Enum syntex_syntax::ast::TokenTree
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[src]
pub enum TokenTree {
Token(Span, Token),
Delimited(Span, Rc<Delimited>),
Sequence(Span, Rc<SequenceRepetition>),
}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 | A single token |
Delimited | A delimited sequence of token trees |
Sequence | A kleene-style repetition sequence with a span |
Methods
impl TokenTree
fn len(&self) -> usize
fn get_tt(&self, index: usize) -> TokenTree
fn get_span(&self) -> Span
Returns the Span corresponding to this token tree.
fn parse(cx: &ExtCtxt, mtch: &[TokenTree], tts: &[TokenTree]) -> NamedParseResult
Use this token tree as a matcher to parse given tts.