Crate bexeval

Crate bexeval 

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§bexeval

Bexeval is a Rust crate for evaluating mathematical expressions with integer numeric types written as strings.

§Features

  • Parse and evaluate simple mathematical expressions.
    • Basic arithmetic operations: +, -, *, /, %, &, |, ^, <<, >>, !(operator not)
    • Comparison operators (Return 1 if true, 0 if false): ==, !=, <, <=, >, >=
    • Parentheses for expression grouping
    • Common mathematical functions (possibility of adding more functions in the future): pow, count_ones, abs…
  • Can select primitive integer type as the numeric value type: u8, u16, u32, u64, usize, i8, i16, i32, i64, isize
  • Support for variables.
  • Minimal dependencies (only num-traits).

§Usage

Add the bexeval crate to your Cargo.toml file:

[dependencies]
bexeval = "<version>"

Then, in your Rust code:

use bexeval::*;
 
let parser = Parser::<i32>::new();
assert_eq!(parser.eval("1 + 2 * max(3, 4) - (8 ^ 5)").unwrap(), 1 + 2 * 3.max(4) - (8 ^ 5));
 
assert_eq!(parser.eval_context("1 + x", &[("x", 5)]).unwrap(), 1 + 5);
 
assert_eq!(parser.eval(&format!("1 + {}", 5)).unwrap(), 1 + 5);

The context argument stores information about the variable in array of tuples(&str, T).

Wrapping operations are used for operations that may overflow. (wrapping_add, wrapping_mul…)

Be careful of overflow.

Dividing by zero causes panic.

You can assign numerical values to variables and evaluate them using Context.

let mut ctx = Context::<u8>::new();
 
ctx.assign("x", 1);
assert_eq!(ctx.eval("x + 3").unwrap(), 4);
ctx.assign_stmt("y = x + 5").unwrap();
assert_eq!(ctx.eval("y + x * 2").unwrap(), 8);
 
// wrapping operation
assert_eq!(ctx.eval("y + x * (pow(2, 8) - 1)").unwrap(), 5);

§Available function

  • pow
  • abs
  • abs_diff (Available even with rustc versions below 1.60)
  • count_ones
  • count_zeros
  • leading_zeros
  • trailing_zeros
  • rotate_left
  • rotate_right

§API Documentation

Detailed API documentation can be found here.

§License

This project is licensed under the MIT license.

Re-exports§

pub use crate::value_type::Integer;
pub use crate::parser::Parser;
pub use crate::parser::ParserError;
pub use crate::context::Context;

Modules§

context
parser
value_type