vendor/syn/src/macros.rs

   1 macro_rules! ast_struct {
   2     (
   3         [$($attrs_pub:tt)*]
   4         struct $name:ident #full $($rest:tt)*
   5     ) => {
   6         #[cfg(feature = "full")]
   7         $($attrs_pub)* struct $name $($rest)*
   8
   9         #[cfg(not(feature = "full"))]
  10         $($attrs_pub)* struct $name {
  11             _noconstruct: ::std::marker::PhantomData<::proc_macro2::Span>,
  12         }
  13
  14         #[cfg(all(not(feature = "full"), feature = "printing"))]
  15         impl ::quote::ToTokens for $name {
  16             fn to_tokens(&self, _: &mut ::proc_macro2::TokenStream) {
  17                 unreachable!()
  18             }
  19         }
  20     };
  21
  22     (
  23         [$($attrs_pub:tt)*]
  24         struct $name:ident $($rest:tt)*
  25     ) => {
  26         $($attrs_pub)* struct $name $($rest)*
  27     };
  28
  29     ($($t:tt)*) => {
  30         strip_attrs_pub!(ast_struct!($($t)*));
  31     };
  32 }
  33
  34 macro_rules! ast_enum {
  35     // Drop the `#no_visit` attribute, if present.
  36     (
  37         [$($attrs_pub:tt)*]
  38         enum $name:ident #no_visit $($rest:tt)*
  39     ) => (
  40         ast_enum!([$($attrs_pub)*] enum $name $($rest)*);
  41     );
  42
  43     (
  44         [$($attrs_pub:tt)*]
  45         enum $name:ident $($rest:tt)*
  46     ) => (
  47         $($attrs_pub)* enum $name $($rest)*
  48     );
  49
  50     ($($t:tt)*) => {
  51         strip_attrs_pub!(ast_enum!($($t)*));
  52     };
  53 }
  54
  55 macro_rules! ast_enum_of_structs {
  56     (
  57         $(#[$enum_attr:meta])*
  58         $pub:ident $enum:ident $name:ident #$tag:ident $body:tt
  59         $($remaining:tt)*
  60     ) => {
  61         ast_enum!($(#[$enum_attr])* $pub $enum $name #$tag $body);
  62         ast_enum_of_structs_impl!($pub $enum $name $body $($remaining)*);
  63     };
  64
  65     (
  66         $(#[$enum_attr:meta])*
  67         $pub:ident $enum:ident $name:ident $body:tt
  68         $($remaining:tt)*
  69     ) => {
  70         ast_enum!($(#[$enum_attr])* $pub $enum $name $body);
  71         ast_enum_of_structs_impl!($pub $enum $name $body $($remaining)*);
  72     };
  73 }
  74
  75 macro_rules! ast_enum_of_structs_impl {
  76     (
  77         $pub:ident $enum:ident $name:ident {
  78             $(
  79                 $(#[$variant_attr:meta])*
  80                 $variant:ident $( ($($member:ident)::+) )*,
  81             )*
  82         }
  83
  84         $($remaining:tt)*
  85     ) => {
  86         check_keyword_matches!(pub $pub);
  87         check_keyword_matches!(enum $enum);
  88
  89         $($(
  90             ast_enum_from_struct!($name::$variant, $($member)::+);
  91         )*)*
  92
  93         #[cfg(feature = "printing")]
  94         generate_to_tokens! {
  95             $($remaining)*
  96             ()
  97             tokens
  98             $name { $($variant $($($member)::+)*,)* }
  99         }
 100     };
 101 }
 102
 103 macro_rules! ast_enum_from_struct {
 104     // No From<TokenStream> for verbatim variants.
 105     ($name:ident::Verbatim, $member:ident) => {};
 106
 107     // No From<TokenStream> for private variants.
 108     ($name:ident::$variant:ident, crate::private) => {};
 109
 110     ($name:ident::$variant:ident, $member:ident) => {
 111         impl From<$member> for $name {
 112             fn from(e: $member) -> $name {
 113                 $name::$variant(e)
 114             }
 115         }
 116     };
 117 }
 118
 119 #[cfg(feature = "printing")]
 120 macro_rules! generate_to_tokens {
 121     (do_not_generate_to_tokens $($foo:tt)*) => ();
 122
 123     (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident, $($next:tt)*}) => {
 124         generate_to_tokens!(
 125             ($($arms)* $name::$variant => {})
 126             $tokens $name { $($next)* }
 127         );
 128     };
 129
 130     (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident $member:ident, $($next:tt)*}) => {
 131         generate_to_tokens!(
 132             ($($arms)* $name::$variant(_e) => _e.to_tokens($tokens),)
 133             $tokens $name { $($next)* }
 134         );
 135     };
 136
 137     (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident crate::private, $($next:tt)*}) => {
 138         generate_to_tokens!(
 139             ($($arms)* $name::$variant(_) => unreachable!(),)
 140             $tokens $name { $($next)* }
 141         );
 142     };
 143
 144     (($($arms:tt)*) $tokens:ident $name:ident {}) => {
 145         #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
 146         impl ::quote::ToTokens for $name {
 147             fn to_tokens(&self, $tokens: &mut ::proc_macro2::TokenStream) {
 148                 match self {
 149                     $($arms)*
 150                 }
 151             }
 152         }
 153     };
 154 }
 155
 156 macro_rules! strip_attrs_pub {
 157     ($mac:ident!($(#[$m:meta])* $pub:ident $($t:tt)*)) => {
 158         check_keyword_matches!(pub $pub);
 159
 160         $mac!([$(#[$m])* $pub] $($t)*);
 161     };
 162 }
 163
 164 macro_rules! check_keyword_matches {
 165     (struct struct) => {};
 166     (enum enum) => {};
 167     (pub pub) => {};
 168 }