Dictionary - a C++ template class to emulate VBScript's "Scripting.Dictionary" collection

Monday Mar 8th 1999 by James Curran

Dictionary - a C++ template class to emulate VBScript's "Scripting.Dictionary" collection

Dictionary  is a C++ template designed to duplicate the functionality, and, for the most part, the syntax of the Scripting.Dictionary ActiveX object built into VBA and VBScript.  It derives from an STL map<> template, so any of the STL algorithms will also work with it.  All of it's member functions are inlined, so there's only a Dictionary.h file.  There is no Dictionary.cpp.

In the examples below, the left side are taken directly from Microsoft published documentation for the Scripting.Dictionary ActiveX.  The right side is the equivalent C++ code using the Dictionary<> template.  As you can see, the syntax is nearly identical, with the only significant different is that the data types of the dictionary must to predefined, and the C++ methods require parentheses where the VBScript methods don't.

'VBScript sample code from Add Method
Dim d
Set d = CreateObject("Scripting.Dictionary")
d.Add "a", "Athens"
d.Add "b", "Belgrade"
d.Add "c", "Cairo"

Dictionary<string, string>    d;
d.Add("a", "Athens");
d.Add("b", "Belgrade");
d.Add("c", "Cairo");

VBScript sample code from both Count property & Keys method
dim a
a = d.Keys
For i = 0 to d.Count -1
s = s & a(i) & "<BR>"

vector<string>    a;
string            s;
a = d.Keys();
for (int i = 0; i < d.Count(); i++)
        s = s + a[i] + '\n';
VBScript sample code from Items method
dim a
a = d.Items
For i = 0 to d.Count -1
   s = s & a(i) & "<BR>"

vector<string>    a = d.Items();
for (i = 0; i < d.Count(); i++)
   cout << a[i] << endl;   
VBScript sample code from Exists method
If d.Exists("c") Then
    msg = "Specified key exists."
    msg = "Specified key doesn't exist."
End If

if (d.Exists("c"))
   cout << "Key: 'c' Exists" << endl;
   cout << "Key: 'c' does not exist" << endl;
VBScript sample code from Remove method
(docs never explain the return value of Remove method)
a = d.Remove("b") 'Remove second pair

VBScript sample code from Key property
d.Key("c") = "d" 'Set key for "c" to "d".

d.Key("c") = "d";
VBScript sample code from RemoveAll method
(docs never explain the return value of RemoveAll method)
a = d.RemoveAll 'Clear the dictionary


Summary of Public Interface:

// Dictionary.h: interface/implementation for the Dictionary class.
// Dictionary is a templatized class which is a direct copy of
// the VBScript Scripting.Dictionary object.  All methods
// and properties are provided with a syntax that is either
// identical to the VBS implementation, or with only trivial
// differences (mainly, C++ member functions require parentheses
// where VBScript methods don't)
// Copyright 1998, James M. Curran, All Rights reserved.
//  May be used freely, provided copyright noticed remains.
//  May not be sold in source code form.
// email: JamesCurran@Mvps.org
//   WWW: http://www.NJTheater.Com/JamesCurran
template<typename KEY, typename ITEM>
class Dictionary  : std::map<KEY, ITEM>
	Dictionary() {};
	virtual ~Dictionary(){};
	void			Add(KEY k, ITEM i);
	bool 			Exists(KEY k) 	const;
	size_type 		Count() 	const;
	void 			Remove(KEY k);
	void 			RemoveAll();
	std::vector<KEY>	Keys() 		const;
	std::vector<ITEM>	Items()		const;
	DKH			Key(KEY k);
	DIH			Item(KEY k);
	DIH 			operator[](KEY k);
	DIH 			operator()(KEY k);
	friend std::ostream& 	operator<<(std::ostream& os, const DIH& dih);

Note:   Anything above the returns a DIH or DKH can appear on either the right or left side of an assignment,  (although Key() is a bit pointless on the right hand side).  eg:

    dict.Item("a") = "Apple";
    dict("a") = "Apple";
    dict["a"] = "Apple";

are all legal (and equivalent).

Demo is included with header file.  Just compile & link a source file with the following three lines:

#include "dictionary.h"
void main()	{ dictionary_test();	}
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