Fix parsing of indices in Eshell expansions

Previously, more-complex index expansions, like '$var[":" 0]' or
'$var[$(expr) 0]' failed to parse correctly.

* lisp/eshell/esh-var.el (Commentary): Clarify indexing and length
expansions.
(eshell-parse-indices): Expand docstring and support parsing inside
double-quotes.
(eshell-eval-indices): New function.
(eshell-parse-variable): Use it.

* test/lisp/eshell/esh-var-tests.el (eshell-test-value): New defvar.
(esh-var-test/interp-var-indices,
(esh-var-test/interp-var-split-indices)
(esh-var-test/interp-var-string-split-indices)
(esh-var-test/interp-var-regexp-split-indices)
(esh-var-test/interp-var-assoc, esh-var-test/interp-var-length-list)
(esh-var-test/interp-var-length-string)
(esh-var-test/interp-var-length-alist)
(esh-var-test/quoted-interp-var-indices)
(esh-var-test/quoted-interp-var-split-indices)
(esh-var-test/quoted-interp-var-string-split-indices)
(esh-var-test/quoted-interp-var-regexp-split-indices)
(esh-var-test/quoted-interp-var-assoc)
(esh-var-test/quoted-interp-var-length-list)
(esh-var-test/quoted-interp-var-length-string)
(esh-var-test/quoted-interp-var-length-alist): New tests.

* doc/misc/eshell.texi (Dollars Expansion): Expand and reword
documentation for indexing and length expansions.

1 files changed, 31 insertions, 28 deletions

diff --git a/lisp/eshell/esh-var.el b/lisp/eshell/esh-var.el
index 24fdbde3cfb..6f08a3fbc45 100644
--- a/lisp/eshell/esh-var.el
+++ b/lisp/eshell/esh-var.el
@@ -39,11 +39,6 @@
 ;;
 ;; 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
@@ -61,38 +56,36 @@
 ;; Evaluates an eshell subcommand, redirecting the output to a
 ;; temporary file, and returning the file name.
 ;;
-;;   $ANYVAR[10]
+;;   $EXPR[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.
+;; 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.
 ;;
-;;   $ANYVAR[: 10]
+;;   $EXPR[10 20]
 ;;
-;; As above, except that splitting occurs at the colon now.
+;; As above, but instead of returning a single element, it now returns a
+;; list of two elements.
 ;;
-;;   $ANYVAR[: 10 20]
+;;   $EXPR[: 10]
 ;;
-;; 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.
+;; Like $EXPR[10], except that splitting occurs at the colon now.
 ;;
-;;   $ANYVAR["\\\\" 10]
+;;   $EXPR["\\\\" 10]
 ;;
 ;; Separate on backslash characters.  Actually, the first argument --
 ;; if it doesn't have the form of a number, or a plain variable name
 ;; -- can be any regular expression.  So to split on numbers, use
-;; '$ANYVAR["[0-9]+" 10 20]'.
+;; '$EXPR["[0-9]+" 10 20]'.
 ;;
-;;   $ANYVAR[hello]
+;;   $EXPR[hello]
 ;;
-;; Calls `assoc' on ANYVAR with 'hello', expecting it to be an alist.
+;; Calls `assoc' on $EXPR with 'hello', expecting it to be an alist.
 ;;
-;;   $#ANYVAR[hello]
+;;   $#EXPR
 ;;
-;; Returns the length of the cdr of the element of ANYVAR who car is
-;; equal to "hello".
+;; 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
@@ -416,7 +409,7 @@ process any indices that come after the variable reference."
 		       (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 ',indices)) ,value))
+	  value `(let ((indices (eshell-eval-indices ',indices))) ,value))
     (if get-len
 	`(length ,value)
       value)))
@@ -504,19 +497,29 @@ Possible options are:
 (defvar eshell-glob-function)
 
 (defun eshell-parse-indices ()
-  "Parse and return a list of list of 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)
-	  (let (eshell-glob-function)
-	    (setq indices (cons (eshell-parse-arguments (point) end)
-				indices)))
+          (eshell-with-temp-command (or (eshell-parse-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)
   "Get the value for the variable NAME."
   (let* ((alias (assoc name eshell-variable-aliases-list))