This module implements the Cursor container type, which works similar to the .cursor similar to the .cursor pragma. It creates a non-owning and unsafe view into the source location, and is meant as a temporary solution until first-class view-types become stable enough to be used in the compiler.

Once first-class view-types are stable, all usages of Cursor[T] are to be replaced with usage of lent T.

There is nothing preventing the ``Cursor`` living longer than the borrowed from location.

Types

Cursor[T] = distinct ptr T

Not as efficient as a built-in cursor location (i.e. with .cursor), but works when used for fields that are not of ref or closure type.

While neither an intended nor encouraged (it is actively discouraged) use case, compared to .cursor, all modifications to the borrowed- from location through handles other than the Cursor are observable through the cursor.

Source Edit

Procs

func `[]`[T](x: Cursor[T]): lent T {.inline.}: Dereferences the cursor x. A procedure is used instead of a template in order to prevent modifications of the pointed-to location Source Edit

Templates

template `[]`[I: Ordinal; T: seq](s: Cursor[T]; i: I): untyped: Source Edit
template cursor[T](x: T): untyped: Creates an unsafe view into x Source Edit
template len[T: seq](s: Cursor[T]): int: Source Edit

compiler/utils/cursors

Types

Procs

Templates