private StringBuilder DescribeState(MutableDotItemSet state, StringBuilder output, string indent)
{
foreach (var item in state)
{
output.Append(indent);
DescribeItem(item, output).AppendLine();
}
return(output);
}
private MutableDotItemSet GoTo(IEnumerable <DotItem> itemSet, int token)
{
var result = new MutableDotItemSet();
foreach (var item in itemSet)
{
if (item.NextToken == token)
{
result.Add(item.CreateNextItem());
}
}
return(ClosureLr0(result));
}
// TODO: Separate Closure from the lookahead closuring to get cached closure item sets
private MutableDotItemSet ClosureLr0(MutableDotItemSet itemSet)
{
var result = new MutableDotItemSet();
result.AddRange(itemSet);
bool modified;
do
{
modified = false;
// result may grow during iterations
for (int i = 0; i != result.Count; ++i)
{
var item = result[i];
if (!item.IsReduce && !grammar.IsTerminal(item.NextToken))
{
int X = item.NextToken;
foreach (var childProd in grammar.GetProductions(X))
{
var newItem = new DotItem(childProd, 0)
{
LA = TokenSet.Mutable()
};
var index = result.IndexOf(newItem);
if (index < 0)
{
result.Add(newItem);
modified = true;
}
else
{
var existing = result[index];
existing.LA.AddAll(newItem.LA);
}
}
}
}
}while (modified);
return(result);
}
private MutableDotItemSet GoTo(IEnumerable<DotItem> itemSet, int token)
{
var result = new MutableDotItemSet();
foreach (var item in itemSet)
{
if (item.NextToken == token)
{
result.Add(item.CreateNextItem());
}
}
return ClosureLr0(result);
}
// TODO: Separate Closure from the lookahead closuring to get cached closure item sets
private MutableDotItemSet ClosureLr0(MutableDotItemSet itemSet)
{
var result = new MutableDotItemSet();
result.AddRange(itemSet);
bool modified;
do
{
modified = false;
// result may grow during iterations
for (int i = 0; i != result.Count; ++i)
{
var item = result[i];
if (!item.IsReduce && !grammar.IsTerminal(item.NextToken))
{
int X = item.NextToken;
foreach (var childProd in grammar.GetProductions(X))
{
var newItem = new DotItem(childProd, 0)
{
LA = TokenSet.Mutable()
};
var index = result.IndexOf(newItem);
if (index < 0)
{
result.Add(newItem);
modified = true;
}
else
{
var existing = result[index];
existing.LA.AddAll(newItem.LA);
}
}
}
}
}
while (modified);
return result;
}