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

// Take a look at the license at the top of the repository in the LICENSE file.

pub mod interface;
pub mod subclass;

use proc_macro2::Span;

use crate::utils::{parse_optional_nested_meta_items, NestedMetaItem};

/// The parsing of `#[object_subclass]` and `#[object_interface]` is subtly different.
enum AttrKind {
    Interface,
    Subclass,
}

/// The parsed input for the object impl attributes..
///
/// This is used for both the `#[object_subclass]` and `#[object_interface]` attributes.
pub struct Input {
    attrs: Vec<syn::Attribute>,
    generics: syn::Generics,
    trait_path: syn::Path,
    self_ty: syn::Ident,
    unsafety: Option<syn::token::Unsafe>,
    items: Vec<syn::ImplItem>,
    meta_dynamic: Option<MetaDynamic>,
}

impl Input {
    /// Parse an `#[object_interface]` attribute.
    pub fn parse_interface(input: syn::parse::ParseStream) -> syn::Result<Self> {
        Self::parse(AttrKind::Interface, input)
    }

    /// Parse an `#[object_subclass]` attribute.
    pub fn parse_subclass(input: syn::parse::ParseStream) -> syn::Result<Self> {
        Self::parse(AttrKind::Subclass, input)
    }

    /// Parse an `#[object_subclass]` or `#[object_interface]` depending on the attribute kind.
    fn parse(kind: AttrKind, input: syn::parse::ParseStream) -> syn::Result<Self> {
        let wrong_place_msg = match kind {
            AttrKind::Interface => {
                "This macro should be used on `impl` block for `glib::ObjectInterface` trait"
            }
            AttrKind::Subclass => {
                "This macro should be used on `impl` block for `glib::ObjectSubclass` trait"
            }
        };

        let syn::ItemImpl {
            mut attrs,
            generics,
            trait_,
            self_ty,
            unsafety,
            items,
            ..
        } = input
            .parse()
            .map_err(|_| syn::Error::new(Span::call_site(), wrong_place_msg))?;

        // The type must be a path
        let self_ty = match *self_ty {
            syn::Type::Path(syn::TypePath { path, .. }) => path.require_ident().cloned(),
            _ => Err(syn::Error::new(
                syn::spanned::Spanned::span(&self_ty),
                "expected this path to be an identifier",
            )),
        }?;

        let meta_dynamic = MetaDynamic::parse_and_remove(kind, &mut attrs)?;

        let trait_path = trait_
            .as_ref()
            .ok_or_else(|| syn::Error::new(Span::call_site(), wrong_place_msg))?
            .1
            .clone();

        Ok(Self {
            attrs,
            generics,
            trait_path,
            self_ty,
            unsafety,
            items,
            meta_dynamic,
        })
    }
}

/// A meta attribute to indicate that the class / interface is dynamic.
///
/// Depending on the object kind this can be either
/// - `#[object_subclass_dynamic]`
/// - `#[object_interface_dynamic]`
struct MetaDynamic {
    plugin_type: Option<syn::Path>,
    lazy_registration: bool,
}

impl MetaDynamic {
    /// Parse `#[object_subclass_dynamic]` / `#[object_interface_dynamic]`
    fn parse_and_remove(
        kind: AttrKind,
        attrs: &mut Vec<syn::Attribute>,
    ) -> syn::Result<Option<Self>> {
        let attr_name = match kind {
            AttrKind::Interface => "object_interface_dynamic",
            AttrKind::Subclass => "object_subclass_dynamic",
        };

        let mut plugin_type = NestedMetaItem::<syn::Path>::new("plugin_type").value_required();
        let mut lazy_registration =
            NestedMetaItem::<syn::LitBool>::new("lazy_registration").value_required();

        let found = parse_optional_nested_meta_items(
            &*attrs,
            attr_name,
            &mut [&mut plugin_type, &mut lazy_registration],
        )?
        .is_some();

        if found {
            // remove attribute from the attribute list because it is not a real proc_macro_attribute
            attrs.retain(|attr| !attr.path().is_ident(attr_name));

            Ok(Some(Self {
                plugin_type: plugin_type.value,
                lazy_registration: lazy_registration.value.map(|b| b.value).unwrap_or_default(),
            }))
        } else {
            Ok(None)
        }
    }
}