Define cross compiler, token and handle

Define cross compiler, token and handle.

Cross compiler : 

• A cross compiler is a type of compiler that generates machine code targeted to run on a system different than the one generating it.
• For EX: A compiler that runs on windows platform also gererates a code that runs on linux platform is called a cross compiler.

Token :

• Token is a sequence of characters that can be treated as a unit in the grammar of the programming languages called token.
• A token is a pair consisting of a token name and an optional attribute value token like: identifiers,keywords,operators,special symbols,constants.

Handle :

• A "handle" of a string is a substring of a string that match the right side of a production and whose reduction to the non terminal of the production is one step along reverse of right most derivation.