diff options
Diffstat (limited to 'quote/src')
| -rw-r--r-- | quote/src/ext.rs | 112 | ||||
| -rw-r--r-- | quote/src/format.rs | 164 | ||||
| -rw-r--r-- | quote/src/ident_fragment.rs | 72 | ||||
| -rw-r--r-- | quote/src/lib.rs | 948 | ||||
| -rw-r--r-- | quote/src/runtime.rs | 373 | ||||
| -rw-r--r-- | quote/src/spanned.rs | 42 | ||||
| -rw-r--r-- | quote/src/to_tokens.rs | 209 |
7 files changed, 1920 insertions, 0 deletions
diff --git a/quote/src/ext.rs b/quote/src/ext.rs new file mode 100644 index 0000000..9e9b4a5 --- /dev/null +++ b/quote/src/ext.rs @@ -0,0 +1,112 @@ +use super::ToTokens; + +use std::iter; + +use proc_macro2::{TokenStream, TokenTree}; + +/// TokenStream extension trait with methods for appending tokens. +/// +/// This trait is sealed and cannot be implemented outside of the `quote` crate. +pub trait TokenStreamExt: private::Sealed { + /// For use by `ToTokens` implementations. + /// + /// Appends the token specified to this list of tokens. + fn append<U>(&mut self, token: U) + where + U: Into<TokenTree>; + + /// For use by `ToTokens` implementations. + /// + /// ``` + /// # use quote::{quote, TokenStreamExt, ToTokens}; + /// # use proc_macro2::TokenStream; + /// # + /// struct X; + /// + /// impl ToTokens for X { + /// fn to_tokens(&self, tokens: &mut TokenStream) { + /// tokens.append_all(&[true, false]); + /// } + /// } + /// + /// let tokens = quote!(#X); + /// assert_eq!(tokens.to_string(), "true false"); + /// ``` + fn append_all<I>(&mut self, iter: I) + where + I: IntoIterator, + I::Item: ToTokens; + + /// For use by `ToTokens` implementations. + /// + /// Appends all of the items in the iterator `I`, separated by the tokens + /// `U`. + fn append_separated<I, U>(&mut self, iter: I, op: U) + where + I: IntoIterator, + I::Item: ToTokens, + U: ToTokens; + + /// For use by `ToTokens` implementations. + /// + /// Appends all tokens in the iterator `I`, appending `U` after each + /// element, including after the last element of the iterator. + fn append_terminated<I, U>(&mut self, iter: I, term: U) + where + I: IntoIterator, + I::Item: ToTokens, + U: ToTokens; +} + +impl TokenStreamExt for TokenStream { + fn append<U>(&mut self, token: U) + where + U: Into<TokenTree>, + { + self.extend(iter::once(token.into())); + } + + fn append_all<I>(&mut self, iter: I) + where + I: IntoIterator, + I::Item: ToTokens, + { + for token in iter { + token.to_tokens(self); + } + } + + fn append_separated<I, U>(&mut self, iter: I, op: U) + where + I: IntoIterator, + I::Item: ToTokens, + U: ToTokens, + { + for (i, token) in iter.into_iter().enumerate() { + if i > 0 { + op.to_tokens(self); + } + token.to_tokens(self); + } + } + + fn append_terminated<I, U>(&mut self, iter: I, term: U) + where + I: IntoIterator, + I::Item: ToTokens, + U: ToTokens, + { + for token in iter { + token.to_tokens(self); + term.to_tokens(self); + } + } +} + +mod private { + use proc_macro2::TokenStream; + + pub trait Sealed {} + + impl Sealed for TokenStream {} +} diff --git a/quote/src/format.rs b/quote/src/format.rs new file mode 100644 index 0000000..13c8811 --- /dev/null +++ b/quote/src/format.rs @@ -0,0 +1,164 @@ +/// Formatting macro for constructing `Ident`s. +/// +/// <br> +/// +/// # Syntax +/// +/// Syntax is copied from the [`format!`] macro, supporting both positional and +/// named arguments. +/// +/// Only a limited set of formatting traits are supported. The current mapping +/// of format types to traits is: +/// +/// * `{}` ⇒ [`IdentFragment`] +/// * `{:o}` ⇒ [`Octal`](`std::fmt::Octal`) +/// * `{:x}` ⇒ [`LowerHex`](`std::fmt::LowerHex`) +/// * `{:X}` ⇒ [`UpperHex`](`std::fmt::UpperHex`) +/// * `{:b}` ⇒ [`Binary`](`std::fmt::Binary`) +/// +/// See [`std::fmt`] for more information. +/// +/// <br> +/// +/// # IdentFragment +/// +/// Unlike `format!`, this macro uses the [`IdentFragment`] formatting trait by +/// default. This trait is like `Display`, with a few differences: +/// +/// * `IdentFragment` is only implemented for a limited set of types, such as +/// unsigned integers and strings. +/// * [`Ident`] arguments will have their `r#` prefixes stripped, if present. +/// +/// [`Ident`]: `proc_macro2::Ident` +/// +/// <br> +/// +/// # Hygiene +/// +/// The [`Span`] of the first `Ident` argument is used as the span of the final +/// identifier, falling back to [`Span::call_site`] when no identifiers are +/// provided. +/// +/// ``` +/// # use quote::format_ident; +/// # let ident = format_ident!("Ident"); +/// // If `ident` is an Ident, the span of `my_ident` will be inherited from it. +/// let my_ident = format_ident!("My{}{}", ident, "IsCool"); +/// assert_eq!(my_ident, "MyIdentIsCool"); +/// ``` +/// +/// Alternatively, the span can be overridden by passing the `span` named +/// argument. +/// +/// ``` +/// # use quote::format_ident; +/// # const IGNORE_TOKENS: &'static str = stringify! { +/// let my_span = /* ... */; +/// # }; +/// # let my_span = proc_macro2::Span::call_site(); +/// format_ident!("MyIdent", span = my_span); +/// ``` +/// +/// [`Span`]: `proc_macro2::Span` +/// [`Span::call_site`]: `proc_macro2::Span::call_site` +/// +/// <p><br></p> +/// +/// # Panics +/// +/// This method will panic if the resulting formatted string is not a valid +/// identifier. +/// +/// <br> +/// +/// # Examples +/// +/// Composing raw and non-raw identifiers: +/// ``` +/// # use quote::format_ident; +/// let my_ident = format_ident!("My{}", "Ident"); +/// assert_eq!(my_ident, "MyIdent"); +/// +/// let raw = format_ident!("r#Raw"); +/// assert_eq!(raw, "r#Raw"); +/// +/// let my_ident_raw = format_ident!("{}Is{}", my_ident, raw); +/// assert_eq!(my_ident_raw, "MyIdentIsRaw"); +/// ``` +/// +/// Integer formatting options: +/// ``` +/// # use quote::format_ident; +/// let num: u32 = 10; +/// +/// let decimal = format_ident!("Id_{}", num); +/// assert_eq!(decimal, "Id_10"); +/// +/// let octal = format_ident!("Id_{:o}", num); +/// assert_eq!(octal, "Id_12"); +/// +/// let binary = format_ident!("Id_{:b}", num); +/// assert_eq!(binary, "Id_1010"); +/// +/// let lower_hex = format_ident!("Id_{:x}", num); +/// assert_eq!(lower_hex, "Id_a"); +/// +/// let upper_hex = format_ident!("Id_{:X}", num); +/// assert_eq!(upper_hex, "Id_A"); +/// ``` +#[macro_export] +macro_rules! format_ident { + ($fmt:expr) => { + $crate::format_ident_impl!([ + ::std::option::Option::None, + $fmt + ]) + }; + + ($fmt:expr, $($rest:tt)*) => { + $crate::format_ident_impl!([ + ::std::option::Option::None, + $fmt + ] $($rest)*) + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! format_ident_impl { + // Final state + ([$span:expr, $($fmt:tt)*]) => { + $crate::__rt::mk_ident(&format!($($fmt)*), $span) + }; + + // Span argument + ([$old:expr, $($fmt:tt)*] span = $span:expr) => { + $crate::format_ident_impl!([$old, $($fmt)*] span = $span,) + }; + ([$old:expr, $($fmt:tt)*] span = $span:expr, $($rest:tt)*) => { + $crate::format_ident_impl!([ + ::std::option::Option::Some::<$crate::__rt::Span>($span), + $($fmt)* + ] $($rest)*) + }; + + // Named argument + ([$span:expr, $($fmt:tt)*] $name:ident = $arg:expr) => { + $crate::format_ident_impl!([$span, $($fmt)*] $name = $arg,) + }; + ([$span:expr, $($fmt:tt)*] $name:ident = $arg:expr, $($rest:tt)*) => { + match $crate::__rt::IdentFragmentAdapter(&$arg) { + arg => $crate::format_ident_impl!([$span.or(arg.span()), $($fmt)*, $name = arg] $($rest)*), + } + }; + + // Positional argument + ([$span:expr, $($fmt:tt)*] $arg:expr) => { + $crate::format_ident_impl!([$span, $($fmt)*] $arg,) + }; + ([$span:expr, $($fmt:tt)*] $arg:expr, $($rest:tt)*) => { + match $crate::__rt::IdentFragmentAdapter(&$arg) { + arg => $crate::format_ident_impl!([$span.or(arg.span()), $($fmt)*, arg] $($rest)*), + } + }; +} diff --git a/quote/src/ident_fragment.rs b/quote/src/ident_fragment.rs new file mode 100644 index 0000000..09ead65 --- /dev/null +++ b/quote/src/ident_fragment.rs @@ -0,0 +1,72 @@ +use proc_macro2::{Ident, Span}; +use std::fmt; + +/// Specialized formatting trait used by `format_ident!`. +/// +/// [`Ident`] arguments formatted using this trait will have their `r#` prefix +/// stripped, if present. +/// +/// See [`format_ident!`] for more information. +pub trait IdentFragment { + /// Format this value as an identifier fragment. + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result; + + /// Span associated with this `IdentFragment`. + /// + /// If non-`None`, may be inherited by formatted identifiers. + fn span(&self) -> Option<Span> { + None + } +} + +impl<'a, T: IdentFragment + ?Sized> IdentFragment for &'a T { + fn span(&self) -> Option<Span> { + <T as IdentFragment>::span(*self) + } + + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + IdentFragment::fmt(*self, f) + } +} + +impl<'a, T: IdentFragment + ?Sized> IdentFragment for &'a mut T { + fn span(&self) -> Option<Span> { + <T as IdentFragment>::span(*self) + } + + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + IdentFragment::fmt(*self, f) + } +} + +impl IdentFragment for Ident { + fn span(&self) -> Option<Span> { + Some(self.span()) + } + + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + let id = self.to_string(); + if id.starts_with("r#") { + fmt::Display::fmt(&id[2..], f) + } else { + fmt::Display::fmt(&id[..], f) + } + } +} + +// Limited set of types which this is implemented for, as we want to avoid types +// which will often include non-identifier characters in their `Display` impl. +macro_rules! ident_fragment_display { + ($($T:ty),*) => { + $( + impl IdentFragment for $T { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::Display::fmt(self, f) + } + } + )* + } +} + +ident_fragment_display!(bool, str, String); +ident_fragment_display!(u8, u16, u32, u64, u128, usize); diff --git a/quote/src/lib.rs b/quote/src/lib.rs new file mode 100644 index 0000000..3341a16 --- /dev/null +++ b/quote/src/lib.rs @@ -0,0 +1,948 @@ +//! This crate provides the [`quote!`] macro for turning Rust syntax tree data +//! structures into tokens of source code. +//! +//! [`quote!`]: macro.quote.html +//! +//! Procedural macros in Rust receive a stream of tokens as input, execute +//! arbitrary Rust code to determine how to manipulate those tokens, and produce +//! a stream of tokens to hand back to the compiler to compile into the caller's +//! crate. Quasi-quoting is a solution to one piece of that — producing +//! tokens to return to the compiler. +//! +//! The idea of quasi-quoting is that we write *code* that we treat as *data*. +//! Within the `quote!` macro, we can write what looks like code to our text +//! editor or IDE. We get all the benefits of the editor's brace matching, +//! syntax highlighting, indentation, and maybe autocompletion. But rather than +//! compiling that as code into the current crate, we can treat it as data, pass +//! it around, mutate it, and eventually hand it back to the compiler as tokens +//! to compile into the macro caller's crate. +//! +//! This crate is motivated by the procedural macro use case, but is a +//! general-purpose Rust quasi-quoting library and is not specific to procedural +//! macros. +//! +//! ```toml +//! [dependencies] +//! quote = "1.0" +//! ``` +//! +//! <br> +//! +//! # Example +//! +//! The following quasi-quoted block of code is something you might find in [a] +//! procedural macro having to do with data structure serialization. The `#var` +//! syntax performs interpolation of runtime variables into the quoted tokens. +//! Check out the documentation of the [`quote!`] macro for more detail about +//! the syntax. See also the [`quote_spanned!`] macro which is important for +//! implementing hygienic procedural macros. +//! +//! [a]: https://serde.rs/ +//! [`quote_spanned!`]: macro.quote_spanned.html +//! +//! ``` +//! # use quote::quote; +//! # +//! # let generics = ""; +//! # let where_clause = ""; +//! # let field_ty = ""; +//! # let item_ty = ""; +//! # let path = ""; +//! # let value = ""; +//! # +//! let tokens = quote! { +//! struct SerializeWith #generics #where_clause { +//! value: &'a #field_ty, +//! phantom: core::marker::PhantomData<#item_ty>, +//! } +//! +//! impl #generics serde::Serialize for SerializeWith #generics #where_clause { +//! fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> +//! where +//! S: serde::Serializer, +//! { +//! #path(self.value, serializer) +//! } +//! } +//! +//! SerializeWith { +//! value: #value, +//! phantom: core::marker::PhantomData::<#item_ty>, +//! } +//! }; +//! ``` + +// Quote types in rustdoc of other crates get linked to here. +#![doc(html_root_url = "https://docs.rs/quote/1.0.2")] + +#[cfg(all( + not(all(target_arch = "wasm32", target_os = "unknown")), + feature = "proc-macro" +))] +extern crate proc_macro; + +mod ext; +mod format; +mod ident_fragment; +mod to_tokens; + +// Not public API. +#[doc(hidden)] +#[path = "runtime.rs"] +pub mod __rt; + +pub use crate::ext::TokenStreamExt; +pub use crate::ident_fragment::IdentFragment; +pub use crate::to_tokens::ToTokens; + +// Not public API. +#[doc(hidden)] +pub mod spanned; + +/// The whole point. +/// +/// Performs variable interpolation against the input and produces it as +/// [`proc_macro2::TokenStream`]. +/// +/// Note: for returning tokens to the compiler in a procedural macro, use +/// `.into()` on the result to convert to [`proc_macro::TokenStream`]. +/// +/// [`TokenStream`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.TokenStream.html +/// +/// <br> +/// +/// # Interpolation +/// +/// Variable interpolation is done with `#var` (similar to `$var` in +/// `macro_rules!` macros). This grabs the `var` variable that is currently in +/// scope and inserts it in that location in the output tokens. Any type +/// implementing the [`ToTokens`] trait can be interpolated. This includes most +/// Rust primitive types as well as most of the syntax tree types from the [Syn] +/// crate. +/// +/// [`ToTokens`]: trait.ToTokens.html +/// [Syn]: https://github.com/dtolnay/syn +/// +/// Repetition is done using `#(...)*` or `#(...),*` again similar to +/// `macro_rules!`. This iterates through the elements of any variable +/// interpolated within the repetition and inserts a copy of the repetition body +/// for each one. The variables in an interpolation may be a `Vec`, slice, +/// `BTreeSet`, or any `Iterator`. +/// +/// - `#(#var)*` — no separators +/// - `#(#var),*` — the character before the asterisk is used as a separator +/// - `#( struct #var; )*` — the repetition can contain other tokens +/// - `#( #k => println!("{}", #v), )*` — even multiple interpolations +/// +/// <br> +/// +/// # Hygiene +/// +/// Any interpolated tokens preserve the `Span` information provided by their +/// `ToTokens` implementation. Tokens that originate within the `quote!` +/// invocation are spanned with [`Span::call_site()`]. +/// +/// [`Span::call_site()`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.Span.html#method.call_site +/// +/// A different span can be provided through the [`quote_spanned!`] macro. +/// +/// [`quote_spanned!`]: macro.quote_spanned.html +/// +/// <br> +/// +/// # Return type +/// +/// The macro evaluates to an expression of type `proc_macro2::TokenStream`. +/// Meanwhile Rust procedural macros are expected to return the type +/// `proc_macro::TokenStream`. +/// +/// The difference between the two types is that `proc_macro` types are entirely +/// specific to procedural macros and cannot ever exist in code outside of a +/// procedural macro, while `proc_macro2` types may exist anywhere including +/// tests and non-macro code like main.rs and build.rs. This is why even the +/// procedural macro ecosystem is largely built around `proc_macro2`, because +/// that ensures the libraries are unit testable and accessible in non-macro +/// contexts. +/// +/// There is a [`From`]-conversion in both directions so returning the output of +/// `quote!` from a procedural macro usually looks like `tokens.into()` or +/// `proc_macro::TokenStream::from(tokens)`. +/// +/// [`From`]: https://doc.rust-lang.org/std/convert/trait.From.html +/// +/// <br> +/// +/// # Examples +/// +/// ### Procedural macro +/// +/// The structure of a basic procedural macro is as follows. Refer to the [Syn] +/// crate for further useful guidance on using `quote!` as part of a procedural +/// macro. +/// +/// [Syn]: https://github.com/dtolnay/syn +/// +/// ``` +/// # #[cfg(any())] +/// extern crate proc_macro; +/// # extern crate proc_macro2; +/// +/// # #[cfg(any())] +/// use proc_macro::TokenStream; +/// # use proc_macro2::TokenStream; +/// use quote::quote; +/// +/// # const IGNORE_TOKENS: &'static str = stringify! { +/// #[proc_macro_derive(HeapSize)] +/// # }; +/// pub fn derive_heap_size(input: TokenStream) -> TokenStream { +/// // Parse the input and figure out what implementation to generate... +/// # const IGNORE_TOKENS: &'static str = stringify! { +/// let name = /* ... */; +/// let expr = /* ... */; +/// # }; +/// # +/// # let name = 0; +/// # let expr = 0; +/// +/// let expanded = quote! { +/// // The generated impl. +/// impl heapsize::HeapSize for #name { +/// fn heap_size_of_children(&self) -> usize { +/// #expr +/// } +/// } +/// }; +/// +/// // Hand the output tokens back to the compiler. +/// TokenStream::from(expanded) +/// } +/// ``` +/// +/// <p><br></p> +/// +/// ### Combining quoted fragments +/// +/// Usually you don't end up constructing an entire final `TokenStream` in one +/// piece. Different parts may come from different helper functions. The tokens +/// produced by `quote!` themselves implement `ToTokens` and so can be +/// interpolated into later `quote!` invocations to build up a final result. +/// +/// ``` +/// # use quote::quote; +/// # +/// let type_definition = quote! {...}; +/// let methods = quote! {...}; +/// +/// let tokens = quote! { +/// #type_definition +/// #methods +/// }; +/// ``` +/// +/// <p><br></p> +/// +/// ### Constructing identifiers +/// +/// Suppose we have an identifier `ident` which came from somewhere in a macro +/// input and we need to modify it in some way for the macro output. Let's +/// consider prepending the identifier with an underscore. +/// +/// Simply interpolating the identifier next to an underscore will not have the +/// behavior of concatenating them. The underscore and the identifier will +/// continue to be two separate tokens as if you had written `_ x`. +/// +/// ``` +/// # use proc_macro2::{self as syn, Span}; +/// # use quote::quote; +/// # +/// # let ident = syn::Ident::new("i", Span::call_site()); +/// # +/// // incorrect +/// quote! { +/// let mut _#ident = 0; +/// } +/// # ; +/// ``` +/// +/// The solution is to build a new identifier token with the correct value. As +/// this is such a common case, the [`format_ident!`] macro provides a +/// convenient utility for doing so correctly. +/// +/// ``` +/// # use proc_macro2::{Ident, Span}; +/// # use quote::{format_ident, quote}; +/// # +/// # let ident = Ident::new("i", Span::call_site()); +/// # +/// let varname = format_ident!("_{}", ident); +/// quote! { +/// let mut #varname = 0; +/// } +/// # ; +/// ``` +/// +/// Alternatively, the APIs provided by Syn and proc-macro2 can be used to +/// directly build the identifier. This is roughly equivalent to the above, but +/// will not handle `ident` being a raw identifier. +/// +/// ``` +/// # use proc_macro2::{self as syn, Span}; +/// # use quote::quote; +/// # +/// # let ident = syn::Ident::new("i", Span::call_site()); +/// # +/// let concatenated = format!("_{}", ident); +/// let varname = syn::Ident::new(&concatenated, ident.span()); +/// quote! { +/// let mut #varname = 0; +/// } +/// # ; +/// ``` +/// +/// <p><br></p> +/// +/// ### Making method calls +/// +/// Let's say our macro requires some type specified in the macro input to have +/// a constructor called `new`. We have the type in a variable called +/// `field_type` of type `syn::Type` and want to invoke the constructor. +/// +/// ``` +/// # use quote::quote; +/// # +/// # let field_type = quote!(...); +/// # +/// // incorrect +/// quote! { +/// let value = #field_type::new(); +/// } +/// # ; +/// ``` +/// +/// This works only sometimes. If `field_type` is `String`, the expanded code +/// contains `String::new()` which is fine. But if `field_type` is something +/// like `Vec<i32>` then the expanded code is `Vec<i32>::new()` which is invalid +/// syntax. Ordinarily in handwritten Rust we would write `Vec::<i32>::new()` +/// but for macros often the following is more convenient. +/// +/// ``` +/// # use quote::quote; +/// # +/// # let field_type = quote!(...); +/// # +/// quote! { +/// let value = <#field_type>::new(); +/// } +/// # ; +/// ``` +/// +/// This expands to `<Vec<i32>>::new()` which behaves correctly. +/// +/// A similar pattern is appropriate for trait methods. +/// +/// ``` +/// # use quote::quote; +/// # +/// # let field_type = quote!(...); +/// # +/// quote! { +/// let value = <#field_type as core::default::Default>::default(); +/// } +/// # ; +/// ``` +/// +/// <p><br></p> +/// +/// ### Interpolating text inside of doc comments +/// +/// Neither doc comments nor string literals get interpolation behavior in +/// quote: +/// +/// ```compile_fail +/// quote! { +/// /// try to interpolate: #ident +/// /// +/// /// ... +/// } +/// ``` +/// +/// ```compile_fail +/// quote! { +/// #[doc = "try to interpolate: #ident"] +/// } +/// ``` +/// +/// Macro calls in a doc attribute are not valid syntax: +/// +/// ```compile_fail +/// quote! { +/// #[doc = concat!("try to interpolate: ", stringify!(#ident))] +/// } +/// ``` +/// +/// Instead the best way to build doc comments that involve variables is by +/// formatting the doc string literal outside of quote. +/// +/// ```rust +/// # use proc_macro2::{Ident, Span}; +/// # use quote::quote; +/// # +/// # const IGNORE: &str = stringify! { +/// let msg = format!(...); +/// # }; +/// # +/// # let ident = Ident::new("var", Span::call_site()); +/// # let msg = format!("try to interpolate: {}", ident); +/// quote! { +/// #[doc = #msg] +/// /// +/// /// ... +/// } +/// # ; +/// ``` +/// +/// <p><br></p> +/// +/// ### Indexing into a tuple struct +/// +/// When interpolating indices of a tuple or tuple struct, we need them not to +/// appears suffixed as integer literals by interpolating them as [`syn::Index`] +/// instead. +/// +/// [`syn::Index`]: https://docs.rs/syn/1.0/syn/struct.Index.html +/// +/// ```compile_fail +/// let i = 0usize..self.fields.len(); +/// +/// // expands to 0 + self.0usize.heap_size() + self.1usize.heap_size() + ... +/// // which is not valid syntax +/// quote! { +/// 0 #( + self.#i.heap_size() )* +/// } +/// ``` +/// +/// ``` +/// # use proc_macro2::{Ident, TokenStream}; +/// # use quote::quote; +/// # +/// # mod syn { +/// # use proc_macro2::{Literal, TokenStream}; +/// # use quote::{ToTokens, TokenStreamExt}; +/// # +/// # pub struct Index(usize); +/// # +/// # impl From<usize> for Index { +/// # fn from(i: usize) -> Self { +/// # Index(i) +/// # } +/// # } +/// # +/// # impl ToTokens for Index { +/// # fn to_tokens(&self, tokens: &mut TokenStream) { +/// # tokens.append(Literal::usize_unsuffixed(self.0)); +/// # } +/// # } +/// # } +/// # +/// # struct Struct { +/// # fields: Vec<Ident>, +/// # } +/// # +/// # impl Struct { +/// # fn example(&self) -> TokenStream { +/// let i = (0..self.fields.len()).map(syn::Index::from); +/// +/// // expands to 0 + self.0.heap_size() + self.1.heap_size() + ... +/// quote! { +/// 0 #( + self.#i.heap_size() )* +/// } +/// # } +/// # } +/// ``` +#[macro_export] +macro_rules! quote { + ($($tt:tt)*) => { + $crate::quote_spanned!($crate::__rt::Span::call_site()=> $($tt)*) + }; +} + +/// Same as `quote!`, but applies a given span to all tokens originating within +/// the macro invocation. +/// +/// <br> +/// +/// # Syntax +/// +/// A span expression of type [`Span`], followed by `=>`, followed by the tokens +/// to quote. The span expression should be brief — use a variable for +/// anything more than a few characters. There should be no space before the +/// `=>` token. +/// +/// [`Span`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.Span.html +/// +/// ``` +/// # use proc_macro2::Span; +/// # use quote::quote_spanned; +/// # +/// # const IGNORE_TOKENS: &'static str = stringify! { +/// let span = /* ... */; +/// # }; +/// # let span = Span::call_site(); +/// # let init = 0; +/// +/// // On one line, use parentheses. +/// let tokens = quote_spanned!(span=> Box::into_raw(Box::new(#init))); +/// +/// // On multiple lines, place the span at the top and use braces. +/// let tokens = quote_spanned! {span=> +/// Box::into_raw(Box::new(#init)) +/// }; +/// ``` +/// +/// The lack of space before the `=>` should look jarring to Rust programmers +/// and this is intentional. The formatting is designed to be visibly +/// off-balance and draw the eye a particular way, due to the span expression +/// being evaluated in the context of the procedural macro and the remaining +/// tokens being evaluated in the generated code. +/// +/// <br> +/// +/// # Hygiene +/// +/// Any interpolated tokens preserve the `Span` information provided by their +/// `ToTokens` implementation. Tokens that originate within the `quote_spanned!` +/// invocation are spanned with the given span argument. +/// +/// <br> +/// +/// # Example +/// +/// The following procedural macro code uses `quote_spanned!` to assert that a +/// particular Rust type implements the [`Sync`] trait so that references can be +/// safely shared between threads. +/// +/// [`Sync`]: https://doc.rust-lang.org/std/marker/trait.Sync.html +/// +/// ``` +/// # use quote::{quote_spanned, TokenStreamExt, ToTokens}; +/// # use proc_macro2::{Span, TokenStream}; +/// # +/// # struct Type; +/// # +/// # impl Type { +/// # fn span(&self) -> Span { +/// # Span::call_site() +/// # } +/// # } +/// # +/// # impl ToTokens for Type { +/// # fn to_tokens(&self, _tokens: &mut TokenStream) {} +/// # } +/// # +/// # let ty = Type; +/// # let call_site = Span::call_site(); +/// # +/// let ty_span = ty.span(); +/// let assert_sync = quote_spanned! {ty_span=> +/// struct _AssertSync where #ty: Sync; +/// }; +/// ``` +/// +/// If the assertion fails, the user will see an error like the following. The +/// input span of their type is hightlighted in the error. +/// +/// ```text +/// error[E0277]: the trait bound `*const (): std::marker::Sync` is not satisfied +/// --> src/main.rs:10:21 +/// | +/// 10 | static ref PTR: *const () = &(); +/// | ^^^^^^^^^ `*const ()` cannot be shared between threads safely +/// ``` +/// +/// In this example it is important for the where-clause to be spanned with the +/// line/column information of the user's input type so that error messages are +/// placed appropriately by the compiler. +#[macro_export] +macro_rules! quote_spanned { + ($span:expr=> $($tt:tt)*) => {{ + let mut _s = $crate::__rt::TokenStream::new(); + let _span: $crate::__rt::Span = $span; + $crate::quote_each_token!(_s _span $($tt)*); + _s + }}; +} + +// Extract the names of all #metavariables and pass them to the $call macro. +// +// in: pounded_var_names!(then!(...) a #b c #( #d )* #e) +// out: then!(... b); +// then!(... d); +// then!(... e); +#[macro_export] +#[doc(hidden)] +macro_rules! pounded_var_names { + ($call:ident! $extra:tt $($tts:tt)*) => { + $crate::pounded_var_names_with_context!($call! $extra + (@ $($tts)*) + ($($tts)* @) + ) + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! pounded_var_names_with_context { + ($call:ident! $extra:tt ($($b1:tt)*) ($($curr:tt)*)) => { + $( + $crate::pounded_var_with_context!($call! $extra $b1 $curr); + )* + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! pounded_var_with_context { + ($call:ident! $extra:tt $b1:tt ( $($inner:tt)* )) => { + $crate::pounded_var_names!($call! $extra $($inner)*); + }; + + ($call:ident! $extra:tt $b1:tt [ $($inner:tt)* ]) => { + $crate::pounded_var_names!($call! $extra $($inner)*); + }; + + ($call:ident! $extra:tt $b1:tt { $($inner:tt)* }) => { + $crate::pounded_var_names!($call! $extra $($inner)*); + }; + + ($call:ident!($($extra:tt)*) # $var:ident) => { + $crate::$call!($($extra)* $var); + }; + + ($call:ident! $extra:tt $b1:tt $curr:tt) => {}; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! quote_bind_into_iter { + ($has_iter:ident $var:ident) => { + // `mut` may be unused if $var occurs multiple times in the list. + #[allow(unused_mut)] + let (mut $var, i) = $var.quote_into_iter(); + let $has_iter = $has_iter | i; + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! quote_bind_next_or_break { + ($var:ident) => { + let $var = match $var.next() { + Some(_x) => $crate::__rt::RepInterp(_x), + None => break, + }; + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! quote_each_token { + ($tokens:ident $span:ident $($tts:tt)*) => { + $crate::quote_tokens_with_context!($tokens $span + (@ @ @ @ @ @ $($tts)*) + (@ @ @ @ @ $($tts)* @) + (@ @ @ @ $($tts)* @ @) + (@ @ @ $(($tts))* @ @ @) + (@ @ $($tts)* @ @ @ @) + (@ $($tts)* @ @ @ @ @) + ($($tts)* @ @ @ @ @ @) + ); + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! quote_tokens_with_context { + ($tokens:ident $span:ident + ($($b3:tt)*) ($($b2:tt)*) ($($b1:tt)*) + ($($curr:tt)*) + ($($a1:tt)*) ($($a2:tt)*) ($($a3:tt)*) + ) => { + $( + $crate::quote_token_with_context!($tokens $span $b3 $b2 $b1 $curr $a1 $a2 $a3); + )* + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! quote_token_with_context { + ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt @ $a1:tt $a2:tt $a3:tt) => {}; + + ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt (#) ( $($inner:tt)* ) * $a3:tt) => {{ + use $crate::__rt::ext::*; + let has_iter = $crate::__rt::ThereIsNoIteratorInRepetition; + $crate::pounded_var_names!(quote_bind_into_iter!(has_iter) () $($inner)*); + let _: $crate::__rt::HasIterator = has_iter; + // This is `while true` instead of `loop` because if there are no + // iterators used inside of this repetition then the body would not + // contain any `break`, so the compiler would emit unreachable code + // warnings on anything below the loop. We use has_iter to detect and + // fail to compile when there are no iterators, so here we just work + // around the unneeded extra warning. + while true { + $crate::pounded_var_names!(quote_bind_next_or_break!() () $($inner)*); + $crate::quote_each_token!($tokens $span $($inner)*); + } + }}; + ($tokens:ident $span:ident $b3:tt $b2:tt # (( $($inner:tt)* )) * $a2:tt $a3:tt) => {}; + ($tokens:ident $span:ident $b3:tt # ( $($inner:tt)* ) (*) $a1:tt $a2:tt $a3:tt) => {}; + + ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt (#) ( $($inner:tt)* ) $sep:tt *) => {{ + use $crate::__rt::ext::*; + let mut _i = 0usize; + let has_iter = $crate::__rt::ThereIsNoIteratorInRepetition; + $crate::pounded_var_names!(quote_bind_into_iter!(has_iter) () $($inner)*); + let _: $crate::__rt::HasIterator = has_iter; + while true { + $crate::pounded_var_names!(quote_bind_next_or_break!() () $($inner)*); + if _i > 0 { + $crate::quote_token!($tokens $span $sep); + } + _i += 1; + $crate::quote_each_token!($tokens $span $($inner)*); + } + }}; + ($tokens:ident $span:ident $b3:tt $b2:tt # (( $($inner:tt)* )) $sep:tt * $a3:tt) => {}; + ($tokens:ident $span:ident $b3:tt # ( $($inner:tt)* ) ($sep:tt) * $a2:tt $a3:tt) => {}; + ($tokens:ident $span:ident # ( $($inner:tt)* ) * (*) $a1:tt $a2:tt $a3:tt) => { + // https://github.com/dtolnay/quote/issues/130 + $crate::quote_token!($tokens $span *); + }; + ($tokens:ident $span:ident # ( $($inner:tt)* ) $sep:tt (*) $a1:tt $a2:tt $a3:tt) => {}; + + ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt (#) $var:ident $a2:tt $a3:tt) => { + $crate::ToTokens::to_tokens(&$var, &mut $tokens); + }; + ($tokens:ident $span:ident $b3:tt $b2:tt # ($var:ident) $a1:tt $a2:tt $a3:tt) => {}; + ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt ($curr:tt) $a1:tt $a2:tt $a3:tt) => { + $crate::quote_token!($tokens $span $curr); + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! quote_token { + ($tokens:ident $span:ident ( $($inner:tt)* )) => { + $tokens.extend({ + let mut g = $crate::__rt::Group::new( + $crate::__rt::Delimiter::Parenthesis, + $crate::quote_spanned!($span=> $($inner)*), + ); + g.set_span($span); + Some($crate::__rt::TokenTree::from(g)) + }); + }; + + ($tokens:ident $span:ident [ $($inner:tt)* ]) => { + $tokens.extend({ + let mut g = $crate::__rt::Group::new( + $crate::__rt::Delimiter::Bracket, + $crate::quote_spanned!($span=> $($inner)*), + ); + g.set_span($span); + Some($crate::__rt::TokenTree::from(g)) + }); + }; + + ($tokens:ident $span:ident { $($inner:tt)* }) => { + $tokens.extend({ + let mut g = $crate::__rt::Group::new( + $crate::__rt::Delimiter::Brace, + $crate::quote_spanned!($span=> $($inner)*), + ); + g.set_span($span); + Some($crate::__rt::TokenTree::from(g)) + }); + }; + + ($tokens:ident $span:ident +) => { + $crate::__rt::push_add(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident +=) => { + $crate::__rt::push_add_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident &) => { + $crate::__rt::push_and(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident &&) => { + $crate::__rt::push_and_and(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident &=) => { + $crate::__rt::push_and_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident @) => { + $crate::__rt::push_at(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident !) => { + $crate::__rt::push_bang(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ^) => { + $crate::__rt::push_caret(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ^=) => { + $crate::__rt::push_caret_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident :) => { + $crate::__rt::push_colon(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ::) => { + $crate::__rt::push_colon2(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ,) => { + $crate::__rt::push_comma(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident /) => { + $crate::__rt::push_div(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident /=) => { + $crate::__rt::push_div_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident .) => { + $crate::__rt::push_dot(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ..) => { + $crate::__rt::push_dot2(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ...) => { + $crate::__rt::push_dot3(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ..=) => { + $crate::__rt::push_dot_dot_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident =) => { + $crate::__rt::push_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ==) => { + $crate::__rt::push_eq_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident >=) => { + $crate::__rt::push_ge(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident >) => { + $crate::__rt::push_gt(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident <=) => { + $crate::__rt::push_le(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident <) => { + $crate::__rt::push_lt(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident *=) => { + $crate::__rt::push_mul_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident !=) => { + $crate::__rt::push_ne(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident |) => { + $crate::__rt::push_or(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident |=) => { + $crate::__rt::push_or_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ||) => { + $crate::__rt::push_or_or(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident #) => { + $crate::__rt::push_pound(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ?) => { + $crate::__rt::push_question(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ->) => { + $crate::__rt::push_rarrow(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident <-) => { + $crate::__rt::push_larrow(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident %) => { + $crate::__rt::push_rem(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident %=) => { + $crate::__rt::push_rem_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident =>) => { + $crate::__rt::push_fat_arrow(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident ;) => { + $crate::__rt::push_semi(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident <<) => { + $crate::__rt::push_shl(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident <<=) => { + $crate::__rt::push_shl_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident >>) => { + $crate::__rt::push_shr(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident >>=) => { + $crate::__rt::push_shr_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident *) => { + $crate::__rt::push_star(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident -) => { + $crate::__rt::push_sub(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident -=) => { + $crate::__rt::push_sub_eq(&mut $tokens, $span); + }; + + ($tokens:ident $span:ident $other:tt) => { + $crate::__rt::parse(&mut $tokens, $span, stringify!($other)); + }; +} diff --git a/quote/src/runtime.rs b/quote/src/runtime.rs new file mode 100644 index 0000000..4a1c14c --- /dev/null +++ b/quote/src/runtime.rs @@ -0,0 +1,373 @@ +use crate::{IdentFragment, ToTokens, TokenStreamExt}; +use std::fmt; +use std::ops::BitOr; + +pub use proc_macro2::*; + +pub struct HasIterator; // True +pub struct ThereIsNoIteratorInRepetition; // False + +impl BitOr<ThereIsNoIteratorInRepetition> for ThereIsNoIteratorInRepetition { + type Output = ThereIsNoIteratorInRepetition; + fn bitor(self, _rhs: ThereIsNoIteratorInRepetition) -> ThereIsNoIteratorInRepetition { + ThereIsNoIteratorInRepetition + } +} + +impl BitOr<ThereIsNoIteratorInRepetition> for HasIterator { + type Output = HasIterator; + fn bitor(self, _rhs: ThereIsNoIteratorInRepetition) -> HasIterator { + HasIterator + } +} + +impl BitOr<HasIterator> for ThereIsNoIteratorInRepetition { + type Output = HasIterator; + fn bitor(self, _rhs: HasIterator) -> HasIterator { + HasIterator + } +} + +impl BitOr<HasIterator> for HasIterator { + type Output = HasIterator; + fn bitor(self, _rhs: HasIterator) -> HasIterator { + HasIterator + } +} + +/// Extension traits used by the implementation of `quote!`. These are defined +/// in separate traits, rather than as a single trait due to ambiguity issues. +/// +/// These traits expose a `quote_into_iter` method which should allow calling +/// whichever impl happens to be applicable. Calling that method repeatedly on +/// the returned value should be idempotent. +pub mod ext { + use super::RepInterp; + use super::{HasIterator as HasIter, ThereIsNoIteratorInRepetition as DoesNotHaveIter}; + use crate::ToTokens; + use std::collections::btree_set::{self, BTreeSet}; + use std::slice; + + /// Extension trait providing the `quote_into_iter` method on iterators. + pub trait RepIteratorExt: Iterator + Sized { + fn quote_into_iter(self) -> (Self, HasIter) { + (self, HasIter) + } + } + + impl<T: Iterator> RepIteratorExt for T {} + + /// Extension trait providing the `quote_into_iter` method for + /// non-iterable types. These types interpolate the same value in each + /// iteration of the repetition. + pub trait RepToTokensExt { + /// Pretend to be an iterator for the purposes of `quote_into_iter`. + /// This allows repeated calls to `quote_into_iter` to continue + /// correctly returning DoesNotHaveIter. + fn next(&self) -> Option<&Self> { + Some(self) + } + + fn quote_into_iter(&self) -> (&Self, DoesNotHaveIter) { + (self, DoesNotHaveIter) + } + } + + impl<T: ToTokens + ?Sized> RepToTokensExt for T {} + + /// Extension trait providing the `quote_into_iter` method for types that + /// can be referenced as an iterator. + pub trait RepAsIteratorExt<'q> { + type Iter: Iterator; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter); + } + + impl<'q, 'a, T: RepAsIteratorExt<'q> + ?Sized> RepAsIteratorExt<'q> for &'a T { + type Iter = T::Iter; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) { + <T as RepAsIteratorExt>::quote_into_iter(*self) + } + } + + impl<'q, 'a, T: RepAsIteratorExt<'q> + ?Sized> RepAsIteratorExt<'q> for &'a mut T { + type Iter = T::Iter; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) { + <T as RepAsIteratorExt>::quote_into_iter(*self) + } + } + + impl<'q, T: 'q> RepAsIteratorExt<'q> for [T] { + type Iter = slice::Iter<'q, T>; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) { + (self.iter(), HasIter) + } + } + + impl<'q, T: 'q> RepAsIteratorExt<'q> for Vec<T> { + type Iter = slice::Iter<'q, T>; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) { + (self.iter(), HasIter) + } + } + + impl<'q, T: 'q> RepAsIteratorExt<'q> for BTreeSet<T> { + type Iter = btree_set::Iter<'q, T>; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) { + (self.iter(), HasIter) + } + } + + macro_rules! array_rep_slice { + ($($l:tt)*) => { + $( + impl<'q, T: 'q> RepAsIteratorExt<'q> for [T; $l] { + type Iter = slice::Iter<'q, T>; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) { + (self.iter(), HasIter) + } + } + )* + } + } + + array_rep_slice!( + 0 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 + ); + + impl<'q, T: RepAsIteratorExt<'q>> RepAsIteratorExt<'q> for RepInterp<T> { + type Iter = T::Iter; + + fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) { + self.0.quote_into_iter() + } + } +} + +// Helper type used within interpolations to allow for repeated binding names. +// Implements the relevant traits, and exports a dummy `next()` method. +#[derive(Copy, Clone)] +pub struct RepInterp<T>(pub T); + +impl<T> RepInterp<T> { + // This method is intended to look like `Iterator::next`, and is called when + // a name is bound multiple times, as the previous binding will shadow the + // original `Iterator` object. This allows us to avoid advancing the + // iterator multiple times per iteration. + pub fn next(self) -> Option<T> { + Some(self.0) + } +} + +impl<T: Iterator> Iterator for RepInterp<T> { + type Item = T::Item; + + fn next(&mut self) -> Option<Self::Item> { + self.0.next() + } +} + +impl<T: ToTokens> ToTokens for RepInterp<T> { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.0.to_tokens(tokens); + } +} + +fn is_ident_start(c: u8) -> bool { + (b'a' <= c && c <= b'z') || (b'A' <= c && c <= b'Z') || c == b'_' +} + +fn is_ident_continue(c: u8) -> bool { + (b'a' <= c && c <= b'z') || (b'A' <= c && c <= b'Z') || c == b'_' || (b'0' <= c && c <= b'9') +} + +fn is_ident(token: &str) -> bool { + let mut iter = token.bytes(); + let first_ok = iter.next().map(is_ident_start).unwrap_or(false); + + first_ok && iter.all(is_ident_continue) +} + +pub fn parse(tokens: &mut TokenStream, span: Span, s: &str) { + if is_ident(s) { + // Fast path, since idents are the most common token. + tokens.append(Ident::new(s, span)); + } else { + let s: TokenStream = s.parse().expect("invalid token stream"); + tokens.extend(s.into_iter().map(|mut t| { + t.set_span(span); + t + })); + } +} + +macro_rules! push_punct { + ($name:ident $char1:tt) => { + pub fn $name(tokens: &mut TokenStream, span: Span) { + let mut punct = Punct::new($char1, Spacing::Alone); + punct.set_span(span); + tokens.append(punct); + } + }; + ($name:ident $char1:tt $char2:tt) => { + pub fn $name(tokens: &mut TokenStream, span: Span) { + let mut punct = Punct::new($char1, Spacing::Joint); + punct.set_span(span); + tokens.append(punct); + let mut punct = Punct::new($char2, Spacing::Alone); + punct.set_span(span); + tokens.append(punct); + } + }; + ($name:ident $char1:tt $char2:tt $char3:tt) => { + pub fn $name(tokens: &mut TokenStream, span: Span) { + let mut punct = Punct::new($char1, Spacing::Joint); + punct.set_span(span); + tokens.append(punct); + let mut punct = Punct::new($char2, Spacing::Joint); + punct.set_span(span); + tokens.append(punct); + let mut punct = Punct::new($char3, Spacing::Alone); + punct.set_span(span); + tokens.append(punct); + } + }; +} + +push_punct!(push_add '+'); +push_punct!(push_add_eq '+' '='); +push_punct!(push_and '&'); +push_punct!(push_and_and '&' '&'); +push_punct!(push_and_eq '&' '='); +push_punct!(push_at '@'); +push_punct!(push_bang '!'); +push_punct!(push_caret '^'); +push_punct!(push_caret_eq '^' '='); +push_punct!(push_colon ':'); +push_punct!(push_colon2 ':' ':'); +push_punct!(push_comma ','); +push_punct!(push_div '/'); +push_punct!(push_div_eq '/' '='); +push_punct!(push_dot '.'); +push_punct!(push_dot2 '.' '.'); +push_punct!(push_dot3 '.' '.' '.'); +push_punct!(push_dot_dot_eq '.' '.' '='); +push_punct!(push_eq '='); +push_punct!(push_eq_eq '=' '='); +push_punct!(push_ge '>' '='); +push_punct!(push_gt '>'); +push_punct!(push_le '<' '='); +push_punct!(push_lt '<'); +push_punct!(push_mul_eq '*' '='); +push_punct!(push_ne '!' '='); +push_punct!(push_or '|'); +push_punct!(push_or_eq '|' '='); +push_punct!(push_or_or '|' '|'); +push_punct!(push_pound '#'); +push_punct!(push_question '?'); +push_punct!(push_rarrow '-' '>'); +push_punct!(push_larrow '<' '-'); +push_punct!(push_rem '%'); +push_punct!(push_rem_eq '%' '='); +push_punct!(push_fat_arrow '=' '>'); +push_punct!(push_semi ';'); +push_punct!(push_shl '<' '<'); +push_punct!(push_shl_eq '<' '<' '='); +push_punct!(push_shr '>' '>'); +push_punct!(push_shr_eq '>' '>' '='); +push_punct!(push_star '*'); +push_punct!(push_sub '-'); +push_punct!(push_sub_eq '-' '='); + +// Helper method for constructing identifiers from the `format_ident!` macro, +// handling `r#` prefixes. +// +// Directly parsing the input string may produce a valid identifier, +// although the input string was invalid, due to ignored characters such as +// whitespace and comments. Instead, we always create a non-raw identifier +// to validate that the string is OK, and only parse again if needed. +// +// The `is_ident` method defined above is insufficient for validation, as it +// will reject non-ASCII identifiers. +pub fn mk_ident(id: &str, span: Option<Span>) -> Ident { + let span = span.unwrap_or_else(Span::call_site); + + let is_raw = id.starts_with("r#"); + let unraw = Ident::new(if is_raw { &id[2..] } else { id }, span); + if !is_raw { + return unraw; + } + + // At this point, the identifier is raw, and the unraw-ed version of it was + // successfully converted into an identifier. Try to produce a valid raw + // identifier by running the `TokenStream` parser, and unwrapping the first + // token as an `Ident`. + // + // FIXME: When `Ident::new_raw` becomes stable, this method should be + // updated to call it when available. + match id.parse::<TokenStream>() { + Ok(ts) => { + let mut iter = ts.into_iter(); + match (iter.next(), iter.next()) { + (Some(TokenTree::Ident(mut id)), None) => { + id.set_span(span); + id + } + _ => unreachable!("valid raw ident fails to parse"), + } + } + Err(_) => unreachable!("valid raw ident fails to parse"), + } +} + +// Adapts from `IdentFragment` to `fmt::Display` for use by the `format_ident!` +// macro, and exposes span information from these fragments. +// +// This struct also has forwarding implementations of the formatting traits +// `Octal`, `LowerHex`, `UpperHex`, and `Binary` to allow for their use within +// `format_ident!`. +#[derive(Copy, Clone)] +pub struct IdentFragmentAdapter<T: IdentFragment>(pub T); + +impl<T: IdentFragment> IdentFragmentAdapter<T> { + pub fn span(&self) -> Option<Span> { + self.0.span() + } +} + +impl<T: IdentFragment> fmt::Display for IdentFragmentAdapter<T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + IdentFragment::fmt(&self.0, f) + } +} + +impl<T: IdentFragment + fmt::Octal> fmt::Octal for IdentFragmentAdapter<T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::Octal::fmt(&self.0, f) + } +} + +impl<T: IdentFragment + fmt::LowerHex> fmt::LowerHex for IdentFragmentAdapter<T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::LowerHex::fmt(&self.0, f) + } +} + +impl<T: IdentFragment + fmt::UpperHex> fmt::UpperHex for IdentFragmentAdapter<T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::UpperHex::fmt(&self.0, f) + } +} + +impl<T: IdentFragment + fmt::Binary> fmt::Binary for IdentFragmentAdapter<T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::Binary::fmt(&self.0, f) + } +} diff --git a/quote/src/spanned.rs b/quote/src/spanned.rs new file mode 100644 index 0000000..55168bd --- /dev/null +++ b/quote/src/spanned.rs @@ -0,0 +1,42 @@ +use crate::ToTokens; +use proc_macro2::{Span, TokenStream}; + +pub trait Spanned { + fn __span(&self) -> Span; +} + +impl Spanned for Span { + fn __span(&self) -> Span { + *self + } +} + +impl<T: ?Sized + ToTokens> Spanned for T { + fn __span(&self) -> Span { + join_spans(self.into_token_stream()) + } +} + +fn join_spans(tokens: TokenStream) -> Span { + let mut iter = tokens.into_iter().filter_map(|tt| { + // FIXME: This shouldn't be required, since optimally spans should + // never be invalid. This filter_map can probably be removed when + // https://github.com/rust-lang/rust/issues/43081 is resolved. + let span = tt.span(); + let debug = format!("{:?}", span); + if debug.ends_with("bytes(0..0)") { + None + } else { + Some(span) + } + }); + + let first = match iter.next() { + Some(span) => span, + None => return Span::call_site(), + }; + + iter.fold(None, |_prev, next| Some(next)) + .and_then(|last| first.join(last)) + .unwrap_or(first) +} diff --git a/quote/src/to_tokens.rs b/quote/src/to_tokens.rs new file mode 100644 index 0000000..7f98083 --- /dev/null +++ b/quote/src/to_tokens.rs @@ -0,0 +1,209 @@ +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 + } +} |