From C + + to. NET: Mapping native C + + to a common type system

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The unexpected place of the keyword

Inherited

Copy semantics

Lessons in the new language

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In this column, the text query Language (TQL) query class hierarchy is converted from C + + to the. NET Common Type System (CTS). Here, I will use C++/CLI, but you can also use C #. The main advantage of C++/CLI is that it enables the application to be progressively transformed so that the source code level can mix native and managed C + + code. First, let's take a look at the implementation of the native Query base class, as shown in Figure 1.

Figure1 Native abstract Query base class

#include <vector>
#include <iostream>
#include <set>
#include <string>
#include <utility>
using namespace Std;
typedef pair< short, short > location;
Class Query {
Public
Virtual ~query () {delete _solution;}
query& operator= (const query&);
Virtual Set of operations ...
virtual void eval () = 0;
Virtual Query *clone () const = 0;
Virtual ostream& print (ostream &os) const = 0;
virtual bool Add_op (query*) {return true;}
virtual void display_solution (ostream &os = cout, int tabcnt = 0);
Actions that have been incorporated into the scope of the query
void Handle_tab (ostream &os, int tabcnt) const;
void Display_partial_solution ();
Const set< Short > *solution ();
Const vector< location > *locations () const {return &_loc;}
Supports the recognition of parentheses embedded in the query,
such as Alice && (Fiery | | magical)
void Lparen (short lp) {_lparen = LP;}
void Rparen (short rp) {_rparen = RP;}
Short Lparen () {return _lparen;}
Short Rparen () {return _rparen;}
void Print_lparen (short cnt, ostream& OS) const;
void Print_rparen (short cnt, ostream& OS) const;
Protected

Query (): _lparen (0), _rparen (0), _solution (0) {}
Query (const query &AMP;RHS)
: _loc (Rhs._loc), _solution (0),
_lparen (Rhs._lparen), _rparen (Rhs._rparen)
{}
Query (const vector<location> &loc)
: _loc (Loc), _solution (0),
_lparen (0), _rparen (0)
{}
set<short>* _vec2set (const vector<location>*);
Short _lparen;
Short _rparen;
Vector<location> _loc;
Set<short> *_solution;
};