RegEx Engine in C++

This is a C++ engine written for regular expression matching. It supports various regular expression features and utilizes tokens, a lexer pass, a top-down recursive descent parser, and a backtracking mechanism.

Features Supported

• Match End ($): Matches the end of a string.
• Wildcard (.): Matches any character except a newline.
• Escaping (\): Escapes special characters.
• Non-capturing Group ((?:...)): Groups without capturing.
• Match Start (^): Matches the beginning of a string.
• Range Element ([^a-zA-Z059]): Matches any character not in the specified range.
• Quantifiers (?, *, +): Specifies match count (0-1, 0+, 1+).
• Grouping ((...)): Groups expressions.
• Alternative (|): Matches one of multiple alternatives.
• Named Group ((?<name>...)): Names a capturing group.
• Whitespace (\s): Matches whitespace.
• Curly Brace Quantification ({min,max}): Matches a specific or range of occurrences.

Architecture

• Lexer: The lexer tokenizes the regular expression input.
• Top-down Recursive Descent Parser: Parses the tokenized input following a top-down approach.
• Backtracking Mechanism: Handles the backtracking process to match expressions efficiently.

Running the Project

To run all the tests after cloning the project, execute the following command in the terminal:

make all
make clean

or to run an individual test for say, lexer :

make lexer
./lexer
make clean