//Expression que l'on a le droit de mettre devant une etoile
public static NodeAST MatchStarable(StringCursor stringCursor)
{
if (stringCursor.Match('('))
{
return(MatchParenthesis(stringCursor));
}
return(MatchConstant(stringCursor));
}
// Algo réalisé à l'aide de la grammaire formelle
public static NodeAST MatchRegex(StringCursor stringCursor)
{
NodeAST node = MatchAlternative(stringCursor);
if (node.Type == NodeASTType.Error)
{
return(node);
}
return(stringCursor.Match('\0') ? node : NodeAST.CreateError());
}
public static NodeAST MatchConstant(StringCursor stringCursor)
{
if (!char.IsLetterOrDigit(stringCursor.Current))
{
return(NodeAST.CreateError());
}
NodeAST node = new NodeAST(NodeASTType.Constant, stringCursor.Current);
stringCursor.Next();
return(node);
}
//Expression starable qui contient, ou pas, une étoile
public static NodeAST MatchStar(StringCursor stringCursor)
{
NodeAST node = MatchStarable(stringCursor);
if (node.Type == NodeASTType.Error)
{
return(node);
}
if (stringCursor.Match('*'))
{
stringCursor.Next();
return(new NodeAST(NodeASTType.Star, new NodeAST[] { node }));
}
return(node);
}
public static NodeAST MatchConcatenation(StringCursor stringCursor)
{
List <NodeAST> children = new List <NodeAST>();
do
{
NodeAST node = MatchStar(stringCursor);
if (node.Type == NodeASTType.Error)
{
return(node);
}
children.Add(node);
} while (stringCursor.Match('(') || char.IsLetterOrDigit(stringCursor.Current));
return((children.Count == 1) ? children[0] : new NodeAST(NodeASTType.Concatenation, children.ToArray()));
}
public static NodeAST MatchParenthesis(StringCursor stringCursor)
{
if (!stringCursor.Match('('))
{
return(NodeAST.CreateError());
}
stringCursor.Next();
NodeAST node = MatchAlternative(stringCursor);
if (node.Type == NodeASTType.Error)
{
return(node);
}
if (!stringCursor.Match(')'))
{
return(NodeAST.CreateError());
}
stringCursor.Next();
return(node);
}
public static NodeAST MatchAlternative(StringCursor stringCursor)
{
NodeAST node = MatchConcatenation(stringCursor);
if (node.Type == NodeASTType.Error)
{
return(node);
}
List <NodeAST> children = new List <NodeAST>();
children.Add(node);
while (stringCursor.Match('|'))
{
stringCursor.Next();
node = MatchConcatenation(stringCursor);
if (node.Type == NodeASTType.Error)
{
return(node);
}
children.Add(node);
}
return((children.Count == 1) ? children[0] : new NodeAST(NodeASTType.Alternative, children.ToArray()));
}