Memento_Exercise.cpp

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#include <iostream>
#include <sstream>
#include <vector>
 
#include "helpers/formatstring.h"
#include "helpers/replace.h"
 
#include "Memento_Exercise.h"
#include "Memento.h"
 
namespace // Anonymous
{
    using namespace DesignPatternExamples_cpp;
    
    std::vector<IMemento::shared_ptr_t> _mementoUndoList;
 
    void Memento_SaveForUndo(Memento_TextObject& text, std::string operation)
    {
        IMemento::shared_ptr_t memento = text.GetMemento(operation);
        _mementoUndoList.push_back(memento);
    }
 
 
    void Memento_Operation_Replace(Memento_TextObject& source, std::string searchPattern, std::string replaceText)
    {
        source.SetText(Helpers::Replace(source.Text(), searchPattern.c_str(), replaceText.c_str()));
    }
 
    void Memento_Operation_Reverse(Memento_TextObject& source)
    {
        std::ostringstream output;
        std::string text = source.Text();
        for (size_t index = 0; index < text.size(); ++index)
        {
            output << text[text.size() - 1 - index];
        }
        source.SetText(output.str());
    }
 
    void Memento_Undo(Memento_TextObject& text)
    {
        if (!_mementoUndoList.empty())
        {
            IMemento::shared_ptr_t lastMemento = _mementoUndoList.back();
            _mementoUndoList.pop_back();
            text.RestoreMemento(lastMemento);
 
            // Show off what we (un)did.
            std::cout
                << Helpers::formatstring("    undoing operation %-31s: \"%s\"",
                    lastMemento->Name().c_str(), text.ToString().c_str())
                << std::endl;
        }
    }
 
    void Memento_ApplyReplaceOperation(Memento_TextObject& text, std::string searchPattern, std::string replaceText)
    {
        std::string operationName = Helpers::formatstring("Replace '%s' with '%s'",
            searchPattern.c_str(), replaceText.c_str());
        Memento_SaveForUndo(text, operationName);
        Memento_Operation_Replace(text, searchPattern, replaceText);
        std::cout
            << Helpers::formatstring("    operation %-31s: \"%s\"", operationName.c_str(), text.ToString().c_str())
            << std::endl;
    }
 
 
    void Memento_ApplyReverseOperation(Memento_TextObject& text)
    {
        std::string operationName = "Reverse";
        Memento_SaveForUndo(text, operationName);
        Memento_Operation_Reverse(text);
        std::cout
            << Helpers::formatstring("    operation %-31s: \"%s\"", operationName.c_str(), text.ToString().c_str())
            << std::endl;
    }
 
} // end namespace Anonmyous
 
 
namespace DesignPatternExamples_cpp
{
 
    // ! [Using Memento in C++]
    void Memento_Exercise()
    {
        std::cout << std::endl;
        std::cout << "Memento Exercise" << std::endl;
 
        // Start with a fresh undo list.
        _mementoUndoList.clear();
 
        // The base text object to work from.
        Memento_TextObject text("This is a line of text on which to experiment.");
 
        std::cout
            << Helpers::formatstring("  Starting text: \"%s\"", text.ToString().c_str())
            << std::endl;
 
        // Apply four operations to the text.
        Memento_ApplyReplaceOperation(text, "text", "painting");
        Memento_ApplyReplaceOperation(text, "on", "off");
        Memento_ApplyReverseOperation(text);
        Memento_ApplyReplaceOperation(text, "i", "!");
 
        std::cout << "  Now perform undo until back to original" << std::endl;
 
        // Now undo the four operations.
        Memento_Undo(text);
        Memento_Undo(text);
        Memento_Undo(text);
        Memento_Undo(text);
 
        std::cout
            << Helpers::formatstring("  Final text   : \"%s\"", text.ToString().c_str())
            << std::endl;
 
        std::cout << "  Done." << std::endl;
    }
    // ! [Using Memento in C++]
 
} // end namespace