internal void ReplaceSource(NfaNode oldSource, NfaNode newSource)
{
// owner is the target node here
unlink(owner.Connections.from, oldSource);
foreach (NfaEdge.Fiber fiber in unlink(oldSource.Connections.to, owner))
{
Link(newSource, fiber, owner);
}
}
internal void ReplaceTarget(NfaNode oldTarget, NfaNode newTarget)
{
// owner is the source node here
unlink(owner.Connections.to, oldTarget);
foreach (NfaEdge.Fiber fiber in unlink(oldTarget.Connections.from, owner))
{
Link(owner, fiber, newTarget);
}
}
internal void ConnectTo(NfaNode targetNode, NfaEdge edge)
{
// store current edges, to work with clear space between given nodes
Connections this_connections = this.Connections.Reset();
Connections targetNode_connections = targetNode.Connections.Reset();
// fibers in edge are sorted from the longest to the shortest
foreach (IEnumerable <NfaEdge.Fiber> fiber_chain in edge.Fibers)
{
connectBetween(this, targetNode, fiber_chain.Reverse());
}
// merge previous edges with newly created
this.Connections.Merge(this_connections);
targetNode.Connections.Merge(targetNode_connections);
}
// UTF-8 by definition differentiates head of bytes, but the tail can be shared
// thus we handle the chain in reverse order to merge the tails
static private void connectBetween(NfaNode start, NfaNode end, IEnumerable <NfaEdge.Fiber> revFiberChain)
{
if (revFiberChain.Count() == 1)
{
start.linkTo(end, revFiberChain.Single());
}
else
{
NfaNode prec_node = end.Connections.From
.Where(it => it.Item1.Equals(revFiberChain.First()))
.Select(it => it.Item2)
.SingleOrDefault();
if (prec_node == null)
{
prec_node = new NfaNode();
prec_node.linkTo(end, revFiberChain.First());
}
connectBetween(start, prec_node, revFiberChain.Skip(1));
}
}
private void linkTo(NfaNode target, NfaEdge.Fiber fiber)
{
Connections.Link(this, fiber, target);
}
internal Nfa()
{
this.StartNode = new NfaNode();
}
static private IEnumerable <NfaEdge.Fiber> unlink(List <Tuple <NfaEdge.Fiber, NfaNode> > links, NfaNode node)
{
var removed = new List <NfaEdge.Fiber>();
for (int i = links.Count - 1; i >= 0; --i)
{
if (links[i].Item2 == node)
{
removed.Add(links[i].Item1);
links.RemoveAt(i);
}
}
return(removed);
}
static internal void Link(NfaNode source, NfaEdge.Fiber fiber, NfaNode target)
{
source.Connections.to.Add(Tuple.Create(fiber, target));
target.Connections.from.Add(Tuple.Create(fiber, source));
}
internal Connections(NfaNode owner)
{
this.owner = owner;
init();
}
