# Enum syn::TokenTree [−] [src]

    pub enum TokenTree {
        Token(Token),
        Delimited(Delimited),
    }

When the main rust parser encounters a syntax-extension invocation, it parses the arguments to the invocation as a token-tree. This is a very loose structure, such that all sorts of different AST-fragments can be passed to syntax extensions using a uniform type.

If the syntax extension is an MBE macro, it will attempt to match its LHS token tree against the provided token tree, and if it finds a match, will transcribe the RHS token tree, splicing in any captured `macro_parser::matched_nonterminals` into the `SubstNt`s it finds.

The RHS of an MBE macro is the only place `SubstNt`s are substituted. Nothing special happens to misnamed or misplaced `SubstNt`s.

## Variants

`Token(Token)`

A single token

`Delimited(Delimited)`

A delimited sequence of token trees

## Trait Implementations

### `impl ToTokens for TokenTree`
[src]

#### `fn to_tokens(&self, tokens: &mut Tokens)`
[src]

Write `self` to the given `Tokens`. Read more

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

#### `fn fmt(&self, __arg_0: &mut Formatter) -> Result`
[src]

Formats the value using the given formatter. Read more

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

#### `fn clone(&self) -> TokenTree`
[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 Eq for TokenTree`
[src]

### `impl PartialEq for TokenTree`
[src]

#### `fn eq(&self, __arg_0: &TokenTree) -> bool`
[src]

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

#### `fn ne(&self, __arg_0: &TokenTree) -> bool`
[src]

This method tests for `!=`.

### `impl Hash for TokenTree`
[src]

#### `fn hash<__H: Hasher>(&self, __arg_0: &mut __H)`
[src]

Feeds this value into the given [`Hasher`]. Read more

#### `fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,`
1.3.0
[src]

Feeds a slice of this type into the given [`Hasher`]. Read more

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)