wasm_extra_macros 0.1.1

Macros for `wasm_extra` crate.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139

use proc_macro2::{Ident, TokenStream};
use syn::{parse::{Parse, ParseStream, ParseBuffer}, token::{Comma, And}, LitStr, braced, ExprClosure};
use quote::{quote, ToTokens};

pub(crate) enum EventTarget {
    SinglyReferred(Ident),
    DoublyReferred(Ident),
}

impl EventTarget {
    pub(crate) fn target_obj_ident(&self) -> EventTargetObjIdent {
        match self {
            Self::SinglyReferred(ident) => EventTargetObjIdent::SinglyReferred(ident),
            Self::DoublyReferred(_) => EventTargetObjIdent::DoublyReferred,
        }
    }
    pub(crate) fn preprologue(&self) -> Option<ClosurePreprologue> {
        match self {
            Self::SinglyReferred(_) => None,
            Self::DoublyReferred(ident) => Some(ClosurePreprologue { doubly_referred_target: ident }),
        }
    }
}

pub(crate) struct ClosurePreprologue<'a> {
    pub(crate) doubly_referred_target: &'a Ident,
}


impl<'a> ToTokens for ClosurePreprologue<'a> {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        let Self { doubly_referred_target } = self;
        tokens.extend(quote! {
            let __event_target_alias = #doubly_referred_target.as_ref();
        });
    }
}

pub(crate) enum EventTargetObjIdent<'a> {
    SinglyReferred(&'a Ident),
    DoublyReferred,
}

impl<'a> ToTokens for EventTargetObjIdent<'a> {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        match self {
            Self::SinglyReferred(ident) => tokens.extend(quote! { #ident }),
            Self::DoublyReferred => tokens.extend(quote! { __event_target_alias }),
        }
    }
}

pub(crate) struct Args {
    pub(crate) target: EventTarget,
    pub(crate) event: LitStr,
    pub(crate) closure_prologue: TokenStream,
    pub(crate) closure: ExprClosure,
}

#[derive(derive_syn_parse::Parse)]
pub(crate) struct FnMutArgs(pub(crate) Args);

#[derive(derive_syn_parse::Parse)]
pub(crate) struct FnOnceArgs(pub(crate) Args);

impl Parse for EventTarget {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        if input.peek(And) {
            input.parse::<And>()?;
            let ident = input.parse::<Ident>()?;
            Ok(Self::DoublyReferred(ident))
        } else {
            let ident = input.parse::<Ident>()?;
            Ok(Self::SinglyReferred(ident))
        }
    }
}

impl Parse for Args {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let target = input.parse::<EventTarget>()?;
        input.parse::<Comma>()?;
        let event = input.parse::<LitStr>()?;
        input.parse::<Comma>()?;
        let closure_prologue = {
            let contents: ParseBuffer;
            braced!(contents in input);
            contents.parse::<TokenStream>()
        }?;
        input.parse::<Comma>()?;
        let closure = input.parse::<ExprClosure>()?;
        
        Ok(Self { target, event, closure_prologue, closure })
    }
}

impl FnMutArgs {
    pub(crate) fn handle(self) -> TokenStream {
        let Args { target, event, closure_prologue, closure } = self.0;
        let target_obj_ident = target.target_obj_ident();
        let preprologue: Option<ClosurePreprologue> = target.preprologue();
        quote! {
            {
                #preprologue
                #closure_prologue
                let __handler = ::wasm_bindgen::closure::Closure::<dyn ::core::ops::FnMut(_)>::new::<_>(
                    #closure
                );
                #target_obj_ident.add_event_listener_with_callback(
                    #event,
                    ::wasm_bindgen::JsCast::unchecked_ref(__handler.as_ref())
                ).unwrap();
                ::wasm_bindgen::closure::Closure::forget(__handler);
            }
        }
    }
}

impl FnOnceArgs {
    pub(crate) fn handle(self) -> TokenStream {
        let Args { target, event, closure_prologue, closure } = self.0;
        let target_obj_ident = target.target_obj_ident();
        let preprologue: Option<ClosurePreprologue> = target.preprologue();
        quote! {
            {
                #preprologue
                #closure_prologue
                let __handler = ::wasm_bindgen::closure::Closure::once(
                    #closure
                );
                #target_obj_ident.add_event_listener_with_callback(
                    #event,
                    ::wasm_bindgen::JsCast::unchecked_ref(__handler.as_ref())
                ).unwrap();
                ::wasm_bindgen::closure::Closure::forget(__handler);
            }
        }
    }
}