Really simple calculator in Rust

This is a really simple calculator that can parse and compute mathematical expressions.

Rust

This project is written in Rust and uses the tracing crate for logging.

The parser is a top-down operator precedence parser. It supports the following operators:

And the following functions:

It also supports parentheses and nested expressions.

And supports unary operators + and -.

This has been written to be a simple educational tool to understand how to parse mathematical expressions in Rust without any external dependencies.

cargo run -- "1 + 2 * sin(1.9)"

1 + 2 * sin(1.9) -> 2.892600175374829

cargo run -- --help

You can also see the tokens in the expression with the --show-tokens flag:

cargo run -- "1 + 2 * sin(1.9)" --show-tokens

[Number(1.0), Operator('+'), Number(2.0), Operator('*'), Function("sin"), LeftParen, Number(1.9), RightParen]
1 + 2 * sin(1.9) -> 2.892600175374829

And the AST with the --show-ast flag:

cargo run -- "1 + 2 * sin(1.9)" --show-ast

BinaryOp(Number(1.0), '+', BinaryOp(Number(2.0), '*', Function("sin", Number(1.9))))
1 + 2 * sin(1.9) -> 2.892600175374829

This project is licensed under the MIT license. See the LICENSE file for more details.