[elpa] externals/compat aa112d8 63/99: Implement lookup-key handling of keymap lists

[ELPA Syncer]

branch: externals/compat
commit aa112d8bd04174422cf17a2ee8e9a3dca2e9254b
Author: Philip Kaludercic <philipk@posteo.net>
Commit: Philip Kaludercic <philipk@posteo.net>

    Implement lookup-key handling of keymap lists
---
 compat-27.1.el  | 28 ++++++++++++++++++++++++++++
 compat-tests.el | 11 +++++++++++
 2 files changed, 39 insertions(+)

diff --git a/compat-27.1.el b/compat-27.1.el
index 46847bd..c55aa77 100644
--- a/compat-27.1.el
+++ b/compat-27.1.el
@@ -105,6 +105,34 @@ Letter-case is significant, but text properties are 
ignored."
   (when (and redisplay recenter-redisplay)
     (redisplay)))
 
+;;;; Defined in keymap.c
+
+(compat-advise lookup-key (keymap key &optional accept-default)
+  "Look up key sequence KEY in KEYMAP.  Return the definition.
+A value of nil means undefined.  See doc of `define-key'
+for kinds of definitions.
+
+A number as value means KEY is \"too long\"; that is, characters
+or symbols in it except for the last one fail to be a valid
+sequence of prefix characters in KEYMAP.  The number is how many
+characters at the front of KEY it takes to reach a non-prefix
+key.  KEYMAP can also be a list of keymaps.
+
+Normally, `lookup-key' ignores bindings for t, which act as default
+bindings, used when nothing else in the keymap applies; this makes it
+usable as a general function for probing keymaps.  However, if the
+third optional argument ACCEPT-DEFAULT is non-nil, `lookup-key' will
+recognize the default bindings, just as `read-key-sequence' does."
+  (cond
+   ((keymapp keymap)
+    (funcall oldfun keymap key accept-default))
+   ((listp keymap)
+    (catch 'found
+      (dolist (map keymap)
+        (let ((fn (funcall oldfun map key accept-default)))
+          (when fn (throw 'found fn))))))
+   ((signal 'wrong-type-argument (list 'keymapp keymap)))))
+
 ;;;; Defined in json.c
 
 (declare-function json-encode-string "json" (object))
diff --git a/compat-tests.el b/compat-tests.el
index 213c9a4..f2a4114 100644
--- a/compat-tests.el
+++ b/compat-tests.el
@@ -1295,6 +1295,17 @@ the compatibility function."
         (should (equal (gethash "key" obj) ["abc" 2]))
         (should (equal (gethash "yek" obj) :null))))))
 
+(ert-deftest compat-lookup-key ()
+  "Check if `compat-lookup-key' was implemented properly."
+  (let ((a-map (make-sparse-keymap))
+        (b-map (make-sparse-keymap)))
+    (define-key a-map "x" 'foo)
+    (define-key b-map "x" 'bar)
+    (compat-test lookup-key
+      (compat--should* 'foo a-map "x")
+      (compat--should* 'bar b-map "x")
+      (compat--should* 'foo (list a-map b-map) "x")
+      (compat--should* 'bar (list b-map a-map) "x"))))
 
 (provide 'compat-tests)
 ;;; compat-tests.el ends here