/// <summary>
/// Constructor that make a copy a input Lr1Element
/// </summary>
public LR1Element(LR1Element inputLR1)
{
Left = new Token(inputLR1.Left.Content, inputLR1.Left.IsTerminal);
Alpha = new List <Token>(inputLR1.Alpha);
Gamma = new List <Token>(inputLR1.Gamma);
Advance = new List <Token>(inputLR1.Advance);
}
/// <summary>
/// Construction of the first: LR1 element and node.
/// </summary>
/// <returns></returns>
private Node GenerateFirstNode()
{
Production FirstProduction = Productions.First();
Node I0 = new Node();
//first LR1 element
LR1Element FirstElement = new LR1Element(FirstProduction, new List <Token>()
{
new Token("$", true)
});
I0.Elements.Add(FirstElement);
I0 = Cerradura(I0);
return(I0);
}
/// <summary>
/// Handles the expansion of Lr1 elements.
/// </summary>
/// <param name="CurrentNode"></param>
/// <returns></returns>
private Node Cerradura(Node CurrentNode)
{
bool SomethingIsAdded;
do //repeat until there are no more new elements
{
SomethingIsAdded = false;
foreach (LR1Element NodeItem in CurrentNode.Elements.ToList())
{
//General syntax [A -> α.Bβ, {a1, a2, ..an}]
if (NodeItem.Gamma.Count > 0) //only if there is something after the dot
{
Token B = NodeItem.Gamma.First();
if (B.IsTerminal == false)
{
List <Token> βa = new List <Token>();
List <Token> β = new List <Token>(NodeItem.Gamma); //Add all the Gamma tokens
β.RemoveAt(0); //Except for the first token
foreach (Token a in NodeItem.Advance) //Loops for all the Elements from Advance
{
List <Token> ResPrimAdv = new List <Token>(β);
ResPrimAdv.Add(a);
ResPrimAdv = Prims.GetPrimerosDe(ResPrimAdv);
βa.AddRange(ResPrimAdv); //Adding GetPrimerosDe() result
}
βa = βa.Distinct().ToList(); //Deleting all the duplicates
List <Production> BProductions = Productions.FindAll(pred => pred.Left.Content == B.Content);
foreach (Production BProduction in BProductions.ToList())
{
//Finds all productions of B and convert to the Lr1elements of the form [B -> .γ, b]
LR1Element BLr1Token = new LR1Element(BProduction, βa); //construction B-Production
if (!CurrentNode.CheckIfElementExist(BLr1Token))
{
//isnt a repeated Lr1 token so its added to the elements list
CurrentNode.Elements.Add(BLr1Token);
SomethingIsAdded = true;
}
}
}
}
}
} while (SomethingIsAdded);
return(CurrentNode);
}
/// <summary>
/// Links a node with a grammatical symbol to generate new nodes.
/// </summary>
/// <param name="CurrentNode"></param>
/// <param name="X"></param>
/// <returns></returns>
private Node Ir_A(Node CurrentNode, Token X)
{
Node J = new Node();
// for each element [A -> α.Xβ, a] on CurrentNode
foreach (LR1Element Lr1item in CurrentNode.Elements.ToList())
{
if (Lr1item.Gamma.Count > 0) //only if there is something after the dot
{
if (Lr1item.Gamma.First().Content == X.Content) //finded
{
LR1Element Lr1ToAdd = new LR1Element(Lr1item);
Lr1ToAdd.Alpha.Add(Lr1ToAdd.Gamma.First()); //adds X on alpha
Lr1ToAdd.Gamma.RemoveAt(0); //removes X from gamma
J.Elements.Add(Lr1ToAdd);
}
}
}
return(Cerradura(J));
}
/// <summary>
/// Fast method that verifies if there is already an Lr1 token in the node's elements.
/// </summary>
/// <param name="Lr1Token"></param>
/// <returns></returns>
public bool CheckIfElementExist(LR1Element Lr1Token)
{
return(Elements.Any(pred => pred.ToString() == Lr1Token.ToString()));
}
/// Ejemeplo con la información absolutamente necesaria para
/// representar el siguiente AFD
private void InitTestAFD()
{
AFD = new List <Node>();
// Tokens
Token tE = new Token("E", false);
Token tN = new Token("n", true);
Token tP = new Token("+", true);
Token tM = new Token("-", true);
// Lista auxiliar para guadar tokens de anticipacion {$, +, -}
// Este conjunto de tokens se repiten varias veces en este test.
List <Token> commonAdvanceTokens = new List <Token>();
commonAdvanceTokens.Add(new Token("$", true));
commonAdvanceTokens.Add(tP);
commonAdvanceTokens.Add(tM);
// _________________________________________________________________
// Info for Node 0
// _________________________________________________________________
Node n0 = new Node();
n0.Edges.Add(1, tE);
n0.Edges.Add(6, tN);
// _________________________________________________________________
// Info for Node 1
// _________________________________________________________________
Node n1 = new Node();
LR1Element n1elem0 = new LR1Element(); // Node 1 Element 0
n1elem0.Left = new Token("E'", false);
n1elem0.Alpha.Add(tE);
n1elem0.Advance.Add(new Token("$", true));
n1.Elements.Add(n1elem0);
n1.Edges.Add(2, tP);
n1.Edges.Add(4, tM);
// _________________________________________________________________
// Info for Node 2
// _________________________________________________________________
Node n2 = new Node();
n2.Edges.Add(3, tN);
// _________________________________________________________________
// Info for Node 3
// _________________________________________________________________
Node n3 = new Node();
LR1Element n3elem0 = new LR1Element(); // Node 3 Element 0
n3elem0.Left = tE;
n3elem0.Alpha.Add(tE);
n3elem0.Alpha.Add(tP);
n3elem0.Alpha.Add(tN);
n3elem0.Advance.AddRange(commonAdvanceTokens);
n3.Elements.Add(n3elem0);
// _________________________________________________________________
// Info for Node 4
// _________________________________________________________________
Node n4 = new Node();
n4.Edges.Add(5, tN);
// _________________________________________________________________
// Info for Node 5
// _________________________________________________________________
Node n5 = new Node();
LR1Element n5elem0 = new LR1Element(); // Node 5 Element 0
n5elem0.Left = tE;
n5elem0.Alpha.Add(tE);
n5elem0.Alpha.Add(tM);
n5elem0.Alpha.Add(tN);
n5elem0.Advance.AddRange(commonAdvanceTokens);
n5.Elements.Add(n5elem0);
// _________________________________________________________________
// Info for Node 6
// _________________________________________________________________
Node n6 = new Node();
LR1Element n6elem0 = new LR1Element(); // Node 6 Element 0
n6elem0.Left = tE;
n6elem0.Alpha.Add(tN);
n6elem0.Advance.AddRange(commonAdvanceTokens);
n6.Elements.Add(n6elem0);
AFD.Add(n0);
AFD.Add(n1);
AFD.Add(n2);
AFD.Add(n3);
AFD.Add(n4);
AFD.Add(n5);
AFD.Add(n6);
}
