Customize json syntax highlights

after/ftplugin/json.vim

@@ -1,20 +1,2 @@
-" Set custom fold expression
+set conceallevel=2
-setlocal foldmethod=expr
+set concealcursor=n
-setlocal foldexpr=JsonFold(v:lnum)
-
-" Custom fold function
-function! JsonFold(lnum)
-  let l:line = getline(a:lnum)
-
-  if l:line =~ '{' && l:line !~ '}' && l:line !~ '".*{.*"'
-    return 'a1'
-  elseif l:line =~ '[' && l:line !~ ']' && l:line !~ '".*].*"'
-    return 'a1'
-  elseif l:line =~ '}' && l:line !~ '{' && l:line !~ '".*}.*"'
-    return 's1'
-  elseif l:line =~ ']' && l:line !~ '[' && l:line !~ '".*[.*"'
-    return 's1'
-  endif
-
-  return '='
-endfunction

after/syntax/json.vim

@@ -1,5 +0,0 @@
-" Override default group names
-hi link jsonQuote String
-hi link jsonKeyword Keyword
-hi link jsonKeywordMatch Operator
-hi link jsonNoise Operator

syntax/json.vim

@@ -0,0 +1,33 @@
+if exists("b:current_syntax")
+  finish
+endif
+
+syn cluster jsonValue contains=jsonString,jsonNumber,jsonObject,jsonArray,jsonBoolean,jsonNull
+
+syn region jsonString oneline matchgroup=jsonStringEnd start=+"+ skip=+\\"+ end=+"+ concealends contains=jsonCharacter contained
+syn match jsonNumber '-\?\d\+\(\.\d\+\([eE][-+]\?\d\+\)\?\)\?' contained
+syn region jsonObject fold matchgroup=jsonObjectEnd start='{' end='}' transparent contains=jsonName,jsonColon,jsonComma,@jsonValue
+syn region jsonArray fold matchgroup=jsonArrayEnd start='\[' end='\]' transparent contains=jsonComma,@jsonValue
+syn keyword jsonBoolean true false
+syn keyword jsonNull null
+
+syn match jsonCharacter +\\\(["\\\/bfnrt]\|u\x\x\x\x\)+ contained
+syn region jsonName oneline matchgroup=jsonNameEnd start=+"+ skip=+\\"+ end=+"\ze:+ concealends contains=jsonCharacter contained
+syn match jsonColon ':' contained
+syn match jsonComma ',' contained
+
+hi default link jsonString String
+hi default link jsonStringEnd Conceal
+hi default link jsonNumber Number
+hi default link jsonObjectEnd Delimiter
+hi default link jsonArrayEnd Delimiter
+hi default link jsonBoolean Boolean
+hi default link jsonNull Constant
+
+hi default link jsonCharacter SpecialChar
+hi default link jsonName Function
+hi default link jsonNameEnd Conceal
+hi default link jsonColon Delimiter
+hi default link jsonComma Delimiter
+
+let b:current_syntax = 'json'