In preparation for exporting an XML proto format for UAM to consume,
this change brings the XML DOM API more in line with other APIs that
do not make the Namespace a separate node.
Treating Namespace declarations as just properties of an Element
node makes the implementation of algorithms much simpler, as
the constraints that Namespace nodes have only one child
are now built in and traversing to find Element nodes
is much simpler.
Also made a bunch of quality of life improvements, like formatting and
comment style.
Test: make aapt2_tests
Change-Id: Ib97ff1c4252b7907e2cc1f13a448dc4ca3b809a4
This change defines some hardcoded rules to degrade
attributes in newer SDKs to specific older attributes.
An attribute with a degrade rule will generate a new XML for the API
in which the attribute resulting from the degradation was introduced.
Since API 22 (Lollipop MR1), attributes are correctly ignored and do
not need to be versioned. In XML files defined for APIs 22+, the
original and degraded attributes coexist in the same XML file.
One such example is paddingHorizontal, introduced in API 26.
paddingHorizontal degrades to paddingLeft and paddingRight, which
were both introduced in API 1.
Bug: 35763493
Test: make aapt2_tests
Change-Id: I4aa8755a9ee2c0cc5afdc55c3d30093fd3a47f3d
