# [−] [src] Struct proc_macro2::TokenStream

    pub struct TokenStream { /* fields omitted */ }

An abstract stream of tokens, or more concretely a sequence of token trees.

This type provides interfaces for iterating over token trees and for collecting token trees into one stream.

Token stream is both the input and output of `#[proc_macro]`, `#[proc_macro_attribute]` and `#[proc_macro_derive]` definitions.

## Implementations

### `impl TokenStream` [src]

#### `pub fn new() -> TokenStream` [src]

Returns an empty `TokenStream` containing no token trees.

#### `pub fn is_empty(&self) -> bool` [src]

Checks if this `TokenStream` is empty.

## Trait Implementations

### `impl Clone for TokenStream` [src]

#### `fn clone(&self) -> TokenStream` [src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl Debug for TokenStream` [src]

Prints token in a form convenient for debugging.

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl Default for TokenStream` [src]

`TokenStream::default()` returns an empty stream, i.e. this is equivalent with `TokenStream::new()`.

#### `fn default() -> Self` [src]

Returns the "default value" for a type. Read more

### `impl Display for TokenStream` [src]

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::Group`s with `Delimiter::None` delimiters and negative numeric literals.

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl Extend<TokenStream> for TokenStream` [src]

#### `fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I)` [src]

Extends a collection with the contents of an iterator. Read more

#### `fn extend_one(&mut self, item: A)` [src]

🔬 This is a nightly-only experimental API. (`extend_one`)

Extends a collection with exactly one element.

#### `fn extend_reserve(&mut self, additional: usize)` [src]

🔬 This is a nightly-only experimental API. (`extend_one`)

Reserves capacity in a collection for the given number of additional elements. Read more

### `impl Extend<TokenTree> for TokenStream` [src]

#### `fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, streams: I)` [src]

Extends a collection with the contents of an iterator. Read more

#### `fn extend_one(&mut self, item: A)` [src]

🔬 This is a nightly-only experimental API. (`extend_one`)

Extends a collection with exactly one element.

#### `fn extend_reserve(&mut self, additional: usize)` [src]

🔬 This is a nightly-only experimental API. (`extend_one`)

Reserves capacity in a collection for the given number of additional elements. Read more

### `impl From<TokenStream> for TokenStream` [src]

#### `fn from(inner: TokenStream) -> TokenStream` [src]

Performs the conversion.

### `impl From<TokenStream> for TokenStream` [src]

#### `fn from(inner: TokenStream) -> TokenStream` [src]

Performs the conversion.

### `impl From<TokenTree> for TokenStream` [src]

#### `fn from(token: TokenTree) -> Self` [src]

Performs the conversion.

### `impl FromIterator<TokenStream> for TokenStream` [src]

#### `fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self` [src]

Creates a value from an iterator. Read more

### `impl FromIterator<TokenTree> for TokenStream` [src]

Collects a number of token trees into a single stream.

#### `fn from_iter<I: IntoIterator<Item = TokenTree>>(streams: I) -> Self` [src]

Creates a value from an iterator. Read more

### `impl FromStr for TokenStream` [src]

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 `LexError`s later.

#### `type Err = LexError`

The associated error which can be returned from parsing.

#### `fn from_str(src: &str) -> Result<TokenStream, LexError>` [src]

Parses a string `s` to return a value of this type. Read more

### `impl IntoIterator for TokenStream` [src]

#### `type Item = TokenTree`

The type of the elements being iterated over.

#### `type IntoIter = IntoIter`

Which kind of iterator are we turning this into?

#### `fn into_iter(self) -> IntoIterⓘ

### Notable traits for IntoIter

`impl Iterator for IntoIter type Item = TokenTree;`
` [src]

Creates an iterator from a value. Read more

## Auto Trait Implementations

### `impl RefUnwindSafe for TokenStream`

### `impl !Send for TokenStream`

### `impl !Sync for TokenStream`

### `impl Unpin for TokenStream`

### `impl UnwindSafe for TokenStream`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<I> IntoIterator for I where
I: Iterator,` [src]

#### `type Item = <I as Iterator>::Item`

The type of the elements being iterated over.

#### `type IntoIter = I`

Which kind of iterator are we turning this into?

#### `pub fn into_iter(self) -> I` [src]

Creates an iterator from a value. Read more

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `pub fn to_owned(&self) -> T` [src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `pub fn clone_into(&self, target: &mut T)` [src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into`)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T> ToString for T where
T: Display + ?Sized,` [src]

#### `pub default fn to_string(&self) -> String` [src]

Converts the given value to a `String`. Read more

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.