Add cl-parse-integer based on parse-integer

* doc/misc/cl.texi (Predicates on Numbers): Document cl-digit-char-p.
(Numerical Functions): Document cl-parse-integer. 

* lisp/calendar/parse-time.el (parse-time-digits): Remove.
(digit-char-p, parse-integer) Moved to cl-lib.el.
(parse-time-tokenize, parse-time-rules, parse-time-string): Use
cl-parse-integer.

* lisp/emacs-lisp/cl-extra.el (cl-parse-integer): New function.

* lisp/emacs-lisp/cl-lib.el (cl-digit-char-table): New var.
(cl-digit-char-p): New function.

* test/automated/cl-lib.el (cl-digit-char-p, cl-parse-integer): New
tests.

Fixes: debbugs:18557

1 files changed, 19 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/cl-lib.el b/lisp/emacs-lisp/cl-lib.el
index c4b9673aa2a..09cc3eee985 100644
--- a/lisp/emacs-lisp/cl-lib.el
+++ b/lisp/emacs-lisp/cl-lib.el
@@ -279,6 +279,25 @@ so that they are registered at compile-time as well as run-time."
   "Return t if INTEGER is even."
   (eq (logand integer 1) 0))
 
+(defconst cl-digit-char-table
+  (let* ((digits (make-vector 256 nil))
+         (populate (lambda (start end base)
+                     (mapc (lambda (i)
+                             (aset digits i (+ base (- i start))))
+                           (number-sequence start end)))))
+    (funcall populate ?0 ?9 0)
+    (funcall populate ?A ?Z 10)
+    (funcall populate ?a ?z 10)
+    digits))
+
+(defun cl-digit-char-p (char &optional radix)
+  "Test if CHAR is a digit in the specified RADIX (default 10).
+If true return the decimal value of digit CHAR in RADIX."
+  (or (<= 2 (or radix 10) 36)
+      (signal 'args-out-of-range (list 'radix radix '(2 36))))
+  (let ((n (aref cl-digit-char-table char)))
+    (and n (< n (or radix 10)) n)))
+
 (defvar cl--random-state
   (vector 'cl--random-state-tag -1 30 (cl--random-time)))