93 lines
2.7 KiB
Rust
93 lines
2.7 KiB
Rust
//! Helper module which defines [`FuncArgs`] to make function calling easier.
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#![cfg(not(feature = "no_function"))]
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#![allow(non_snake_case)]
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use crate::dynamic::Variant;
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use crate::Dynamic;
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#[cfg(feature = "no_std")]
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use std::prelude::v1::*;
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/// Trait that parses arguments to a function call.
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///
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/// Any data type can implement this trait in order to pass arguments to a function call.
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pub trait FuncArgs {
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/// Parse function call arguments into a container.
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///
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/// # Example
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///
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/// ```
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/// use rhai::{Engine, Dynamic, FuncArgs, Scope};
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///
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/// // A struct containing function arguments
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/// struct Options {
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/// pub foo: bool,
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/// pub bar: String,
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/// pub baz: i64,
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/// }
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///
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/// impl FuncArgs for Options {
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/// fn parse<CONTAINER: Extend<Dynamic>>(self, container: &mut CONTAINER) {
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/// container.extend(std::iter::once(self.foo.into()));
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/// container.extend(std::iter::once(self.bar.into()));
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/// container.extend(std::iter::once(self.baz.into()));
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/// }
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/// }
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///
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/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
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/// let options = Options { foo: false, bar: "world".to_string(), baz: 42 };
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///
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/// let engine = Engine::new();
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/// let mut scope = Scope::new();
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///
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/// let ast = engine.compile(
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/// "
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/// fn hello(x, y, z) {
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/// if x { `hello ${y}` } else { y + z }
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/// }
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/// ")?;
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///
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/// let result: String = engine.call_fn(&mut scope, &ast, "hello", options)?;
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///
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/// assert_eq!(result, "world42");
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/// # Ok(())
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/// # }
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/// ```
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fn parse<CONTAINER: Extend<Dynamic>>(self, container: &mut CONTAINER);
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}
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impl<T: Variant + Clone> FuncArgs for Vec<T> {
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#[inline]
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fn parse<CONTAINER: Extend<Dynamic>>(self, container: &mut CONTAINER) {
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container.extend(self.into_iter().map(Variant::into_dynamic));
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}
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}
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/// Macro to implement [`FuncArgs`] for tuples of standard types (each can be
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/// converted into a [`Dynamic`]).
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macro_rules! impl_args {
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($($p:ident),*) => {
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impl<$($p: Variant + Clone),*> FuncArgs for ($($p,)*)
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{
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#[inline]
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#[allow(unused_variables)]
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fn parse<CONTAINER: Extend<Dynamic>>(self, container: &mut CONTAINER) {
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let ($($p,)*) = self;
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$(container.extend(Some($p.into_dynamic()));)*
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}
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}
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impl_args!(@pop $($p),*);
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};
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(@pop) => {
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};
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(@pop $head:ident) => {
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impl_args!();
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};
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(@pop $head:ident $(, $tail:ident)+) => {
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impl_args!($($tail),*);
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};
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}
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impl_args!(A, B, C, D, E, F, G, H, J, K, L, M, N, P, Q, R, S, T, U, V);
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