| use super::TokenStreamExt; |
| |
| use std::borrow::Cow; |
| use std::iter; |
| use std::rc::Rc; |
| |
| use proc_macro2::{Group, Ident, Literal, Punct, Span, TokenStream, TokenTree}; |
| |
| /// Types that can be interpolated inside a `quote!` invocation. |
| /// |
| /// [`quote!`]: macro.quote.html |
| pub trait ToTokens { |
| /// Write `self` to the given `TokenStream`. |
| /// |
| /// The token append methods provided by the [`TokenStreamExt`] extension |
| /// trait may be useful for implementing `ToTokens`. |
| /// |
| /// [`TokenStreamExt`]: trait.TokenStreamExt.html |
| /// |
| /// # Example |
| /// |
| /// Example implementation for a struct representing Rust paths like |
| /// `std::cmp::PartialEq`: |
| /// |
| /// ``` |
| /// use proc_macro2::{TokenTree, Spacing, Span, Punct, TokenStream}; |
| /// use quote::{TokenStreamExt, ToTokens}; |
| /// |
| /// pub struct Path { |
| /// pub global: bool, |
| /// pub segments: Vec<PathSegment>, |
| /// } |
| /// |
| /// impl ToTokens for Path { |
| /// fn to_tokens(&self, tokens: &mut TokenStream) { |
| /// for (i, segment) in self.segments.iter().enumerate() { |
| /// if i > 0 || self.global { |
| /// // Double colon `::` |
| /// tokens.append(Punct::new(':', Spacing::Joint)); |
| /// tokens.append(Punct::new(':', Spacing::Alone)); |
| /// } |
| /// segment.to_tokens(tokens); |
| /// } |
| /// } |
| /// } |
| /// # |
| /// # pub struct PathSegment; |
| /// # |
| /// # impl ToTokens for PathSegment { |
| /// # fn to_tokens(&self, tokens: &mut TokenStream) { |
| /// # unimplemented!() |
| /// # } |
| /// # } |
| /// ``` |
| fn to_tokens(&self, tokens: &mut TokenStream); |
| |
| /// Convert `self` directly into a `TokenStream` object. |
| /// |
| /// This method is implicitly implemented using `to_tokens`, and acts as a |
| /// convenience method for consumers of the `ToTokens` trait. |
| fn to_token_stream(&self) -> TokenStream { |
| let mut tokens = TokenStream::new(); |
| self.to_tokens(&mut tokens); |
| tokens |
| } |
| |
| /// Convert `self` directly into a `TokenStream` object. |
| /// |
| /// This method is implicitly implemented using `to_tokens`, and acts as a |
| /// convenience method for consumers of the `ToTokens` trait. |
| fn into_token_stream(self) -> TokenStream |
| where |
| Self: Sized, |
| { |
| self.to_token_stream() |
| } |
| } |
| |
| impl<'a, T: ?Sized + ToTokens> ToTokens for &'a T { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| (**self).to_tokens(tokens); |
| } |
| } |
| |
| impl<'a, T: ?Sized + ToTokens> ToTokens for &'a mut T { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| (**self).to_tokens(tokens); |
| } |
| } |
| |
| impl<'a, T: ?Sized + ToOwned + ToTokens> ToTokens for Cow<'a, T> { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| (**self).to_tokens(tokens); |
| } |
| } |
| |
| impl<T: ?Sized + ToTokens> ToTokens for Box<T> { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| (**self).to_tokens(tokens); |
| } |
| } |
| |
| impl<T: ?Sized + ToTokens> ToTokens for Rc<T> { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| (**self).to_tokens(tokens); |
| } |
| } |
| |
| impl<T: ToTokens> ToTokens for Option<T> { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| if let Some(ref t) = *self { |
| t.to_tokens(tokens); |
| } |
| } |
| } |
| |
| impl ToTokens for str { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| tokens.append(Literal::string(self)); |
| } |
| } |
| |
| impl ToTokens for String { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| self.as_str().to_tokens(tokens); |
| } |
| } |
| |
| macro_rules! primitive { |
| ($($t:ident => $name:ident)*) => { |
| $( |
| impl ToTokens for $t { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| tokens.append(Literal::$name(*self)); |
| } |
| } |
| )* |
| }; |
| } |
| |
| primitive! { |
| i8 => i8_suffixed |
| i16 => i16_suffixed |
| i32 => i32_suffixed |
| i64 => i64_suffixed |
| i128 => i128_suffixed |
| isize => isize_suffixed |
| |
| u8 => u8_suffixed |
| u16 => u16_suffixed |
| u32 => u32_suffixed |
| u64 => u64_suffixed |
| u128 => u128_suffixed |
| usize => usize_suffixed |
| |
| f32 => f32_suffixed |
| f64 => f64_suffixed |
| } |
| |
| impl ToTokens for char { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| tokens.append(Literal::character(*self)); |
| } |
| } |
| |
| impl ToTokens for bool { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| let word = if *self { "true" } else { "false" }; |
| tokens.append(Ident::new(word, Span::call_site())); |
| } |
| } |
| |
| impl ToTokens for Group { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| tokens.append(self.clone()); |
| } |
| } |
| |
| impl ToTokens for Ident { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| tokens.append(self.clone()); |
| } |
| } |
| |
| impl ToTokens for Punct { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| tokens.append(self.clone()); |
| } |
| } |
| |
| impl ToTokens for Literal { |
| fn to_tokens(&self, tokens: &mut TokenStream) { |
| tokens.append(self.clone()); |
| } |
| } |
| |
| impl ToTokens for TokenTree { |
| fn to_tokens(&self, dst: &mut TokenStream) { |
| dst.append(self.clone()); |
| } |
| } |
| |
| impl ToTokens for TokenStream { |
| fn to_tokens(&self, dst: &mut TokenStream) { |
| dst.extend(iter::once(self.clone())); |
| } |
| |
| fn into_token_stream(self) -> TokenStream { |
| self |
| } |
| } |