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//! Deserialization utilities. use super::Expr; use serde::de; use serde::de::Error; use serde::Deserialize; /// Deserialize into [`Expr`](../struct.Expr.html) and then evaluate using `Expr::eval`. /// /// # Example /// /// ```rust /// #[macro_use] /// extern crate serde_derive; /// extern crate toml; /// extern crate meval; /// use meval::{Expr, Context}; /// /// #[derive(Deserialize)] /// struct Foo { /// #[serde(deserialize_with = "meval::de::as_f64")] /// x: f64, /// } /// /// fn main() { /// let foo: Foo = toml::from_str(r#" x = "cos(1.)" "#).unwrap(); /// assert_eq!(foo.x, 1f64.cos()); /// /// let foo: Result<Foo, _> = toml::from_str(r#" x = "cos(x)" "#); /// assert!(foo.is_err()); /// } /// ``` /// /// See [crate root](../index.html#deserialization) for another example. pub fn as_f64<'de, D: de::Deserializer<'de>>(deserializer: D) -> Result<f64, D::Error> { Expr::deserialize(deserializer)? .eval() .map_err(D::Error::custom) }