/// <summary>
/// Builds a NFA from a unicode code point
/// </summary>
/// <param name="node">An AST node representing a NFA</param>
/// <returns>The equivalent NFA</returns>
private NFA BuildNFAFromCodepoint(ASTNode node)
{
// extract the code point value
string value = node.Value;
value = value.Substring(2, value.Length - 2);
int cpValue = Convert.ToInt32(value, 16);
if (cpValue < 0 || (cpValue >= 0xD800 && cpValue <= 0xDFFF) || cpValue >= 0x110000)
{
OnError(node.Position, "The value U+{0} is not a supported unicode code point", cpValue.ToString("X"));
return(BuildEpsilonNFA());
}
UnicodeCodePoint cp = new UnicodeCodePoint(cpValue);
// build the NFA
NFA automata = NFA.NewMinimal();
char[] data = cp.GetUTF16();
if (data.Length == 1)
{
automata.StateEntry.AddTransition(new CharSpan(data[0], data[0]), automata.StateExit);
}
else
{
NFAState intermediate = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan(data[0], data[0]), intermediate);
intermediate.AddTransition(new CharSpan(data[1], data[1]), automata.StateExit);
}
return(automata);
}
/// <summary>
/// Builds a NFA that matches everything (a single character)
/// </summary>
/// <returns>The equivalent NFA</returns>
private static NFA BuildNFAFromAny()
{
NFA automata = NFA.NewMinimal();
// plane 0 transitions
automata.StateEntry.AddTransition(new CharSpan((char)0x0000, (char)0xD7FF), automata.StateExit);
automata.StateEntry.AddTransition(new CharSpan((char)0xE000, (char)0xFFFF), automata.StateExit);
// surrogate pairs
NFAState intermediate = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan((char)0xD800, (char)0xDBFF), intermediate);
intermediate.AddTransition(new CharSpan((char)0xDC00, (char)0xDFFF), automata.StateExit);
return(automata);
}
/// <summary>
/// Builds a NFA from a piece of text
/// </summary>
/// <param name="node">An AST node representing a NFA</param>
/// <returns>The equivalent NFA</returns>
private NFA BuildNFAFromText(ASTNode node)
{
NFA automata = NFA.NewMinimal();
automata.StateExit = automata.StateEntry;
// build the raw piece of text
string value = node.Value;
bool insensitive = caseInsensitive;
if (value.StartsWith("~"))
{
insensitive = true;
value = value.Substring(2, value.Length - 3);
}
else
{
value = value.Substring(1, value.Length - 2);
}
value = ReplaceEscapees(value);
// build the result
foreach (char c in value)
{
NFAState temp = automata.AddNewState();
if (insensitive && char.IsLetter(c))
{
char c2 = char.IsLower(c) ? char.ToUpper(c) : char.ToLower(c);
automata.StateExit.AddTransition(new CharSpan(c, c), temp);
automata.StateExit.AddTransition(new CharSpan(c2, c2), temp);
}
else
{
automata.StateExit.AddTransition(new CharSpan(c, c), temp);
}
automata.StateExit = temp;
}
return(automata);
}
public void AddNewStateTest()
{
var t1 = new HashSet <int>()
{
1, 2, 3
};
var t2 = new HashSet <int>()
{
1, 4
};
var t3 = new HashSet <int>()
{
2, 3
};
var t4 = new HashSet <int>()
{
3, 4
};
var states = new List <HashSet <int> > {
t1, t2, t3, t4
};
var newState = new HashSet <int>()
{
1, 4
};
Assert.AreEqual(1, NFA.AddNewState(ref newState, ref states));
newState = new HashSet <int>()
{
1, 3
};
Assert.AreEqual(4, NFA.AddNewState(ref newState, ref states));
Assert.IsTrue(states.Contains(newState));
}
/// <summary>
/// Builds a NFA from a character class
/// </summary>
/// <param name="node">An AST node representing a NFA</param>
/// <returns>The equivalent NFA</returns>
private NFA BuildNFAFromClass(ASTNode node)
{
// extract the value
string value = node.Value;
value = value.Substring(1, value.Length - 2);
bool positive = true;
if (value.Length > 0 && value[0] == '^')
{
value = value.Substring(1);
positive = false;
}
// build the character spans
List <CharSpan> spans = new List <CharSpan>();
for (int i = 0; i != value.Length;)
{
// read the first full unicode character
CharValue b = GetCharValue(value, i);
i += b.length;
if (b.chars[0] >= 0xD800 && b.chars[0] <= 0xDFFF)
{
OnError(node.Position, "Unsupported non-plane 0 Unicode character ({0}) in character class", new String(b.chars));
return(BuildEpsilonNFA());
}
if ((i <= value.Length - 2) && (value[i] == '-'))
{
// this is a range, match the '-'
i++;
CharValue e = GetCharValue(value, i);
i += e.length;
if (e.chars[0] >= 0xD800 && e.chars[0] <= 0xDFFF)
{
OnError(node.Position, "Unsupported non-plane 0 Unicode character ({0}) in character class", new String(e.chars));
return(BuildEpsilonNFA());
}
char begin = b.chars.Length == 1 ? b.chars[0] : b.chars[1];
char end = e.chars.Length == 1 ? e.chars[0] : e.chars[1];
if (begin < 0xD800 && end > 0xDFFF)
{
// oooh you ...
spans.Add(new CharSpan(begin, (char)0xD7FF));
spans.Add(new CharSpan((char)0xE000, end));
}
else
{
spans.Add(new CharSpan(begin, end));
}
}
else
{
// this is a normal character
char begin = b.chars.Length == 1 ? b.chars[0] : b.chars[1];
spans.Add(new CharSpan(begin, begin));
}
}
// build the result
NFA automata = NFA.NewMinimal();
if (positive)
{
foreach (CharSpan span in spans)
{
automata.StateEntry.AddTransition(span, automata.StateExit);
}
}
else
{
spans.Sort(new System.Comparison <CharSpan>(CharSpan.Compare));
// TODO: Check for span intersections and overflow of b (when a span ends on 0xFFFF)
char b = (char)0;
for (int i = 0; i != spans.Count; i++)
{
if (spans[i].Begin > b)
{
automata.StateEntry.AddTransition(new CharSpan(b, (char)(spans[i].Begin - 1)), automata.StateExit);
}
b = (char)(spans[i].End + 1);
// skip the surrogate encoding points
if (b >= 0xD800 && b <= 0xDFFF)
{
b = (char)0xE000;
}
}
if (b <= 0xD7FF)
{
automata.StateEntry.AddTransition(new CharSpan(b, (char)0xD7FF), automata.StateExit);
automata.StateEntry.AddTransition(new CharSpan((char)0xE000, (char)0xFFFF), automata.StateExit);
}
else if (b != 0xFFFF)
{
// here b >= 0xE000
automata.StateEntry.AddTransition(new CharSpan(b, (char)0xFFFF), automata.StateExit);
}
// surrogate pairs
NFAState intermediate = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan((char)0xD800, (char)0xDBFF), intermediate);
intermediate.AddTransition(new CharSpan((char)0xDC00, (char)0xDFFF), automata.StateExit);
}
return(automata);
}
/// <summary>
/// Adds a unicode character span to an existing NFA automaton
/// </summary>
/// <param name="automata">The target NFA</param>
/// <param name="span">The unicode span to add</param>
private static void AddUnicodeSpanToNFA(NFA automata, UnicodeSpan span)
{
char[] b = span.Begin.GetUTF16();
char[] e = span.End.GetUTF16();
if (span.IsPlane0)
{
// this span is entirely in plane 0
automata.StateEntry.AddTransition(new CharSpan(b[0], e[0]), automata.StateExit);
}
else if (span.Begin.IsPlane0)
{
// this span has only a part in plane 0
if (b[0] < 0xD800)
{
automata.StateEntry.AddTransition(new CharSpan(b[0], (char)0xD7FF), automata.StateExit);
automata.StateEntry.AddTransition(new CharSpan((char)0xE000, (char)0xFFFF), automata.StateExit);
}
else
{
automata.StateEntry.AddTransition(new CharSpan(b[0], (char)0xFFFF), automata.StateExit);
}
NFAState intermediate = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan((char)0xD800, e[0]), intermediate);
intermediate.AddTransition(new CharSpan((char)0xDC00, e[1]), automata.StateExit);
}
else
{
// this span has no part in plane 0
if (b[0] == e[0])
{
// same first surrogate
NFAState intermediate = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan(b[0], b[0]), intermediate);
intermediate.AddTransition(new CharSpan(b[1], e[1]), automata.StateExit);
}
else if (e[0] == b[0] + 1)
{
// the first surrogates are consecutive encodings
// build lower half
NFAState i1 = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan(b[0], b[0]), i1);
i1.AddTransition(new CharSpan(b[1], (char)0xDFFF), automata.StateExit);
// build upper half
NFAState i2 = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan(e[0], e[0]), i2);
i2.AddTransition(new CharSpan((char)0xDC00, e[1]), automata.StateExit);
}
else
{
// there is at least one surrogate value between the first surrogates of begin and end
// build lower part
NFAState ia = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan(b[0], b[0]), ia);
ia.AddTransition(new CharSpan(b[1], (char)0xDFFF), automata.StateExit);
// build intermediate part
NFAState im = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan((char)(b[0] + 1), (char)(e[0] - 1)), im);
im.AddTransition(new CharSpan((char)0xDC00, (char)0xDFFF), automata.StateExit);
// build upper part
NFAState iz = automata.AddNewState();
automata.StateEntry.AddTransition(new CharSpan(e[0], e[0]), iz);
iz.AddTransition(new CharSpan((char)0xDC00, e[1]), automata.StateExit);
}
}
}
