private void merge(ElementNavigator snap, ElementNavigator diff)
{
(new ElementDefnMerger(_markChanges)).Merge(snap.Current, diff.Current);
// If there are children, move into them, and recursively merge them
if (diff.MoveToFirstChild())
{
if (!snap.HasChildren)
{
// The differential moves into an element that has no children in the base.
// This is allowable if the base's element has a nameReference or a TypeRef,
// in which case needs to be expanded before we can move to the path indicated
// by the differential
if (snap.Current.Type.Count > 1)
throw new NotSupportedException("Differential has a constraint on a choice element {0}, but does so without using a type slice".FormatWith(diff.Path));
expandBaseElement(snap, diff);
}
// Due to how MoveToFirstChild() works, we have to move to the first matching *child*
// when entering the loop for the first time, after that we can look for the next
// matching *sibling*.
bool firstEntry = true;
do
{
if ((firstEntry && !snap.MoveToChild(diff.PathName)) ||
(!firstEntry && !snap.MoveTo(diff.PathName)) ) // HACK: I don't think it should be allowed for a diff to list constraints in the wrong order...
{
throw Error.InvalidOperation("Differential has a constraint for path '{0}', which does not exist in its base", diff.Path);
}
firstEntry = false;
// Child found in both, merge them
if (countChildNameRepeats(diff) > 1 || diff.Current.IsExtension())
{
// The child in the diff repeats or we recognize it as an extension slice -> we're on the first element of a slice!
mergeSlice(snap, diff);
}
else
merge(snap, diff);
}
while (diff.MoveToNext());
// After the merge, return the diff and snapho back to their original position
diff.MoveToParent();
snap.MoveToParent();
}
}