Financial Ops

This crate provides a set of operations for working with financial data, more specifically, avoiding the usage of floating point types.

Usage

use financial_ops::CheckedDecimalOperations;

fn test_add_decimals() {
    let a: u64 = 1_0000;
    let a_decimals = 4;
    let b: u64 = 2_00;
    let b_decimals = 2;

    let (result, decimals) = a.add_decimals_checked(b, a_decimals, b_decimals)?;
    assert_eq!(result, 3_0000);
    assert_eq!(decimals, 4);

    let a: u32 = 123_45;
    let a_decimals = 2;
    let b: u32 = 0_45;
    let b_decimals = 2;

    let (result, decimals) = a.add_decimals_checked(b, a_decimals, b_decimals)?;
    assert_eq!(result, 123_90);
    assert_eq!(decimals, 2);
}

Very useful when dealing with money or blockchain transactions.

Supported operations

Checked

This set of operations will return an Result with the result and the number of decimals, if the operation is successful. If the operation is not successful, it will return a DecimalOperationError.

use financial_ops::CheckedDecimalOperations;

• add_decimals_checked
• sub_decimals_checked
• mul_decimals_checked
• div_decimals_checked
• rem_decimals_checked

Unchecked

This set of operations will return the result and the number of decimals, without any checks, carrying the underlying operation way of handling overflows and underflows.

use financial_ops::DecimalOperations;

• add_decimals
• sub_decimals
• mul_decimals
• div_decimals
• rem_decimals

The checked! macro

The checked! macro rewrites a normal arithmetic expression into a chain of checked operations, recursively, while respecting operator precedence and parentheses. Without an error it evaluates to an Option; with a trailing @ <error> it evaluates to a Result.

use financial_ops::checked;

// Respects precedence: this is `a + (b * c)`, fully checked.
let value: Option<u64> = checked! { 2u64 + 3 * 4 };
assert_eq!(value, Some(14));

// Overflow short-circuits to `None`.
assert_eq!(checked! { u8::MAX + 1u8 }, None);

// With `@ error`, you get a `Result` you can `?` on.
let total = checked! { 2u64 + 2 @ "overflow" }?;
assert_eq!(total, 4);

Supported operators: +, -, *, /, % (mapped to checked_add, checked_sub, checked_mul, checked_div, checked_rem). Each operand is evaluated exactly once, in left-to-right order.