hashtable.h

主要显示了图书馆信息系统的查询

template <class T, class N>
struct HashTableNode
{
	T varValue;
	N varName;
	HashTableNode<T, N> *next;
	N Scope;
	N alias;   //will hold the full name of whatever it is pointing to.
};	

template <class T,class N>
class hashtable
{
	private:
	N currentScope()
		{
			return Scope.Value();
		}

	int hash(N varName,int moder = 10)
		{
			int i = 0;
			for(int q = 0;( q < varName.len() + 1);q++)
				i = i + (q * varName[q]);
			i = i % moder;
			return i;
		}

	public:
		HashTableNode<T, N> *HTNode[10];
		
		hashtable()
		{
			for(int i = 0;i < 10;i++)
				HTNode[i] = NULL;
			Scope.Push("Global");
			ScopeID = "GlobalScope";
		}
		
		~hashtable()
		{
			for (int i = 0;i< 10;i++)
			{
				HTNode[i] = NULL;
			}
		}
		
		
		bool newScope(N ScopeName = "")
		{
			if (ScopeID == "")
			{
				ScopeID = "SystemScope";
				//return true;
			}
			if (ScopeName != "")
			{
				node<N> *temp;
				temp = Scope.First;
				while (temp != NULL)
				{
					if (temp->value == ScopeName) 
					{
						newScope (ScopeName + "X");
						return true;
					}
					temp = temp->next;
				}
				delete [] temp;
				Scope.Push(ScopeName);
				if (Debug) cout << "Starting" << ScopeName << endl;
				return true;
			}
			else
			{
				ScopeID += "X";
				Scope.Push(ScopeID);
				if (Debug) cout << "Starting" << ScopeID << endl;
				return true;
			}
		}
		
		bool endScope()
		{
			N temp;
			temp = currentScope();
			HashTableNode<T, N> *t;

			for (int i = 0;i < 10;i ++)
			{
				t = HTNode[i];
				if (t != NULL)
				{
					while ((t != NULL) && ( t->Scope == temp))
					{
						HTNode[i] = t->next;
						delete t;
						t = HTNode[i];
					}
				}
			}	
			temp = Scope.Pop();
			if (Debug) cout << "ending " <<  temp << endl;
			if (Scope.Value() != "") return true;
			return false;
		}
		
		bool addNode(N varName,T varValue,N iScope = "")
		{
			int i = 0;
			N S;
			S = currentScope();
			if (iScope != "") S = iScope;
			i = hash(varName);
			HashTableNode<T, N> *t;
			t = HTNode[i];
			while (t != NULL)
			{
				if ((t->varName == varName) && ( t->Scope == S )) return false;
				t = t->next;
			}

			t = new HashTableNode<T, N>;
			t->varValue = varValue;
			t->varName = varName;
			t->Scope = S;
			t->next = HTNode[i];
			t->alias = "";
			HTNode[i] = t;
			
			return true;
		}

		bool addAlias(N varName,N AliasName,N iScope = "")
		{			//varName is the pointer AliasName is where it points
			int i = 0;
			N S;
			S = currentScope();
			if (iScope != "") S = iScope;
			i = hash(varName);
			HashTableNode<T, N> *t;
			t = HTNode[i];
			while (t != NULL)
			{
				if ((t->varName == varName) && ( t->Scope == S )) return false;
				t = t->next;
			}

			t = new HashTableNode<T, N>;
			t->varName = varName;
			t->Scope = S;
			t->next = HTNode[i];
			t->alias = AliasName;
			HTNode[i] = t;
			
			return true;
		}

		
		bool ChangeNode(N varName,T varValue)
		{
			N S("");
			if (varName.InStr(':') > 0)
			{
				S = Tokenize(varName,":");
				varName.LTrim(':');
			}
			int i = 0;
			i = hash(varName);
			HashTableNode<T, N> *t;
			t = HTNode[i];
			if (S != "")
				while (t != NULL)
				{
					if ((t->varName == varName) && (t->Scope == S))
					{
					if (t->alias == "")
						t->varValue = varValue;          
					else 
						ChangeNode(t->alias,varValue);
					return true;
					}
					t = t->next;
				}
			else
				while (t != NULL)
				{
					if (t->varName == varName)
					{
					if (t->alias == "")
						t->varValue = varValue;          
					else 
						ChangeNode(t->alias,varValue);
					return true;
					}
					t = t->next;
				}
			return false;
		}
		
		T Value(N varName)
		{
			N S("");
			if (varName.InStr(':') > 0)
			{
				S = Tokenize(varName,":");
				varName.LTrim(':');
			}
			int i = 0;
			i = hash(varName);
			HashTableNode<T, N> *t;
			t = HTNode[i];
			if (S != "")
				while (t != NULL)
				{
					if ((t->varName == varName) && (t->Scope == S))
					{
						if (t->alias == "") return t->varValue;
						else return Value(t->alias);
					}
					t = t->next;
				}
			else
				while (t != NULL)
				{
					if (t->varName == varName)  
					{
						if (t->alias == "") return t->varValue;
						else return Value(t->alias);
					}
					t = t->next;
				}
			return NULL;
		}

		
		bool exists(N varName)
		{
			N S("");
			if (varName.InStr(':') > 0)
			{
				S = Tokenize(varName,":");
				varName.LTrim(':');
			}
			int i = 0;
			i = hash(varName);
			HashTableNode<T, N> *t;
			t = HTNode[i];
			while (t != NULL)
			{
				if (t->varName == varName)  return true;
				t = t->next;
			}
			return false;
		}

		bool existsInScope(N varName)
		{
			int i = 0;
			i = hash(varName);
			HashTableNode<T, N> *t;
			t = HTNode[i];
			while (t != NULL)
			{
				if ((t->varName == varName) && (t->Scope == currentScope())) return true;
				t = t->next;
			}
			return false;

		}

		T Val(N c)
		{
			if (exists(c))
				return (Value(c));
			else if (isNumber(c)) return c;
			else if (isStringVar(c)) return (c.Trim('\''));
			return cEmpty;
		}
		
		N getScope()
		{
			return Scope.front();
		}

		N FullVarName(N varName)
		{
			if (varName.InStr(':') > 0) return varName;
			int i = 0;
			i = hash(varName);
			HashTableNode<T, N> *t;
			t = HTNode[i];
			while (t != NULL)
			{
				if (t->varName == varName)  return t->Scope + ":" + t->varName ;
				t = t->next;
			}
			return cEmpty;
		}

	private:
		stack<N> Scope;
		N ScopeID ;
};