/// <summary>
/// Creates a new state contianing the given value with a reference to the given graph.
/// </summary>
/// <param name="value"></param>
/// <param name="graph"></param>
public StateNode(T value, StateGraph <TKey, T> graph)
{
fromTransitions = new Dictionary <TKey, StateNode <TKey, T> >();
toTransitions = new List <StateNode <TKey, T> >();
Value = value;
Graph = graph;
}
/// <summary>
/// Creates a new parse table from the given graph.
/// </summary>
/// <param name="graph"></param>
public ParseTable(StateGraph <GrammarElement <T>, LRItem <T>[]> graph, NonTerminal <T> startingElement)
{
ActionTable = new Table <int, Terminal <T>, List <ParserAction <T> > >();
GotoTable = new Table <int, NonTerminal <T>, int?>();
//int state = 0;
//build the parse table from the root of the graph
buildParseTable(graph, startingElement); //, state, startingElement, ref state);
}
/// <summary>
/// Builds the parse table from the given graph and starting element.
/// </summary>
/// <param name="graph"></param>
/// <param name="startingElement"></param>
private void buildParseTable(StateGraph <GrammarElement <T>, LRItem <T>[]> graph, NonTerminal <T> startingElement)
{
if (graph == null)
{
throw new ArgumentNullException("graph");
}
if (startingElement == null)
{
throw new ArgumentNullException("startingElement");
}
//clear the tables
ActionTable.Clear();
GotoTable.Clear();
//get the breadth-first traversal of the graph
List <StateNode <GrammarElement <T>, LRItem <T>[]> > t = graph.GetBreadthFirstTraversal().ToList();
//add the transitions for each node in the traversal
for (var i = 0; i < t.Count; i++)
{
//for each transition in the node, add either a shift action or goto action
foreach (KeyValuePair <GrammarElement <T>, StateNode <GrammarElement <T>, LRItem <T>[]> > transition in t[i].FromTransitions)
{
if (transition.Key is Terminal <T> )
{
//add a shift from this state to the next state
addAction((Terminal <T>)transition.Key, i, new ShiftAction <T>(this, t.IndexOf(transition.Value)));
}
else
{
addGoto((NonTerminal <T>)transition.Key, i, t.IndexOf(transition.Value));
}
}
//for each of the items in the state that are at the end of a production,
//add either a reduce action or accept action
foreach (LRItem <T> item in t[i].Value.Where(a => a.IsAtEndOfProduction()))
{
//if we would reduce to the starting element, then accept
if (item.LeftHandSide.Equals(startingElement))
{
addAction(item.LookaheadElement, i, new AcceptAction <T>(this, item));
}
//otherwise, add a reduce action
else
{
addAction(item.LookaheadElement, i, new ReduceAction <T>(this, item));
}
}
}
}
/// <summary>
/// Creates a new Parse Table from the given State Graph.
/// </summary>
/// <param name="graph"></param>
public ParseTable(StateGraph <GrammarElement <T>, LRItem <T>[]> graph)
{
if (graph.Root != null &&
graph.Root.Value.Length > 0)
{
ActionTable = new Table <int, Terminal <T>, List <ParserAction <T> > >();
GotoTable = new Table <int, NonTerminal <T>, int?>();
buildParseTable(graph, graph.Root.Value.First().LeftHandSide);
}
else
{
throw new ArgumentException("The given graph must have at least one item in the root node.", "graph");
}
}
