static MatchResult Match(this Pattern pattern,
ReadOnlyList <LeafPattern> left,
ReadOnlyList <LeafPattern> collected)
{
switch (pattern)
{
case Required required:
{
var l = left;
var c = collected;
foreach (var child in required.Children)
{
bool matched;
(matched, l, c) = child.Match(l, c);
if (!matched)
{
return(new MatchResult(false, left, collected));
}
}
return(new MatchResult(true, l, c));
}
case Either either:
{
var match = new MatchResult(false, left, collected);
foreach (var child in either.Children)
{
if (child.Match(left, collected) is (true, var l, var c) &&
(!match || l.Count < match.Left.Count))
{
match = new MatchResult(true, l, c);
}
}
return(match);
}
case Optional optional:
{
var l = left;
var c = collected;
foreach (var child in optional.Children)
{
(_, l, c) = child.Match(l, c);
}
return(new MatchResult(true, l, c));
}
case OneOrMore oneOrMore:
{
Debug.Assert(oneOrMore.Children.Count == 1);
var l = left;
var c = collected;
ReadOnlyList <LeafPattern>?l_ = null;
var matched = true;
var times = 0;
while (matched)
{
// could it be that something didn't match but changed l or c?
(matched, l, c) = oneOrMore.Children[0].Match(l, c);
times += matched ? 1 : 0;
if (l_ != null && l_.Equals(l))
{
break;
}
l_ = l;
}
if (times >= 1)
{
return(new MatchResult(true, l, c));
}
return(new MatchResult(false, left, collected));
}
case Command command:
{
for (var i = 0; i < left.Count; i++)
{
if (left[i] is Argument {
Value: { } value
})
{
if (value.ToString() == command.Name)
{
return(MatchLeaf(command, i, new Command(command.Name, new ValueObject(true))));
}
break;
}
}
public static MatchResult Match(this Pattern pattern, ReadOnlyList <LeafPattern> left)
{
return(pattern.Match(left, new ReadOnlyList <LeafPattern>()));
}