Move {next,previous}PositionOf() for VisiblePosition to VisibleUnits.cpp

Source/core/editing/VisibleUnits.cpp

Index: Source/core/editing/VisibleUnits.cpp
diff --git a/Source/core/editing/VisibleUnits.cpp b/Source/core/editing/VisibleUnits.cpp
index f60cc4682271ad2669b0e3edcb1fadb6a82e9108..65353feb5cc9d42d40ab4bb5f92ab93931693fe0 100644
--- a/Source/core/editing/VisibleUnits.cpp
+++ b/Source/core/editing/VisibleUnits.cpp
@@ -2337,4 +2337,98 @@ bool isVisuallyEquivalentCandidate(const PositionInComposedTree& position)
     return isVisuallyEquivalentCandidateAlgorithm<EditingInComposedTreeStrategy>(position);
 }
 
+static VisiblePosition skipToEndOfEditingBoundary(const VisiblePosition& pos, const Position& anchor)
+{
+    if (pos.isNull())
+        return pos;
+
+    ContainerNode* highestRoot = highestEditableRoot(anchor);
+    ContainerNode* highestRootOfPos = highestEditableRoot(pos.deepEquivalent());
+
+    // Return |pos| itself if the two are from the very same editable region, or
+    // both are non-editable.
+    if (highestRootOfPos == highestRoot)
+        return pos;
+
+    // If this is not editable but |pos| has an editable root, skip to the end
+    if (!highestRoot && highestRootOfPos)
+        return VisiblePosition(Position(highestRootOfPos, PositionAnchorType::AfterAnchor).parentAnchoredEquivalent());
+
+    // That must mean that |pos| is not editable. Return the next position after
+    // |pos| that is in the same editable region as this position
+    return firstEditableVisiblePositionAfterPositionInRoot(pos.deepEquivalent(), highestRoot);
+}
+
+VisiblePosition nextPositionOf(const VisiblePosition& visiblePosition, EditingBoundaryCrossingRule rule)
+{
+    VisiblePosition next(nextVisuallyDistinctCandidate(visiblePosition.deepEquivalent()), visiblePosition.affinity());
+
+    switch (rule) {
+    case CanCrossEditingBoundary:
+        return next;
+    case CannotCrossEditingBoundary:
+        return honorEditingBoundaryAtOrAfter(next, visiblePosition.deepEquivalent());
+    case CanSkipOverEditingBoundary:
+        return skipToEndOfEditingBoundary(next, visiblePosition.deepEquivalent());
+    }
+    ASSERT_NOT_REACHED();
+    return honorEditingBoundaryAtOrAfter(next, visiblePosition.deepEquivalent());
+}
+
+static VisiblePosition skipToStartOfEditingBoundary(const VisiblePosition& pos, const Position& anchor)
+{
+    if (pos.isNull())
+        return pos;
+
+    ContainerNode* highestRoot = highestEditableRoot(anchor);
+    ContainerNode* highestRootOfPos = highestEditableRoot(pos.deepEquivalent());
+
+    // Return |pos| itself if the two are from the very same editable region, or
+    // both are non-editable.
+    if (highestRootOfPos == highestRoot)
+        return pos;
+
+    // If this is not editable but |pos| has an editable root, skip to the start
+    if (!highestRoot && highestRootOfPos)
+        return VisiblePosition(previousVisuallyDistinctCandidate(Position(highestRootOfPos, PositionAnchorType::BeforeAnchor).parentAnchoredEquivalent()));
+
+    // That must mean that |pos| is not editable. Return the last position
+    // before |pos| that is in the same editable region as this position
+    return lastEditableVisiblePositionBeforePositionInRoot(pos.deepEquivalent(), highestRoot);
+}
+
+VisiblePosition previousPositionOf(const VisiblePosition& visiblePosition, EditingBoundaryCrossingRule rule)
+{
+    Position pos = previousVisuallyDistinctCandidate(visiblePosition.deepEquivalent());
+
+    // return null visible position if there is no previous visible position
+    if (pos.atStartOfTree())
+        return VisiblePosition();
+
+    VisiblePosition prev = VisiblePosition(pos);
+    ASSERT(prev.deepEquivalent() != visiblePosition.deepEquivalent());
+
+#if ENABLE(ASSERT)
+    // we should always be able to make the affinity |TextAffinity::Downstream|,
+    // because going previous from an |TextAffinity::Upstream| position can
+    // never yield another |TextAffinity::Upstream position| (unless line wrap
+    // length is 0!).
+    if (prev.isNotNull() && visiblePosition.affinity() == TextAffinity::Upstream) {
+        ASSERT(inSameLine(PositionWithAffinity(prev.deepEquivalent()), PositionWithAffinity(prev.deepEquivalent(), TextAffinity::Upstream)));
+    }
+#endif
+
+    switch (rule) {
+    case CanCrossEditingBoundary:
+        return prev;
+    case CannotCrossEditingBoundary:
+        return honorEditingBoundaryAtOrBefore(prev, visiblePosition.deepEquivalent());
+    case CanSkipOverEditingBoundary:
+        return skipToStartOfEditingBoundary(prev, visiblePosition.deepEquivalent());
+    }
+
+    ASSERT_NOT_REACHED();
+    return honorEditingBoundaryAtOrBefore(prev, visiblePosition.deepEquivalent());
+}
+
 } // namespace blink