From 2cbdce375bb945fecb3f110437b595dcc6dad566 Mon Sep 17 00:00:00 2001
From: Hiroshi Shirosaki <h.shirosaki@gmail.com>
Date: Tue, 19 Jan 2016 13:40:05 +0900
Subject: [PATCH] Improve regexp performance of italic

Add tests for escaped asterisks.
---
 syntax/markdown.vim | 4 ++--
 test/syntax.vader   | 9 +++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/syntax/markdown.vim b/syntax/markdown.vim
index ec12ef6..452a717 100644
--- a/syntax/markdown.vim
+++ b/syntax/markdown.vim
@@ -35,8 +35,8 @@ syn case ignore
 syn sync linebreaks=1
 
 "additions to HTML groups
-syn region htmlItalic start="\\\@<!\*\ze\S" end="\S\zs\\\@<!\*" keepend oneline
-syn region htmlItalic start="\(^\|\s\)\@<=_\|\\\@<!_\([^_]\+\s\)\@=" end="\S\@<=[^\\]_\|[^\\]_\S\@=" keepend oneline
+syn region htmlItalic start="\\\@<!\*\ze[^\\\*\s]" end="[^\\\*\s]\zs\*" keepend oneline
+syn region htmlItalic start="\\\@<!_\ze[^\\_\s]" end="[^\\_\s]\zs_" keepend oneline
 syn region htmlBold start="\*\*\ze\S" end="\S\zs\*\*" keepend oneline
 syn region htmlBold start="__\ze\S" end="\S\zs__" keepend oneline
 syn region htmlBoldItalic start="\*\*\*\ze\S" end="\S\zs\*\*\*" keepend oneline
diff --git a/test/syntax.vader b/test/syntax.vader
index d985b2c..6f0a694 100644
--- a/test/syntax.vader
+++ b/test/syntax.vader
@@ -55,6 +55,15 @@ Execute (italic with escaped underscores):
   AssertEqual SyntaxOf('c'), 'htmlItalic'
   AssertNotEqual SyntaxOf('d'), 'htmlItalic'
 
+Given markdown;
+a *b\*c* d
+
+Execute (italic with escaped asterisks):
+  AssertNotEqual SyntaxOf('a'), 'htmlItalic'
+  AssertEqual SyntaxOf('b'), 'htmlItalic'
+  AssertEqual SyntaxOf('c'), 'htmlItalic'
+  AssertNotEqual SyntaxOf('d'), 'htmlItalic'
+
 Given markdown;
 a __b\_\_c__ d
 
-- 
2.39.5