Add support for tab-indented code blocks (#207)

Explicit support for tab-indented code blocks

Author: abudden

syntax/pandoc.vim

@@ -142,8 +142,8 @@ function! EnableEmbedsforCodeblocksWithLang(entry)
         let s:langsyntaxfile = matchstr(a:entry, "[^=]*$")
         unlet! b:current_syntax
         exe 'syn include @'.toupper(s:langname).' syntax/'.s:langsyntaxfile.'.vim'
-        exe "syn region pandocDelimitedCodeBlock_" . s:langname . ' start=/\(\_^\(\s\{4,}\)\=\(`\{3,}`*\|\~\{3,}\~*\)\s*\%({[^.]*\.\)\=' . s:langname . '\>.*\n\)\@<=\_^/' .
-		    \' end=/\_$\n\(\(\s\{4,}\)\=\(`\{3,}`*\|\~\{3,}\~*\)\_$\n\_$\)\@=/ contained containedin=pandocDelimitedCodeBlock' .
+        exe "syn region pandocDelimitedCodeBlock_" . s:langname . ' start=/\(\_^\([ ]\{4,}\|\t\)\=\(`\{3,}`*\|\~\{3,}\~*\)\s*\%({[^.]*\.\)\=' . s:langname . '\>.*\n\)\@<=\_^/' .
+		    \' end=/\_$\n\(\([ ]\{4,}\|\t\)\=\(`\{3,}`*\|\~\{3,}\~*\)\_$\n\_$\)\@=/ contained containedin=pandocDelimitedCodeBlock' .
 		    \' contains=@' . toupper(s:langname)
 	exe "syn region pandocDelimitedCodeBlockinBlockQuote_" . s:langname . ' start=/>\s\(`\{3,}`*\|\~\{3,}\~*\)\s*\%({[^.]*\.\)\=' . s:langname . '\>/' .
 		    \ ' end=/\(`\{3,}`*\|\~\{3,}\~*\)/ contained containedin=pandocDelimitedCodeBlock' .
@@ -239,7 +239,7 @@ syn match pandocBlockQuoteMark /\_^\s\{,3}>/ contained containedin=pandocEmphasi
 " }}}
 " Code Blocks: {{{2
 if g:pandoc#syntax#protect#codeblocks == 1
-    syn match pandocCodeblock /\s\{4}.*$/
+    syn match pandocCodeblock /\([ ]\{4}\|\t\).*$/
 endif
 syn region pandocCodeBlockInsideIndent   start=/\(\(\d\|\a\|*\).*\n\)\@<!\(^\(\s\{8,}\|\t\+\)\).*\n/ end=/.\(\n^\s*\n\)\@=/ contained
 "}}}
@@ -371,9 +371,9 @@ syn match pandocTableHeaderWord /\<.\{-}\>/ contained containedin=pandocGridTabl
 " }}}2
 " Delimited Code Blocks: {{{2
 " this is here because we can override strikeouts and subscripts
-syn region pandocDelimitedCodeBlock start=/^\(>\s\)\?\z(\(\s\{4,}\)\=\~\{3,}\~*\)/ end=/^\z1\~*/ skipnl contains=pandocDelimitedCodeBlockStart,pandocDelimitedCodeBlockEnd keepend
-syn region pandocDelimitedCodeBlock start=/^\(>\s\)\?\z(\(\s\{4,}\)\=`\{3,}`*\)/ end=/^\z1`*/ skipnl contains=pandocDelimitedCodeBlockStart,pandocDelimitedCodeBlockEnd keepend
-call s:WithConceal("codeblock_start", 'syn match pandocDelimitedCodeBlockStart /\(\_^\n\_^\(>\s\)\?\(\s\{4,}\)\=\)\@<=\(\~\{3,}\~*\|`\{3,}`*\)/ contained containedin=pandocDelimitedCodeBlock nextgroup=pandocDelimitedCodeBlockLanguage', 'conceal cchar='.s:cchars["codelang"])
+syn region pandocDelimitedCodeBlock start=/^\(>\s\)\?\z(\([ ]\{4,}\|\t\)\=\~\{3,}\~*\)/ end=/^\z1\~*/ skipnl contains=pandocDelimitedCodeBlockStart,pandocDelimitedCodeBlockEnd keepend
+syn region pandocDelimitedCodeBlock start=/^\(>\s\)\?\z(\([ ]\{4,}\|\t\)\=`\{3,}`*\)/ end=/^\z1`*/ skipnl contains=pandocDelimitedCodeBlockStart,pandocDelimitedCodeBlockEnd keepend
+call s:WithConceal("codeblock_start", 'syn match pandocDelimitedCodeBlockStart /\(\_^\n\_^\(>\s\)\?\([ ]\{4,}\|\t\)\=\)\@<=\(\~\{3,}\~*\|`\{3,}`*\)/ contained containedin=pandocDelimitedCodeBlock nextgroup=pandocDelimitedCodeBlockLanguage', 'conceal cchar='.s:cchars["codelang"])
 syn match pandocDelimitedCodeBlockLanguage /\(\s\?\)\@<=.\+\(\_$\)\@=/ contained 
 call s:WithConceal("codeblock_delim", 'syn match pandocDelimitedCodeBlockEnd /\(`\{3,}`*\|\~\{3,}\~*\)\(\_$\n\(>\s\)\?\_$\)\@=/ contained containedin=pandocDelimitedCodeBlock', 'conceal cchar='.s:cchars["codeend"])
 syn match pandocBlockQuoteinDelimitedCodeBlock '^>' contained containedin=pandocDelimitedCodeBlock