Struct rust_expression::Calculator

pub struct Calculator { /* fields omitted */ }

Calculator

See it in action on https://msuesskraut.github.io/calc/index.html. Further examples are in Calculator::execute.

Implementations

impl Calculator

pub fn new() -> Self

constructs an calculator without any known variables

pub fn execute(&mut self, line: &str) -> Result<Value, Error>

Executes a command line. These kinds of statements are supported:

• Expression:

  use rust_expression::{Calculator, Value};
  let mut c = Calculator::new();
  assert_eq!(Ok(Value::Number(3.0)), c.execute("1 + 2"));

• Variable assignments:

  assert_eq!(Ok(Value::Void), c.execute("a := 6"));
  assert_eq!(Ok(Value::Number(36.0)), c.execute("a ^ 2"));

• Solving linear expressions:

  assert_eq!(Ok(Value::Solved {variable: "x".to_string(), value: 4.0}), c.execute("solve 3 * x - 2 = x + a for x"));

• Function definition:

  assert_eq!(Ok(Value::Void), c.execute("fun(x, y) := y - x"));
  assert_eq!(Ok(Value::Number(2.0)), c.execute("fun(1.5 * 2, 3 + a) - 4"));

• Create a plot:

  assert_eq!(Ok(Value::Void), c.execute("f(x) := x ^ 2"));
  
  match c.execute("plot f") {
      Ok(Value::Graph(graph)) => {
          let area = Area::new(-100., -100., 100., 100.);
          let screen = Area::new(0., 0., 60., 40.);
          let plot = graph.plot(&area, &screen).unwrap();
          assert_eq!(Some(20.), plot.points[30]);
      }
      // ...
  }

Trait Implementations

impl Debug for Calculator

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Calculator

fn default() -> Calculator

Returns the “default value” for a type.