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         #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
   8         #[cfg_attr(feature = "clone-impls", derive(Clone))]
   9         $($attrs_pub)* struct $name $($rest)*
  10
  11         #[cfg(not(feature = "full"))]
  12         #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
  13         #[cfg_attr(feature = "clone-impls", derive(Clone))]
  14         $($attrs_pub)* struct $name {
  15             _noconstruct: (),
  16         }
  17
  18         #[cfg(all(not(feature = "full"), feature = "printing"))]
  19         impl ::quote::ToTokens for $name {
  20             fn to_tokens(&self, _: &mut ::proc_macro2::TokenStream) {
  21                 unreachable!()
  22             }
  23         }
  24     };
  25
  26     (
  27         [$($attrs_pub:tt)*]
  28         struct $name:ident #manual_extra_traits $($rest:tt)*
  29     ) => {
  30         #[cfg_attr(feature = "extra-traits", derive(Debug))]
  31         #[cfg_attr(feature = "clone-impls", derive(Clone))]
  32         $($attrs_pub)* struct $name $($rest)*
  33     };
  34
  35     (
  36         [$($attrs_pub:tt)*]
  37         struct $name:ident #manual_extra_traits_debug $($rest:tt)*
  38     ) => {
  39         #[cfg_attr(feature = "clone-impls", derive(Clone))]
  40         $($attrs_pub)* struct $name $($rest)*
  41     };
  42
  43     (
  44         [$($attrs_pub:tt)*]
  45         struct $name:ident $($rest:tt)*
  46     ) => {
  47         #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
  48         #[cfg_attr(feature = "clone-impls", derive(Clone))]
  49         $($attrs_pub)* struct $name $($rest)*
  50     };
  51
  52     ($($t:tt)*) => {
  53         strip_attrs_pub!(ast_struct!($($t)*));
  54     };
  55 }
  56
  57 macro_rules! ast_enum {
  58     // Drop the `#no_visit` attribute, if present.
  59     (
  60         [$($attrs_pub:tt)*]
  61         enum $name:ident #no_visit $($rest:tt)*
  62     ) => (
  63         ast_enum!([$($attrs_pub)*] enum $name $($rest)*);
  64     );
  65
  66     (
  67         [$($attrs_pub:tt)*]
  68         enum $name:ident #manual_extra_traits $($rest:tt)*
  69     ) => (
  70         #[cfg_attr(feature = "extra-traits", derive(Debug))]
  71         #[cfg_attr(feature = "clone-impls", derive(Clone))]
  72         $($attrs_pub)* enum $name $($rest)*
  73     );
  74
  75     (
  76         [$($attrs_pub:tt)*]
  77         enum $name:ident $($rest:tt)*
  78     ) => (
  79         #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
  80         #[cfg_attr(feature = "clone-impls", derive(Clone))]
  81         $($attrs_pub)* enum $name $($rest)*
  82     );
  83
  84     ($($t:tt)*) => {
  85         strip_attrs_pub!(ast_enum!($($t)*));
  86     };
  87 }
  88
  89 macro_rules! ast_enum_of_structs {
  90     (
  91         $(#[$enum_attr:meta])*
  92         $pub:ident $enum:ident $name:ident #$tag:ident $body:tt
  93         $($remaining:tt)*
  94     ) => {
  95         ast_enum!($(#[$enum_attr])* $pub $enum $name #$tag $body);
  96         ast_enum_of_structs_impl!($pub $enum $name $body $($remaining)*);
  97     };
  98
  99     (
 100         $(#[$enum_attr:meta])*
 101         $pub:ident $enum:ident $name:ident $body:tt
 102         $($remaining:tt)*
 103     ) => {
 104         ast_enum!($(#[$enum_attr])* $pub $enum $name $body);
 105         ast_enum_of_structs_impl!($pub $enum $name $body $($remaining)*);
 106     };
 107 }
 108
 109 macro_rules! ast_enum_of_structs_impl {
 110     (
 111         $pub:ident $enum:ident $name:ident {
 112             $(
 113                 $(#[$variant_attr:meta])*
 114                 $variant:ident $( ($member:ident) )*,
 115             )*
 116         }
 117
 118         $($remaining:tt)*
 119     ) => {
 120         check_keyword_matches!(pub $pub);
 121         check_keyword_matches!(enum $enum);
 122
 123         $($(
 124             ast_enum_from_struct!($name::$variant, $member);
 125         )*)*
 126
 127         #[cfg(feature = "printing")]
 128         generate_to_tokens! {
 129             $($remaining)*
 130             ()
 131             tokens
 132             $name { $($variant $($member)*,)* }
 133         }
 134     };
 135 }
 136
 137 macro_rules! ast_enum_from_struct {
 138     // No From<TokenStream> for verbatim variants.
 139     ($name:ident::Verbatim, $member:ident) => {};
 140
 141     ($name:ident::$variant:ident, $member:ident) => {
 142         impl From<$member> for $name {
 143             fn from(e: $member) -> $name {
 144                 $name::$variant(e)
 145             }
 146         }
 147     };
 148 }
 149
 150 #[cfg(feature = "printing")]
 151 macro_rules! generate_to_tokens {
 152     (do_not_generate_to_tokens $($foo:tt)*) => ();
 153
 154     (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident, $($next:tt)*}) => {
 155         generate_to_tokens!(
 156             ($($arms)* $name::$variant => {})
 157             $tokens $name { $($next)* }
 158         );
 159     };
 160
 161     (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident $member:ident, $($next:tt)*}) => {
 162         generate_to_tokens!(
 163             ($($arms)* $name::$variant(_e) => _e.to_tokens($tokens),)
 164             $tokens $name { $($next)* }
 165         );
 166     };
 167
 168     (($($arms:tt)*) $tokens:ident $name:ident {}) => {
 169         impl ::quote::ToTokens for $name {
 170             fn to_tokens(&self, $tokens: &mut ::proc_macro2::TokenStream) {
 171                 match self {
 172                     $($arms)*
 173                 }
 174             }
 175         }
 176     };
 177 }
 178
 179 macro_rules! strip_attrs_pub {
 180     ($mac:ident!($(#[$m:meta])* $pub:ident $($t:tt)*)) => {
 181         check_keyword_matches!(pub $pub);
 182
 183         $mac!([$(#[$m])* $pub] $($t)*);
 184     };
 185 }
 186
 187 macro_rules! check_keyword_matches {
 188     (struct struct) => {};
 189     (enum enum) => {};
 190     (pub pub) => {};
 191 }