Background

The primary objective of this project began as an investigative and learning endeavor with the goal of developing several key components: a tokenizer, a parser capable of generating a parse tree, and an interpreter capable of evaluating the resulting parse tree. I chose to work with the dice notation grammar, which, despite its apparent simplicity, contains some intricate concepts, along with a multitude of modifiers. I have also explored this path once before, but instead of writing everything myself, I utilized PEG (Peggy.js).

My secondary objective is to create a versatile library that can be integrated into different types of projects, including rust projects, browser-based environments, and NodeJS projects, by leveraging WebAssembly (Wasm). This dual focus on both the core functionality and cross-environment usability ultimately forms the core of my experimentation.

Features

droll consists of three main crates:

• The droll library that can be utilized in other rust projects

• The droll-cli tool that can be utilized as a free standing cli tool to parse dice notation and roll dice

• The droll-wasm npm library that can be utilized directly in web and nodejs projects

droll parses the dice notation by utilizing a operator-precedence parser according to the following grammar rules (The grammar is EBNF format).

<expr> ::= <roll-expr>
         | <expr> '+' <expr>
         | <expr> '-' <expr>

<roll-expr> ::= <primary>
              | <expr> 'd' <expr>

<primary> ::= <number>
            | '+' <primary>
            | '-' <primary>
            | 'd' <expr>

<number> ::= <non-zero-digit> { <digit> }

<non-zero-digit> ::= '1' .. '9'

<digit> ::= '0' .. '9'