TokenStream in proc_macro - Rust (original) (raw)
Struct TokenStream
1.15.0 · Source
pub struct TokenStream(/* private fields */);Expand description
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.
This is both the input and output of #[proc_macro], #[proc_macro_attribute]and #[proc_macro_derive] definitions.
1.29.0 · Source
Returns an empty TokenStream containing no token trees.
1.29.0 · Source
Checks if this TokenStream is empty.
🔬This is a nightly-only experimental API. (proc_macro_expand #90765)
Parses this TokenStream as an expression and attempts to expand any macros within it. Returns the expanded TokenStream.
Currently only expressions expanding to literals will succeed, although this may be relaxed in the future.
NOTE: In error conditions, expand_expr may leave macros unexpanded, report an error, failing compilation, and/or return an Err(..). The specific behavior for any error condition, and what conditions are considered errors, is unspecified and may change in the future.
Prints token in a form convenient for debugging.
Prints the token stream as a string that is supposed to be losslessly convertible back into the same token stream (modulo spans), except for possibly TokenTree::Groups with Delimiter::None delimiters and negative numeric literals.
Note: the exact form of the output is subject to change, e.g. there might be changes in the whitespace used between tokens. Therefore, you should_not_ do any kind of simple substring matching on the output string (as produced by to_string) to implement a proc macro, because that matching might stop working if such changes happen. Instead, you should work at theTokenTree level, e.g. matching against TokenTree::Ident,TokenTree::Punct, or TokenTree::Literal.
Extends a collection with the contents of an iterator. Read more
🔬This is a nightly-only experimental API. (extend_one #72631)
Extends a collection with exactly one element.
🔬This is a nightly-only experimental API. (extend_one #72631)
Reserves capacity in a collection for the given number of additional elements. Read more
Extends a collection with the contents of an iterator. Read more
🔬This is a nightly-only experimental API. (extend_one #72631)
Extends a collection with exactly one element.
🔬This is a nightly-only experimental API. (extend_one #72631)
Reserves capacity in a collection for the given number of additional elements. Read more
Creates a token stream containing a single token tree.
Converts to this type from the input type.
A “flattening” operation on token streams, collects token trees from multiple token streams into a single stream.
Collects a number of token trees into a single stream.
Attempts to break the string into tokens and parse those tokens into a token stream. May fail for a number of reasons, for example, if the string contains unbalanced delimiters or characters not existing in the language. All tokens in the parsed stream get Span::call_site() spans.
NOTE: some errors may cause panics instead of returning LexError. We reserve the right to change these errors into LexErrors later.
The associated error which can be returned from parsing.
Parses a string s to return a value of this type. Read more
The type of the elements being iterated over.
Which kind of iterator are we turning this into?
Creates an iterator from a value. Read more
🔬This is a nightly-only experimental API. (proc_macro_totokens #130977)
Write self to the given TokenStream. Read more
🔬This is a nightly-only experimental API. (proc_macro_totokens #130977)
Convert self directly into a TokenStream object. Read more
🔬This is a nightly-only experimental API. (proc_macro_totokens #130977)
Convert self directly into a TokenStream object. Read more