summaryrefslogtreecommitdiff
path: root/lisp/eshell/esh-var.el
blob: 4e3fda73afbc1c13a6c49f2052e6f1470a00f684 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
;;; esh-var.el --- handling of variables

;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004,
;;   2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.

;; Author: John Wiegley <johnw@gnu.org>

;; 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; These are the possible variable interpolation syntaxes.  Also keep
;; in mind that if an argument looks like a number, it will be
;; converted to a number.  This is not significant when invoking
;; external commands, but it's important when calling Lisp functions.
;;
;;   $VARIABLE
;;
;; Interval the value of an environment variable, or a Lisp variable
;;
;;   $ALSO-VAR
;;
;; "-" is a valid part of a variable name.
;;
;;   $<MYVAR>-TOO
;;
;; Only "MYVAR" is part of the variable name in this case.
;;
;;   $#VARIABLE
;;
;; Returns the length of the value of VARIABLE.  This could also be
;; done using the `length' Lisp function.
;;
;;   $(lisp)
;;
;; Returns result of lisp evaluation.  Note: Used alone like this, it
;; is identical to just saying (lisp); but with the variable expansion
;; form, the result may be interpolated a larger string, such as
;; '$(lisp)/other'.
;;
;;   ${command}
;;
;; Returns the value of an eshell subcommand.  See the note above
;; regarding Lisp evaluations.
;;
;;   $ANYVAR[10]
;;
;; Return the 10th element of ANYVAR.  If ANYVAR's value is a string,
;; it will be split in order to make it a list.  The splitting will
;; occur at whitespace.
;;
;;   $ANYVAR[: 10]
;;
;; As above, except that splitting occurs at the colon now.
;;
;;   $ANYVAR[: 10 20]
;;
;; As above, but instead of returning just a string, it now returns a
;; list of two strings.  If the result is being interpolated into a
;; larger string, this list will be flattened into one big string,
;; with each element separated by a space.
;;
;;   $ANYVAR["\\\\" 10]
;;
;; Separate on backslash characters.  Actually, the first argument --
;; if it doesn't have the form of a number, or a plain variable name
;; -- can be any regular expression.  So to split on numbers, use
;; '$ANYVAR["[0-9]+" 10 20]'.
;;
;;   $ANYVAR[hello]
;;
;; Calls `assoc' on ANYVAR with 'hello', expecting it to be an alist.
;;
;;   $#ANYVAR[hello]
;;
;; Returns the length of the cdr of the element of ANYVAR who car is
;; equal to "hello".
;;
;; There are also a few special variables defined by Eshell.  '$$' is
;; the value of the last command (t or nil, in the case of an external
;; command).  This makes it possible to chain results:
;;
;;   /tmp $ echo /var/spool/mail/johnw
;;   /var/spool/mail/johnw
;;   /tmp $ dirname $$
;;   /var/spool/mail/
;;   /tmp $ cd $$
;;   /var/spool/mail $
;;
;; '$_' refers to the last argument of the last command.  And $?
;; contains the exit code of the last command (0 or 1 for Lisp
;; functions, based on successful completion).

(provide 'esh-var)

(eval-when-compile
  (require 'pcomplete)
  (require 'esh-test)
  (require 'esh-util)
  (require 'esh-opt)
  (require 'esh-mode))
(require 'env)
(require 'ring)

(defgroup eshell-var nil
  "Variable interpolation is introduced whenever the '$' character
appears unquoted in any argument (except when that argument is
surrounded by single quotes).  It may be used to interpolate a
variable value, a subcommand, or even the result of a Lisp form."
  :tag "Variable handling"
  :group 'eshell)

;;; User Variables:

(defcustom eshell-var-load-hook '(eshell-var-initialize)
  "*A list of functions to call when loading `eshell-var'."
  :type 'hook
  :group 'eshell-var)

(defcustom eshell-prefer-lisp-variables nil
  "*If non-nil, prefer Lisp variables to environment variables."
  :type 'boolean
  :group 'eshell-var)

(defcustom eshell-complete-export-definition t
  "*If non-nil, completing names for `export' shows current definition."
  :type 'boolean
  :group 'eshell-var)

(defcustom eshell-modify-global-environment nil
  "*If non-nil, using `export' changes Emacs's global environment."
  :type 'boolean
  :group 'eshell-var)

(defcustom eshell-variable-name-regexp "[A-Za-z0-9_-]+"
  "*A regexp identifying what constitutes a variable name reference.
Note that this only applies for '$NAME'.  If the syntax '$<NAME>' is
used, then NAME can contain any character, including angle brackets,
if they are quoted with a backslash."
  :type 'regexp
  :group 'eshell-var)

(defcustom eshell-variable-aliases-list
  '(;; for eshell.el
    ("COLUMNS" (lambda (indices) (window-width)) t)
    ("LINES" (lambda (indices) (window-height)) t)

    ;; for eshell-cmd.el
    ("_" (lambda (indices)
	   (if (not indices)
	       (car (last eshell-last-arguments))
	     (eshell-apply-indices eshell-last-arguments
				   indices))))
    ("?" eshell-last-command-status)
    ("$" eshell-last-command-result)
    ("0" eshell-command-name)
    ("1" (lambda (indices) (nth 0 eshell-command-arguments)))
    ("2" (lambda (indices) (nth 1 eshell-command-arguments)))
    ("3" (lambda (indices) (nth 2 eshell-command-arguments)))
    ("4" (lambda (indices) (nth 3 eshell-command-arguments)))
    ("5" (lambda (indices) (nth 4 eshell-command-arguments)))
    ("6" (lambda (indices) (nth 5 eshell-command-arguments)))
    ("7" (lambda (indices) (nth 6 eshell-command-arguments)))
    ("8" (lambda (indices) (nth 7 eshell-command-arguments)))
    ("9" (lambda (indices) (nth 8 eshell-command-arguments)))
    ("*" (lambda (indices)
	   (if (not indices)
	       eshell-command-arguments
	     (eshell-apply-indices eshell-command-arguments
				   indices)))))
  "*This list provides aliasing for variable references.
It is very similar in concept to what `eshell-user-aliases-list' does
for commands.  Each member of this defines defines the name of a
command, and the Lisp value to return for that variable if it is
accessed via the syntax '$NAME'.

If the value is a function, that function will be called with two
arguments: the list of the indices that was used in the reference, and
whether the user is requesting the length of the ultimate element.
For example, a reference of '$NAME[10][20]' would result in the
function for alias `NAME' being called (assuming it were aliased to a
function), and the arguments passed to this function would be the list
'(10 20)', and nil."
  :type '(repeat (list string sexp
		       (choice (const :tag "Copy to environment" t)
			       (const :tag "Use only in Eshell" nil))))
  :group 'eshell-var)

(put 'eshell-variable-aliases-list 'risky-local-variable t)

;;; Functions:

(defun eshell-var-initialize ()
  "Initialize the variable handle code."
  ;; Break the association with our parent's environment.  Otherwise,
  ;; changing a variable will affect all of Emacs.
  (unless eshell-modify-global-environment
    (set (make-local-variable 'process-environment)
	 (eshell-copy-environment)))

  (define-key eshell-command-map [(meta ?v)] 'eshell-insert-envvar)

  (set (make-local-variable 'eshell-special-chars-inside-quoting)
       (append eshell-special-chars-inside-quoting '(?$)))
  (set (make-local-variable 'eshell-special-chars-outside-quoting)
       (append eshell-special-chars-outside-quoting '(?$)))

  (add-hook 'eshell-parse-argument-hook 'eshell-interpolate-variable t t)

  (add-hook 'eshell-prepare-command-hook
	    'eshell-handle-local-variables nil t)

  (when (eshell-using-module 'eshell-cmpl)
    (add-hook 'pcomplete-try-first-hook
	      'eshell-complete-variable-reference nil t)
    (add-hook 'pcomplete-try-first-hook
	      'eshell-complete-variable-assignment nil t)))

(defun eshell-handle-local-variables ()
  "Allow for the syntax 'VAR=val <command> <args>'."
  ;; strip off any null commands, which can only happen if a variable
  ;; evaluates to nil, such as "$var x", where `var' is nil.  The
  ;; command name in that case becomes `x', for compatibility with
  ;; most regular shells (the difference is that they do an
  ;; interpolation pass before the argument parsing pass, but Eshell
  ;; does both at the same time).
  (while (and (not eshell-last-command-name)
	      eshell-last-arguments)
    (setq eshell-last-command-name (car eshell-last-arguments)
	  eshell-last-arguments (cdr eshell-last-arguments)))
  (let ((setvar "\\`\\([A-Za-z_][A-Za-z0-9_]*\\)=\\(.*\\)\\'")
	(command (eshell-stringify eshell-last-command-name))
	(args eshell-last-arguments))
    ;; local variable settings (such as 'CFLAGS=-O2 make') are handled
    ;; by making the whole command into a subcommand, and calling
    ;; setenv immediately before the command is invoked.  This means
    ;; that 'BLAH=x cd blah' won't work exactly as expected, but that
    ;; is by no means a typical use of local environment variables.
    (if (and command (string-match setvar command))
	(throw
	 'eshell-replace-command
	 (list
	  'eshell-as-subcommand
	  (append
	   (list 'progn)
	   (let ((l (list t)))
	     (while (string-match setvar command)
	       (nconc
		l (list
		   (list 'setenv (match-string 1 command)
			 (match-string 2 command)
			 (= (length (match-string 2 command)) 0))))
	       (setq command (eshell-stringify (car args))
		     args (cdr args)))
	     (cdr l))
	   (list (list 'eshell-named-command
		       command (list 'quote args)))))))))

(defun eshell-interpolate-variable ()
  "Parse a variable interpolation.
This function is explicit for adding to `eshell-parse-argument-hook'."
  (when (and (eq (char-after) ?$)
	     (/= (1+ (point)) (point-max)))
    (forward-char)
    (list 'eshell-escape-arg
	  (eshell-parse-variable))))

(defun eshell/define (var-alias definition)
  "Define a VAR-ALIAS using DEFINITION."
  (if (not definition)
      (setq eshell-variable-aliases-list
	    (delq (assoc var-alias eshell-variable-aliases-list)
		  eshell-variable-aliases-list))
    (let ((def (assoc var-alias eshell-variable-aliases-list))
	  (alias-def
	   (list var-alias
		 (list 'quote (if (= (length definition) 1)
				  (car definition)
				definition)))))
      (if def
	  (setq eshell-variable-aliases-list
		(delq (assoc var-alias eshell-variable-aliases-list)
		      eshell-variable-aliases-list)))
      (setq eshell-variable-aliases-list
	    (cons alias-def
		  eshell-variable-aliases-list))))
  nil)

(defun eshell/export (&rest sets)
  "This alias allows the `export' command to act as bash users expect."
  (while sets
    (if (and (stringp (car sets))
	     (string-match "^\\([^=]+\\)=\\(.*\\)" (car sets)))
	(setenv (match-string 1 (car sets))
		(match-string 2 (car sets))))
    (setq sets (cdr sets))))

(defun pcomplete/eshell-mode/export ()
  "Completion function for Eshell's `export'."
  (while (pcomplete-here
	  (if eshell-complete-export-definition
	      process-environment
	    (eshell-envvar-names)))))

(defun eshell/unset (&rest args)
  "Unset an environment variable."
  (while args
    (if (stringp (car args))
	(setenv (car args) nil t))
    (setq args (cdr args))))

(defun pcomplete/eshell-mode/unset ()
  "Completion function for Eshell's `unset'."
  (while (pcomplete-here (eshell-envvar-names))))

(defun eshell/setq (&rest args)
  "Allow command-ish use of `setq'."
  (let (last-value)
    (while args
      (let ((sym (intern (car args)))
	    (val (cadr args)))
	(setq last-value (set sym val)
	      args (cddr args))))
    last-value))

(defun pcomplete/eshell-mode/setq ()
  "Completion function for Eshell's `setq'."
  (while (and (pcomplete-here (all-completions pcomplete-stub
					       obarray 'boundp))
	      (pcomplete-here))))

(defun eshell/env (&rest args)
  "Implemention of `env' in Lisp."
  (eshell-init-print-buffer)
  (eshell-eval-using-options
   "env" args
   '((?h "help" nil nil "show this usage screen")
     :external "env"
     :usage "<no arguments>")
   (eshell-for setting (sort (eshell-environment-variables)
			     'string-lessp)
     (eshell-buffered-print setting "\n"))
   (eshell-flush)))

(defun eshell-insert-envvar (envvar-name)
  "Insert ENVVAR-NAME into the current buffer at point."
  (interactive
   (list (read-envvar-name "Name of environment variable: " t)))
  (insert-and-inherit "$" envvar-name))

(defun eshell-envvar-names (&optional environment)
  "Return a list of currently visible environment variable names."
  (mapcar (function
	   (lambda (x)
	     (substring x 0 (string-match "=" x))))
	  (or environment process-environment)))

(defun eshell-environment-variables ()
  "Return a `process-environment', fully updated.
This involves setting any variable aliases which affect the
environment, as specified in `eshell-variable-aliases-list'."
  (let ((process-environment (eshell-copy-environment)))
    (eshell-for var-alias eshell-variable-aliases-list
      (if (nth 2 var-alias)
	  (setenv (car var-alias)
		  (eshell-stringify
		   (or (eshell-get-variable (car var-alias)) "")))))
    process-environment))

(defun eshell-parse-variable ()
  "Parse the next variable reference at point.
The variable name could refer to either an environment variable, or a
Lisp variable.  The priority order depends on the setting of
`eshell-prefer-lisp-variables'.

Its purpose is to call `eshell-parse-variable-ref', and then to
process any indices that come after the variable reference."
  (let* ((get-len (when (eq (char-after) ?#)
		    (forward-char) t))
	 value indices)
    (setq value (eshell-parse-variable-ref)
	  indices (and (not (eobp))
		       (eq (char-after) ?\[)
		       (eshell-parse-indices))
	  value (list 'let
		      (list (list 'indices
				  (list 'quote indices)))
		      value))
    (if get-len
	(list 'length value)
      value)))

(defun eshell-parse-variable-ref ()
  "Eval a variable reference.
Returns a Lisp form which, if evaluated, will return the value of the
variable.

Possible options are:

  NAME          an environment or Lisp variable value
  <LONG-NAME>   disambiguates the length of the name
  {COMMAND}     result of command is variable's value
  (LISP-FORM)   result of Lisp form is variable's value"
  (let (end)
    (cond
     ((eq (char-after) ?{)
      (let ((end (eshell-find-delimiter ?\{ ?\})))
	(if (not end)
	    (throw 'eshell-incomplete ?\{)
	  (prog1
	      (list 'eshell-convert
		    (list 'eshell-command-to-value
			  (list 'eshell-as-subcommand
				(eshell-parse-command
				 (cons (1+ (point)) end)))))
	    (goto-char (1+ end))))))
     ((memq (char-after) '(?\' ?\"))
      (let ((name (if (eq (char-after) ?\')
		      (eshell-parse-literal-quote)
		    (eshell-parse-double-quote))))
	(if name
	  (list 'eshell-get-variable (eval name) 'indices))))
     ((eq (char-after) ?\<)
      (let ((end (eshell-find-delimiter ?\< ?\>)))
	(if (not end)
	    (throw 'eshell-incomplete ?\<)
	  (let* ((temp (make-temp-file temporary-file-directory))
		 (cmd (concat (buffer-substring (1+ (point)) end)
			      " > " temp)))
	    (prog1
		(list
		 'let (list (list 'eshell-current-handles
				  (list 'eshell-create-handles temp
					(list 'quote 'overwrite))))
		 (list
		  'progn
		  (list 'eshell-as-subcommand
			(eshell-parse-command cmd))
		  (list 'ignore
			(list 'nconc 'eshell-this-command-hook
			      (list 'list
				    (list 'function
					  (list 'lambda nil
						(list 'delete-file temp))))))
		  (list 'quote temp)))
	      (goto-char (1+ end)))))))
     ((eq (char-after) ?\()
      (condition-case err
	  (list 'eshell-command-to-value
		(list 'eshell-lisp-command
		      (list 'quote (read (current-buffer)))))
	(end-of-file
	 (throw 'eshell-incomplete ?\())))
     ((assoc (char-to-string (char-after))
	     eshell-variable-aliases-list)
      (forward-char)
      (list 'eshell-get-variable
	    (char-to-string (char-before)) 'indices))
     ((looking-at eshell-variable-name-regexp)
      (prog1
	  (list 'eshell-get-variable (match-string 0) 'indices)
	(goto-char (match-end 0))))
     (t
      (error "Invalid variable reference")))))

(eshell-deftest var interp-cmd
  "Interpolate command result"
  (eshell-command-result-p "+ ${+ 1 2} 3" "6\n"))

(eshell-deftest var interp-lisp
  "Interpolate Lisp form evalution"
  (eshell-command-result-p "+ $(+ 1 2) 3" "6\n"))

(eshell-deftest var interp-concat
  "Interpolate and concat command"
  (eshell-command-result-p "+ ${+ 1 2}3 3" "36\n"))

(eshell-deftest var interp-concat-lisp
  "Interpolate and concat Lisp form"
  (eshell-command-result-p "+ $(+ 1 2)3 3" "36\n"))

(eshell-deftest var interp-concat2
  "Interpolate and concat two commands"
  (eshell-command-result-p "+ ${+ 1 2}${+ 1 2} 3" "36\n"))

(eshell-deftest var interp-concat-lisp2
  "Interpolate and concat two Lisp forms"
  (eshell-command-result-p "+ $(+ 1 2)$(+ 1 2) 3" "36\n"))

(defun eshell-parse-indices ()
  "Parse and return a list of list of indices."
  (let (indices)
    (while (eq (char-after) ?\[)
      (let ((end (eshell-find-delimiter ?\[ ?\])))
	(if (not end)
	    (throw 'eshell-incomplete ?\[)
	  (forward-char)
	  (let (eshell-glob-function)
	    (setq indices (cons (eshell-parse-arguments (point) end)
				indices)))
	  (goto-char (1+ end)))))
    (nreverse indices)))

(defun eshell-get-variable (name &optional indices)
  "Get the value for the variable NAME."
  (let* ((alias (assoc name eshell-variable-aliases-list))
	 (var (if alias
		  (cadr alias)
		name)))
    (if (and alias (functionp var))
	(funcall var indices)
      (eshell-apply-indices
       (cond
	((stringp var)
	 (let ((sym (intern-soft var)))
	   (if (and sym (boundp sym)
		    (or eshell-prefer-lisp-variables
			(not (getenv var))))
	       (symbol-value sym)
	     (getenv var))))
	((symbolp var)
	 (symbol-value var))
	(t
	 (error "Unknown variable `%s'" (eshell-stringify var))))
       indices))))

(defun eshell-apply-indices (value indices)
  "Apply to VALUE all of the given INDICES, returning the sub-result.
The format of INDICES is:

  ((INT-OR-NAME-OR-OTHER INT-OR-NAME INT-OR-NAME ...)
   ...)

Each member of INDICES represents a level of nesting.  If the first
member of a sublist is not an integer or name, and the value it's
reference is a string, that will be used as the regexp with which is
to divide the string into sub-parts.  The default is whitespace.
Otherwise, each INT-OR-NAME refers to an element of the list value.
Integers imply a direct index, and names, an associate lookup using
`assoc'.

For example, to retrieve the second element of a user's record in
'/etc/passwd', the variable reference would look like:

  ${egrep johnw /etc/passwd}[: 2]"
  (while indices
    (let ((refs (car indices)))
      (when (stringp value)
	(let (separator)
	  (if (not (or (not (stringp (caar indices)))
		       (string-match
			(concat "^" eshell-variable-name-regexp "$")
			(caar indices))))
	      (setq separator (caar indices)
		    refs (cdr refs)))
	  (setq value
		(mapcar 'eshell-convert
			(split-string value separator)))))
      (cond
       ((< (length refs) 0)
	(error "Invalid array variable index: %s"
	       (eshell-stringify refs)))
       ((= (length refs) 1)
	(setq value (eshell-index-value value (car refs))))
       (t
	(let ((new-value (list t)))
	  (while refs
	    (nconc new-value
		   (list (eshell-index-value value
					     (car refs))))
	    (setq refs (cdr refs)))
	  (setq value (cdr new-value))))))
    (setq indices (cdr indices)))
  value)

(defun eshell-index-value (value index)
  "Reference VALUE using the given INDEX."
  (if (stringp index)
      (cdr (assoc index value))
    (cond
     ((ring-p value)
      (if (> index (ring-length value))
	  (error "Index exceeds length of ring")
	(ring-ref value index)))
     ((listp value)
      (if (> index (length value))
	  (error "Index exceeds length of list")
	(nth index value)))
     ((vectorp value)
      (if (> index (length value))
	  (error "Index exceeds length of vector")
	(aref value index)))
     (t
      (error "Invalid data type for indexing")))))

;;;_* Variable name completion

(defun eshell-complete-variable-reference ()
  "If there is a variable reference, complete it."
  (let ((arg (pcomplete-actual-arg)) index)
    (when (setq index
		(string-match
		 (concat "\\$\\(" eshell-variable-name-regexp
			 "\\)?\\'") arg))
      (setq pcomplete-stub (substring arg (1+ index)))
      (throw 'pcomplete-completions (eshell-variables-list)))))

(defun eshell-variables-list ()
  "Generate list of applicable variables."
  (let ((argname pcomplete-stub)
	completions)
    (eshell-for alias eshell-variable-aliases-list
      (if (string-match (concat "^" argname) (car alias))
	  (setq completions (cons (car alias) completions))))
    (sort
     (append
      (mapcar
       (function
	(lambda (varname)
	  (let ((value (eshell-get-variable varname)))
	    (if (and value
		     (stringp value)
		     (file-directory-p value))
		(concat varname "/")
	      varname))))
       (eshell-envvar-names (eshell-environment-variables)))
      (all-completions argname obarray 'boundp)
      completions)
     'string-lessp)))

(defun eshell-complete-variable-assignment ()
  "If there is a variable assignment, allow completion of entries."
  (let ((arg (pcomplete-actual-arg)) pos)
    (when (string-match (concat "\\`" eshell-variable-name-regexp "=") arg)
      (setq pos (match-end 0))
      (if (string-match "\\(:\\)[^:]*\\'" arg)
	  (setq pos (match-end 1)))
      (setq pcomplete-stub (substring arg pos))
      (throw 'pcomplete-completions (pcomplete-entries)))))

;;; Code:

;; arch-tag: 393654fe-bdad-4f27-9a10-b1472ded14cf
;;; esh-var.el ends here