Enum SyntaxExtensionKind

pub enum SyntaxExtensionKind {
    Bang(Box<dyn BangProcMacro + DynSync + DynSend>),
    LegacyBang(Box<dyn TTMacroExpander + DynSync + DynSend>),
    Attr(Box<dyn AttrProcMacro + DynSync + DynSend>),
    LegacyAttr(Box<dyn MultiItemModifier + DynSync + DynSend>),
    NonMacroAttr,
    Derive(Box<dyn MultiItemModifier + DynSync + DynSend>),
    LegacyDerive(Box<dyn MultiItemModifier + DynSync + DynSend>),
    GlobDelegation(Box<dyn GlobDelegationExpander + DynSync + DynSend>),
}

A syntax extension kind.

Variants

Bang(Box<dyn BangProcMacro + DynSync + DynSend>)

A token-based function-like macro.

Tuple Fields

0: Box<dyn BangProcMacro + DynSync + DynSend>

An expander with signature TokenStream -> TokenStream.

LegacyBang(Box<dyn TTMacroExpander + DynSync + DynSend>)

An AST-based function-like macro.

Tuple Fields

0: Box<dyn TTMacroExpander + DynSync + DynSend>

An expander with signature TokenStream -> AST.

Attr(Box<dyn AttrProcMacro + DynSync + DynSend>)

A token-based attribute macro.

Tuple Fields

0: Box<dyn AttrProcMacro + DynSync + DynSend>

An expander with signature (TokenStream, TokenStream) -> TokenStream. The first TokenStream is the attribute itself, the second is the annotated item. The produced TokenStream replaces the input TokenStream.

LegacyAttr(Box<dyn MultiItemModifier + DynSync + DynSend>)

An AST-based attribute macro.

Tuple Fields

0: Box<dyn MultiItemModifier + DynSync + DynSend>

An expander with signature (AST, AST) -> AST. The first AST fragment is the attribute itself, the second is the annotated item. The produced AST fragment replaces the input AST fragment.

NonMacroAttr

A trivial attribute “macro” that does nothing, only keeps the attribute and marks it as inert, thus making it ineligible for further expansion.

Derive(Box<dyn MultiItemModifier + DynSync + DynSend>)

A token-based derive macro.

Tuple Fields

0: Box<dyn MultiItemModifier + DynSync + DynSend>

An expander with signature TokenStream -> TokenStream. The produced TokenStream is appended to the input TokenStream.

FIXME: The text above describes how this should work. Currently it is handled identically to LegacyDerive. It should be migrated to a token-based representation like Bang and Attr, instead of using MultiItemModifier.

LegacyDerive(Box<dyn MultiItemModifier + DynSync + DynSend>)

An AST-based derive macro.

Tuple Fields

0: Box<dyn MultiItemModifier + DynSync + DynSend>

An expander with signature AST -> AST. The produced AST fragment is appended to the input AST fragment.

GlobDelegation(Box<dyn GlobDelegationExpander + DynSync + DynSend>)

A glob delegation.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 24 bytes

Size for each variant:

• Bang: 16 bytes
• LegacyBang: 16 bytes
• Attr: 16 bytes
• LegacyAttr: 16 bytes
• NonMacroAttr: 0 bytes
• Derive: 16 bytes
• LegacyDerive: 16 bytes
• GlobDelegation: 16 bytes