Add comments for some extensions + test

Author: sheerun

after/syntax/c.vim

@@ -7,7 +7,7 @@ if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'cpp-modern') ==
 "                  http://www.vim.org/scripts/script.php?script_id=3064
 " Maintainer:      bfrg <bfrg@users.noreply.github.com>
 " Website:         https://github.com/bfrg/vim-cpp-modern
-" Last Change:     Mar 14, 2020
+" Last Change:     Oct 4, 2020
 "
 " Extended C syntax highlighting including highlighting of user-defined
 " functions.
@@ -17,7 +17,7 @@ if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'cpp-modern') ==
 " ==============================================================================
 
 
-" Highlight some additional keywords in the comments
+" Highlight additional keywords in the comments
 syn keyword cTodo contained BUG NOTE
 
 
@@ -50,25 +50,4 @@ if get(g:, 'cpp_simple_highlight', 0)
     hi link cLabel        Statement
 endif
 
-
-" Operators
-" syn match cOperator "\(<<\|>>\|[-+*/%&^|<>!=]\)="
-" syn match cOperator "<<\|>>\|&&\|||\|++\|--\|->"
-" syn match cOperator "[.!~*&%<>^|=,+-]"
-" syn match cOperator "/[^/*=]"me=e-1
-" syn match cOperator "/$"
-" syn match cOperator "&&\|||"
-" syn match cOperator "[][]"
-
-" Preprocessor
-" syn keyword cDefined defined contained containedin=cDefine
-" hi def link cDefined cDefine
-
-" Delimiters
-" syn match cDelimiter "[();\\]"
-" hi def link cDelimiter Delimiter
-" foldmethod=syntax fix, courtesy of Ivan Freitas
-" syn match cBraces display "[{}]"
-" hi def link cBraces Delimiter
-
 endif

after/syntax/cpp.vim

@@ -36,7 +36,7 @@ let s:tags = '\%(' . join(graphql#javascript_tags(), '\|') . '\)'
 
 if graphql#has_syntax_group('jsTemplateExpression')
   " pangloss/vim-javascript
-  exec 'syntax region graphqlTemplateString start=+' . s:tags . '\@20<=`+ skip=+\\\\\|\\`+ end=+`+ contains=@GraphQLSyntax,jsTemplateExpression,jsSpecial extend'
+  exec 'syntax region graphqlTemplateString matchgroup=jsTemplateString start=+' . s:tags . '\@20<=`+ skip=+\\\\\|\\`+ end=+`+ contains=@GraphQLSyntax,jsTemplateExpression,jsSpecial extend'
   exec 'syntax match graphqlTaggedTemplate +' . s:tags . '\ze`+ nextgroup=graphqlTemplateString'
   syntax region graphqlTemplateExpression start=+${+ end=+}+ contained contains=jsTemplateExpression containedin=graphqlFold keepend
 
@@ -48,7 +48,7 @@ if graphql#has_syntax_group('jsTemplateExpression')
   syn cluster graphqlTaggedTemplate add=graphqlTemplateString
 elseif graphql#has_syntax_group('javaScriptStringT')
   " runtime/syntax/javascript.vim
-  exec 'syntax region graphqlTemplateString start=+' . s:tags . '\@20<=`+ skip=+\\\\\|\\`+ end=+`+ contains=@GraphQLSyntax,javaScriptSpecial,javaScriptEmbed,@htmlPreproc extend'
+  exec 'syntax region graphqlTemplateString matchgroup=javaScriptStringT start=+' . s:tags . '\@20<=`+ skip=+\\\\\|\\`+ end=+`+ contains=@GraphQLSyntax,javaScriptSpecial,javaScriptEmbed,@htmlPreproc extend'
   exec 'syntax match graphqlTaggedTemplate +' . s:tags . '\ze`+ nextgroup=graphqlTemplateString'
   syntax region graphqlTemplateExpression start=+${+ end=+}+ contained contains=@javaScriptEmbededExpr containedin=graphqlFold keepend
 

after/syntax/javascript/graphql.vim

@@ -34,7 +34,7 @@ endif
 
 let s:tags = '\%(' . join(graphql#javascript_tags(), '\|') . '\)'
 
-exec 'syntax region graphqlTemplateString start=+' . s:tags . '\@20<=`+ skip=+\\`+ end=+`+ contains=@GraphQLSyntax,typescriptTemplateSubstitution extend'
+exec 'syntax region graphqlTemplateString matchgroup=typescriptTemplate start=+' . s:tags . '\@20<=`+ skip=+\\`+ end=+`+ contains=@GraphQLSyntax,typescriptTemplateSubstitution extend'
 exec 'syntax match graphqlTaggedTemplate +' . s:tags . '\ze`+ nextgroup=graphqlTemplateString'
 
 " Support expression interpolation ((${...})) inside template strings.

after/syntax/typescript/graphql.vim

@@ -53,6 +53,8 @@ Text enclosed between `$anyword$` pairs, where `anyword` is any non-empty
 sequence of word characters different from those with a special meaning (such
 as `$pgsql$`) is treated as a multi-line string.
 
+When |foldmethod| is set to "syntax", SQL commands can be folded.
+
 Finally, the plugin supports syntax highlighting of arbitrary languages within
 procedure and function blocks. This feature needs to be configured: see
 |g:pgsql_pl|.