private void AssignAction(int state, int token, ParserAction action)
{
int cell = ParserAction.Encode(action);
int currentCell = actionTable.Get(state, token);
if (currentCell == 0)
{
actionTable.Set(state, token, cell);
}
else if (currentCell != cell)
{
int resolvedCell;
if (!TryResolveShiftReduce(currentCell, cell, token, out resolvedCell))
{
RequiresGlr = true;
ParserConflictInfo conflict;
var key = new TransitionKey(state, token);
if (!transitionToConflict.TryGetValue(key, out conflict))
{
conflict = new ParserConflictInfo(state, token);
transitionToConflict[key] = conflict;
conflict.AddAction(currentCell);
}
if (!conflict.Actions.Contains(action))
{
conflict.AddAction(action);
}
}
actionTable.Set(state, token, resolvedCell);
}
}
public static int Encode(ParserAction action)
{
int result = ((byte)action.Kind)
| (action.Value1 << Value1StartBit)
| (action.Size << Value2StartBit)
;
return result;
}
public static ParserActionKind Decode(int cell, ref ParserAction result)
{
ParserActionKind kind = (ParserActionKind)(cell & KindMask);
result.Kind = kind;
if (kind != ParserActionKind.Fail)
{
result.Value1 = (cell & Value1Mask) >> Value1StartBit;
result.Size = (short)((cell & Value2Mask) >> Value2StartBit);
}
return kind;
}
public static ParserActionKind Decode(int cell, ref ParserAction result)
{
ParserActionKind kind = (ParserActionKind)(cell & KindMask);
result.Kind = kind;
if (kind != ParserActionKind.Fail)
{
result.Value1 = (cell & Value1Mask) >> Value1StartBit;
result.Size = (short)((cell & Value2Mask) >> Value2StartBit);
}
return(kind);
}
private ParserAction LookaheadAction(int token)
{
var act = ParserAction.Decode(actionTable(stateStack.PeekTag(), token));
TNode value;
while (act.Kind == ParserActionKind.Reduce)
{
this.currentRule = grammar.Productions[act.ProductionId];
stateStack.Start = stateStack.Count - currentRule.PatternTokens.Length;
value = producer.CreateBranch(
currentRule,
stateStack.PeekTail(currentRule.PatternTokens.Length),
(IStackLookback <TNode>)stateStack);
stateStack.Pop(currentRule.PatternTokens.Length);
act = ParserAction.Decode(actionTable(stateStack.PeekTag(), currentRule.OutcomeToken));
while (act.Kind == ParserActionKind.ShiftReduce) // == GotoReduce
{
stateStack.Push(-1, value);
this.currentRule = grammar.Productions[act.ProductionId];
stateStack.Start = stateStack.Count - currentRule.PatternTokens.Length;
value = producer.CreateBranch(
currentRule,
stateStack.PeekTail(currentRule.PatternTokens.Length),
(IStackLookback <TNode>)stateStack);
stateStack.Pop(currentRule.PatternTokens.Length);
act = ParserAction.Decode(actionTable(stateStack.PeekTag(), currentRule.OutcomeToken));
}
stateStack.Push(act.State, value);
// reduce or final shift
act = ParserAction.Decode(actionTable(act.State, token));
}
return(act);
}
private void GetReductions(State state, int token)
{
pendingReductionsCount = 0;
ParserAction action = GetDfaCell(state, token);
Production rule;
switch (action.Kind)
{
case ParserActionKind.Reduce:
rule = grammar.Productions[action.ProductionId];
pendingReductionsCount = 1;
pendingReductions[0] = new ModifiedReduction(rule, action.Size);
break;
case ParserActionKind.Accept:
accepted = true;
break;
case ParserActionKind.Conflict:
int start = action.Value1;
int last = action.Value1 + action.Value2;
while (start != last)
{
var conflictAction = ParserAction.Decode(conflictActionsTable[start++]);
switch (conflictAction.Kind)
{
case ParserActionKind.Reduce:
var crule = grammar.Productions[conflictAction.ProductionId];
pendingReductions[pendingReductionsCount++]
= new ModifiedReduction(crule, conflictAction.Size);
break;
}
}
break;
}
}
private StreamWriter DescribeAction(
IReportData data,
ParserAction action,
StreamWriter output,
string indent)
{
switch (action.Kind)
{
case ParserActionKind.Shift:
output.Write(indent);
output.Write("Shift to the state I");
output.Write(action.State + "");
output.WriteLine(":");
DescribeState(data, action.State, output, indent + indent);
break;
case ParserActionKind.ShiftReduce:
output.Write(indent);
output.WriteLine("Shift-Reduce on the rule:");
output.Write(indent + indent);
DescribeRule(data, action.ProductionId, output);
output.WriteLine();
break;
case ParserActionKind.Reduce:
output.Write(indent);
output.WriteLine("Reduce on the rule:");
output.Write(indent + indent);
DescribeRule(data, action.ProductionId, output);
output.WriteLine();
break;
case ParserActionKind.Accept:
output.Write(indent);
output.WriteLine("Accept.");
break;
}
return output;
}
private void Reducer(int lookahead = -1)
{
while (!R.IsEmpty)
{
GssReducePath <T> path = R.Dequeue();
int X = path.Rule.OutcomeToken;
int m = path.Size;
GssNode <T> u = path.LeftNode;
State k = u.State;
T z;
if (m == 0)
{
z = producer.GetDefault(X, (IStackLookback <T>)u);
}
else
{
path.CopyDataTo(nodeBuffer);
T Λ = producer.CreateBranch(
path.Rule,
new ArraySlice <T>(nodeBuffer, 0, path.Size),
lookback: path.LeftNode);
int c = u.Layer;
T currentValue;
var Nkey = GetNKey(X, c);
if (N.TryGetValue(Nkey, out currentValue))
{
z = producer.Merge(currentValue, Λ, (IStackLookback <T>)u);
}
else
{
z = Λ;
}
N[Nkey] = z;
}
State l;
var action = ParserAction.Decode(transition(k, X));
switch (action.Kind)
{
case ParserActionKind.Shift:
l = action.State;
break;
case ParserActionKind.ShiftReduce: // Goto-Reduce action
PlanShiftReduce(
u,
X,
z,
action.ProductionId,
action.Size);
continue;
default:
throw new InvalidOperationException(
"Internal error: Non-term action should be shift or shift-reduce, but got "
+ Enum.GetName(typeof(ParserActionKind), action.Kind));
}
bool stateAlreadyExists = gss.GetFrontNode(l, lookahead) != null;
// Goto on non-term produced by rule.
var newLink = gss.Push(u, l, z, lookahead);
if (lookahead < 0)
{
continue;
}
if (stateAlreadyExists)
{
if (newLink != null && m != 0)
{
GetReductions(l, lookahead);
for (int i = 0; i != pendingReductionsCount; ++i)
{
var red = pendingReductions[i];
if (red.Size != 0)
{
R.Enqueue(newLink, red.Rule, red.Size);
}
}
}
}
else
{
var w = gss.GetFrontNode(l, lookahead);
GetReductions(l, lookahead);
//foreach (var red in reductions)
for (int i = 0; i != pendingReductionsCount; ++i)
{
var red = pendingReductions[i];
if (red.Size == 0)
{
R.Enqueue(w, red.Rule, 0);
}
}
if (m != 0)
{
for (int i = 0; i != pendingReductionsCount; ++i)
{
var red = pendingReductions[i];
if (red.Size != 0)
{
R.Enqueue(newLink, red.Rule, red.Size);
}
}
}
}
}
}
private void FillDfaTable(DotState[] states)
{
for (int i = 0; i != states.Length; ++i)
{
var state = states[i];
Debug.Assert(i == state.Index);
foreach (var item in state.Items)
{
if (!item.IsReduce)
{
int nextToken = item.NextToken;
if (canOptimizeReduceStates
&& item.IsShiftReduce
&& !state.Transitions.Exists(t => t.Tokens.Contains(nextToken)))
{
var action = new ParserAction
{
Kind = ParserActionKind.ShiftReduce,
ProductionId = item.ProductionId
};
AssignAction(i, nextToken, action);
}
else
{
var action = new ParserAction
{
Kind = ParserActionKind.Shift,
State = state.GetNextIndex(nextToken)
};
AssignAction(i, nextToken, action);
}
}
else if (item.IsAugmented)
{
var action = new ParserAction { Kind = ParserActionKind.Accept };
AssignAction(i, PredefinedTokens.Eoi, action);
}
else
{
var action = new ParserAction { Kind = ParserActionKind.Reduce, ProductionId = item.ProductionId };
foreach (var lookahead in item.LA)
{
AssignAction(i, lookahead, action);
}
}
}
}
}
private void BuildConflictTable()
{
var conflictList = new List<int>();
foreach (var conflict in transitionToConflict.Values)
{
var refAction = new ParserAction
{
Kind = ParserActionKind.Conflict,
Value1 = conflictList.Count,
Size = (short)conflict.Actions.Count
};
actionTable.Set(conflict.State, conflict.Token, ParserAction.Encode(refAction));
foreach (var action in conflict.Actions)
{
conflictList.Add(ParserAction.Encode(action));
}
}
this.conflictActionTable = conflictList.ToArray();
}
private static ParserAction GetShift(LanguageData data, ParserAction x)
{
switch (x.Kind)
{
case ParserActionKind.Shift:
case ParserActionKind.ShiftReduce:
return x;
case ParserActionKind.Conflict:
int start = x.Value1;
int count = x.Value2;
int last = start + count;
for (; start != last; ++start)
{
var cAction = ParserAction.Decode(data.ParserConflictActionTable[start]);
switch (cAction.Kind)
{
case ParserActionKind.Shift:
case ParserActionKind.ShiftReduce:
return cAction;
}
}
break;
}
return ParserAction.FailAction;
}
private static bool HaveSameShifts(LanguageData data, ParserAction x, ParserAction y)
{
var xShift = GetShift(data, x);
var yShift = GetShift(data, y);
return xShift == yShift;
}
private static bool HaveComptibleReductions(LanguageData data, ParserAction pAction, ParserAction qAction)
{
return
(
pAction.Kind != ParserActionKind.Reduce
&& qAction.Kind != ParserActionKind.Reduce)
||
(
pAction.Kind == ParserActionKind.Reduce
&& qAction.Kind == ParserActionKind.Reduce
&& pAction.ProductionId == qAction.ProductionId
);
}
private bool IsAccepting(State s)
{
int cell = transition(s, PredefinedTokens.Eoi);
return(ParserAction.GetKind(cell) == ParserActionKind.Accept);
}
private void PrintAction(IReportData data, SymbolBase symbol, StreamWriter output, ParserAction action)
{
if (action == null || action.Kind == ParserActionKind.Fail)
{
return;
}
output.Write(Indent);
output.Write(symbol.Name);
output.Write(" ");
switch (action.Kind)
{
case ParserActionKind.Shift:
output.Write("shift and go to state ");
output.Write(action.State);
break;
case ParserActionKind.Reduce:
output.Write("reduce using rule ");
output.Write(action.ProductionId);
break;
case ParserActionKind.ShiftReduce:
output.Write("shift-reduce using rule ");
output.Write(action.ProductionId);
break;
case ParserActionKind.Accept:
output.WriteLine("accept");
break;
}
output.WriteLine();
}
public static ParserAction Decode(int cell)
{
ParserAction result = new ParserAction();
Decode(cell, ref result);
return result;
}
public IReceiver <Msg> Next(Msg envelope)
{
stateStack.BeginEdit();
int id = envelope.Id;
MsgData data = envelope.FirstData;
START:
ParserAction action = LookaheadAction(id);
switch (action.Kind)
{
case ParserActionKind.Fail:
if (isVerifier)
{
return(null);
}
// ReportUnexpectedToken(msg, stateStack.PeekTag());
return(RecoverFromError(envelope));
case ParserActionKind.Resolve:
id = action.RolvedToken;
while (true)
{
if (data.Token == id)
{
// Successfully resolved to a particular token
goto START;
}
data = data.Next;
if (data == null)
{
// Desired token was not present in Msg
goto case ParserActionKind.Fail;
}
}
case ParserActionKind.Fork:
case ParserActionKind.Conflict:
logging.Write(
new LogEntry
{
Severity = Severity.Error,
Location = envelope.Location,
HLocation = envelope.HLocation,
Message = "Hit parser conflict on token " + grammar.SymbolName(envelope.Id)
});
return(null);
case ParserActionKind.Shift:
{
stateStack.Push(action.State, producer.CreateLeaf(envelope, data));
break;
}
case ParserActionKind.ShiftReduce:
{
TNode value = producer.CreateLeaf(envelope, data);
do
{
stateStack.Push(-1, value);
this.currentRule = grammar.Productions[action.ProductionId];
stateStack.Start = stateStack.Count - currentRule.PatternTokens.Length;
value = producer.CreateBranch(
currentRule,
stateStack.PeekTail(currentRule.PatternTokens.Length),
(IStackLookback <TNode>)stateStack);
stateStack.Pop(currentRule.PatternTokens.Length);
action = ParserAction.Decode(actionTable(stateStack.PeekTag(), currentRule.OutcomeToken));
}while (action.Kind == ParserActionKind.ShiftReduce);
if (action.Kind == ParserActionKind.Fail)
{
return(null);
}
Debug.Assert(action.Kind == ParserActionKind.Shift);
stateStack.Push(action.State, value);
break;
}
case ParserActionKind.Accept:
producer.Result = stateStack.Peek();
return(FinalReceiver <Msg> .Instance);
default:
throw new InvalidOperationException("Internal error: Unsupported parser action");
}
stateStack.EndEdit();
this.priorInput = envelope;
return(this);
}
internal void AddAction(ParserAction action)
{
actions.Add(action);
}
private ParserAction GetDfaCell(State state, int token)
{
return(ParserAction.Decode(transition(state, token)));
}
private bool FillAmbiguousTokenActions(DotState[] states, bool isGlr)
{
for (int i = 0; i != states.Length; ++i)
{
var state = states[i];
foreach (var ambToken in grammar.AmbiguousSymbols)
{
var validTokenActions = new Dictionary<int,int>();
foreach (int token in ambToken.Tokens)
{
int cell = data.Get(i, token);
if (cell == 0)
{
continue;
}
validTokenActions.Add(token, cell);
}
switch (validTokenActions.Count)
{
case 0:
// AmbToken is entirely non-acceptable for this state
data.Set(i, ambToken.Index, 0);
break;
case 1:
{
var pair = validTokenActions.First();
if (pair.Key == ambToken.MainToken)
{
// ambToken action is the same as for the main token
data.Set(i, ambToken.Index, pair.Value);
}
else
{
// Resolve ambToken to a one of the underlying tokens.
// In runtime transition will be acceptable when this token
// is in Msg and non-acceptable when this particular token
// is not in Msg.
var action = new ParserAction { Kind = ParserActionKind.Resolve, Value1 = pair.Key };
data.Set(i, ambToken.Index, ParserAction.Encode(action));
}
}
break;
default:
if (validTokenActions.Values.Distinct().Count() == 1)
{
// Multiple tokens but with the same action
goto case 1;
}
if (!isGlr)
{
return false;
}
// This kind of ambiguity requires GLR to follow all alternate tokens
{
var pair = validTokenActions.First();
var forkAction = new ParserAction { Kind = ParserActionKind.Fork, Value1 = pair.Key };
data.Set(i, ambToken.Index, ParserAction.Encode(forkAction));
}
break;
}
}
}
return true;
}
private void FillDfaTable(DotState[] states)
{
for (int i = 0; i != states.Length; ++i)
{
var state = states[i];
foreach (var item in state.Items)
{
if (!item.IsReduce)
{
int nextToken = item.NextToken;
if (canOptimizeReduceStates
&& item.IsShiftReduce
&& !state.Transitions.Exists(t => t.Tokens.Contains(nextToken)))
{
var action = new ParserAction
{
Kind = ParserActionKind.ShiftReduce,
ProductionId = item.ProductionId,
Size = (short)item.Size
};
AddAction(i, nextToken, action);
}
else
{
var action = new ParserAction
{
Kind = ParserActionKind.Shift,
State = state.GetNextIndex(nextToken)
};
AddAction(i, nextToken, action);
}
}
bool isStartRule = item.IsAugmented;
if (item.IsReduce || grammar.IsTailNullable(item))
{
ParserAction action;
if (isStartRule)
{
if (item.Position == 0)
{
continue;
}
else
{
action = new ParserAction { Kind = ParserActionKind.Accept };
}
}
else
{
action = new ParserAction
{
Kind = ParserActionKind.Reduce,
ProductionId = item.ProductionId,
Size = (short)item.Position
};
}
foreach (var lookahead in item.LA)
{
if (!IsValueOnlyEpsilonReduceItem(item, state, lookahead))
{
AddAction(i, lookahead, action);
}
}
}
}
}
}
