Crate `proc_macro`

A support library for macro authors when defining new macros.

This library, provided by the standard distribution, provides the types consumed in the interfaces of procedurally defined macro definitions such as function-like macros #[proc_macro], macro attributes #[proc_macro_attribute] and custom derive attributes #[proc_macro_derive].

See the book for more.

Modules

token_stream Public implementation details for the TokenStream type, such as iterators.
tracked Functionality for adding environment state to the build dependency info.

Structs

Diagnostic A structure representing a diagnostic message and associated children messages.
ExpandError Error returned from TokenStream::expand_expr.
Group A delimited token stream.
Ident An identifier (ident).
LexError Error returned from TokenStream::from_str.
Literal A literal string ("hello"), byte string (b"hello"), C string (c"hello"), character ('a'), byte character (b'a'), an integer or floating point number with or without a suffix (1, 1u8, 2.3, 2.3f32). Boolean literals like true and false do not belong here, they are Idents.
Punct A Punct is a single punctuation character such as +, - or #.
Span A region of source code, along with macro expansion information.
TokenStream The main type provided by this crate, representing an abstract stream of tokens, or, more specifically, a sequence of token trees. The type provides interfaces for iterating over those token trees and, conversely, collecting a number of token trees into one stream.

Enums

ConversionErrorKind Errors returned when trying to retrieve a literal unescaped value.
Delimiter Describes how a sequence of token trees is delimited.
EscapeError
Level An enum representing a diagnostic level.
Spacing Indicates whether a Punct token can join with the following token to form a multi-character operator.
TokenTree A single token or a delimited sequence of token trees (e.g., [1, (), ..]).

Traits

MultiSpan Trait implemented by types that can be converted into a set of Spans.
ToTokens Types that can be interpolated inside a quote! invocation.

Functions

is_available Determines whether proc_macro has been made accessible to the currently running program.

Macros

quote quote!(..) accepts arbitrary tokens and expands into a TokenStream describing the input. For example, quote!(a + b) will produce an expression, that, when evaluated, constructs the TokenStream [Ident("a"), Punct('+', Alone), Ident("b")].