event)
 797   "Handle the :action of the TREE tree-widget.
 798 That is, toggle expansion of the TREE tree-widget.
 799 Ignore the EVENT argument."
 800   (let ((open (not (widget-get tree :open))))
 801     (or open
 802         ;; Before to collapse the node, save children values so next
 803         ;; open can recover them.
 804         (tree-widget-children-value-save tree))
 805     (widget-put tree :open open)
 806     (widget-value-set tree open)
 807     (run-hook-with-args 'tree-widget-after-toggle-functions tree)))
 808
 809 (defun tree-widget-help-echo (tree)
 810   "Return the help-echo string of the TREE tree-widget."
 811   (if (widget-get tree :open)
 812       "Collapse node"
 813     "Expand node"))
 814
 815 (defun tree-widget-expander-p (tree)
 816   "Return non-nil if the TREE tree-widget :expander has to be called.
 817 That is, if TREE :args is nil."
 818   (null (widget-get tree :args)))
 819
 820 (provide 'tree-widget)
 821
 822 ;;; tree-widget.el ends here