130 lines
2.6 KiB
Rust
130 lines
2.6 KiB
Rust
fn simple() -> i32 {
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let y = 10;
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let f = |x| x + y;
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f(2)
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}
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fn crazy_closure() -> (i32, i32, i32) {
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fn inner<T: Copy>(t: T) -> (i32, T, T) {
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struct NonCopy;
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let x = NonCopy;
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let a = 2;
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let b = 40;
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let f = move |y, z, asdf| {
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drop(x);
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(a + b + y + z, asdf, t)
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};
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f(a, b, t)
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}
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inner(10)
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}
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fn closure_arg_adjustment_problem() -> i64 {
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fn once<F: FnOnce(i64)>(f: F) {
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f(2);
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}
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let mut y = 1;
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{
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let f = |x| y += x;
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once(f);
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}
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y
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}
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fn fn_once_closure_with_multiple_args() -> i64 {
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fn once<F: FnOnce(i64, i64) -> i64>(f: F) -> i64 {
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f(2, 3)
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}
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let y = 1;
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{
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let f = |x, z| x + y + z;
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once(f)
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}
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}
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fn boxed_fn_once(f: Box<dyn FnOnce() -> i32>) -> i32 {
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f()
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}
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fn box_dyn() {
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let x: Box<dyn Fn(i32) -> i32> = Box::new(|x| x * 2);
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assert_eq!(x(21), 42);
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let mut i = 5;
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{
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let mut x: Box<dyn FnMut()> = Box::new(|| i *= 2);
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x();
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x();
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}
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assert_eq!(i, 20);
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}
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fn fn_item_as_closure_trait_object() {
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fn foo() {}
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let f: &dyn Fn() = &foo;
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f();
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}
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fn fn_item_with_args_as_closure_trait_object() {
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fn foo(i: i32) {
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assert_eq!(i, 42);
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}
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let f: &dyn Fn(i32) = &foo;
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f(42);
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}
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fn fn_item_with_multiple_args_as_closure_trait_object() {
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fn foo(i: i32, j: i32) {
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assert_eq!(i, 42);
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assert_eq!(j, 55);
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}
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fn bar(i: i32, j: i32, k: f32) {
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assert_eq!(i, 42);
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assert_eq!(j, 55);
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assert_eq!(k, 3.14159)
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}
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let f: &dyn Fn(i32, i32) = &foo;
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f(42, 55);
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let f: &dyn Fn(i32, i32, f32) = &bar;
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f(42, 55, 3.14159);
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}
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fn fn_ptr_as_closure_trait_object() {
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fn foo() {}
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fn bar(u: u32) {
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assert_eq!(u, 42);
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}
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fn baa(u: u32, f: f32) {
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assert_eq!(u, 42);
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assert_eq!(f, 3.141);
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}
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let f: &dyn Fn() = &(foo as fn());
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f();
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let f: &dyn Fn(u32) = &(bar as fn(u32));
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f(42);
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let f: &dyn Fn(u32, f32) = &(baa as fn(u32, f32));
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f(42, 3.141);
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}
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fn main() {
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assert_eq!(simple(), 12);
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assert_eq!(crazy_closure(), (84, 10, 10));
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assert_eq!(closure_arg_adjustment_problem(), 3);
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assert_eq!(fn_once_closure_with_multiple_args(), 6);
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assert_eq!(
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boxed_fn_once(Box::new({
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let x = 13;
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move || x
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})),
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13,
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);
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box_dyn();
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fn_item_as_closure_trait_object();
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fn_item_with_args_as_closure_trait_object();
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fn_item_with_multiple_args_as_closure_trait_object();
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fn_ptr_as_closure_trait_object();
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}
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