Struct proc_macro::TokenStream

pub struct TokenStream(_);

The main type provided by this crate, representing an abstract stream of tokens, or, more specifically, a sequence of token trees. The type provide 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.

The API of this type is intentionally bare-bones, but it'll be expanded over time!

Methods

impl TokenStream

pub fn empty() -> TokenStream

🔬 This is a nightly-only experimental API. (proc_macro #38356)

Returns an empty TokenStream containing no token trees.

pub fn is_empty(&self) -> bool

🔬 This is a nightly-only experimental API. (proc_macro #38356)

Checks if this TokenStream is empty.

Trait Implementations

impl IntoIterator for TokenStream

type Item = TokenTree

The type of the elements being iterated over.

type IntoIter = IntoIter

Which kind of iterator are we turning this into?

Important traits for IntoIter

impl Iterator for IntoIter type Item = TokenTree;

fn into_iter(self) -> IntoIter

Creates an iterator from a value.

impl Clone for TokenStream

fn clone(&self) -> TokenStream

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl !Send for TokenStream

impl !Sync for TokenStream

impl FromStr for TokenStream

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.

NOTE: Some errors may cause panics instead of returning LexError. We reserve the right to change these errors into LexErrors later.

type Err = LexError

The associated error which can be returned from parsing.

fn from_str(src: &str) -> Result<TokenStream, LexError>

Parses a string s to return a value of this type.

impl Display for TokenStream

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.

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Debug for TokenStream

Prints token in a form convenient for debugging.

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl From<TokenTree> for TokenStream

Creates a token stream containing a single token tree.

fn from(tree: TokenTree) -> TokenStream

Performs the conversion.

impl FromIterator<TokenTree> for TokenStream

Collects a number of token trees into a single stream.

fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self

Creates a value from an iterator.

impl FromIterator<TokenStream> for TokenStream

A "flattening" operation on token streams, collects token trees from multiple token streams into a single stream.

fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self

Creates a value from an iterator.