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Extract function registration into a macro to prepare for future packages support.

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This commit is contained in:
Stephen Chung 2020-04-19 22:58:44 +08:00
parent 9015499722
commit 642533aef6
1 changed files with 57 additions and 63 deletions
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120
src/fn_register.rs
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@ -127,6 +127,60 @@ macro_rules! count_args {
( $head:ident $($tail:ident)* ) => { 1_usize + count_args!($($tail)*) };
}
/// This macro creates a closure wrapping a registered function.
macro_rules! make_func {
($fn_name:ident : $fn:ident : $map:expr ; $($par:ident => $clone:expr),*) => {
// ^ function name
// ^ function pointer
// ^ result mapping function
// ^ function parameter generic type name (A, B, C etc.)
// ^ dereferencing function
move |args: &mut FnCallArgs, pos: Position| {
// Check for length at the beginning to avoid per-element bound checks.
const NUM_ARGS: usize = count_args!($($par)*);
if args.len() != NUM_ARGS {
return Err(Box::new(EvalAltResult::ErrorFunctionArgsMismatch($fn_name.clone(), NUM_ARGS, args.len(), pos)));
}
#[allow(unused_variables, unused_mut)]
let mut drain = args.iter_mut();
$(
// Downcast every element, return in case of a type mismatch
let $par: &mut $par = drain.next().unwrap().downcast_mut().unwrap();
)*
// Call the user-supplied function using ($clone) to
// potentially clone the value, otherwise pass the reference.
let r = $fn($(($clone)($par)),*);
$map(r, pos)
};
};
}
/// To Dynamic mapping function.
#[inline]
fn map_dynamic<T: Variant + Clone>(data: T, _pos: Position) -> Result<Dynamic, Box<EvalAltResult>> {
Ok(data.into_dynamic())
}
/// To Dynamic mapping function.
#[inline]
fn map_identity(data: Dynamic, _pos: Position) -> Result<Dynamic, Box<EvalAltResult>> {
Ok(data)
}
/// To Result<Dynamic, EvalAltResult> mapping function.
#[inline]
fn map_result<T: Variant + Clone>(
data: Result<T, EvalAltResult>,
pos: Position,
) -> Result<Dynamic, Box<EvalAltResult>> {
data.map(|v| v.into_dynamic())
.map_err(|err| Box::new(err.set_position(pos)))
}
macro_rules! def_register {
() => {
def_register!(imp);
@ -150,28 +204,7 @@ macro_rules! def_register {
{
fn register_fn(&mut self, name: &str, f: FN) {
let fn_name = name.to_string();
let func = move |args: &mut FnCallArgs, pos: Position| {
// Check for length at the beginning to avoid per-element bound checks.
const NUM_ARGS: usize = count_args!($($par)*);
if args.len() != NUM_ARGS {
return Err(Box::new(EvalAltResult::ErrorFunctionArgsMismatch(fn_name.clone(), NUM_ARGS, args.len(), pos)));
}
#[allow(unused_variables, unused_mut)]
let mut drain = args.iter_mut();
$(
// Downcast every element, return in case of a type mismatch
let $par: &mut $par = drain.next().unwrap().downcast_mut().unwrap();
)*
// Call the user-supplied function using ($clone) to
// potentially clone the value, otherwise pass the reference.
let r = f($(($clone)($par)),*);
Ok(r.into_dynamic())
};
let func = make_func!(fn_name : f : map_dynamic ; $($par => $clone),*);
self.register_fn_raw(name, vec![$(TypeId::of::<$par>()),*], Box::new(func));
}
}
@ -188,26 +221,7 @@ macro_rules! def_register {
{
fn register_dynamic_fn(&mut self, name: &str, f: FN) {
let fn_name = name.to_string();
let func = move |args: &mut FnCallArgs, pos: Position| {
// Check for length at the beginning to avoid per-element bound checks.
const NUM_ARGS: usize = count_args!($($par)*);
if args.len() != NUM_ARGS {
return Err(Box::new(EvalAltResult::ErrorFunctionArgsMismatch(fn_name.clone(), NUM_ARGS, args.len(), pos)));
}
#[allow(unused_variables, unused_mut)]
let mut drain = args.iter_mut();
$(
// Downcast every element, return in case of a type mismatch
let $par: &mut $par = drain.next().unwrap().downcast_mut().unwrap();
)*
// Call the user-supplied function using ($clone) to
// potentially clone the value, otherwise pass the reference.
Ok(f($(($clone)($par)),*))
};
let func = make_func!(fn_name : f : map_identity ; $($par => $clone),*);
self.register_fn_raw(name, vec![$(TypeId::of::<$par>()),*], Box::new(func));
}
}
@ -225,27 +239,7 @@ macro_rules! def_register {
{
fn register_result_fn(&mut self, name: &str, f: FN) {
let fn_name = name.to_string();
let func = move |args: &mut FnCallArgs, pos: Position| {
// Check for length at the beginning to avoid per-element bound checks.
const NUM_ARGS: usize = count_args!($($par)*);
if args.len() != NUM_ARGS {
return Err(Box::new(EvalAltResult::ErrorFunctionArgsMismatch(fn_name.clone(), NUM_ARGS, args.len(), pos)));
}
#[allow(unused_variables, unused_mut)]
let mut drain = args.iter_mut();
$(
// Downcast every element, return in case of a type mismatch
let $par: &mut $par = drain.next().unwrap().downcast_mut().unwrap();
)*
// Call the user-supplied function using ($clone) to
// potentially clone the value, otherwise pass the reference.
f($(($clone)($par)),*).map(|r| r.into_dynamic())
.map_err(|err| Box::new(err.set_position(pos)))
};
let func = make_func!(fn_name : f : map_result ; $($par => $clone),*);
self.register_fn_raw(name, vec![$(TypeId::of::<$par>()),*], Box::new(func));
}
}