Variants

Variants allow one root RIF target to delegate syntax to another RIF file, for example an ARM state and a Thumb state.

Declaration in the Root

@SUPPORTS thumb

@ASMVARIANT thumb:
.MODE SWITCH
.ENTER "ENTER_thumb"
.EXIT "EXIT_thumb"
@END

The variant file is named thumb.rif and is resolved according to the linker searching directory. A variant file may contain only definitions and Rules:

@define thumb_word

@rule ENTER_thumb:
-> KW "thumb"

@rule EXIT_thumb:
-> KW "endthumb"

The root tables, configuration, linker, and other global context remain shared. The variant does not create a second Gram session or an independent symbol space.

Modes

SWITCH describes a state change in the target assembler. ENCAPSULATE describes a nested syntax region. Both modes use .ENTER and .EXIT Rules to define how the transition is emitted and closed.

RIF detects duplicate variant loads and cycles. Before execution, it validates that every .ENTER and .EXIT Rule exists in the shared Rule set.

Package Variants

When a target is packed, variant source files are included in the source graph. The package's dependency order allows the variant files to be loaded without filesystem lookups at runtime.