/// <summary>
/// Executes the given LR reduction
/// </summary>
/// <param name="production">A LR reduction</param>
private void Reduce(LRProduction production)
{
Symbol variable = symVariables[production.Head];
builder.ReductionPrepare(production.Head, production.ReductionLength, production.HeadAction);
for (int i = 0; i != production.BytecodeLength; i++)
{
LROpCode op = production[i];
switch (op.Base)
{
case LROpCodeBase.SemanticAction:
{
SemanticAction action = symActions[production[i + 1].DataValue];
i++;
action.Invoke(variable, builder);
break;
}
case LROpCodeBase.AddVirtual:
{
int index = production[i + 1].DataValue;
builder.ReductionAddVirtual(index, op.TreeAction);
i++;
break;
}
default:
builder.ReductionPop(op.TreeAction);
break;
}
}
builder.Reduce();
}
/// <summary>
/// Gets the dependencies on nullable variables
/// </summary>
/// <param name="production">The production of a nullable variable</param>
/// <returns>The list of the nullable variables' indices that this production depends on</returns>
private static List <int> GetNullableDependencies(LRProduction production)
{
List <int> result = new List <int>();
for (int i = 0; i != production.BytecodeLength; i++)
{
LROpCode op = production[i];
switch (op.Base)
{
case LROpCodeBase.SemanticAction:
{
i++;
break;
}
case LROpCodeBase.AddVirtual:
{
i++;
break;
}
case LROpCodeBase.AddNullVariable:
{
result.Add(production[i + 1].DataValue);
i++;
break;
}
default:
break;
}
}
return(result);
}
/// <summary>
/// Loads a new instance of the LRProduction class from a binary representation
/// </summary>
/// <param name="reader">The binary reader to read from</param>
public LRProduction(BinaryReader reader)
{
head = reader.ReadUInt16();
headAction = (TreeAction)reader.ReadByte();
reducLength = reader.ReadByte();
bytecode = new LROpCode[reader.ReadByte()];
for (int i = 0; i != bytecode.Length; i++)
{
bytecode[i] = new LROpCode(reader);
}
}
/// <summary>
/// Builds the SPPF
/// </summary>
/// <param name="generation">The current GSS generation</param>
/// <param name="production">The LR production</param>
/// <param name="first">The first label of the path</param>
/// <param name="path">The reduction path</param>
/// <returns>The identifier of the corresponding SPPF node</returns>
private int BuildSPPF(int generation, LRProduction production, int first, GSSPath path)
{
Symbol variable = symVariables[production.Head];
sppf.ReductionPrepare(first, path, production.ReductionLength);
for (int i = 0; i != production.BytecodeLength; i++)
{
LROpCode op = production[i];
switch (op.Base)
{
case LROpCodeBase.SemanticAction:
{
SemanticAction action = symActions[production[i + 1].DataValue];
i++;
action.Invoke(variable, sppf);
break;
}
case LROpCodeBase.AddVirtual:
{
int index = production[i + 1].DataValue;
sppf.ReductionAddVirtual(index, op.TreeAction);
i++;
break;
}
case LROpCodeBase.AddNullVariable:
{
int index = production[i + 1].DataValue;
sppf.ReductionAddNullable(nullables[index], op.TreeAction);
i++;
break;
}
default:
sppf.ReductionPop(op.TreeAction);
break;
}
}
return(sppf.Reduce(generation, production.Head, production.HeadAction));
}