public override void Emit(SourceBuilder sourceCode)
{
// emit initialization with element mapped from unique index
string tempVariableForUniqueResult = NamesOfEntities.MapByUniqueTemporary(PatternElementName);
sourceCode.AppendFrontFormat("if({0}==null || !({0} is {1}))",
tempVariableForUniqueResult, IsNode ? "GRGEN_LIBGR.INode" : "GRGEN_LIBGR.IEdge");
// emit check failed code
sourceCode.Append("{\n");
sourceCode.Indent();
CheckFailedOperations.Emit(sourceCode);
sourceCode.Unindent();
sourceCode.AppendFront("}\n");
// assign the value to the candidate variable, cast it to the variable type
string typeOfVariableContainingCandidate = "GRGEN_LGSP."
+ (IsNode ? "LGSPNode" : "LGSPEdge");
string variableContainingCandidate = NamesOfEntities.CandidateVariable(PatternElementName);
sourceCode.AppendFrontFormat("{0} = ({1}){2};\n",
variableContainingCandidate, typeOfVariableContainingCandidate, tempVariableForUniqueResult);
}