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.
A delimited sequence of token trees
Use this token tree as a matcher to parse given tts.
Check if this TokenTree is equal to the other, regardless of span information.
Retrieve the TokenTree's span.
Modify the TokenTree
's span in-place.
Indicates if the stream is a token that is equal to the provided token.
Returns the opening delimiter as a token tree.
Returns the closing delimiter as a token tree.
This method tests for self
and other
values to be equal, and is used by ==
. Read more
This method tests for !=
.
Performs copy-assignment from source
. Read more
Formats the value using the given formatter. Read more
Creates owned data from borrowed data, usually by cloning. Read more
🔬 This is a nightly-only experimental API. (toowned_clone_into
)
recently added
Uses borrowed data to replace owned data, usually by cloning. Read more
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
🔬 This is a nightly-only experimental API. (get_type_id
)
this method will likely be replaced by an associated static
Create an error for a missing method specialization. Defaults to panicking with type, trait & method names. S
is the encoder/decoder state type, T
is the type being encoded/decoded, and the arguments are the names of the trait and method that should've been overridden. Read more