Crate asciimath

Expand description

A mathematical expression parsing and evaluation library.

§Evaluating an expression with variables

eval is perfect for cases when you just need to evaluate an expression once, with a given a set of variables.

use asciimath::{eval, scope};

let expression = "(x + y * 4) ^ 3";
let variables = scope! {
   "x" => 8,
   "y" => 12.25
};

assert_eq!(Ok(185193.0), eval(expression, &variables));

§Compiling Expressions for Repeated Evaluation

The example below demonstrates parsing and evaluation of an expression with two sets of variables.

The Scope is passed to the compiler for disambiguation in cases of implicit multiplication and function calls.

use asciimath::{compile, scope, Evaluate};

let scope_one = scope! {
   "x" => 8,
   "y" => 12.25
};
let scope_two = scope! {
   "x" => 3,
   "y" => 0
};
let expression = compile("(x + y * 4) ^ 3", &scope_one).unwrap();

assert_eq!(Ok(185193.0), expression.eval_with(&scope_one));
assert_eq!(Ok(27.0), expression.eval_with(&scope_two));

§Custom Functions

A lot of effort has been put into making custom functions as easy to write as possible.

use asciimath::{eval, scope, CustomFn};

let my_sum: CustomFn = |args| Ok(args.iter().sum());

let scope = scope! {
  "x" => 1,
  "my_sum" => my_sum,
};

assert_eq!(Ok(6.0), eval("my_sum(x, 2, 3)", &scope));