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master 51a86b6 1/2: Count (not X) as a switch condition
From: |
Mattias Engdegård |
Subject: |
master 51a86b6 1/2: Count (not X) as a switch condition |
Date: |
Tue, 20 Jul 2021 13:31:26 -0400 (EDT) |
branch: master
commit 51a86b6a0504d580d3e10efe41abf3ae42c90711
Author: Mattias Engdegård <mattiase@acm.org>
Commit: Mattias Engdegård <mattiase@acm.org>
Count (not X) as a switch condition
* lisp/emacs-lisp/bytecomp.el (byte-compile--cond-switch-prefix):
Treat (not VAR) and (null VAR) as (eq VAR nil) when computing the
extent of switch ops.
---
lisp/emacs-lisp/bytecomp.el | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 6970c8a..2968f1a 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -4340,6 +4340,16 @@ Return (TAIL VAR TEST CASES), where:
(push value keys)
(push (cons (list value) (or body '(t))) cases))
t))))
+ ;; Treat (not X) as (eq X nil).
+ (`((,(or 'not 'null) ,(and var (pred symbolp))) . ,body)
+ (and (or (eq var switch-var) (not switch-var))
+ (progn
+ (setq switch-var var)
+ (setq switch-test 'eq)
+ (unless (memq nil keys)
+ (push nil keys)
+ (push (cons (list nil) (or body '(t))) cases))
+ t)))
(`((,(and fn (or 'memq 'memql 'member)) ,var ,expr) . ,body)
(and (symbolp var)
(or (eq var switch-var) (not switch-var))