;;; esh-var.el --- handling of variables -*- lexical-binding:t -*-
;; Copyright (C) 1999-2022 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 <https://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
;; $'MYVAR'-TOO
;;
;; Only "MYVAR" is part of the variable name in this case.
;;
;; $(lisp)
;;
;; Returns result of Lisp evaluation. Note: Used alone like this, it
;; is identical to just saying (lisp); but with the variable expansion
;; form, the result may be interpolated a larger string, such as
;; '$(lisp)/other'.
;;
;; ${command}
;;
;; Returns the value of an eshell subcommand. See the note above
;; regarding Lisp evaluations.
;;
;; $<command>
;;
;; Evaluates an eshell subcommand, redirecting the output to a
;; temporary file, and returning the file name.
;;
;; $EXPR[10]
;;
;; Return the 10th element of $EXPR, which can be any dollar
;; expression. If $EXPR's value is a string, it will be split in
;; order to make it a list. The splitting will occur at whitespace.
;;
;; $EXPR[10 20]
;;
;; As above, but instead of returning a single element, it now returns a
;; list of two elements.
;;
;; $EXPR[: 10]
;;
;; Like $EXPR[10], except that splitting occurs at the colon now.
;;
;; $EXPR["\\\\" 10]
;;
;; Separate on backslash characters. Actually, the first argument --
;; if it doesn't have the form of a number -- can be any regular
;; expression. So to split on numbers, use '$EXPR["[0-9]+" 10 20]'.
;;
;; $EXPR[hello]
;;
;; Calls `assoc' on $EXPR with 'hello', expecting it to be an alist.
;;
;; $#EXPR
;;
;; Returns the length of the value of $EXPR. This could also be
;; done using the `length' Lisp function.
;;
;; 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 $?
;; contains the exit code of the last command (0 or 1 for Lisp
;; functions, based on successful completion).
;;; Code:
(require 'esh-util)
(require 'esh-cmd)
(require 'esh-opt)
(require 'esh-module)
(require 'esh-arg)
(require 'esh-io)
(require 'pcomplete)
(require 'ring)
(defconst eshell-inside-emacs (format "%s,eshell" emacs-version)
"Value for the `INSIDE_EMACS' environment variable.")
(defgroup eshell-var nil
"Variable interpolation is introduced whenever the `$' 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 nil
"A list of functions to call when loading `eshell-var'."
:version "24.1" ; removed eshell-var-initialize
:type 'hook)
(defcustom eshell-prefer-lisp-variables nil
"If non-nil, prefer Lisp variables to environment variables."
:type 'boolean)
(defcustom eshell-complete-export-definition t
"If non-nil, completing names for `export' shows current definition."
:type 'boolean)
(defcustom eshell-modify-global-environment nil
"If non-nil, using `export' changes Emacs's global environment."
:type 'boolean)
(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)
(defcustom eshell-variable-aliases-list
`(;; for eshell.el
("COLUMNS" ,(lambda () (window-body-width nil 'remap)) t t)
("LINES" ,(lambda () (window-body-height nil 'remap)) t t)
("INSIDE_EMACS" eshell-inside-emacs t)
;; for eshell-cmd.el
("_" ,(lambda (indices quoted)
(if (not indices)
(car (last eshell-last-arguments))
(eshell-apply-indices eshell-last-arguments
indices quoted))))
("?" eshell-last-command-status)
("$" eshell-last-command-result)
;; for em-alias.el and em-script.el
("0" eshell-command-name)
("1" ,(lambda () (nth 0 eshell-command-arguments)) nil t)
("2" ,(lambda () (nth 1 eshell-command-arguments)) nil t)
("3" ,(lambda () (nth 2 eshell-command-arguments)) nil t)
("4" ,(lambda () (nth 3 eshell-command-arguments)) nil t)
("5" ,(lambda () (nth 4 eshell-command-arguments)) nil t)
("6" ,(lambda () (nth 5 eshell-command-arguments)) nil t)
("7" ,(lambda () (nth 6 eshell-command-arguments)) nil t)
("8" ,(lambda () (nth 7 eshell-command-arguments)) nil t)
("9" ,(lambda () (nth 8 eshell-command-arguments)) nil t)
("*" eshell-command-arguments))
"This list provides aliasing for variable references.
Each member is of the following form:
(NAME VALUE [COPY-TO-ENVIRONMENT] [SIMPLE-FUNCTION])
NAME defines the name of the variable, VALUE is a Lisp value used to
compute the string value that will be returned when the variable is
accessed via the syntax `$NAME'.
If VALUE is a function, its behavior depends on the value of
SIMPLE-FUNCTION. If SIMPLE-FUNCTION is nil, call VALUE with two
arguments: the list of the indices that were used in the reference,
and either t or nil depending on whether or not the variable was
quoted with double quotes. For example, if `NAME' were aliased
to a function, a reference of `$NAME[10][20]' would result in that
function being called with the arguments `((\"10\") (\"20\"))' and
nil.
If SIMPLE-FUNCTION is non-nil, call the function with no arguments
and then pass its return value to `eshell-apply-indices'.
If VALUE is a string, return the value for the variable with that
name in the current environment. If no variable with that name exists
in the environment, but if a symbol with that same name exists and has
a value bound to it, return that symbol's value instead. You can
prefer symbol values over environment values by setting the value
of `eshell-prefer-lisp-variables' to t.
If VALUE is a symbol, return the value bound to it.
If VALUE has any other type, signal an error.
Additionally, if COPY-TO-ENVIRONMENT is non-nil, the alias should be
copied (a.k.a. \"exported\") to the environment of created subprocesses."
:type '(repeat (list string sexp
(choice (const :tag "Copy to environment" t)
(const :tag "Use only in Eshell" nil))
(choice (const :tag "Call without argument" t)
(const :tag "Call with 2 arguments" nil))))
:risky t)
(defvar-keymap eshell-var-mode-map
"C-c M-v" #'eshell-insert-envvar)
;;; Functions:
(define-minor-mode eshell-var-mode
"Minor mode for the esh-var module.
\\{eshell-var-mode-map}"
:keymap eshell-var-mode-map)
(defun eshell-var-initialize () ;Called from `eshell-mode' via intern-soft!
"Initialize the variable handle code."
;; Break the association with our parent's environment. Otherwise,
;; changing a variable will affect all of Emacs.
(unless eshell-modify-global-environment
(setq-local process-environment (eshell-copy-environment)))
(setq-local eshell-special-chars-inside-quoting
(append eshell-special-chars-inside-quoting '(?$)))
(setq-local 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))))
;; FIXME the real "env" command does more than this, it runs a program
;; in a modified environment.
(defun eshell/env (&rest args)
"Implementation 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>")
(dolist (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 (lambda (x)
(substring x 0 (string-search "=" 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)))
(dolist (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 get-len)
indices (and (not (eobp))
(eq (char-after) ?\[)
(eshell-parse-indices))
;; This is an expression that will be evaluated by `eshell-do-eval',
;; which only support let-binding of dynamically-scoped vars
value `(let ((indices (eshell-eval-indices ',indices))) ,value))
(when get-len
(setq value `(length ,value)))
(when eshell-current-quoted
(setq value `(eshell-stringify ,value)))
value))
(defun eshell-parse-variable-ref (&optional modifier-p)
"Eval a variable reference.
Returns a Lisp form which, if evaluated, will return the value of the
variable.
If MODIFIER-P is non-nil, the value of the variable will be
modified by some function. If MODIFIER-P is nil, the value will be
used as-is; this allows optimization of some kinds of variable
references.
Possible variable references are:
NAME an environment or Lisp variable value
\"LONG-NAME\" disambiguates the length of the name
`LONG-NAME' as above
{COMMAND} result of command is variable's value
(LISP-FORM) result of Lisp form is variable's value
<COMMAND> write the output of command to a temporary file;
result is the file name"
(cond
((eq (char-after) ?{)
(let ((end (eshell-find-delimiter ?\{ ?\})))
(if (not end)
(throw 'eshell-incomplete ?\{)
(forward-char)
(prog1
`(eshell-apply-indices
(eshell-convert
(eshell-command-to-value
(eshell-as-subcommand
,(let ((subcmd (or (eshell-unescape-inner-double-quote end)
(cons (point) end)))
(eshell-current-quoted nil))
(eshell-parse-command subcmd))))
;; If this is a simple double-quoted form like
;; "${COMMAND}" (i.e. no indices after the subcommand
;; and no `#' modifier before), ensure we convert to a
;; single string. This avoids unnecessary work
;; (e.g. splitting the output by lines) when it would
;; just be joined back together afterwards.
,(when (and (not modifier-p) eshell-current-quoted)
'(not indices)))
indices ,eshell-current-quoted)
(goto-char (1+ end))))))
((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
`(let ((eshell-current-handles
(eshell-create-handles ,temp 'overwrite)))
(progn
(eshell-as-subcommand
,(let ((eshell-current-quoted nil))
(eshell-parse-command cmd)))
(ignore
(nconc eshell-this-command-hook
;; Quote this lambda; it will be evaluated
;; by `eshell-do-eval', which requires very
;; particular forms in order to work
;; properly. See bug#54190.
(list (function
(lambda ()
(delete-file ,temp)
(when-let ((buffer (get-file-buffer ,temp)))
(kill-buffer buffer)))))))
(eshell-apply-indices ,temp indices ,eshell-current-quoted)))
(goto-char (1+ end)))))))
((eq (char-after) ?\()
(condition-case nil
`(eshell-apply-indices
(eshell-command-to-value
(eshell-lisp-command
',(read (or (eshell-unescape-inner-double-quote (point-max))
(current-buffer)))))
indices ,eshell-current-quoted)
(end-of-file
(throw 'eshell-incomplete ?\())))
((looking-at (rx-to-string
`(or "'" ,(if eshell-current-quoted "\\\"" "\""))))
(eshell-with-temp-command
(or (eshell-unescape-inner-double-quote (point-max))
(cons (point) (point-max)))
(let ((name (if (eq (char-after) ?\')
(eshell-parse-literal-quote)
(eshell-parse-double-quote))))
(when name
`(eshell-get-variable ,(eval name) indices ,eshell-current-quoted)))))
((assoc (char-to-string (char-after))
eshell-variable-aliases-list)
(forward-char)
`(eshell-get-variable ,(char-to-string (char-before)) indices
,eshell-current-quoted))
((looking-at eshell-variable-name-regexp)
(prog1
`(eshell-get-variable ,(match-string 0) indices ,eshell-current-quoted)
(goto-char (match-end 0))))
(t
(error "Invalid variable reference"))))
(defvar eshell-glob-function)
(defun eshell-parse-indices ()
"Parse and return a list of index-lists.
For example, \"[0 1][2]\" becomes:
((\"0\" \"1\") (\"2\")."
(let (indices)
(while (eq (char-after) ?\[)
(let ((end (eshell-find-delimiter ?\[ ?\])))
(if (not end)
(throw 'eshell-incomplete ?\[)
(forward-char)
(eshell-with-temp-command (or (eshell-unescape-inner-double-quote end)
(cons (point) end))
(let (eshell-glob-function (eshell-current-quoted nil))
(setq indices (cons (eshell-parse-arguments
(point-min) (point-max))
indices))))
(goto-char (1+ end)))))
(nreverse indices)))
(defun eshell-eval-indices (indices)
"Evaluate INDICES, a list of index-lists generated by `eshell-parse-indices'."
(mapcar (lambda (i) (mapcar #'eval i)) indices))
(defun eshell-get-variable (name &optional indices quoted)
"Get the value for the variable NAME.
INDICES is a list of index-lists (see `eshell-parse-indices').
If QUOTED is non-nil, this was invoked inside double-quotes."
(if-let ((alias (assoc name eshell-variable-aliases-list)))
(let ((target (nth 1 alias)))
(cond
((functionp target)
(if (nth 3 alias)
(eshell-apply-indices (funcall target) indices quoted)
(condition-case nil
(funcall target indices quoted)
(wrong-number-of-arguments
(display-warning
:warning (concat "Function for `eshell-variable-aliases-list' "
"entry should accept two arguments: INDICES "
"and QUOTED.'"))
(funcall target indices)))))
((symbolp target)
(eshell-apply-indices (symbol-value target) indices quoted))
(t
(eshell-get-variable target indices quoted))))
(unless (stringp name)
(error "Unknown variable `%s'" (eshell-stringify name)))
(eshell-apply-indices
(let ((sym (intern-soft name)))
(if (and sym (boundp sym)
(or eshell-prefer-lisp-variables
(memq sym eshell--local-vars) ; bug#15372
(not (getenv name))))
(symbol-value sym)
(getenv name)))
indices quoted)))
(defun eshell-apply-indices (value indices &optional quoted)
"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
referencing 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'.
If QUOTED is non-nil, this was invoked inside double-quotes.
This affects the behavior of splitting strings: without quoting,
the split values are converted to numbers via
`eshell-convert-to-number' if possible; with quoting, they're
left as strings.
For example, to retrieve the second element of a user's record in
'/etc/passwd', the variable reference would look like:
${grep johnw /etc/passwd}[: 2]"
(while indices
(let ((refs (car indices)))
(when (stringp value)
(let (separator (index (caar indices)))
(when (and (stringp index)
(not (get-text-property 0 'number index)))
(setq separator index
refs (cdr refs)))
(setq value (split-string value separator))
(unless quoted
(setq value (mapcar #'eshell-convert-to-number value)))))
(cond
((< (length refs) 0)
(error "Invalid array variable index: %s"
(eshell-stringify refs)))
((= (length refs) 1)
(setq value (eshell-index-value value (car refs))))
(t
(let ((new-value (list t)))
(while refs
(nconc new-value
(list (eshell-index-value value
(car refs))))
(setq refs (cdr refs)))
(setq value (cdr new-value))))))
(setq indices (cdr indices)))
value)
(defun eshell-index-value (value index)
"Reference VALUE using the given INDEX."
(when (and (stringp index) (get-text-property 0 'number index))
(setq index (string-to-number index)))
(if (integerp index)
(cond
((ring-p value)
(if (> index (ring-length value))
(error "Index exceeds length of ring")
(ring-ref value index)))
((listp value)
(if (> index (length value))
(error "Index exceeds length of list")
(nth index value)))
((vectorp value)
(if (> index (length value))
(error "Index exceeds length of vector")
(aref value index)))
(t
(error "Invalid data type for indexing")))
;; INDEX is some non-integer value, so treat VALUE as an alist.
(cdr (assoc index value))))
;;;_* Variable name completion
(defun eshell-complete-variable-reference ()
"If there is a variable reference, complete it."
(let ((arg (pcomplete-actual-arg)) index)
(when (setq index
(string-match
(concat "\\$\\(" 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)
(dolist (alias eshell-variable-aliases-list)
(if (string-match (concat "^" argname) (car alias))
(setq completions (cons (car alias) completions))))
(sort
(append
(mapcar
(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)))))
(provide 'esh-var)
;;; esh-var.el ends here