Enum proc_macro::Spacing
1.29.0 · source · pub enum Spacing {
Joint,
Alone,
}Expand description
Indicates whether a Punct token can join with the following token
to form a multi-character operator.
Variants§
Joint
A Punct token can join with the following token to form a multi-character operator.
In token streams constructed using proc macro interfaces, Joint punctuation tokens can be
followed by any other tokens. However, in token streams parsed from source code, the
compiler will only set spacing to Joint in the following cases.
- When a
Punctis immediately followed by anotherPunctwithout a whitespace. E.g.+isJointin+=and++. - When a single quote
'is immediately followed by an identifier without a whitespace. E.g.'isJointin'lifetime.
This list may be extended in the future to enable more token combinations.
Alone
A Punct token cannot join with the following token to form a multi-character operator.
Alone punctuation tokens can be followed by any other tokens. In token streams parsed
from source code, the compiler will set spacing to Alone in all cases not covered by the
conditions for Joint above. E.g. + is Alone in + =, +ident and +(). In
particular, tokens not followed by anything will be marked as Alone.