better markdown lexer

Author: zhangyuannie

Diff for: lexers/m/markdown.go

@@ -40,7 +40,7 @@ func markdownRules() Rules {
 		},
 		"inline": {
 			{`\\.`, Text, nil},
-			{`(\s)([*_][^*_]+[*_])(\W|\n)`, ByGroups(Text, GenericEmph, Text), nil},
+			{`(\s)(\*|_)((?:(?!\2).)*)(\2)((?=\W|\n))`, ByGroups(Text, GenericEmph, GenericEmph, GenericEmph, Text), nil},
 			{`(\s)((\*\*|__).*?)\3((?=\W|\n))`, ByGroups(Text, GenericStrong, GenericStrong, Text), nil},
 			{`(\s)(~~[^~]+~~)((?=\W|\n))`, ByGroups(Text, GenericDeleted, Text), nil},
 			{"`[^`]+`", LiteralStringBacktick, nil},

Diff for: lexers/testdata/markdown.actual

@@ -4,18 +4,20 @@
 
 Multiple **bold** on the **same line**.
 
+Multiple _italic_ on the *same_line*.
+
 ## user defined function in cql
 
 ```javascript
-  column.substring(0,num) 
+  column.substring(0,num)
 ```
 
 ```cql
 CREATE FUNCTION IF NOT EXISTS cycling.left (column TEXT,num int)
 RETURNS NULL ON NULL INPUT
 RETURNS text
-LANGUAGE javascript AS $$ 
-  column.substring(0,num) 
+LANGUAGE javascript AS $$
+  column.substring(0,num)
 $$;
 
 CREATE OR REPLACE FUNCTION cycling.fLog (input double)
@@ -34,7 +36,7 @@ CREATE TABLE emp (
   last_user text
 );
 
-select 
+select
   $my_tag$aoeuaoeu$my_tag$ as blah
 ;
 

Diff for: lexers/testdata/markdown.expected

@@ -16,6 +16,10 @@
   {"type":"GenericStrong","value":"**bold**"},
   {"type":"Text","value":" on the "},
   {"type":"GenericStrong","value":"**same line**"},
+  {"type":"Text","value":".\n\nMultiple "},
+  {"type":"GenericEmph","value":"_italic_"},
+  {"type":"Text","value":" on the "},
+  {"type":"GenericEmph","value":"*same_line*"},
   {"type":"Text","value":".\n\n"},
   {"type":"GenericSubheading","value":"## user defined function in cql\n"},
   {"type":"Text","value":"\n"},
@@ -29,7 +33,7 @@
   {"type":"Punctuation","value":","},
   {"type":"NameOther","value":"num"},
   {"type":"Punctuation","value":")"},
-  {"type":"Text","value":" \n"},
+  {"type":"Text","value":"\n"},
   {"type":"LiteralString","value":"```"},
   {"type":"Text","value":"\n\n"},
   {"type":"LiteralString","value":"```cql\n"},
@@ -78,7 +82,7 @@
   {"type":"Keyword","value":"AS"},
   {"type":"TextWhitespace","value":" "},
   {"type":"LiteralStringHeredoc","value":"$$"},
-  {"type":"Text","value":" \n  "},
+  {"type":"Text","value":"\n  "},
   {"type":"NameOther","value":"column"},
   {"type":"Punctuation","value":"."},
   {"type":"NameOther","value":"substring"},
@@ -87,7 +91,7 @@
   {"type":"Punctuation","value":","},
   {"type":"NameOther","value":"num"},
   {"type":"Punctuation","value":")"},
-  {"type":"Text","value":" \n"},
+  {"type":"Text","value":"\n"},
   {"type":"LiteralStringHeredoc","value":"$$"},
   {"type":"Punctuation","value":";"},
   {"type":"TextWhitespace","value":"\n\n"},
@@ -191,7 +195,7 @@
   {"type":"Punctuation","value":");"},
   {"type":"Text","value":"\n\n"},
   {"type":"Keyword","value":"select"},
-  {"type":"Text","value":" \n  "},
+  {"type":"Text","value":"\n  "},
   {"type":"LiteralStringHeredoc","value":"$my_tag$aoeuaoeu$my_tag$"},
   {"type":"Text","value":" "},
   {"type":"Keyword","value":"as"},