diff options
Diffstat (limited to 'lisp/env.el')
| -rw-r--r-- | lisp/env.el | 23 |
1 files changed, 10 insertions, 13 deletions
diff --git a/lisp/env.el b/lisp/env.el index 9e3aed95f8a..5618404cb67 100644 --- a/lisp/env.el +++ b/lisp/env.el @@ -57,31 +57,28 @@ If it is also not t, RET does not exit if it does non-null completion." ;; History list for VALUE argument to setenv. (defvar setenv-history nil) +(defconst env--substitute-vars-regexp + "\\$\\(?:\\(?1:[[:alnum:]_]+\\)\\|{\\(?1:[^{}]+\\)}\\|\\$\\)") -(defun substitute-env-vars (string) +(defun substitute-env-vars (string &optional only-defined) "Substitute environment variables referred to in STRING. `$FOO' where FOO is an environment variable name means to substitute the value of that variable. The variable name should be terminated with a character not a letter, digit or underscore; otherwise, enclose the entire variable name in braces. For instance, in `ab$cd-x', `$cd' is treated as an environment variable. +If ONLY-DEFINED is nil, references to undefined environment variables +are replaced by the empty string; if it is non-nil, they are left unchanged. Use `$$' to insert a single dollar sign." (let ((start 0)) - (while (string-match - (eval-when-compile - (rx (or (and "$" (submatch (1+ (regexp "[[:alnum:]_]")))) - (and "${" (submatch (minimal-match (0+ anything))) "}") - "$$"))) - string start) + (while (string-match env--substitute-vars-regexp string start) (cond ((match-beginning 1) (let ((value (getenv (match-string 1 string)))) + (if (and (null value) only-defined) + (setq start (match-end 0)) (setq string (replace-match (or value "") t t string) - start (+ (match-beginning 0) (length value))))) - ((match-beginning 2) - (let ((value (getenv (match-string 2 string)))) - (setq string (replace-match (or value "") t t string) - start (+ (match-beginning 0) (length value))))) + start (+ (match-beginning 0) (length value)))))) (t (setq string (replace-match "$" t t string) start (+ (match-beginning 0) 1))))) @@ -185,7 +182,7 @@ VARIABLE should be a string. Value is nil if VARIABLE is undefined in the environment. Otherwise, value is a string. If optional parameter FRAME is non-nil, then it should be a -frame. This function will look up VARIABLE in its 'environment +frame. This function will look up VARIABLE in its `environment' parameter. Otherwise, this function searches `process-environment' for |