Add optional support for comments

ftplugin/json.vim

@@ -16,6 +16,11 @@ if !exists("g:vim_json_warnings")
 	let g:vim_json_warnings = 1
 end
 
+"have comments off by default
+if !exists("g:vim_json_comments")
+	let g:vim_json_comments = 0
+end
+
 "set concealcursor blank by default
 "this should turn off the concealing in the current line (where the cursor is at),
 "on all modes (normal, visual, insert)

readme.md

@@ -23,6 +23,7 @@ Specific customizations
 	* Warn about *[missing commas](https://github.com/elzr/vim-json/issues/18)* between elements of an object [and elsewhere](https://github.com/elzr/vim-json/issues/34).
 	* Warn about *trailing commas* after the last element in arrays or objects.
 	* (All warnings can be turned off with a `let g:vim_json_warnings=0` in your `vimrc`.) 
+* Optionally allow comment syntax highlighting. (turn this on with a `let g:vim_json_comments=1` in your `vimrc`.)
 * Recognize `.jsonp` file type. In [JSONP](http://stackoverflow.com/questions/2067472/what-is-jsonp-all-about), the wrapping function call at the beginning and the closing semicolon are recognized.
 
 Screenshots

syntax/json.vim

@@ -60,9 +60,11 @@ if (!exists("g:vim_json_warnings") || g:vim_json_warnings==1)
 	" Syntax: Decimals smaller than one should begin with 0 (so .1 should be 0.1).
 	syn match   jsonNumError  "\:\@<=[[:blank:]\r\n]*\zs\.\d\+"
 
-	" Syntax: No comments in JSON, see http://stackoverflow.com/questions/244777/can-i-comment-a-json-file
-	syn match   jsonCommentError  "//.*"
-	syn match   jsonCommentError  "\(/\*\)\|\(\*/\)"
+  if (!exists("g:vim_json_comments") || g:vim_json_comments==0)
+    " Syntax: No comments in JSON, see http://stackoverflow.com/questions/244777/can-i-comment-a-json-file
+    syn match   jsonCommentError  "//.*"
+    syn match   jsonCommentError  "\(/\*\)\|\(\*/\)"
+  endif
 
 	" Syntax: No semicolons in JSON
 	syn match   jsonSemicolonError  ";"
@@ -77,6 +79,14 @@ if (!exists("g:vim_json_warnings") || g:vim_json_warnings==1)
 	syn match   jsonMissingCommaError /\(true\|false\)\_s\+\ze"/ "true/false as value
 endif
 
+" COMMENTS ****************************************************
+if (exists("g:vim_json_comments") && g:vim_json_comments==1)
+  syn keyword jsonCommentTodo  TODO FIXME XXX TBD contained
+  syn match   jsonLineComment  "\/\/.*" contains=@Spell,jsonCommentTodo
+  syn match   jsonCommentSkip  "^[ \t]*\*\($\|[ \t]\+\)"
+  syn region  jsonComment      start="/\*"  end="\*/" contains=@Spell,jsonCommentTodo
+endif
+
 " ********************************************** END OF ERROR WARNINGS
 " Allowances for JSONP: function call at the beginning of the file,
 " parenthesis and semicolon at the end.
@@ -117,6 +127,13 @@ if version >= 508 || !exists("did_json_syn_inits")
 		hi def link jsonNoQuotesError				Error
 		hi def link jsonTripleQuotesError		Error
   endif
+
+  if (exists("g:vim_json_comments") && g:vim_json_comments==1)
+    hi def link jsonCommentTodo Todo
+    hi def link jsonLineComment Comment
+    hi def link jsonComment     Comment
+  endif
+
   hi def link jsonQuote			Quote
   hi def link jsonNoise			Noise
 endif