Enum syn::TokenTree

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 SubstNts it finds.

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

Variants

Token(Token)

A single token

Delimited(Delimited)

A delimited sequence of token trees

Trait Implementations

impl Eq for TokenTree

impl Clone for TokenTree

fn clone(&self) -> TokenTree

Returns a copy of the value.

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

Performs copy-assignment from source.

impl PartialEq<TokenTree> for TokenTree

fn eq(&self, other: &TokenTree) -> bool

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

fn ne(&self, other: &TokenTree) -> bool

This method tests for !=.

impl Hash for TokenTree

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

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

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

impl Debug for TokenTree

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

Formats the value using the given formatter.

impl ToTokens for TokenTree

fn to_tokens(&self, tokens: &mut Tokens)

Write self to the given Tokens.