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Diffstat (limited to 'syn/src/custom_keyword.rs')
| -rw-r--r-- | syn/src/custom_keyword.rs | 252 |
1 files changed, 0 insertions, 252 deletions
diff --git a/syn/src/custom_keyword.rs b/syn/src/custom_keyword.rs deleted file mode 100644 index 200e847..0000000 --- a/syn/src/custom_keyword.rs +++ /dev/null @@ -1,252 +0,0 @@ -/// Define a type that supports parsing and printing a given identifier as if it -/// were a keyword. -/// -/// # Usage -/// -/// As a convention, it is recommended that this macro be invoked within a -/// module called `kw` or `keyword` and that the resulting parser be invoked -/// with a `kw::` or `keyword::` prefix. -/// -/// ``` -/// mod kw { -/// syn::custom_keyword!(whatever); -/// } -/// ``` -/// -/// The generated syntax tree node supports the following operations just like -/// any built-in keyword token. -/// -/// - [Peeking] — `input.peek(kw::whatever)` -/// -/// - [Parsing] — `input.parse::<kw::whatever>()?` -/// -/// - [Printing] — `quote!( ... #whatever_token ... )` -/// -/// - Construction from a [`Span`] — `let whatever_token = kw::whatever(sp)` -/// -/// - Field access to its span — `let sp = whatever_token.span` -/// -/// [Peeking]: parse::ParseBuffer::peek -/// [Parsing]: parse::ParseBuffer::parse -/// [Printing]: quote::ToTokens -/// [`Span`]: proc_macro2::Span -/// -/// # Example -/// -/// This example parses input that looks like `bool = true` or `str = "value"`. -/// The key must be either the identifier `bool` or the identifier `str`. If -/// `bool`, the value may be either `true` or `false`. If `str`, the value may -/// be any string literal. -/// -/// The symbols `bool` and `str` are not reserved keywords in Rust so these are -/// not considered keywords in the `syn::token` module. Like any other -/// identifier that is not a keyword, these can be declared as custom keywords -/// by crates that need to use them as such. -/// -/// ``` -/// use syn::{LitBool, LitStr, Result, Token}; -/// use syn::parse::{Parse, ParseStream}; -/// -/// mod kw { -/// syn::custom_keyword!(bool); -/// syn::custom_keyword!(str); -/// } -/// -/// enum Argument { -/// Bool { -/// bool_token: kw::bool, -/// eq_token: Token![=], -/// value: LitBool, -/// }, -/// Str { -/// str_token: kw::str, -/// eq_token: Token![=], -/// value: LitStr, -/// }, -/// } -/// -/// impl Parse for Argument { -/// fn parse(input: ParseStream) -> Result<Self> { -/// let lookahead = input.lookahead1(); -/// if lookahead.peek(kw::bool) { -/// Ok(Argument::Bool { -/// bool_token: input.parse::<kw::bool>()?, -/// eq_token: input.parse()?, -/// value: input.parse()?, -/// }) -/// } else if lookahead.peek(kw::str) { -/// Ok(Argument::Str { -/// str_token: input.parse::<kw::str>()?, -/// eq_token: input.parse()?, -/// value: input.parse()?, -/// }) -/// } else { -/// Err(lookahead.error()) -/// } -/// } -/// } -/// ``` -#[macro_export(local_inner_macros)] -macro_rules! custom_keyword { - ($ident:ident) => { - #[allow(non_camel_case_types)] - pub struct $ident { - pub span: $crate::export::Span, - } - - #[doc(hidden)] - #[allow(non_snake_case)] - pub fn $ident<__S: $crate::export::IntoSpans<[$crate::export::Span; 1]>>( - span: __S, - ) -> $ident { - $ident { - span: $crate::export::IntoSpans::into_spans(span)[0], - } - } - - impl $crate::export::Default for $ident { - fn default() -> Self { - $ident { - span: $crate::export::Span::call_site(), - } - } - } - - impl_parse_for_custom_keyword!($ident); - impl_to_tokens_for_custom_keyword!($ident); - impl_clone_for_custom_keyword!($ident); - impl_extra_traits_for_custom_keyword!($ident); - }; -} - -// Not public API. -#[cfg(feature = "parsing")] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_parse_for_custom_keyword { - ($ident:ident) => { - // For peek. - impl $crate::token::CustomToken for $ident { - fn peek(cursor: $crate::buffer::Cursor) -> $crate::export::bool { - if let Some((ident, _rest)) = cursor.ident() { - ident == stringify!($ident) - } else { - false - } - } - - fn display() -> &'static $crate::export::str { - concat!("`", stringify!($ident), "`") - } - } - - impl $crate::parse::Parse for $ident { - fn parse(input: $crate::parse::ParseStream) -> $crate::parse::Result<$ident> { - input.step(|cursor| { - if let $crate::export::Some((ident, rest)) = cursor.ident() { - if ident == stringify!($ident) { - return $crate::export::Ok(($ident { span: ident.span() }, rest)); - } - } - $crate::export::Err(cursor.error(concat!( - "expected `", - stringify!($ident), - "`" - ))) - }) - } - } - }; -} - -// Not public API. -#[cfg(not(feature = "parsing"))] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_parse_for_custom_keyword { - ($ident:ident) => {}; -} - -// Not public API. -#[cfg(feature = "printing")] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_to_tokens_for_custom_keyword { - ($ident:ident) => { - impl $crate::export::ToTokens for $ident { - fn to_tokens(&self, tokens: &mut $crate::export::TokenStream2) { - let ident = $crate::Ident::new(stringify!($ident), self.span); - $crate::export::TokenStreamExt::append(tokens, ident); - } - } - }; -} - -// Not public API. -#[cfg(not(feature = "printing"))] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_to_tokens_for_custom_keyword { - ($ident:ident) => {}; -} - -// Not public API. -#[cfg(feature = "clone-impls")] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_clone_for_custom_keyword { - ($ident:ident) => { - impl $crate::export::Copy for $ident {} - - impl $crate::export::Clone for $ident { - fn clone(&self) -> Self { - *self - } - } - }; -} - -// Not public API. -#[cfg(not(feature = "clone-impls"))] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_clone_for_custom_keyword { - ($ident:ident) => {}; -} - -// Not public API. -#[cfg(feature = "extra-traits")] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_extra_traits_for_custom_keyword { - ($ident:ident) => { - impl $crate::export::Debug for $ident { - fn fmt(&self, f: &mut $crate::export::Formatter) -> $crate::export::fmt::Result { - $crate::export::Formatter::write_str( - f, - concat!("Keyword [", stringify!($ident), "]"), - ) - } - } - - impl $crate::export::Eq for $ident {} - - impl $crate::export::PartialEq for $ident { - fn eq(&self, _other: &Self) -> $crate::export::bool { - true - } - } - - impl $crate::export::Hash for $ident { - fn hash<__H: $crate::export::Hasher>(&self, _state: &mut __H) {} - } - }; -} - -// Not public API. -#[cfg(not(feature = "extra-traits"))] -#[doc(hidden)] -#[macro_export] -macro_rules! impl_extra_traits_for_custom_keyword { - ($ident:ident) => {}; -} |