/// <summary>
/// Calculates the first sets of all grammaticals of the given <paramref name="grammar"/>.
/// </summary>
/// <param name="grammar">The grammaticals which are to examen, are in this grammar.</param>
/// <param name="epsilon_grammaticals">Set of the epsilon capable grammaticals of the given
/// <paramref name="grammar"/>. (see <see cref="EpsilonGrammaticals"/>)</param>
/// <returns>The first sets for all the grammaticals of the given <paramref name="grammar"/>.</returns>
/// <exception cref="ArgumentNullException"> if any of the parameters is <c>null</c>.</exception>
public static IDictionary<GrammaticalSymbol, ISet<TerminalSymbol>> Build(
ExtendedGrammar grammar, ISet<GrammaticalSymbol> epsilon_grammaticals)
{
if( grammar == null )
throw new ArgumentNullException("grammar");
if( epsilon_grammaticals == null )
throw new ArgumentNullException("epsilon_grammaticals");
// Relation matrix
var f_plus = new RelationMatrix(grammar.Terminals.Count + grammar.Grammaticals.Count);
RelationMatrix.TransitiveClosure(F_Relation(grammar), f_plus);
// Build the first_sets
var first_sets = new Dictionary<GrammaticalSymbol, ISet<TerminalSymbol>>();
foreach( var gr in grammar.Grammaticals )
{
int gr_index = grammar.GlobalIndexOf(gr);
// Put all terminals being in relation with gr into gr's first_set
var first_set = new HashSet<TerminalSymbol>();
foreach( var tr in grammar.Terminals )
if( f_plus[gr_index, grammar.GlobalIndexOf(tr)] )
first_set.Add(tr);
if( epsilon_grammaticals.Contains(gr) )
first_set.Add(EpsilonSymbol.Instance);
first_sets.Add(gr, first_set);
}
return first_sets;
}
private static RelationMatrix B_Relation( IGrammar grammar, ISet<GrammaticalSymbol> epsilon_grammaticals )
{
var relation = new RelationMatrix(grammar.Terminals.Count + grammar.Grammaticals.Count);
foreach( var rule in grammar.Rules )
for( int i = 1; i < rule.RightHandSide.Count; ++i )
{
relation[
grammar.GlobalIndexOf(rule.RightHandSide[i - 1]),
grammar.GlobalIndexOf(rule.RightHandSide[i])] = true;
for( int j = i + 1; j < rule.RightHandSide.Count; ++j )
if( rule.RightHandSide[j - 1] is GrammaticalSymbol &&
epsilon_grammaticals.Contains((GrammaticalSymbol)rule.RightHandSide[j - 1]) )
{
relation[
grammar.GlobalIndexOf(rule.RightHandSide[i - 1]),
grammar.GlobalIndexOf(rule.RightHandSide[j])] = true;
}
else
{
break;
}
}
return relation;
}
internal static RelationMatrix F_Relation( IGrammar grammar )
{
var relation = new RelationMatrix(grammar.Terminals.Count + grammar.Grammaticals.Count);
foreach( var rule in grammar.Rules )
if( rule.RightHandSide.Count > 0 )
relation[
grammar.GlobalIndexOf(rule.LeftHandSide),
grammar.GlobalIndexOf(rule.RightHandSide[0])] = true;
return relation;
}
public static void TransitiveClosure( RelationMatrix relation, RelationMatrix result )
{
var temp = relation.Copy();
relation.CopyTo(result);
for( int i = 0; i < relation.Dimension - 1; ++i )
{
WharshallAlg(temp, relation, result);
result.CopyTo(temp);
}
}
public static void WharshallAlg( RelationMatrix left, RelationMatrix right, RelationMatrix result )
{
if( left == null )
throw new ArgumentNullException("left");
if( right == null )
throw new ArgumentNullException("right");
if( result == null )
throw new ArgumentNullException("result");
if( left.Dimension != right.Dimension || left.Dimension != result.Dimension )
throw new ArgumentException("Dimension mismatch.");
for( int j = 0; j < left.Dimension; ++j )
for( int i = 0; i < left.Dimension; ++i )
if( left[i, j] )
for( int k = 0; k < left.Dimension; ++k )
if( right[j, k] )
result[i, k] = true;
}
/// <summary>
/// Calculates the follow sets of all grammaticals of the given <paramref name="grammar"/>.
/// </summary>
/// <param name="grammar">The grammaticals which are to examen, are in this grammar.</param>
/// <param name="epsilon_grammaticals">Set of the epsilon capable grammaticals of the given
/// <paramref name="grammar"/>. (see <see cref="EpsilonGrammaticals"/>)</param>
/// <returns>The first sets for all the grammaticals of the given <paramref name="grammar"/>.</returns>
/// <exception cref="ArgumentNullException"> if any of the parameters is <c>null</c>.</exception>
public static IDictionary<GrammaticalSymbol, ISet<TerminalSymbol>> Build(
ExtendedGrammar grammar, ISet<GrammaticalSymbol> epsilon_grammaticals)
{
if( grammar == null )
throw new ArgumentNullException("grammar");
if( epsilon_grammaticals == null )
throw new ArgumentNullException("epsilon_grammaticals");
int symbol_count = grammar.Terminals.Count + grammar.Grammaticals.Count;
var f_star = new RelationMatrix(symbol_count);
RelationMatrix.TransitiveClosure(FirstSets.F_Relation(grammar), f_star);
RelationMatrix.ReflexiveClosure(f_star);
var l_star = new RelationMatrix(symbol_count);
RelationMatrix.TransitiveClosure(L_Relations(grammar, epsilon_grammaticals), l_star);
RelationMatrix.ReflexiveClosure(l_star);
var b = B_Relation(grammar, epsilon_grammaticals);
var tmp = new RelationMatrix(symbol_count);
var lbf = new RelationMatrix(symbol_count);
RelationMatrix.WharshallAlg(l_star, b, tmp);
RelationMatrix.WharshallAlg(tmp, f_star, lbf);
// Build the follow_sets
var follow_sets = new Dictionary<GrammaticalSymbol, ISet<TerminalSymbol>>();
foreach( var gr in grammar.Grammaticals )
{
int gr_index = grammar.GlobalIndexOf(gr);
// Put all terminals being in relation with gr into gr's follow_set
var follow_set = new HashSet<TerminalSymbol>();
foreach( var tr in grammar.Terminals )
if( lbf[gr_index, grammar.GlobalIndexOf(tr)] )
follow_set.Add(tr);
follow_sets.Add(gr, follow_set);
}
return follow_sets;
}
private static RelationMatrix L_Relations( IGrammar grammar, ISet<GrammaticalSymbol> epsilon_grammaticals )
{
var relation = new RelationMatrix(grammar.Terminals.Count + grammar.Grammaticals.Count);
foreach( var rule in grammar.Rules )
if( rule.RightHandSide.Count > 0 )
{
relation[
grammar.GlobalIndexOf(rule.RightHandSide[rule.RightHandSide.Count - 1]),
grammar.GlobalIndexOf(rule.LeftHandSide)] = true;
for( int i = rule.RightHandSide.Count - 2; i >= 0; --i )
if( rule.RightHandSide[i + 1] is GrammaticalSymbol &&
epsilon_grammaticals.Contains((GrammaticalSymbol)rule.RightHandSide[i + 1]) )
{
relation[
grammar.GlobalIndexOf(rule.RightHandSide[i]),
grammar.GlobalIndexOf(rule.LeftHandSide)] = true;
}
else
{
break;
}
}
return relation;
}
public static void ReflexiveClosure( RelationMatrix relation )
{
// Set the diagonal to 'true's.
for( int i = 0; i < relation.Dimension; ++i )
relation[i, i] = true;
}
/// <summary>
/// Tells if this matrix is considered equal to the given one.
/// </summary>
/// <param name="other">The other matrix to compare with.</param>
/// <returns><c>true</c> if the given matrix is equal to this, <c>false</c> otherwise.</returns>
public bool Equals( RelationMatrix other )
{
return other != null &&
this.dim == other.dim &&
Array.Equals(this.relations, other.relations);
}
/// <summary>
/// Copies the content of this matrix into the given <paramref name="other"/> one.
/// The dimensions of the matrices must be the same.
/// </summary>
/// <param name="other">The matrix to copy into.</param>
/// <exception cref="ArgumentNullException"> if <paramref name="other"/> is <c>null</c>.</exception>
/// <exception cref="ArguemtnException"> if <paramref name="other"/> has not the same dimension as this matrix.</exception>
public void CopyTo( RelationMatrix other )
{
if( other == null )
throw new ArgumentNullException("other");
if( this.dim != other.dim )
throw new ArgumentException("Dimension mismatch.");
for( int i = 0; i < this.dim; ++i )
for( int j = 0; j < this.dim; ++j )
other.relations[i, j] = this.relations[i, j];
}
/// <summary>
/// Creates and returns a new matrix instance with the contents of this matrix.
/// </summary>
/// <returns>A new instance, a copy of this.</returns>
public RelationMatrix Copy()
{
var copy = new RelationMatrix(this.dim);
this.CopyTo(copy);
return copy;
}