2019-03-28 14:39:50 +00:00
|
|
|
use std::fmt;
|
|
|
|
|
2019-06-06 17:53:30 +00:00
|
|
|
use crate::error::EvalexprResult;
|
|
|
|
use crate::value::Value;
|
2019-03-15 18:26:25 +00:00
|
|
|
|
2019-03-20 09:32:49 +00:00
|
|
|
pub(crate) mod builtin;
|
2019-03-19 18:08:23 +00:00
|
|
|
|
2019-03-20 09:32:49 +00:00
|
|
|
/// A user-defined function.
|
2019-03-27 17:09:20 +00:00
|
|
|
/// Functions can be used in expressions by storing them in a `Context`.
|
2019-03-20 09:32:49 +00:00
|
|
|
///
|
|
|
|
/// # Examples
|
|
|
|
///
|
|
|
|
/// ```rust
|
|
|
|
/// use evalexpr::*;
|
|
|
|
///
|
2019-03-27 17:09:20 +00:00
|
|
|
/// let mut context = HashMapContext::new();
|
2019-05-04 11:43:29 +00:00
|
|
|
/// context.set_function("id".into(), Function::new(Box::new(|argument| {
|
|
|
|
/// Ok(argument.clone())
|
2019-03-27 17:09:20 +00:00
|
|
|
/// }))).unwrap(); // Do proper error handling here
|
|
|
|
/// assert_eq!(eval_with_context("id(4)", &context), Ok(Value::from(4)));
|
2019-03-20 09:32:49 +00:00
|
|
|
/// ```
|
2019-03-15 18:26:25 +00:00
|
|
|
pub struct Function {
|
2019-06-06 17:53:30 +00:00
|
|
|
function: Box<dyn Fn(&Value) -> EvalexprResult<Value>>,
|
2019-03-18 17:21:07 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
impl Function {
|
2019-03-20 09:32:49 +00:00
|
|
|
/// Creates a user-defined function.
|
|
|
|
///
|
2019-05-04 11:43:29 +00:00
|
|
|
/// The `function` is a boxed function that takes a `Value` and returns a `EvalexprResult<Value, Error>`.
|
2019-06-06 17:53:30 +00:00
|
|
|
pub fn new(function: Box<dyn Fn(&Value) -> EvalexprResult<Value>>) -> Self {
|
2019-05-04 11:54:19 +00:00
|
|
|
Self { function }
|
2019-03-18 17:21:07 +00:00
|
|
|
}
|
|
|
|
|
2019-05-04 11:43:29 +00:00
|
|
|
pub(crate) fn call(&self, argument: &Value) -> EvalexprResult<Value> {
|
|
|
|
(self.function)(argument)
|
2019-03-18 17:21:07 +00:00
|
|
|
}
|
2019-03-18 16:02:45 +00:00
|
|
|
}
|
2019-03-28 14:39:50 +00:00
|
|
|
|
|
|
|
impl fmt::Debug for Function {
|
|
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
|
2019-05-04 11:54:19 +00:00
|
|
|
write!(f, "Function {{ [...] }}")
|
2019-03-28 14:39:50 +00:00
|
|
|
}
|
|
|
|
}
|