String Calculator

A small package containing eval methods to compute formulas inside strings.

How to use

Simply import the eval you need and use it.

use string_calculator::eval_f64;

fn main() {
  println!("{}", eval_f64("(2+3) / 2".to_string(), 0.0)); // 2.5
}

Features

By default, all features are enabled. If you only want a specific eval method, use the feature associated with it's name in the list:

• eval_complex
• eval_decimal
• eval_f64
• eval_i64
• eval_number

Example:

[dependencies]
string_calculator = { version = "0.4", default-features = false, features = ["eval_decimal"] }

Operators

Since there's a lot of things that could be simplified visually, here's the full list of operators implemented.

1. Add (x+y) This operator handle the addition between two number. Example: 1 + 2 = 3
2. Subtract (x-y) This operator handle the subtraction between two number. Example: 2 - 1 = 1
3. Multiply (x*y) This operator handle the multiplication between two number. Example: 3 * 2 = 6
4. Divide (x/y) This operator handle the division between two number. Example: 4 / 2 = 2
5. Modulo (x%y) (only in eval_decimal, eval_number, eval_f64 and eval_i64) This operator handle the rest of the euclidian division between two number. Example: 4 % 2 = 0
6. Left Shift (x<<y) (only in eval_i64) This operator shift the bits of x to y positions to the left (it's the same as multiplying by 2^y). Example: 1 << 2 = 4
7. Right Shift (x>>y) (only in eval_i64) This operator shift the bits of x to y positions to the right (it's the same as dividing by 2^y). Example: 4 >> 2 = 1
8. PowerOf (x^y) This operator handle the power of x by y, x and y being both numbers. Example: 3^3 = 27
9. Subscript support (x²) This operator handle the power of x by using the superscript notation (such as ²) for integers, x being a number. Example: 5² = 25
10. Factorial (x!) (only in eval_decimal, eval_number, eval_f64 and eval_i64) This operator handle the factorial of a real x. Example: 5! = 120
11. DegToRad (x°) (only in eval_complex, eval_number and eval_f64) This operator handle the conversion from degree to radian. You should note that it's priority is the same as multiplication. Example: 3° = 0.05235987755982989
12. RadToDeg (x rad) (only in eval_complex, eval_number and eval_f64) This operator handle the conversion from radian to degree. You should note that it's priority is the same as multiplication. Example: 3 rad = 171.8873385393

Constants

1. Pi (π) (only in eval_complex, eval_number, eval_decimal and eval_f64) Pi is available as pi or π.
2. E (e) (only in eval_complex, eval_number, eval_decimal and eval_f64) E is available as e.

Function notation

Some function can be written purely using their original mathematical notation if wanted.

1. Floor (⌊x⌋) (only in eval_f64, eval_number and eval_decimal) This function gives the greatest integer less than or equal to x. Example: ⌊2.4⌋ = 2
2. Ceiling (⌈x⌉) (only in eval_f64, eval_number and eval_decimal) This function gives the smallest integer greater or equal to x. Example: ⌈2.4⌉ = 3

Functions

1. Absolute value (abs(x))
2. Signum (sgn(x), sign(x), signum(x)) (only in eval_decimal, eval_f64, eval_number and eval_i64)
3. Power (pow(x,y))
4. Square root (sqrt(x))
5. Root (root(x, n))
6. Modulo (mod(x,y)) (only in eval_decimal, eval_number, eval_f64 and eval_i64)
7. Exponential (exp(x), exp2(x))
8. Logarithm (ln(x), lb(x), log(x, b))
9. Extremum (min(...X), max(...X)) (only in eval_decimal, eval_number, eval_f64 and eval_i64)
10. Avg (avg(...X)) (only in eval_decimal, eval_number, eval_f64 and eval_i64)
11. Median (median(...X), med(...X)) (only in eval_decimal, eval_number, eval_f64 and eval_i64)
12. Truncate (trunc(x), truncate(x)) (only in eval_f64, eval_number and eval_decimal)
13. Floor (floor(x)) (only in eval_f64, eval_number and eval_decimal)
14. Ceil (ceil(x)) (only in eval_f64, eval_number and eval_decimal)
15. Round (round(x)) (only in eval_f64, eval_number and eval_decimal)
16. Lambert W (lambert_w(x), w(x)) (only in eval_f64, eval_number and eval_decimal)
17. Iterated Logarithm (ilog(x, b)) (only in eval_f64, eval_number and eval_decimal)
18. Sin (sin(θ)) (only in eval_complex, eval_number and eval_f64)
19. Asin (asin(x)) (only in eval_complex, eval_number and eval_f64)
20. cos (cos(θ)) (only in eval_complex, eval_number and eval_f64)
21. Acos (acos(x)) (only in eval_complex, eval_number and eval_f64)
22. Tan (tan(θ)) (only in eval_complex, eval_number and eval_f64)
23. Atan (atan(x)) (only in eval_complex, eval_number and eval_f64)
24. Sinh (sinh(θ)) (only in eval_complex, eval_number and eval_f64)
25. Asinh (asinh(x), arsinh(x)) (only in eval_complex, eval_number and eval_f64)
26. Cosh (cosh(θ)) (only in eval_complex, eval_number and eval_f64)
27. Acosh (acosh(x), arcosh(x)) (only in eval_complex, eval_number and eval_f64)
28. Tanh (tanh(θ)) (only in eval_complex, eval_number and eval_f64)
29. Atanh (atanh(x), artanh(x)) (only in eval_complex, eval_number and eval_f64)
30. Atan 2 (atan2(y, x)) (only in eval_f64 and eval_number)
31. GCD (gcd(...X)) (only in eval_i64)
32. LCM (lcm(...X)) (only in eval_i64)

Placeholder Getter

The @ symbol is used here as a placeholder for the value you want to put into the eval_XXXXX. In the case you're writting a calculator, it might be useful to use your previous answer for example.