From: Adam Porter <adam@alphapapa.net>
Date: Mon, 9 Mar 2020 18:01:32 +0000 (-0500)
Subject: * lisp/emacs-lisp/cl-macs.el: Add cl-type pattern
X-Git-Tag: emacs-28.0.90~1639
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=44fe0043d3671676867f302865b15bc3d90217b9;p=emacs.git

* lisp/emacs-lisp/cl-macs.el: Add cl-type pattern

* lisp/emacs-lisp/cl-macs.el:
((pcase-defmacro type)): Add 'cl-type' pattern.

* test/lisp/emacs-lisp/pcase-tests.el (pcase-tests-cl-type): Add test.

* doc/lispref/control.texi (pcase Macro): Update manual.

With thanks to Stefan Monnier and Eli Zaretskii for their guidance.
---

diff --git a/doc/lispref/control.texi b/doc/lispref/control.texi
index 22b665bc931..5026d0a4d70 100644
--- a/doc/lispref/control.texi
+++ b/doc/lispref/control.texi
@@ -555,6 +555,16 @@ Two symbols to avoid are @code{t}, which behaves like @code{_}
 Likewise, it makes no sense to bind keyword symbols
 (@pxref{Constant Variables}).
 
+@item (cl-type @var{type})
+Matches if @var{expval} is of type @var{type}, which is a type
+descriptor as accepted by @code{cl-typep} (@pxref{cl-typep,,,cl,Common
+Lisp Extensions}).  Examples:
+
+@lisp
+(cl-type integer)
+(cl-type (integer 0 10))
+@end lisp
+
 @item (pred @var{function})
 Matches if the predicate @var{function} returns non-@code{nil}
 when called on @var{expval}.  The test can be negated with the syntax
diff --git a/etc/NEWS b/etc/NEWS
index 36dc98d8c09..ef115d0ae01 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -545,6 +545,11 @@ in better code.
 ---
 *** New function 'pcase-compile-patterns' to write other macros.
 
+*** Added 'cl-type' pattern.
+The new 'cl-type' pattern compares types using 'cl-typep', which allows
+comparing simple types like '(cl-type integer)', as well as forms like
+'(cl-type (integer 0 10))'.
+
 +++
 ** profiler.el
 The results displayed by 'profiler-report' now have the usage figures
diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index cff43689405..caf8bba2f8c 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -3623,6 +3623,14 @@ STRUCT and SLOT-NAME are symbols.  INST is a structure instance."
                         "use `with-eval-after-load' instead." "28.1")
 (run-hooks 'cl-macs-load-hook)
 
+;;; Pcase type pattern.
+
+;;;###autoload
+(pcase-defmacro cl-type (type)
+  "Pcase pattern that matches objects of TYPE.
+TYPE is a type descriptor as accepted by `cl-typep', which see."
+  `(pred (pcase--flip cl-typep ',type)))
+
 ;; Local variables:
 ;; generated-autoload-file: "cl-loaddefs.el"
 ;; End:
diff --git a/test/lisp/emacs-lisp/pcase-tests.el b/test/lisp/emacs-lisp/pcase-tests.el
index 2120139ec18..02d3878ad08 100644
--- a/test/lisp/emacs-lisp/pcase-tests.el
+++ b/test/lisp/emacs-lisp/pcase-tests.el
@@ -100,4 +100,14 @@
     (should (equal (funcall f 'b1) '(4 5 nil nil)))
     (should (equal (funcall f 'b2) '(nil nil 8 9)))))
 
+(ert-deftest pcase-tests-cl-type ()
+  (should (equal (pcase 1
+                   ((cl-type integer) 'integer))
+                 'integer))
+  (should (equal (pcase 1
+                   ((cl-type (integer 0 2)) 'integer-0<=n<=2))
+                 'integer-0<=n<=2))
+  (should-error (pcase 1
+                  ((cl-type notatype) 'integer))))
+
 ;;; pcase-tests.el ends here.