257 lines
9.6 KiB
Rust
257 lines
9.6 KiB
Rust
//! Module which defines the function registration mechanism.
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#![allow(non_snake_case)]
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use crate::any::{Any, Dynamic};
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use crate::engine::{Engine, FnCallArgs};
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use crate::parser::Position;
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use crate::result::EvalAltResult;
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use crate::stdlib::{any::TypeId, boxed::Box, string::ToString, vec};
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/// A trait to register custom functions with the `Engine`.
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pub trait RegisterFn<FN, ARGS, RET> {
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/// Register a custom function with the `Engine`.
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///
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/// # Example
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///
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/// ```
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/// # fn main() -> Result<(), rhai::EvalAltResult> {
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/// use rhai::{Engine, RegisterFn};
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///
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/// // Normal function
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/// fn add(x: i64, y: i64) -> i64 {
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/// x + y
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/// }
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///
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/// let mut engine = Engine::new();
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///
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/// // You must use the trait rhai::RegisterFn to get this method.
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/// engine.register_fn("add", add);
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///
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/// assert_eq!(engine.eval::<i64>("add(40, 2)")?, 42);
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///
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/// // You can also register a closure.
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/// engine.register_fn("sub", |x: i64, y: i64| x - y );
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///
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/// assert_eq!(engine.eval::<i64>("sub(44, 2)")?, 42);
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/// # Ok(())
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/// # }
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/// ```
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fn register_fn(&mut self, name: &str, f: FN);
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}
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/// A trait to register custom functions that return `Dynamic` values with the `Engine`.
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pub trait RegisterDynamicFn<FN, ARGS> {
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/// Register a custom function returning `Dynamic` values with the `Engine`.
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///
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/// # Example
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///
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/// ```
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/// # fn main() -> Result<(), rhai::EvalAltResult> {
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/// use rhai::{Engine, Dynamic, RegisterDynamicFn};
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///
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/// // Function that returns a Dynamic value
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/// fn return_the_same_as_dynamic(x: i64) -> Dynamic {
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/// Box::new(x)
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/// }
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///
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/// let mut engine = Engine::new();
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///
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/// // You must use the trait rhai::RegisterDynamicFn to get this method.
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/// engine.register_dynamic_fn("get_any_number", return_the_same_as_dynamic);
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///
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/// assert_eq!(engine.eval::<i64>("get_any_number(42)")?, 42);
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/// # Ok(())
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/// # }
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/// ```
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fn register_dynamic_fn(&mut self, name: &str, f: FN);
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}
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/// A trait to register fallible custom functions returning Result<_, EvalAltResult> with the `Engine`.
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pub trait RegisterResultFn<FN, ARGS, RET> {
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/// Register a custom fallible function with the `Engine`.
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///
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/// # Example
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///
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/// ```
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/// use rhai::{Engine, RegisterResultFn, EvalAltResult};
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///
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/// // Normal function
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/// fn div(x: i64, y: i64) -> Result<i64, EvalAltResult> {
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/// if y == 0 {
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/// // '.into()' automatically converts to 'EvalAltResult::ErrorRuntime'
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/// Err("division by zero!".into())
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/// } else {
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/// Ok(x / y)
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/// }
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/// }
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///
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/// let mut engine = Engine::new();
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///
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/// // You must use the trait rhai::RegisterResultFn to get this method.
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/// engine.register_result_fn("div", div);
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///
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/// engine.eval::<i64>("div(42, 0)")
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/// .expect_err("expecting division by zero error!");
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/// ```
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fn register_result_fn(&mut self, name: &str, f: FN);
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}
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// These types are used to build a unique _marker_ tuple type for each combination
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// of function parameter types in order to make each trait implementation unique.
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// That is because stable Rust currently does not allow distinguishing implementations
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// based purely on parameter types of traits (Fn, FnOnce and FnMut).
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//
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// For example:
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//
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// `RegisterFn<FN, (Mut<A>, B, Ref<C>), R>`
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//
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// will have the function prototype constraint to:
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//
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// `FN: (&mut A, B, &C) -> R`
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//
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// These types are not actually used anywhere.
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pub struct Mut<T>(T);
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//pub struct Ref<T>(T);
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/// Identity dereferencing function.
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#[inline]
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fn identity<T>(data: T) -> T {
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data
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}
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/// This macro counts the number of arguments via recursion.
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macro_rules! count_args {
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() => { 0_usize };
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( $head:ident $($tail:ident)* ) => { 1_usize + count_args!($($tail)*) };
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}
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macro_rules! def_register {
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() => {
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def_register!(imp);
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};
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(imp $($par:ident => $mark:ty => $param:ty => $clone:expr),*) => {
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// ^ function parameter generic type name
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// ^ function parameter marker type (T, Ref<T> or Mut<T>)
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// ^ function parameter actual type
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// ^ dereferencing function
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impl<
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$($par: Any + Clone,)*
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FN: Fn($($param),*) -> RET + 'static,
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RET: Any
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> RegisterFn<FN, ($($mark,)*), RET> for Engine<'_>
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{
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fn register_fn(&mut self, name: &str, f: FN) {
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let fn_name = name.to_string();
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let fun = move |args: &mut FnCallArgs, pos: Position| {
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// Check for length at the beginning to avoid per-element bound checks.
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const NUM_ARGS: usize = count_args!($($par)*);
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if args.len() != NUM_ARGS {
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return Err(EvalAltResult::ErrorFunctionArgsMismatch(fn_name.clone(), NUM_ARGS, args.len(), pos));
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}
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#[allow(unused_variables, unused_mut)]
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let mut drain = args.iter_mut();
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$(
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// Downcast every element, return in case of a type mismatch
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let $par = drain.next().unwrap().downcast_mut::<$par>().unwrap();
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)*
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// Call the user-supplied function using ($clone) to
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// potentially clone the value, otherwise pass the reference.
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let r = f($(($clone)($par)),*);
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Ok(Box::new(r) as Dynamic)
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};
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self.register_fn_raw(name, vec![$(TypeId::of::<$par>()),*], Box::new(fun));
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}
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}
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impl<
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$($par: Any + Clone,)*
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FN: Fn($($param),*) -> Dynamic + 'static,
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> RegisterDynamicFn<FN, ($($mark,)*)> for Engine<'_>
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{
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fn register_dynamic_fn(&mut self, name: &str, f: FN) {
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let fn_name = name.to_string();
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let fun = move |args: &mut FnCallArgs, pos: Position| {
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// Check for length at the beginning to avoid per-element bound checks.
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const NUM_ARGS: usize = count_args!($($par)*);
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if args.len() != NUM_ARGS {
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return Err(EvalAltResult::ErrorFunctionArgsMismatch(fn_name.clone(), NUM_ARGS, args.len(), pos));
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}
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#[allow(unused_variables, unused_mut)]
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let mut drain = args.iter_mut();
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$(
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// Downcast every element, return in case of a type mismatch
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let $par = drain.next().unwrap().downcast_mut::<$par>().unwrap();
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)*
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// Call the user-supplied function using ($clone) to
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// potentially clone the value, otherwise pass the reference.
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Ok(f($(($clone)($par)),*))
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};
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self.register_fn_raw(name, vec![$(TypeId::of::<$par>()),*], Box::new(fun));
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}
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}
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impl<
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$($par: Any + Clone,)*
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FN: Fn($($param),*) -> Result<RET, EvalAltResult> + 'static,
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RET: Any
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> RegisterResultFn<FN, ($($mark,)*), RET> for Engine<'_>
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{
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fn register_result_fn(&mut self, name: &str, f: FN) {
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let fn_name = name.to_string();
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let fun = move |args: &mut FnCallArgs, pos: Position| {
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// Check for length at the beginning to avoid per-element bound checks.
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const NUM_ARGS: usize = count_args!($($par)*);
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if args.len() != NUM_ARGS {
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return Err(EvalAltResult::ErrorFunctionArgsMismatch(fn_name.clone(), NUM_ARGS, args.len(), pos));
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}
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#[allow(unused_variables, unused_mut)]
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let mut drain = args.iter_mut();
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$(
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// Downcast every element, return in case of a type mismatch
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let $par = drain.next().unwrap().downcast_mut::<$par>().unwrap();
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)*
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// Call the user-supplied function using ($clone) to
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// potentially clone the value, otherwise pass the reference.
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f($(($clone)($par)),*).map(|r| Box::new(r) as Dynamic)
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.map_err(|err| err.set_position(pos))
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};
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self.register_fn_raw(name, vec![$(TypeId::of::<$par>()),*], Box::new(fun));
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}
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}
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//def_register!(imp_pop $($par => $mark => $param),*);
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};
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($p0:ident $(, $p:ident)*) => {
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def_register!(imp $p0 => $p0 => $p0 => Clone::clone $(, $p => $p => $p => Clone::clone)*);
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def_register!(imp $p0 => Mut<$p0> => &mut $p0 => identity $(, $p => $p => $p => Clone::clone)*);
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// handle the first parameter ^ first parameter passed through
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// others passed by value (cloned) ^
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// No support for functions where the first argument is a reference
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//def_register!(imp $p0 => Ref<$p0> => &$p0 => identity $(, $p => $p => $p => Clone::clone)*);
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def_register!($($p),*);
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};
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// (imp_pop) => {};
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// (imp_pop $head:ident => $head_mark:ty => $head_param:ty $(,$tail:ident => $tail_mark:ty => $tp:ty)*) => {
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// def_register!(imp $($tail => $tail_mark => $tp),*);
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// };
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}
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#[rustfmt::skip]
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def_register!(A, B, C, D, E, F, G, H, J, K, L, M, N, P, Q, R, S, T, U, V);
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