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;;; 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 <>
;; 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
;; 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 <>.
;;; 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.
;; Interval the value of an environment variable, or a Lisp variable
;; "-" is a valid part of a variable name.
;; Only "MYVAR" is part of the variable name in this case.
;; 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 $?
;; contains the exit code of the last command (0 or 1 for Lisp
;; functions, based on successful completion).
(provide 'esh-var)
(require 'pcomplete)
(require 'esh-test)
(require 'esh-util)
(require 'esh-opt)
(require 'esh-mode))
(require 'env)
(require 'ring)
(defgroup eshell-var nil
"Variable interpolation is introduced whenever the '$' 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
("?" eshell-last-command-status)
("$" eshell-last-command-result)
("0" eshell-command-name)
("1" (lambda (indices) (nth 0 eshell-command-arguments)))
("2" (lambda (indices) (nth 1 eshell-command-arguments)))
("3" (lambda (indices) (nth 2 eshell-command-arguments)))
("4" (lambda (indices) (nth 3 eshell-command-arguments)))
("5" (lambda (indices) (nth 4 eshell-command-arguments)))
("6" (lambda (indices) (nth 5 eshell-command-arguments)))
("7" (lambda (indices) (nth 6 eshell-command-arguments)))
("8" (lambda (indices) (nth 7 eshell-command-arguments)))
("9" (lambda (indices) (nth 8 eshell-command-arguments)))
("*" (lambda (indices)
(if (not indices)
(eshell-apply-indices eshell-command-arguments
"*This list provides aliasing for variable references.
It is very similar in concept to what `eshell-user-aliases-list' does
for commands. Each member of this defines defines the name of a
command, and the Lisp value to return for that variable if it is
accessed via the syntax '$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 '$NAME[10][20]' would result in the
function for alias `NAME' being called (assuming it were aliased to a
function), and the arguments passed to this function would be the list
'(10 20)', and nil."
:type '(repeat (list string sexp
(choice (const :tag "Copy to environment" t)
(const :tag "Use only in Eshell" nil))))
:group 'eshell-var)
(put 'eshell-variable-aliases-list 'risky-local-variable t)
;;; Functions:
(defun eshell-var-initialize ()
"Initialize the variable handle code."
;; Break the association with our parent's environment. Otherwise,
;; changing a variable will affect all of Emacs.
(unless eshell-modify-global-environment
(set (make-local-variable 'process-environment)
(define-key eshell-command-map [(meta ?v)] 'eshell-insert-envvar)
(set (make-local-variable 'eshell-special-chars-inside-quoting)
(append eshell-special-chars-inside-quoting '(?$)))
(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)
(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))
(list 'progn)
(let ((l (list t)))
(while (string-match setvar command)
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)))
(list 'eshell-escape-arg
(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)
(let ((def (assoc var-alias eshell-variable-aliases-list))
(list var-alias
(list 'quote (if (= (length definition) 1)
(car definition)
(if def
(setq eshell-variable-aliases-list
(delq (assoc var-alias eshell-variable-aliases-list)
(setq eshell-variable-aliases-list
(cons alias-def
(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
(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))))
(defun pcomplete/eshell-mode/setq ()
"Completion function for Eshell's `setq'."
(while (and (pcomplete-here (all-completions pcomplete-stub
obarray 'boundp))
(defun eshell/env (&rest args)
"Implemention of `env' in Lisp."
"env" args
'((?h "help" nil nil "show this usage screen")
:external "env"
:usage "<no arguments>")
(eshell-for setting (sort (eshell-environment-variables)
(eshell-buffered-print setting "\n"))
(defun eshell-insert-envvar (envvar-name)
"Insert ENVVAR-NAME into the current buffer at point."
(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)
(or (eshell-get-variable (car var-alias)) "")))))
(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
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) ?\[)
value (list 'let
(list (list 'indices
(list 'quote indices)))
(if get-len
(list 'length value)
(defun eshell-parse-variable-ref ()
"Eval a variable reference.
Returns a Lisp form which, if evaluated, will return the value of the
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)
((eq (char-after) ?{)
(let ((end (eshell-find-delimiter ?\{ ?\})))
(if (not end)
(throw 'eshell-incomplete ?\{)
(list 'eshell-convert
(list 'eshell-command-to-value
(list 'eshell-as-subcommand
(cons (1+ (point)) end)))))
(goto-char (1+ end))))))
((memq (char-after) '(?\' ?\"))
(let ((name (if (eq (char-after) ?\')
(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)))
'let (list (list 'eshell-current-handles
(list 'eshell-create-handles temp
(list 'quote 'overwrite))))
(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)))))
(throw 'eshell-incomplete ?\())))
((assoc (char-to-string (char-after))
(list 'eshell-get-variable
(char-to-string (char-before)) 'indices))
((looking-at eshell-variable-name-regexp)
(list 'eshell-get-variable (match-string 0) 'indices)
(goto-char (match-end 0))))
(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 ?\[)
(let (eshell-glob-function)
(setq indices (cons (eshell-parse-arguments (point) end)
(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)
(if (and alias (functionp var))
(funcall var indices)
((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))
(error "Unknown variable `%s'" (eshell-stringify var))))
(defun eshell-apply-indices (value indices)
"Apply to VALUE all of the given INDICES, returning the sub-result.
The format of INDICES is:
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
For example, to retrieve the second element of a user's record in
'/etc/passwd', the variable reference would look like:
${egrep johnw /etc/passwd}[: 2]"
(while indices
(let ((refs (car indices)))
(when (stringp value)
(let (separator)
(if (not (or (not (stringp (caar indices)))
(concat "^" eshell-variable-name-regexp "$")
(caar indices))))
(setq separator (caar indices)
refs (cdr refs)))
(setq value
(mapcar 'eshell-convert
(split-string value separator)))))
((< (length refs) 0)
(error "Invalid array variable index: %s"
(eshell-stringify refs)))
((= (length refs) 1)
(setq value (eshell-index-value value (car refs))))
(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)))
(defun eshell-index-value (value index)
"Reference VALUE using the given INDEX."
(if (stringp index)
(cdr (assoc index value))
((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)))
(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
(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)
(eshell-for alias eshell-variable-aliases-list
(if (string-match (concat "^" argname) (car alias))
(setq completions (cons (car alias) completions))))
(lambda (varname)
(let ((value (eshell-get-variable varname)))
(if (and value
(stringp value)
(file-directory-p value))
(concat varname "/")
(eshell-envvar-names (eshell-environment-variables)))
(all-completions argname obarray 'boundp)
(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
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