num_parser allows you to easily parse strings into math expressions and evaluate them.
- Binary and unary operators
- Supports multiple value types:
- Bool,
- Int,
- Float,
- Complex,
- Vector
- Built-in functions
- Built-in constants
- User-defined functions:
f(x,y) = xsin(y)+ysin(x) - User-defined var:
a = pi/2orb = a+2 - Define you own functions with macros.
- Understands ambiguous syntax, like:
g(x) = pisinx - Recursion:
f(x) = branch(x<=2, 1, f(x-1)+f(x-2)) - Serde support
- No panicking
Much more will be implemented in future releases!
Evaluating simple static expressions:
use num_parser::*; assert_eq!(eval("2+2").unwrap(), Value::from(4)); assert_eq!(eval("sin(pi)").unwrap(), Value::from(0)); assert_eq!(eval("re(10+3i)").unwrap(), Value::from(10));
Using contexts:
use num_parser::*; let mut context = Context::default(); // Declaring a function let res = eval_with_mutable_context( "f(x) = branch(x<=2, 1, f(x-1) + f(x-2))", &mut context ).unwrap(); // Result is None assert_eq!(res, None); // Calling the function. We could just use eval_with_static_context at this point let res = eval_with_mutable_context("f(10)", &mut context).unwrap(); assert_eq!(res, Some(Value::from(55)));
Values are contained inside the Value enum, which provides useful functions to access the contained data:
use num_parser::Value; let value = Value::Float(1.0); assert_eq!(value.as_bool().unwrap(), true); assert_eq!(value.as_int().unwrap(), 1); assert_eq!(value.as_float().unwrap(), 1.0); assert_eq!(value.as_complex().unwrap(), num::complex::Complex::new(1.0, 0.0)); assert_eq!(value.as_vector(), vec![Value::Float(1.0)]); // Assign type implicitly: let implicit = Value::from(1.0); assert_eq!(value, implicit);
Note that, even thought the initial value was a float, it has been cast into ints and bools. This was possible since the value had no decimal part and it was a one. If these conditions were not met, the cast would have failed.
Binary operators:
| Operator | Description | Precedence |
|---|---|---|
| ^ | Exponentiation | 90 |
| / | Division | 70 |
| * | Multiplication | 70 |
| % | Modulo | 70 |
| + | Sum | 60 |
| - | Subtraction | 60 |
| < | Less than | 50 |
| > | Greater than | 50 |
| <= | Less or equal to | 50 |
| >= | Greater or equal to | 50 |
| == | Equal to | 40 |
| != | Not equal to | 40 |
| && | Logical AND | 30 |
| || | Logical OR | 20 |
| , | Aggregation. Creates vectors | 10 |
| = | Assignment. Used for functions and vars declarations | 0 |
Unary operators:
| Operator | Description | Precedence |
|---|---|---|
| ! | Logical NOT | 80 |
| - | Negation | 60 |
| Function | Parameters Amount | Description |
|---|---|---|
min |
>=1 | Returns the minimum value. |
max |
>=1 | Returns the maximum value. |
floor |
1 | Returns the greatest lower integer. |
ceil |
1 | Returns the lowest greater integer. |
round |
1 | Returns the rounded integer. |
ln |
1 | Returns the natural log of the number. |
log |
2 (base, arg) | Returns the logarithm of the number with the specified base. |
exp |
1 | Returns e^(arg). |
rand |
2 (min, max) | Returns a random float between the two number specified. |
abs |
1 | Returns the absolute value of a number. |
sqrt |
1 | Returns the square root of a number. |
branch |
3 (condition, true, false) | Returns the second argument if the condition is true, the third if it is false. |
sin |
1 | Returns the sine of the angle. |
cos |
1 | Returns the cosine of the angle. |
tan |
1 | Returns the tangent of the angle. |
asin |
1 | Returns the arcsine of the angle. |
acos |
1 | Returns the arccosine of the angle. |
atan |
1 | Returns the arctangent of the angle. |
sinh |
1 | Returns the hyperbolic sine of the angle. |
cosh |
1 | Returns the hyperbolic cosine of the angle. |
tanh |
1 | Returns the hyperbolic tangent of the angle. |
asinh |
1 | Returns the hyperbolic arcsine of the angle. |
acosh |
1 | Returns the hyperbolic arccosine of the angle. |
atanh |
1 | Returns the hyperbolic arctangent of the angle. |
re |
1 | Returns the natural part of the number. |
im |
1 | Returns the imaginary part of the number. |
polar |
1 | Returns the polar form (r, theta) of the complex number. |
arg |
1 | Returns the principal arg of the number. |
norm |
1 | Returns the length of the vector (re, im). |
Contexts allows you keep track of user-defined functions and variables, as well as settings. They can be created as follows:
use num_parser::*; // Generate the default context let mut default = Context::default(); // Generate a custom context let mut custom = Context::new( settings::Rounding::NoRounding, settings::AngleUnit::Degree, settings::DepthLimit::NoLimit );
You can use the optional feature serde_support to let all the public structs
derive Serialize and
Deserialize.
[dependencies] num = { version = "<version>", features = [ "serde_support" ] }
num_parser is licensed under a MIT License.
Feel free to open issues and pull requests for any problems or ideas you come up with.