escapeRegex function
Escapes special regex characters in str
so that it can be used as a
literal match inside of a RegExp.
The special characters are: \ ^ $ . | +
( ) { }
as defined here: http://ecma-international.org/ecma-262/5.1/#sec-15.10
Implementation
String escapeRegex(String str) => str.splitMapJoin(_specialChars,
onMatch: (Match m) => '\\${m.group(0)}', onNonMatch: (s) => s);