Enum syntax::tokenstream::TokenTree

pub enum TokenTree {
    Token(Span, Token),
    Delimited(DelimSpan, DelimToken, TokenStream),
}

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(Span, Token)

A single token

Delimited(DelimSpan, DelimToken, TokenStream)

A delimited sequence of token trees

Methods

impl TokenTree

pub fn parse(
    cx: &ExtCtxt,
    mtch: &[TokenTree],
    tts: TokenStream
) -> NamedParseResult

Use this token tree as a matcher to parse given tts.

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

Checks if this TokenTree is equal to the other, regardless of span information.

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

pub fn span(&self) -> Span

Retrieves the TokenTree's span.

pub fn set_span(&mut self, span: Span)

Modify the TokenTree's span in-place.

pub fn eq_token(&self, t: Token) -> bool

Indicates if the stream is a token that is equal to the provided token.

pub fn joint(self) -> TokenStream

pub fn open_tt(span: Span, delim: DelimToken) -> TokenTree

Returns the opening delimiter as a token tree.

pub fn close_tt(span: Span, delim: DelimToken) -> TokenTree

Returns the closing delimiter as a token tree.

Trait Implementations

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 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 From<TokenTree> for TokenStream

fn from(tree: TokenTree) -> TokenStream

Performs the conversion.

impl From<TokenTree> for TreeAndJoint

fn from(tree: TokenTree) -> TreeAndJoint

Performs the conversion.

impl Debug for TokenTree

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

Formats the value using the given formatter.

impl Encodable for TokenTree

fn encode<__S: Encoder>(&self, s: &mut __S) -> Result<(), __S::Error>

impl Decodable for TokenTree

fn decode<__D: Decoder>(d: &mut __D) -> Result<TokenTree, __D::Error>