Markdown: skip the area of frontmatter

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

Author: masatake

Units/parser-markdown.r/frontmatter.d/args.ctags

@@ -0,0 +1 @@
+--sort=no

Units/parser-markdown.r/frontmatter.d/expected.tags

@@ -0,0 +1 @@
+About this input	input.md	/^# About this input$/;"	c

Units/parser-markdown.r/frontmatter.d/input.md

@@ -0,0 +1,13 @@
+---
+title: Python
+draft: false
+date: 2021-05-16T13:15:31-05:00
+tags: ['code','python']
+menu:
+    main:
+        parent: 'code'
+---
+
+# About this input
+
+This input is taken from #3027 at github submitted by @rickalex21.

optlib/markdown.c

@@ -42,6 +42,7 @@ static void initializeMarkdownParser (const langType language)
 		"    } def\n"
 		"}}");
 
+	addLanguageRegexTable (language, "frontmatter");
 	addLanguageRegexTable (language, "main");
 	addLanguageRegexTable (language, "main_sharp");
 	addLanguageRegexTable (language, "chapter");
@@ -63,6 +64,18 @@ static void initializeMarkdownParser (const langType language)
 	addLanguageRegexTable (language, "codeblockBacktick");
 	addLanguageRegexTable (language, "codeblockTildes");
 
+	addLanguageTagMultiTableRegex (language, "frontmatter",
+	                               "^(---[\n]).*(---[\n])",
+	                               "", "", "{tjump=main}", NULL);
+	addLanguageTagMultiTableRegex (language, "frontmatter",
+	                               "^(;;;[\n]).*(;;;[\n])",
+	                               "", "", "{tjump=main}", NULL);
+	addLanguageTagMultiTableRegex (language, "frontmatter",
+	                               "^(\\+\\+\\+[\n]).*(\\+\\+\\+[\n])",
+	                               "", "", "{tjump=main}", NULL);
+	addLanguageTagMultiTableRegex (language, "frontmatter",
+	                               "^.",
+	                               "", "", "{_advanceTo=0start}{tjump=main}", NULL);
 	addLanguageTagMultiTableRegex (language, "main",
 	                               "^#",
 	                               "", "", "{_advanceTo=0start}{tjump=main_sharp}", NULL);

optlib/markdown.ctags

@@ -60,6 +60,7 @@
     } def
 }}
 
+--_tabledef-Markdown=frontmatter
 --_tabledef-Markdown=main
 --_tabledef-Markdown=main_sharp
 --_tabledef-Markdown=chapter
@@ -99,6 +100,24 @@
 --_mtable-regex-Markdown=code/^[ \t]*````*[ \t]*([a-zA-Z0-9][-#+a-zA-Z0-9]*)?[^`\n]*[\n]//{tenter=codeblockBacktick}{_guest=\1,0end,}
 --_mtable-regex-Markdown=code/^[ \t]*~~~~*[ \t]*([a-zA-Z0-9][-#+a-zA-Z0-9]*)?[^~\n]*[\n]//{tenter=codeblockTildes}{_guest=\1,0end,}
 
+#
+# Frontmatter
+#
+# https://gohugo.io/content-management/front-matter/
+#
+
+# YAML area
+--_mtable-regex-Markdown=frontmatter/(---[\n]).*(---[\n])//{tjump=main}
+
+# JSON area
+--_mtable-regex-Markdown=frontmatter/(;;;[\n]).*(;;;[\n])//{tjump=main}
+
+# TOML area
+--_mtable-regex-Markdown=frontmatter/(\+\+\+[\n]).*(\+\+\+[\n])//{tjump=main}
+
+# No frontmatter
+--_mtable-regex-Markdown=frontmatter/.//{_advanceTo=0start}{tjump=main}
+
 
 #
 # Main