1 ;;; esh-var.el --- handling of variables
3 ;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
6 ;; Author: John Wiegley <johnw@gnu.org>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
25 ;; These are the possible variable interpolation syntaxes. Also keep
26 ;; in mind that if an argument looks like a number, it will be
27 ;; converted to a number. This is not significant when invoking
28 ;; external commands, but it's important when calling Lisp functions.
32 ;; Interval the value of an environment variable, or a Lisp variable
36 ;; "-" is a valid part of a variable name.
40 ;; Only "MYVAR" is part of the variable name in this case.
44 ;; Returns the length of the value of VARIABLE. This could also be
45 ;; done using the `length' Lisp function.
49 ;; Returns result of lisp evaluation. Note: Used alone like this, it
50 ;; is identical to just saying (lisp); but with the variable expansion
51 ;; form, the result may be interpolated a larger string, such as
56 ;; Returns the value of an eshell subcommand. See the note above
57 ;; regarding Lisp evaluations.
61 ;; Return the 10th element of ANYVAR. If ANYVAR's value is a string,
62 ;; it will be split in order to make it a list. The splitting will
63 ;; occur at whitespace.
67 ;; As above, except that splitting occurs at the colon now.
71 ;; As above, but instead of returning just a string, it now returns a
72 ;; list of two strings. If the result is being interpolated into a
73 ;; larger string, this list will be flattened into one big string,
74 ;; with each element separated by a space.
78 ;; Separate on backslash characters. Actually, the first argument --
79 ;; if it doesn't have the form of a number, or a plain variable name
80 ;; -- can be any regular expression. So to split on numbers, use
81 ;; '$ANYVAR["[0-9]+" 10 20]'.
85 ;; Calls `assoc' on ANYVAR with 'hello', expecting it to be an alist.
89 ;; Returns the length of the cdr of the element of ANYVAR who car is
92 ;; There are also a few special variables defined by Eshell. '$$' is
93 ;; the value of the last command (t or nil, in the case of an external
94 ;; command). This makes it possible to chain results:
96 ;; /tmp $ echo /var/spool/mail/johnw
97 ;; /var/spool/mail/johnw
103 ;; '$_' refers to the last argument of the last command. And $?
104 ;; contains the exit code of the last command (0 or 1 for Lisp
105 ;; functions, based on successful completion).
118 (defgroup eshell-var nil
119 "Variable interpolation is introduced whenever the '$' character
120 appears unquoted in any argument (except when that argument is
121 surrounded by single quotes). It may be used to interpolate a
122 variable value, a subcommand, or even the result of a Lisp form."
123 :tag "Variable handling"
128 (defcustom eshell-var-load-hook '(eshell-var-initialize)
129 "*A list of functions to call when loading `eshell-var'."
133 (defcustom eshell-prefer-lisp-variables nil
134 "*If non-nil, prefer Lisp variables to environment variables."
138 (defcustom eshell-complete-export-definition t
139 "*If non-nil, completing names for `export' shows current definition."
143 (defcustom eshell-modify-global-environment nil
144 "*If non-nil, using `export' changes Emacs's global environment."
148 (defcustom eshell-variable-name-regexp "[A-Za-z0-9_-]+"
149 "*A regexp identifying what constitutes a variable name reference.
150 Note that this only applies for '$NAME'. If the syntax '$<NAME>' is
151 used, then NAME can contain any character, including angle brackets,
152 if they are quoted with a backslash."
156 (defcustom eshell-variable-aliases-list
158 ("COLUMNS" (lambda (indices) (window-width)) t)
159 ("LINES" (lambda (indices) (window-height)) t)
162 ("_" (lambda (indices)
164 (car (last eshell-last-arguments))
165 (eshell-apply-indices eshell-last-arguments
167 ("?" eshell-last-command-status)
168 ("$" eshell-last-command-result)
169 ("0" eshell-command-name)
170 ("1" (lambda (indices) (nth 0 eshell-command-arguments)))
171 ("2" (lambda (indices) (nth 1 eshell-command-arguments)))
172 ("3" (lambda (indices) (nth 2 eshell-command-arguments)))
173 ("4" (lambda (indices) (nth 3 eshell-command-arguments)))
174 ("5" (lambda (indices) (nth 4 eshell-command-arguments)))
175 ("6" (lambda (indices) (nth 5 eshell-command-arguments)))
176 ("7" (lambda (indices) (nth 6 eshell-command-arguments)))
177 ("8" (lambda (indices) (nth 7 eshell-command-arguments)))
178 ("9" (lambda (indices) (nth 8 eshell-command-arguments)))
179 ("*" (lambda (indices)
181 eshell-command-arguments
182 (eshell-apply-indices eshell-command-arguments
184 "*This list provides aliasing for variable references.
185 It is very similar in concept to what `eshell-user-aliases-list' does
186 for commands. Each member of this defines defines the name of a
187 command, and the Lisp value to return for that variable if it is
188 accessed via the syntax '$NAME'.
190 If the value is a function, that function will be called with two
191 arguments: the list of the indices that was used in the reference, and
192 whether the user is requesting the length of the ultimate element.
193 For example, a reference of '$NAME[10][20]' would result in the
194 function for alias `NAME' being called (assuming it were aliased to a
195 function), and the arguments passed to this function would be the list
197 :type '(repeat (list string sexp
198 (choice (const :tag "Copy to environment" t)
199 (const :tag "Use only in Eshell" nil))))
202 (put 'eshell-variable-aliases-list 'risky-local-variable t)
206 (defun eshell-var-initialize ()
207 "Initialize the variable handle code."
208 ;; Break the association with our parent's environment. Otherwise,
209 ;; changing a variable will affect all of Emacs.
210 (unless eshell-modify-global-environment
211 (set (make-local-variable 'process-environment)
212 (eshell-copy-environment)))
214 (define-key eshell-command-map [(meta ?v)] 'eshell-insert-envvar)
216 (set (make-local-variable 'eshell-special-chars-inside-quoting)
217 (append eshell-special-chars-inside-quoting '(?$)))
218 (set (make-local-variable 'eshell-special-chars-outside-quoting)
219 (append eshell-special-chars-outside-quoting '(?$)))
221 (add-hook 'eshell-parse-argument-hook 'eshell-interpolate-variable t t)
223 (add-hook 'eshell-prepare-command-hook
224 'eshell-handle-local-variables nil t)
226 (when (eshell-using-module 'eshell-cmpl)
227 (add-hook 'pcomplete-try-first-hook
228 'eshell-complete-variable-reference nil t)
229 (add-hook 'pcomplete-try-first-hook
230 'eshell-complete-variable-assignment nil t)))
232 (defun eshell-handle-local-variables ()
233 "Allow for the syntax 'VAR=val <command> <args>'."
234 ;; strip off any null commands, which can only happen if a variable
235 ;; evaluates to nil, such as "$var x", where `var' is nil. The
236 ;; command name in that case becomes `x', for compatibility with
237 ;; most regular shells (the difference is that they do an
238 ;; interpolation pass before the argument parsing pass, but Eshell
239 ;; does both at the same time).
240 (while (and (not eshell-last-command-name)
241 eshell-last-arguments)
242 (setq eshell-last-command-name (car eshell-last-arguments)
243 eshell-last-arguments (cdr eshell-last-arguments)))
244 (let ((setvar "\\`\\([A-Za-z_][A-Za-z0-9_]*\\)=\\(.*\\)\\'")
245 (command (eshell-stringify eshell-last-command-name))
246 (args eshell-last-arguments))
247 ;; local variable settings (such as 'CFLAGS=-O2 make') are handled
248 ;; by making the whole command into a subcommand, and calling
249 ;; setenv immediately before the command is invoked. This means
250 ;; that 'BLAH=x cd blah' won't work exactly as expected, but that
251 ;; is by no means a typical use of local environment variables.
252 (if (and command (string-match setvar command))
254 'eshell-replace-command
256 'eshell-as-subcommand
260 (while (string-match setvar command)
263 (list 'setenv (match-string 1 command)
264 (match-string 2 command)
265 (= (length (match-string 2 command)) 0))))
266 (setq command (eshell-stringify (car args))
269 (list (list 'eshell-named-command
270 command (list 'quote args)))))))))
272 (defun eshell-interpolate-variable ()
273 "Parse a variable interpolation.
274 This function is explicit for adding to `eshell-parse-argument-hook'."
275 (when (and (eq (char-after) ?$)
276 (/= (1+ (point)) (point-max)))
278 (list 'eshell-escape-arg
279 (eshell-parse-variable))))
281 (defun eshell/define (var-alias definition)
282 "Define a VAR-ALIAS using DEFINITION."
284 (setq eshell-variable-aliases-list
285 (delq (assoc var-alias eshell-variable-aliases-list)
286 eshell-variable-aliases-list))
287 (let ((def (assoc var-alias eshell-variable-aliases-list))
290 (list 'quote (if (= (length definition) 1)
294 (setq eshell-variable-aliases-list
295 (delq (assoc var-alias eshell-variable-aliases-list)
296 eshell-variable-aliases-list)))
297 (setq eshell-variable-aliases-list
299 eshell-variable-aliases-list))))
302 (defun eshell/export (&rest sets)
303 "This alias allows the `export' command to act as bash users expect."
305 (if (and (stringp (car sets))
306 (string-match "^\\([^=]+\\)=\\(.*\\)" (car sets)))
307 (setenv (match-string 1 (car sets))
308 (match-string 2 (car sets))))
309 (setq sets (cdr sets))))
311 (defun pcomplete/eshell-mode/export ()
312 "Completion function for Eshell's `export'."
313 (while (pcomplete-here
314 (if eshell-complete-export-definition
316 (eshell-envvar-names)))))
318 (defun eshell/unset (&rest args)
319 "Unset an environment variable."
321 (if (stringp (car args))
322 (setenv (car args) nil t))
323 (setq args (cdr args))))
325 (defun pcomplete/eshell-mode/unset ()
326 "Completion function for Eshell's `unset'."
327 (while (pcomplete-here (eshell-envvar-names))))
329 (defun eshell/setq (&rest args)
330 "Allow command-ish use of `setq'."
333 (let ((sym (intern (car args)))
335 (setq last-value (set sym val)
339 (defun pcomplete/eshell-mode/setq ()
340 "Completion function for Eshell's `setq'."
341 (while (and (pcomplete-here (all-completions pcomplete-stub
345 (defun eshell/env (&rest args)
346 "Implemention of `env' in Lisp."
347 (eshell-init-print-buffer)
348 (eshell-eval-using-options
350 '((?h "help" nil nil "show this usage screen")
352 :usage "<no arguments>")
353 (eshell-for setting (sort (eshell-environment-variables)
355 (eshell-buffered-print setting "\n"))
358 (defun eshell-insert-envvar (envvar-name)
359 "Insert ENVVAR-NAME into the current buffer at point."
361 (list (read-envvar-name "Name of environment variable: " t)))
362 (insert-and-inherit "$" envvar-name))
364 (defun eshell-envvar-names (&optional environment)
365 "Return a list of currently visible environment variable names."
368 (substring x 0 (string-match "=" x))))
369 (or environment process-environment)))
371 (defun eshell-environment-variables ()
372 "Return a `process-environment', fully updated.
373 This involves setting any variable aliases which affect the
374 environment, as specified in `eshell-variable-aliases-list'."
375 (let ((process-environment (eshell-copy-environment)))
376 (eshell-for var-alias eshell-variable-aliases-list
377 (if (nth 2 var-alias)
378 (setenv (car var-alias)
380 (or (eshell-get-variable (car var-alias)) "")))))
381 process-environment))
383 (defun eshell-parse-variable ()
384 "Parse the next variable reference at point.
385 The variable name could refer to either an environment variable, or a
386 Lisp variable. The priority order depends on the setting of
387 `eshell-prefer-lisp-variables'.
389 Its purpose is to call `eshell-parse-variable-ref', and then to
390 process any indices that come after the variable reference."
391 (let* ((get-len (when (eq (char-after) ?#)
394 (setq value (eshell-parse-variable-ref)
395 indices (and (not (eobp))
396 (eq (char-after) ?\[)
397 (eshell-parse-indices))
400 (list 'quote indices)))
406 (defun eshell-parse-variable-ref ()
407 "Eval a variable reference.
408 Returns a Lisp form which, if evaluated, will return the value of the
411 Possible options are:
413 NAME an environment or Lisp variable value
414 <LONG-NAME> disambiguates the length of the name
415 {COMMAND} result of command is variable's value
416 (LISP-FORM) result of Lisp form is variable's value"
419 ((eq (char-after) ?{)
420 (let ((end (eshell-find-delimiter ?\{ ?\})))
422 (throw 'eshell-incomplete ?\{)
424 (list 'eshell-convert
425 (list 'eshell-command-to-value
426 (list 'eshell-as-subcommand
427 (eshell-parse-command
428 (cons (1+ (point)) end)))))
429 (goto-char (1+ end))))))
430 ((memq (char-after) '(?\' ?\"))
431 (let ((name (if (eq (char-after) ?\')
432 (eshell-parse-literal-quote)
433 (eshell-parse-double-quote))))
435 (list 'eshell-get-variable (eval name) 'indices))))
436 ((eq (char-after) ?\<)
437 (let ((end (eshell-find-delimiter ?\< ?\>)))
439 (throw 'eshell-incomplete ?\<)
440 (let* ((temp (make-temp-file temporary-file-directory))
441 (cmd (concat (buffer-substring (1+ (point)) end)
445 'let (list (list 'eshell-current-handles
446 (list 'eshell-create-handles temp
447 (list 'quote 'overwrite))))
450 (list 'eshell-as-subcommand
451 (eshell-parse-command cmd))
453 (list 'nconc 'eshell-this-command-hook
457 (list 'delete-file temp))))))
459 (goto-char (1+ end)))))))
460 ((eq (char-after) ?\()
462 (list 'eshell-command-to-value
463 (list 'eshell-lisp-command
464 (list 'quote (read (current-buffer)))))
466 (throw 'eshell-incomplete ?\())))
467 ((assoc (char-to-string (char-after))
468 eshell-variable-aliases-list)
470 (list 'eshell-get-variable
471 (char-to-string (char-before)) 'indices))
472 ((looking-at eshell-variable-name-regexp)
474 (list 'eshell-get-variable (match-string 0) 'indices)
475 (goto-char (match-end 0))))
477 (error "Invalid variable reference")))))
479 (eshell-deftest var interp-cmd
480 "Interpolate command result"
481 (eshell-command-result-p "+ ${+ 1 2} 3" "6\n"))
483 (eshell-deftest var interp-lisp
484 "Interpolate Lisp form evalution"
485 (eshell-command-result-p "+ $(+ 1 2) 3" "6\n"))
487 (eshell-deftest var interp-concat
488 "Interpolate and concat command"
489 (eshell-command-result-p "+ ${+ 1 2}3 3" "36\n"))
491 (eshell-deftest var interp-concat-lisp
492 "Interpolate and concat Lisp form"
493 (eshell-command-result-p "+ $(+ 1 2)3 3" "36\n"))
495 (eshell-deftest var interp-concat2
496 "Interpolate and concat two commands"
497 (eshell-command-result-p "+ ${+ 1 2}${+ 1 2} 3" "36\n"))
499 (eshell-deftest var interp-concat-lisp2
500 "Interpolate and concat two Lisp forms"
501 (eshell-command-result-p "+ $(+ 1 2)$(+ 1 2) 3" "36\n"))
503 (defun eshell-parse-indices ()
504 "Parse and return a list of list of indices."
506 (while (eq (char-after) ?\[)
507 (let ((end (eshell-find-delimiter ?\[ ?\])))
509 (throw 'eshell-incomplete ?\[)
511 (let (eshell-glob-function)
512 (setq indices (cons (eshell-parse-arguments (point) end)
514 (goto-char (1+ end)))))
517 (defun eshell-get-variable (name &optional indices)
518 "Get the value for the variable NAME."
519 (let* ((alias (assoc name eshell-variable-aliases-list))
523 (if (and alias (functionp var))
524 (funcall var indices)
525 (eshell-apply-indices
528 (let ((sym (intern-soft var)))
529 (if (and sym (boundp sym)
530 (or eshell-prefer-lisp-variables
537 (error "Unknown variable `%s'" (eshell-stringify var))))
540 (defun eshell-apply-indices (value indices)
541 "Apply to VALUE all of the given INDICES, returning the sub-result.
542 The format of INDICES is:
544 ((INT-OR-NAME-OR-OTHER INT-OR-NAME INT-OR-NAME ...)
547 Each member of INDICES represents a level of nesting. If the first
548 member of a sublist is not an integer or name, and the value it's
549 reference is a string, that will be used as the regexp with which is
550 to divide the string into sub-parts. The default is whitespace.
551 Otherwise, each INT-OR-NAME refers to an element of the list value.
552 Integers imply a direct index, and names, an associate lookup using
555 For example, to retrieve the second element of a user's record in
556 '/etc/passwd', the variable reference would look like:
558 ${egrep johnw /etc/passwd}[: 2]"
560 (let ((refs (car indices)))
561 (when (stringp value)
563 (if (not (or (not (stringp (caar indices)))
565 (concat "^" eshell-variable-name-regexp "$")
567 (setq separator (caar indices)
570 (mapcar 'eshell-convert
571 (split-string value separator)))))
574 (error "Invalid array variable index: %s"
575 (eshell-stringify refs)))
577 (setq value (eshell-index-value value (car refs))))
579 (let ((new-value (list t)))
582 (list (eshell-index-value value
584 (setq refs (cdr refs)))
585 (setq value (cdr new-value))))))
586 (setq indices (cdr indices)))
589 (defun eshell-index-value (value index)
590 "Reference VALUE using the given INDEX."
592 (cdr (assoc index value))
595 (if (> index (ring-length value))
596 (error "Index exceeds length of ring")
597 (ring-ref value index)))
599 (if (> index (length value))
600 (error "Index exceeds length of list")
603 (if (> index (length value))
604 (error "Index exceeds length of vector")
607 (error "Invalid data type for indexing")))))
609 ;;;_* Variable name completion
611 (defun eshell-complete-variable-reference ()
612 "If there is a variable reference, complete it."
613 (let ((arg (pcomplete-actual-arg)) index)
616 (concat "\\$\\(" eshell-variable-name-regexp
618 (setq pcomplete-stub (substring arg (1+ index)))
619 (throw 'pcomplete-completions (eshell-variables-list)))))
621 (defun eshell-variables-list ()
622 "Generate list of applicable variables."
623 (let ((argname pcomplete-stub)
625 (eshell-for alias eshell-variable-aliases-list
626 (if (string-match (concat "^" argname) (car alias))
627 (setq completions (cons (car alias) completions))))
633 (let ((value (eshell-get-variable varname)))
636 (file-directory-p value))
639 (eshell-envvar-names (eshell-environment-variables)))
640 (all-completions argname obarray 'boundp)
644 (defun eshell-complete-variable-assignment ()
645 "If there is a variable assignment, allow completion of entries."
646 (let ((arg (pcomplete-actual-arg)) pos)
647 (when (string-match (concat "\\`" eshell-variable-name-regexp "=") arg)
648 (setq pos (match-end 0))
649 (if (string-match "\\(:\\)[^:]*\\'" arg)
650 (setq pos (match-end 1)))
651 (setq pcomplete-stub (substring arg pos))
652 (throw 'pcomplete-completions (pcomplete-entries)))))
656 ;; arch-tag: 393654fe-bdad-4f27-9a10-b1472ded14cf
657 ;;; esh-var.el ends here