public bool Equals(MultiState <SYMBOL_ENUM, TREE_NODE> comp)
{
if (Object.ReferenceEquals(comp, null))
{
return(false);
}
if (Object.ReferenceEquals(this, comp))
{
return(true);
}
return(items.SetEquals(comp.items));
}
internal bool Merge(MultiState <SYMBOL_ENUM, TREE_NODE> incomingState,
Dictionary <Production <SYMBOL_ENUM, TREE_NODE>, Dictionary <int, SymbolChunkSet <SYMBOL_ENUM> > > precomputedRhsFirsts,
int lookaheadWidth)
{
bool changed = false;
itemsLookaheadsStamp = Math.Max(itemsLookaheadsStamp, incomingState.itemsLookaheadsStamp);
// merge shifts
foreach (SingleState <SYMBOL_ENUM, TREE_NODE> existing_state in this.items)
{
if (existing_state.Merge(incomingState.items.GetValue(existing_state), timeStamp))
{
changed = true;
}
}
addClosuresLookaheads(precomputedRhsFirsts, lookaheadWidth);
return(changed);
}
internal bool CanBeMerged(MultiState <SYMBOL_ENUM, TREE_NODE> newState)
{
// todo: comparer can be improved -- unseen terminals here can be considered as equal
// however this means the merge can increase the number of stored items
// and this means that after merge new shift moves should be created for added items
// ERROR WARNING
// this migh be not 100% correct, consider such mergers
// expr -> PLUS . expr { func1 };
// expr -> MINUS . expr { func1 }; // same function
// against
// expr -> MUL . expr { func2 };
// normaly we would like to set precedence between MINUS, PLUS and MUL
// but because MINUS and PLUS are merged, we have only MINUS-MUL precedence conflict
// we rely on the fact func1 is the same, BUT it is a fragile assumption
// pay attention when facing strange behaviour if such merger (which is my own idea) still makes sense
// the cores are different
if (!items.SetEquals(newState.items)) // [@STATE_EQ]
{
return(false);
}
// check by lookahead (the input which triggers the action) if there are no conflicts on actions
foreach (SymbolChunk <SYMBOL_ENUM> lookahead in this.reduceLookaheads().Concat(newState.reduceLookaheads()).Distinct())
{
// [@STATE_EQ]
var this_reduces = this.reduceStatesByLookahead(lookahead).ToHashSet(stateComparer);
var comp_reduces = newState.reduceStatesByLookahead(lookahead).ToHashSet(stateComparer);
if (this_reduces.Count + comp_reduces.Count > 1 && !this_reduces.SetEquals(comp_reduces))
{
return(false);
}
}
return(true);
}
public Node(MultiState <SYMBOL_ENUM, TREE_NODE> state)
{
State = state;
EdgesTo = new Dictionary <SYMBOL_ENUM, Node <SYMBOL_ENUM, TREE_NODE> >();
sources = new HashSet <Tuple <SYMBOL_ENUM, Node <SYMBOL_ENUM, TREE_NODE> > >();
}
internal Node <SYMBOL_ENUM, TREE_NODE> Find(MultiState <SYMBOL_ENUM, TREE_NODE> state)
{
return(nodes.SingleOrDefault(it => it.State.Equals(state)));
}