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
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163

//! Extensions for [`syn`] types.

use proc_macro2::Span;
use sealed::sealed;
use syn::{punctuated::Punctuated, token};

/// Extension of a [`syn::Data`].
#[sealed]
pub trait Data {
    /// Parses [`syn::Fields::Named`] from this consumed [`syn::Data::Struct`]
    /// and returns owning iterator over them.
    ///
    /// # Errors
    ///
    /// - If this [`syn::Data`] is not a [`syn::Data::Struct`].
    /// - If this [`syn::Data::Struct`] doesn't consist of
    ///   [`syn::Fields::Named`].
    fn named_fields(self) -> syn::Result<Punctuated<syn::Field, token::Comma>>;

    /// Parses [`syn::Fields::Named`] from this borrowed [`syn::Data::Struct`]
    /// and returns referencing iterator over them.
    ///
    /// # Errors
    ///
    /// - If this [`syn::Data`] is not a [`syn::Data::Struct`].
    /// - If this [`syn::Data::Struct`] doesn't consist of
    ///   [`syn::Fields::Named`].
    fn named_fields_ref(
        &self,
    ) -> syn::Result<&Punctuated<syn::Field, token::Comma>>;

    /// Parses [`syn::Fields::Unnamed`] from this consumed [`syn::Data::Struct`]
    /// and returns owning iterator over them.
    ///
    /// # Errors
    ///
    /// - If this [`syn::Data`] is not a [`syn::Data::Struct`].
    /// - If this [`syn::Data::Struct`] doesn't consist of
    ///   [`syn::Fields::Unnamed`].
    fn unnamed_fields(
        self,
    ) -> syn::Result<Punctuated<syn::Field, token::Comma>>;

    /// Parses [`syn::Fields::Unnamed`] from this borrowed [`syn::Data::Struct`]
    /// and returns referencing iterator over them.
    ///
    /// # Errors
    ///
    /// - If this [`syn::Data`] is not a [`syn::Data::Struct`].
    /// - If this [`syn::Data::Struct`] doesn't consist of
    ///   [`syn::Fields::Unnamed`].
    fn unnamed_fields_ref(
        &self,
    ) -> syn::Result<&Punctuated<syn::Field, token::Comma>>;
}

#[sealed]
impl Data for syn::Data {
    fn named_fields(self) -> syn::Result<Punctuated<syn::Field, token::Comma>> {
        match self {
            syn::Data::Struct(data) => match data.fields {
                syn::Fields::Named(f) => Ok(f.named),
                fields => Err(syn::Error::new_spanned(
                    fields,
                    "expected named struct fields only",
                )),
            },
            syn::Data::Enum(data) => Err(syn::Error::new_spanned(
                data.enum_token,
                "expected struct only",
            )),
            syn::Data::Union(data) => Err(syn::Error::new_spanned(
                data.union_token,
                "expected struct only",
            )),
        }
    }

    fn named_fields_ref(
        &self,
    ) -> syn::Result<&Punctuated<syn::Field, token::Comma>> {
        match self {
            syn::Data::Struct(data) => match &data.fields {
                syn::Fields::Named(f) => Ok(&f.named),
                fields => Err(syn::Error::new_spanned(
                    fields,
                    "expected named struct fields only",
                )),
            },
            syn::Data::Enum(data) => Err(syn::Error::new_spanned(
                data.enum_token,
                "expected struct only",
            )),
            syn::Data::Union(data) => Err(syn::Error::new_spanned(
                data.union_token,
                "expected struct only",
            )),
        }
    }

    fn unnamed_fields(
        self,
    ) -> syn::Result<Punctuated<syn::Field, token::Comma>> {
        match self {
            syn::Data::Struct(data) => match data.fields {
                syn::Fields::Unnamed(f) => Ok(f.unnamed),
                fields => Err(syn::Error::new_spanned(
                    fields,
                    "expected unnamed struct fields only",
                )),
            },
            syn::Data::Enum(data) => Err(syn::Error::new_spanned(
                data.enum_token,
                "expected struct only",
            )),
            syn::Data::Union(data) => Err(syn::Error::new_spanned(
                data.union_token,
                "expected struct only",
            )),
        }
    }

    fn unnamed_fields_ref(
        &self,
    ) -> syn::Result<&Punctuated<syn::Field, token::Comma>> {
        match self {
            syn::Data::Struct(data) => match &data.fields {
                syn::Fields::Unnamed(f) => Ok(&f.unnamed),
                fields => Err(syn::Error::new_spanned(
                    fields,
                    "expected unnamed struct fields only",
                )),
            },
            syn::Data::Enum(data) => Err(syn::Error::new_spanned(
                data.enum_token,
                "expected struct only",
            )),
            syn::Data::Union(data) => Err(syn::Error::new_spanned(
                data.union_token,
                "expected struct only",
            )),
        }
    }
}

/// Extension of a [`syn::Ident`](struct@syn::Ident).
#[sealed]
pub trait Ident {
    /// Creates a new [`syn::Ident`] out of the given string value with a
    /// [`Span::call_site`].
    ///
    /// [`syn::Ident`]: struct@syn::Ident
    #[must_use]
    fn new_on_call_site(ident: &str) -> syn::Ident;
}

#[sealed]
impl Ident for syn::Ident {
    #[inline]
    fn new_on_call_site(string: &str) -> Self {
        Self::new(string, Span::call_site())
    }
}