Support lone '$' in Go templates.

Author: alecthomas

Diff for: lexers/g/go.go

@@ -87,7 +87,7 @@ func goTemplateRules() Rules {
 			{`(range|if|else|while|with|template|end|true|false|nil|and|call|html|index|js|len|not|or|print|printf|println|urlquery|eq|ne|lt|le|gt|ge)\b`, Keyword, nil},
 			{`\||:?=|,`, Operator, nil},
 			{`[$]?[^\W\d]\w*`, NameOther, nil},
-			{`[$]?\.(?:[^\W\d]\w*)?`, NameAttribute, nil},
+			{`\$|[$]?\.(?:[^\W\d]\w*)?`, NameAttribute, nil},
 			{`"(\\\\|\\"|[^"])*"`, LiteralString, nil},
 			{`-?\d+i`, LiteralNumber, nil},
 			{`-?\d+\.\d*([Ee][-+]\d+)?i`, LiteralNumber, nil},

Diff for: lexers/testdata/go-text-template.actual

@@ -7,4 +7,6 @@
 
 {{ range $idx, $value := $variable }}
 Hello {{ $idx }}
-{{ end }}
+{{ end }}
+
+{{ $ }}

Diff for: lexers/testdata/go-text-template.expected

@@ -46,5 +46,11 @@
   {"type":"TextWhitespace","value":" "},
   {"type":"Keyword","value":"end"},
   {"type":"TextWhitespace","value":" "},
+  {"type":"CommentPreproc","value":"}}"},
+  {"type":"Other","value":"\n\n"},
+  {"type":"CommentPreproc","value":"{{"},
+  {"type":"TextWhitespace","value":" "},
+  {"type":"NameAttribute","value":"$"},
+  {"type":"TextWhitespace","value":" "},
   {"type":"CommentPreproc","value":"}}"}
 ]