Regular Expressions applications in the creation of Compilers for Programming Languages
In programming, a regular expression is an expression that explains a pattern for a string. A
string matches a regular expression if that string follows the pattern of that regular expression.
For example, you may want to create an account system, allowing usernames to only have
uppercase and lowercase letters, and numbers. While a user is registering, you can check their
desired username against a regular expression involving only alphanumeric characters (A-Z, a-z,
0-9). If it matches, then the username is valid to your requests. If it does not, the user has put in a
character that does not follow the pattern of the regular expression.
In regular expressions, you can match certain characters, match a certain quanity of characters,
match the casing of characters (or just ignore it overall), and plenty more.
A compiler is a computer program (or set of programs) that transforms source code written in a
programming language (the source language) into another computer language (the target
language, often having a binary form known as object code). The most common reason for
wanting to transform source code is to create an executable program.
The name "compiler" is primarily used for programs that translate source code from a high-level
programming language to a lower level language (e.g., assembly language or machine code). If
the compiled program can run on a computer whose CPU or operating system is different from
the one on which the compiler runs, the compiler is known as a cross-compiler. A program that
translates from a low level language to a higher level one is a decompiler. A program that
translates between high-level languages is usually called a language translator, source to source
translator, or language converter. A language rewriter is usually a program that translates the
form of expressions without a change of language.
A compiler is likely to perform many or all of the following operations: lexical analysis,
preprocessing, parsing, semantic analysis (Syntax-directed translation), code generation, and
code optimization.
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