/// <summary>
/// constructor, construct parser table
/// </summary>
public Parser(Grammar grammar)
{
_lrGotos = new List <int[]>();
_gotoPrecedence = new List <int[]>();
_lr0Items = new List <LR0Item>();
_lr1Items = new List <LR1Item>();
_lr0States = new List <HashSet <int> >();
_lr0Kernels = new List <HashSet <int> >();
_lalrStates = new List <HashSet <int> >();
_terminals = new HashSet <int>();
_nonterminals = new HashSet <int>();
_lalrPropogations = new List <IDictionary <int, IList <LALRPropogation> > >();
_grammar = grammar;
_productions = new List <Production>();
_productionDerivation = new List <Derivation>();
_productionPrecedence = new List <int>();
var nTokens = _grammar.SymbolNames.Length;
_firstSets = new HashSet <int> [nTokens];
PopulateProductions();
InitSymbols();
GenerateLR0Items();
ComputeFirstSets();
ConvertLR0ItemsToKernels();
var nLalrStates = InitLALRTables();
CalculateLookAheads();
_parseTable = new ParseTable(nLalrStates, nTokens);
GenerateParseTable();
}
public Parser(ParserGenerator p)
{
parser_generator = p;
parse_table = parser_generator.ParseTable;
Reset();
int i = 0;
foreach (string x in parser_generator.Grammar.Tokens)
{
token_type.Add(x, i++);
}
}
/// <summary>
/// Generates the parse table given the lalr states, and grammar
/// </summary>
void GenerateParseTable()
{
m_parseTable = new ParseTable();
m_parseTable.Actions = new Action[m_lalrStates.Count, m_grammar.Tokens.Length + 1];
for (int nStateID = 0; nStateID < m_lalrStates.Count; nStateID++)
{
HashSet <int> lalrState = m_lalrStates[nStateID];
for (int nToken = -1; nToken < m_grammar.Tokens.Length; nToken++)
{
List <Action> actions = new List <Action>();
string sToken = "$";
if (nToken >= 0)
{
sToken = m_grammar.Tokens[nToken];
if (m_lrGotos[nStateID][nToken] >= 0)
{
actions.Add(new Action {
ActionType = ActionType.Shift, ActionParameter = m_lrGotos[nStateID][nToken]
});
}
}
foreach (int nLR1ItemID in lalrState)
{
LR1Item lr1Item = m_lr1Items[nLR1ItemID];
LR0Item lr0Item = m_lr0Items[lr1Item.LR0ItemID];
if ((lr0Item.Position == m_productions[lr0Item.Production].Right.Length) && lr1Item.LookAhead == nToken)
{
Action action = new Action {
ActionType = ActionType.Reduce, ActionParameter = lr0Item.Production
};
if (!ListContainsAction(actions, action))
{
actions.Add(action);
}
}
}
int nMaxPrecedence = int.MinValue;
List <Action> importantActions = new List <Action>();
foreach (Action action in actions)
{
int nActionPrecedence = int.MinValue;
if (action.ActionType == ActionType.Shift)
{
nActionPrecedence = m_gotoPrecedence[nStateID][nToken]; //nToken will never be -1
}
else if (action.ActionType == ActionType.Reduce)
{
nActionPrecedence = m_productionPrecedence[action.ActionParameter];
}
if (nActionPrecedence > nMaxPrecedence)
{
nMaxPrecedence = nActionPrecedence;
importantActions.Clear();
importantActions.Add(action);
}
else if (nActionPrecedence == nMaxPrecedence)
{
importantActions.Add(action);
}
}
if (importantActions.Count == 1)
{
m_parseTable.Actions[nStateID, nToken + 1] = importantActions[0];
}
else if (importantActions.Count > 1)
{
Action shiftAction = null;
List <Action> reduceActions = new List <Action>();
foreach (Action action in importantActions)
{
if (action.ActionType == ActionType.Reduce)
{
reduceActions.Add(action);
}
else
{
shiftAction = action;
}
}
Derivation derv = m_grammar.PrecedenceGroups[-nMaxPrecedence].Derivation;
if (derv == Derivation.LeftMost && reduceActions.Count == 1)
{
m_parseTable.Actions[nStateID, nToken + 1] = reduceActions[0];
}
else if (derv == Derivation.RightMost && shiftAction != null)
{
m_parseTable.Actions[nStateID, nToken + 1] = shiftAction;
}
else
{
if (derv == Derivation.None && reduceActions.Count == 1)
{
Debug.Console.WriteLine("Error, shift-reduce conflict in grammar");
}
else
{
Debug.Console.WriteLine("Error, reduce-reduce conflict in grammar");
}
m_parseTable.Actions[nStateID, nToken + 1] = new Action {
ActionType = ActionType.Error, ActionParameter = nToken
};
}
}
else
{
m_parseTable.Actions[nStateID, nToken + 1] = new Action {
ActionType = ActionType.Error, ActionParameter = nToken
};
}
}
}
}
