tree 67e8afbdada19fa3b7a4cf8111ef580989d6dc27
parent 489a9e5cdf7ca30c789feeca5081d367c7474006
author Googler <noreply@google.com> 1573758085 -0800
committer Copybara-Service <copybara-worker@google.com> 1573758231 -0800

bazel syntax: simplify StarlarkMutable

A sequence may be mutable (list) or not (tuple, range).
This change breaks the subclass relationship between Sequence
and StarlarkMutable so that Tuple and RangeList do not implement it.

This change also deletes the StarlarkMutable abstract base classes
(BaseMutableWrapper, MutableCollection, BaseMutableList, MutableMap), partly
because they would now require Mutable and non-Mutable variants,
but more importantly because, through getContentsUnsafe, they force
inefficiency on all concrete implementations: either the internal representation
must itself be a List, which adds another allocation and indirection, or
getContentsUnsafe must lazily allocate a List wrapper, which generates
unnecessary garbage. A follow-up change will move the accessor methods
down into list and tuple and specialize them to the representation.

Pushing MutableMap down into Dict caused it to have two methods named get,
one annotated and one not. This exposed a bug in which
SkylarkInterfaceUtils.getSkylarkCallable gets confused
as two which method has the annotation.
For now I renamed Dict.get to get2 as the fix is slightly tricky.

StarlarkMutable's lock and unlock methods were in effect moved to EvalUtils.
Its isImmutable and isHashable methods are left abstract. They are
easy enough for subclasses to implement.

The StarlarkMutable class was effectively a "mix in", a base class that one
extends to get some help with implementation. Mixins are not a good
fit with single-inheritance OO languages. This change makes it an interface
with a default implementation of its sole remaining method, checkMutability,
that subclasses should really not override.

Also:
- update the two flavors (mutable/immutable) of Args
- delete mutability methods of RangeList and Tuple.
- delete SHALLOW_IMMUTABLE, which is no longer needed.
- remove unused Mutability from test of serialization.
- add some TODOs.
PiperOrigin-RevId: 280466438