commit 38e9f84f23e9694d414a257afc74da5210f68b59
author Nektarios Paisios <nektar@chromium.org> Thu Jul 29 11:36:44 2021
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Jul 29 11:36:44 2021
tree a1707b560a379349efbfb72b743442786698d880
parent 5ebd6820c3a0acb25185585c7f452f898fdbef24

Fixes comparisons between two positions that are in different subtrees

There are two modes in which AXPosition can work:
1. On Windows and Linux, non-leaf nodes expose an embedded object character for every child node.
2. On all other platforms non-leaf nodes expose their inner text.
Both modes are essential for the correct functioning of AXPosition.
For the first mode however, when two AXPositions are compared, and at least one of them
is a text position, we would erroniously try to compare the two positions
at their common anchor by first adjusting the positions to be after the embedded object character representing
their common anchor. This was in order to comply with the IAccessible2 Spec which dictates that
any position inside an embedded object, unless if it is at its start, should be represented by a position right after it, in order for
selection to work properly with existing assistive software.
However, if the positions compared are in different subtrees branching off the common anchor, making this
adjustment would be both unnecessary as well as erronious:
++kRootWebArea <embedded_object> <embedded_object>
++++kParagraph "1"
++++kParagraph "2"
A text position right after "1" in the first paragraph when compared with a text/tree position right before the second paragraph,
would erroniously compare as equal. However, even though logically these two positions appear to be
equal, in practice they are not because the first could represent a paragraph end boundary, whilst
the second a paragraph start boundary.
This would be made important when we fix paragraph end boundaries in an upcoming patch.

Also, adds a few missing "else" keywords, which by their absence were
causing some computational work (possibly expensive work) to be repeated twice.

Lastly, comments were updated and made easier to understand.

Split out from:
https://chromium-review.googlesource.com/c/chromium/src/+/3001275/

R=dmazzoni@chromium.org

AX-Relnotes: n/a.
Bug: 1135589, 1147543, 1027753, 1015408
Change-Id: Ia19a5939bae8d706260d7dc72b7d7a342a2d6c32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3056923
Commit-Queue: Nektarios Paisios <nektar@chromium.org>
Auto-Submit: Nektarios Paisios <nektar@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Adam Ettenberger <Adam.Ettenberger@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#906659}