KeywordToken:

Keywords (reserved words) using in eiffel that are not operatos or separators

LiteralToken:

Literals written in program, such as numericals or strings in format "string"

NewLineToken:

Newline symbol \n

OperatorToken:

Operators used in eiffel, including symbols (ex: +, -, $) and reserved words (ex: implies)

SeparatorToken:

Separators used in eiffel, including symbols (ex: {, ( ) and reserved words (ex: do, end) #####IdentifierToken: Names of variables, classes , etc. Everything written in programm which is not reserved.

A.N.

1. Eiffel doesn't contain primitive datatypes (they are all classes) so we don't consider them as keywords
2. Some operators and separators may be complex (ex: :=, <<) but we recognize them as single ones (ex : and =, < and <) considering further parsing in syntax and semantic analysis