cgp-macro-lib 0.7.0

Context-generic programming core component macros implemented as a library.
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
140
141
142
143
144
145
146
147

use alloc::boxed::Box;
use alloc::vec;
use alloc::vec::Vec;

use proc_macro2::TokenStream;
use quote::{ToTokens, quote};
use syn::punctuated::Punctuated;
use syn::token::Comma;
use syn::{ImplItem, ImplItemType, ItemImpl, Path, Type, parse2};

use crate::delegate_components::define_struct;
use crate::delegate_components::merge_generics::merge_generics;
use crate::parse::{DelegateEntry, DelegateKey, DelegateMode, DelegateValue, ImplGenerics};

pub fn impl_delegate_components<T>(
    target_type: &Type,
    target_generics: &ImplGenerics,
    delegate_entries: &Punctuated<DelegateEntry<T>, Comma>,
) -> syn::Result<TokenStream>
where
    T: ToTokens,
{
    let mut out = TokenStream::new();

    for entry in delegate_entries.iter() {
        let source = &entry.value;
        for component in entry.keys.iter() {
            let impls = impl_delegate_component(
                target_type,
                target_generics,
                component,
                source,
                &entry.mode,
            )?;

            out.extend(impls);
        }

        if let DelegateValue::New(value) = source {
            let struct_ident = &value.struct_ident;

            let item_struct = define_struct(struct_ident, &value.struct_generics)?;

            let (impl_generics, type_generics, _) = value.struct_generics.split_for_impl();

            let target_type: Type = parse2(quote! { #struct_ident #type_generics })?;

            let impl_generics = parse2(quote! { #impl_generics })?;

            let inner_impls =
                impl_delegate_components(&target_type, &impl_generics, &value.entries)?;

            out.extend(item_struct.to_token_stream());
            out.extend(inner_impls);
        }
    }

    Ok(out)
}

pub fn impl_delegate_component<T>(
    target_type: &Type,
    target_generics: &ImplGenerics,
    component: &DelegateKey<T>,
    value: &DelegateValue,
    mode: &DelegateMode,
) -> syn::Result<TokenStream>
where
    T: ToTokens,
{
    let component_type = &component.ty;

    let delegate_target_type = match mode {
        DelegateMode::Provider(_) => value.as_type(),
        DelegateMode::Direct(_) => {
            let value_type = value.as_type();
            parse2(quote! {
                < #value_type as DelegateComponent< #component_type > >::Delegate
            })?
        }
    };

    let delegate_trait_path: Path = parse2(quote!(DelegateComponent < #component_type >))?;

    let delegate_type: ImplItemType = parse2(quote!(type Delegate = #delegate_target_type;))?;

    let mut delegate_generics =
        merge_generics(&target_generics.generics, &component.generics.generics);

    if mode.is_direct() {
        let value_type = value.as_type();
        let where_clause = delegate_generics.make_where_clause();

        where_clause.predicates.push(parse2(
            quote!( #value_type : DelegateComponent< #component_type > ),
        )?);
    }

    let is_provider_generics = {
        let mut generics = delegate_generics.clone();

        generics.params.push(parse2(quote!(__Context__))?);
        generics.params.push(parse2(quote!(__Params__))?);

        let where_clause = generics.make_where_clause();

        where_clause.predicates.push(parse2(
            quote!( #delegate_target_type : IsProviderFor< #component_type, __Context__, __Params__ > ),
        )?);

        generics
    };

    let delegate_impl = ItemImpl {
        attrs: Vec::new(),
        defaultness: None,
        unsafety: None,
        impl_token: Default::default(),
        generics: delegate_generics,
        trait_: Some((None, delegate_trait_path, Default::default())),
        self_ty: Box::new(target_type.clone()),
        brace_token: Default::default(),
        items: vec![ImplItem::Type(delegate_type)],
    };

    let is_provider_trait_path: Path =
        parse2(quote!( IsProviderFor< #component_type, __Context__, __Params__ > ))?;

    let is_provider_impl = ItemImpl {
        attrs: Vec::new(),
        defaultness: None,
        unsafety: None,
        impl_token: Default::default(),
        generics: is_provider_generics,
        trait_: Some((None, is_provider_trait_path, Default::default())),
        self_ty: Box::new(target_type.clone()),
        brace_token: Default::default(),
        items: Default::default(),
    };

    let out = quote! {
        #delegate_impl
        #is_provider_impl
    };

    Ok(out)
}