terminal and non-terminal symbols.
Example of terminal symbols:
BOOLEANLITERAL -> @"true|false";
DECIMALINTEGERLITERAL-> @"[0-9]+(UL|Ul|uL|ul|LU|Lu|lU|lu|U|u|L|l)?";
REALLITERAL -> @"([0-9]+\.[0-9]+([eE][+-]?[0-9]+)?([fFdDMm]?)?)|(\.[0-9]+([eE][+-]?[0-9]+)?([fFdDMm]?)?)|([0-9]+([eE][+-]?[0-9]+)([fFdDMm]?)?)|([0-9]+([fFdDMm]?))";
HEXINTEGERLITERAL -> @"0(x|X)[0-9a-fA-F]+";
STRINGLITERAL -> @"\""(\""\""|[^\""])*\"""; // shortcut implementation, not quite ready
FUNCTION -> @"[a-zA-Z_][a-zA-Z0-9_]*(?=\s*\()"; // matches only when followed by (
VARIABLE -> @"[a-zA-Z_][a-zA-Z0-9_]*(?!\s*\()"; // matches only when NOT followed by (
CONSTANT -> @"(?i)pi|e";
BRACEOPEN -> @"{\s*";
BRACECLOSE -> @"\s*}";
BRACKETOPEN -> @"\(\s*";
BRACKETCLOSE -> @"\s*\)";
SEMICOLON -> @";";
PLUSPLUS -> @"\+\+";
MINUSMINUS -> @"--";
PIPEPIPE -> @"\|\|";
AMPAMP -> @"&&";
AMP -> @"&(?!&)"; // matches only when NOT followed by second &
POWER -> @"\^";
PLUS -> @"\+";
MINUS -> @"-";
EQUAL -> @"==";
ASSIGN -> @"=";
NOTEQUAL -> @"!=|<>";
NOT -> @"!";
ASTERIKS -> @"\*";
SLASH -> @"/";
PERCENT -> @"%";
QUESTIONMARK -> @"\?";
COMMA -> @",";
LESSEQUAL -> @"<=";
GREATEREQUAL -> @">=";
LESSTHAN -> @"<(?!>)"; // matches only when not followed by >
GREATERTHAN -> @">";
COLON -> @":";
EOF -> @"^$";
[Skip] WHITESPACE -> @"\s+";