private async Task <node> getNodeAt(
long index, IAccessContext <CSScope> context)
{
return(await context.InChild(
new CSScope(valueScope : InfiniteIntervalScope.Create(
RWScope.Read, 0, index + 1),
name : $"scope for getNodeAt {index}"),
async subContext =>
{
await subContext.UntilAvailable(new CSScope(valueScope :
InfiniteIntervalScope.Create(RWScope.Read, 0, 1),
name : $"UntilAvailable scope in getNodeAt {index}"));
node currentNode = state.FirstNode;
for (long i = 1; i <= index; i++)
{
await subContext.UntilAvailable(new CSScope(
valueScope: InfiniteIntervalScope.Create(
RWScope.Read, i, i + 1),
name: "UntilAvailable scope in " +
$"getNodeAt {index}"));
currentNode = currentNode.Successor;
}
return currentNode;
}));
}
private async Task <Tuple <node, int> > getLastNode(
node startNode, int startIndex, IAccessContext <CSScope> context)
{
return(await context.InChild(
new CSScope(valueScope : InfiniteIntervalScope.Create(
RWScope.Read, startIndex + 1, null)),
async subContext =>
{
node currentNode = startNode;
for (int index = startIndex + 1; ; index++)
{
/* read the node at position index */
await subContext.UntilAvailable(new CSScope(valueScope:
InfiniteIntervalScope.Create(
RWScope.Read, index, index + 1)));
if (currentNode.Successor == null)
{
return Tuple.Create(currentNode, index - 1);
}
currentNode = currentNode.Successor;
subContext.RequiredScope = new CSScope(valueScope:
InfiniteIntervalScope.Create(
RWScope.Read, index + 1, null));
}
}));
}
private async Task <Tuple <node, int> > getLastNode(
IAccessContext <CSScope> context,
node startNode = null, int startIndex = -1)
{
if (startNode == null)
{
startIndex = -1;
}
return(await context.InChild(new CSScope(
valueScope : InfiniteIntervalScope.Create(
RWScope.Read, startIndex + 1, null),
name : "scope for getLastNode"),
async subContext =>
{
if (startNode == null)
{
node firstNode = await getFirstNode(subContext);
if (firstNode == null)
{
return null;
}
startNode = firstNode;
startIndex = 0;
}
var t = getLastNode(startNode, startIndex, subContext);
subContext.Dispose();
return await t;
}));
}
private async Task incrementNextIndex(
IAccessContext <enumeratorScope> subContext)
{
/* These two statemets (InChild and UntilAvailable)
* could possibly be combined to a single
* (extension) method for AccessContext. */
await subContext.InChild(new enumeratorScope(
nextIndex : RWScope.ReadWrite), async c =>
{
await subContext.UntilAvailable();
nextIndex++;
});
}