Computer-Based Construction of Arbitrarily Complex Formal Grammar Expressions

A method, system and computer program product for building an expression, including utilizing any formal grammar of a context-free language, displaying an expression on a computer display via a graphical user interface, replacing at least one non-terminal display object within the displayed expression with any of at least one non-terminal display object and at least one terminal display object, and repeating the replacing step a plurality of times for a plurality of non-terminal display objects until no non-terminal display objects remain in the displayed expression, wherein the non-terminal display objects correspond to non-terminal elements within the grammar, and wherein the terminal display objects correspond to terminal elements within the grammar.