language_cpp: backport number highlighting from c (#1818)

data/plugins/language_cpp.lua

@@ -1,6 +1,11 @@
 -- mod-version:3
 local syntax = require "core.syntax"
 
+-- integer suffix combinations as a regex
+local isuf = [[(?:[lL][uU]|ll[uU]|LL[uU]|[uU][lL]\b|[uU]ll|[uU]LL|[uU]|[lL]\b|ll|LL)?]]
+-- float suffix combinations as a Lua pattern / regex
+local fsuf = "[fFlL]?"
+
 syntax.add {
   name = "C++",
   files = {
@@ -15,9 +20,13 @@ syntax.add {
     { pattern = { "/%*", "%*/" },           type = "comment"  },
     { pattern = { '"', '"', '\\' },         type = "string"   },
     { pattern = { "'", "'", '\\' },         type = "string"   },
-    { pattern = "0x%x+[%x']*",              type = "number"   },
-    { pattern = "%d+[%d%.'eE]*f?",          type = "number"   },
-    { pattern = "%.?%d+[%d']*f?",           type = "number"   },
+    { regex   = "0x[0-9a-fA-f]+"..isuf,     type = "number"   },
+    { regex   = "0()[0-7]+"..isuf,          type = { "keyword", "number" } },
+    { pattern = "%d+%.%d*[Ee]%d+"..fsuf,    type = "number"   },
+    { pattern = "%d+[Ee]%d+"..fsuf,         type = "number"   },
+    { pattern = "%d+%.%d*"..fsuf,           type = "number"   },
+    { pattern = "%.%d+"..fsuf,              type = "number"   },
+    { regex   = "\\d+"..isuf,               type = "number"   },
     { pattern = "[%+%-=/%*%^%%<>!~|:&]",    type = "operator" },
     { pattern = "##",                       type = "operator" },
     { pattern = "struct%s()[%a_][%w_]*",    type = {"keyword", "keyword2"} },