// todo: horrible
private Nonterminal GetFresh()
{
var originalNonterminals = _grammar.GetNonterminals();
Nonterminal result;
do
{
result = Nonterminal.Of("X_" + _freshx);
_freshx++;
} while (originalNonterminals.Contains(result));
return(result);
}
private Nonterminal RandomNonterminal(int numNonterminals, bool allowStart = true)
{
int num;
if (allowStart)
{
num = _rand.Next(0, numNonterminals);
}
else
{
num = _rand.Next(1, numNonterminals);
}
return(Nonterminal.Of("X_" + num));
}
/// <summary>
/// Turns a string like
/// <X> -> <X> 'a' <X>
/// into a production.
/// Nonterminals must be surrounded by angled brackets, terminals must be surrounded by single quotes, and everything must be separated by spaces.
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public static Production Production(string s)
{
var match = ProductionRegex.Match(s);
if (!match.Success)
{
throw new Exception("Didn't find valid string");
}
var lhsMatch = match.Groups["lhs"];
var ntMatch = match.Groups["nt"];
var tMatch = match.Groups["t"];
var weightMatch = match.Groups["weight"];
if (!lhsMatch.Success)
{
throw new Exception("Didn't find LHS");
}
double weight;
if (!double.TryParse(weightMatch.Value, out weight))
{
weight = 1.0;
}
var rhsList = new SortedList <int, Word>();
foreach (Capture capture in ntMatch.Captures)
{
var word = Nonterminal.Of(capture.Value);
rhsList.Add(capture.Index, word);
}
foreach (Capture capture in tMatch.Captures)
{
var word = Terminal.Of(capture.Value);
rhsList.Add(capture.Index, word);
}
var rhs = new Sentence(rhsList.Values);
var lhs = Nonterminal.Of(lhsMatch.Value);
var retval = new Production(lhs, rhs, weight);
return(retval);
}
public Production(string lhsName, Word rhsOnlyWord, double weight = 1.0) : this(Nonterminal.Of(lhsName), new Sentence(rhsOnlyWord), weight)
{
}
public Production(string lhsName, Sentence rhs, double weight = 1.0) : this(Nonterminal.Of(lhsName), rhs, weight)
{
}