Lexical Analyzer (scanner) Definition/Meaning:
The part of a compiler that breaks up the input into
meaningful units, e.g. names, constants, reserved words, operators. The lexical
analyzer will also remove redundant characters, e.g. spaces, and may deal with
character-set mappings, e.g. replacing uppercase letters by the equivalent
lower-case letters. The units recognized by the lexical analyzer are called
tokens, and are output in some conveniently coded form for subsequent processing
by the compiler.