private LRParsingTable(int stateCount, ProductionTable productionTable)
{
this.Rows = new LRParsingTableRow[stateCount];
int numRules = productionTable.Productions.Sum(production => production.Rules.Count);
this.Productions = new Rule[numRules];
for (int i = 0; i < this.Rows.Length; i++)
{
this.Rows[i] = new LRParsingTableRow();
}
}
public static LRParsingTable From(CLRStateGenerator stateMachine, ProductionTable productionTable)
{
var table = new LRParsingTable(stateMachine.States.Count, productionTable);
var kernelLookup = new Dictionary <Kernel, int>();
var ruleLookup = new Dictionary <Rule, int>();
// Create rule lookup table
int ptr = 0;
foreach (var production in productionTable.Productions)
{
foreach (var rule in production.Rules)
{
table.Productions[ptr] = rule;
ruleLookup[rule] = ptr++;
}
}
// Create state lookup table
ptr = 0;
foreach (var entry in stateMachine.States)
{
kernelLookup[entry.Key] = ptr++;
}
foreach (var stateEntry in stateMachine.States)
{
var tableRow = table.Rows[kernelLookup[stateEntry.Key]];
foreach (var groupEntry in stateEntry.Value.GroupRulesBySymbolAfter())
{
var symbol = groupEntry.Key;
// SHIFT?
if (symbol.Type == SymbolType.Token)
{
var action = new LRParsingTableAction(ActionType.Shift, kernelLookup[groupEntry.Value]);
Debug.Assert(!tableRow.Actions.ContainsKey(symbol.ID) || tableRow.Actions[symbol.ID].Type != ActionType.Reduce, $"Shift/reduce conflict in the syntax grammar");
tableRow.Actions.Add(symbol.ID, action);
}
// GOTO?
if (symbol.Type == SymbolType.Production)
{
int stateID = kernelLookup[groupEntry.Value];
tableRow.GOTO.Add(symbol.ID, stateID);
}
}
// REDUCE?
foreach (var itemset in stateEntry.Value.Closure.Where(s => s.SymbolAfter == null))
{
foreach (var lookahead in itemset.Lookahead)
{
if (tableRow.Actions.ContainsKey(lookahead.ID))
{
Debug.Assert(false, $"{tableRow.Actions[lookahead.ID].Type.ToString()}/Reduce conflict in the syntax grammar");
}
tableRow.Actions.Add(lookahead.ID, new LRParsingTableAction(ActionType.Reduce, ruleLookup[itemset.Rule]));
}
}
}
table.Rows[1].Actions[Symbol.EndStream.ID] = new LRParsingTableAction(ActionType.Accept, -1);
return(table);
}