private void expandCoverSets(CoverSets <SYMBOL_ENUM> minSets, CoverSets <SYMBOL_ENUM> expSets)
{
bool changed = true;
while (changed)
{
changed = false;
foreach (KeyValuePair <SYMBOL_ENUM, Dictionary <SymbolChunk <SYMBOL_ENUM>, SYMBOL_ENUM> > cover_pair in expSets.Entries.ToArray())
{
foreach (KeyValuePair <SymbolChunk <SYMBOL_ENUM>, SYMBOL_ENUM> pair in cover_pair.Value.ToArray())
{
SYMBOL_ENUM sym = pair.Key.Symbols.Single();
if (terminals.Contains(sym))
{
continue;
}
// here we get info from initial set, not from expanding one
if (expSets.Add(cover_pair.Key, minSets[sym], sym))
{
changed = true;
}
}
}
}
}
public BuilderHorizonSets(Productions <SYMBOL_ENUM, TREE_NODE> productions, int lookaheadWidth,
FirstSets <SYMBOL_ENUM> firstSets,
CoverSets <SYMBOL_ENUM> coverSets,
FollowSets <SYMBOL_ENUM> followSets)
: base(productions, lookaheadWidth)
{
this.firstSets = firstSets;
this.followSets = followSets;
this.coverSets = coverSets;
if (!coverSets.HasNonTerminals || lookaheadWidth != coverSets.LookaheadWidth)
{
throw new ArgumentException("Internal error.");
}
}
private CoverSets <SYMBOL_ENUM> initCoverSets()
{
var cover_sets = new CoverSets <SYMBOL_ENUM>();
foreach (SYMBOL_ENUM sym in terminals)
{
var set = new SymbolChunkSet <SYMBOL_ENUM>();
set.Add(SymbolChunk.Create(sym));
cover_sets.Add(sym, set, sym);
}
// fill non terminals with everything found in the productions, terminals will stay as they are added here
// non terminals will serve as generators
foreach (SYMBOL_ENUM non_term in nonTerminals)
{
var set = new SymbolChunkSet <SYMBOL_ENUM>();
foreach (Production <SYMBOL_ENUM, TREE_NODE> prod in productions.FilterByLhs(non_term))
{
foreach (SYMBOL_ENUM sym in prod.RhsSymbols)
{
// if we have error symbol inside production it means LHS cover all non-terminals, because
// error symbol for that LHS covers everything except what stands after error symbol (stop marker)
// thus, everything except stop marker plus stop marker gives --> everything
if (sym.Equals(syntaxErrorSymbol))
{
set.Add(terminals.Select(it => SymbolChunk.Create(it)));
}
else
{
set.Add(SymbolChunk.Create(sym));
}
}
}
cover_sets.Add(non_term, set, non_term);
}
return(cover_sets);
}
