public void Action(Expansion e)
{
if (e is OneOrMore)
{
if (Semanticize.EmptyExpansionExists(((OneOrMore)e).Expansion))
{
CSharpCCErrors.SemanticError(e, "Expansion within \"(...)+\" can be matched by empty string.");
}
}
else if (e is ZeroOrMore)
{
if (Semanticize.EmptyExpansionExists(((ZeroOrMore)e).Expansion))
{
CSharpCCErrors.SemanticError(e, "Expansion within \"(...)*\" can be matched by empty string.");
}
}
else if (e is ZeroOrOne)
{
if (Semanticize.EmptyExpansionExists(((ZeroOrOne)e).Expansion))
{
CSharpCCErrors.SemanticError(e, "Expansion within \"(...)?\" can be matched by empty string.");
}
}
}
public static void choiceCalc(Choice choice)
{
int first = firstChoice(choice);
// dbl[i] and dbr[i] are lists of size limited matches for choice i
// of choice. dbl ignores matches with semantic lookaheads (when force_la_check
// is false), while dbr ignores semantic lookahead.
IList <MatchInfo>[] dbl = new IList <MatchInfo> [choice.Choices.Count];
IList <MatchInfo>[] dbr = new IList <MatchInfo> [choice.Choices.Count];
int[] minLA = new int[choice.Choices.Count - 1];
MatchInfo[] overlapInfo = new MatchInfo[choice.Choices.Count - 1];
int[] other = new int[choice.Choices.Count - 1];
MatchInfo m;
IList <MatchInfo> v;
bool overlapDetected;
for (int la = 1; la <= Options.getChoiceAmbiguityCheck(); la++)
{
MatchInfo.laLimit = la;
LookaheadWalk.considerSemanticLA = !Options.getForceLaCheck();
for (int i = first; i < choice.Choices.Count - 1; i++)
{
LookaheadWalk.sizeLimitedMatches = new List <MatchInfo>();
m = new MatchInfo();
m.firstFreeLoc = 0;
v = new List <MatchInfo>();
v.Add(m);
LookaheadWalk.genFirstSet(v, (Expansion)choice.Choices[i]);
dbl[i] = LookaheadWalk.sizeLimitedMatches;
}
LookaheadWalk.considerSemanticLA = false;
for (int i = first + 1; i < choice.Choices.Count; i++)
{
LookaheadWalk.sizeLimitedMatches = new List <MatchInfo>();
m = new MatchInfo();
m.firstFreeLoc = 0;
v = new List <MatchInfo>();
v.Add(m);
LookaheadWalk.genFirstSet(v, (Expansion)choice.Choices[i]);
dbr[i] = LookaheadWalk.sizeLimitedMatches;
}
if (la == 1)
{
for (int i = first; i < choice.Choices.Count - 1; i++)
{
Expansion exp = (Expansion)choice.Choices[i];
if (Semanticize.EmptyExpansionExists(exp))
{
CSharpCCErrors.Warning(exp,
"This choice can expand to the empty token sequence " +
"and will therefore always be taken in favor of the choices appearing later.");
break;
}
else if (CodeCheck(dbl[i]))
{
CSharpCCErrors.Warning(exp,
"CSHARPCODE non-terminal will force this choice to be taken " +
"in favor of the choices appearing later.");
break;
}
}
}
overlapDetected = false;
for (int i = first; i < choice.Choices.Count - 1; i++)
{
for (int j = i + 1; j < choice.Choices.Count; j++)
{
if ((m = overlap(dbl[i], dbr[j])) != null)
{
minLA[i] = la + 1;
overlapInfo[i] = m;
other[i] = j;
overlapDetected = true;
break;
}
}
}
if (!overlapDetected)
{
break;
}
}
for (int i = first; i < choice.Choices.Count - 1; i++)
{
if (explicitLA((Expansion)choice.Choices[i]) && !Options.getForceLaCheck())
{
continue;
}
if (minLA[i] > Options.getChoiceAmbiguityCheck())
{
CSharpCCErrors.Warning("Choice conflict involving two expansions at");
Console.Error.Write(" line " + ((Expansion)choice.Choices[i]).Line);
Console.Error.Write(", column " + ((Expansion)choice.Choices[i]).Column);
Console.Error.Write(" and line " + ((Expansion)choice.Choices[other[i]]).Line);
Console.Error.Write(", column " + ((Expansion)choice.Choices[other[i]]).Column);
Console.Error.WriteLine(" respectively.");
Console.Error.WriteLine(" A common prefix is: " + image(overlapInfo[i]));
Console.Error.WriteLine(" Consider using a lookahead of " + minLA[i] + " or more for earlier expansion.");
}
else if (minLA[i] > 1)
{
CSharpCCErrors.Warning("Choice conflict involving two expansions at");
Console.Error.Write(" line " + ((Expansion)choice.Choices[i]).Line);
Console.Error.Write(", column " + ((Expansion)choice.Choices[i]).Column);
Console.Error.Write(" and line " + ((Expansion)choice.Choices[other[i]]).Line);
Console.Error.Write(", column " + ((Expansion)choice.Choices[other[i]]).Column);
Console.Error.WriteLine(" respectively.");
Console.Error.WriteLine(" A common prefix is: " + image(overlapInfo[i]));
Console.Error.WriteLine(" Consider using a lookahead of " + minLA[i] + " for earlier expansion.");
}
}
}
