flyweight.c

来自「《设计模式－可复用面向对象软件的基础》的经典模式源码实例」· C语言 代码 · 共 132 行

/*
*/
#include "defs.H"
class Window;
class GlyphContext;
class Font {
  public:
    Font(char*);
};
class BTree;
/*
*/
class Glyph {
public:
    virtual ~Glyph();

    virtual void Draw(Window*, GlyphContext&);
/*
*/
    virtual void SetFont(Font*, GlyphContext&);
    virtual Font* GetFont(GlyphContext&);
/*
*/
    virtual void First(GlyphContext&);
    virtual void Next(GlyphContext&);
    virtual bool IsDone(GlyphContext&);
    virtual Glyph* Current(GlyphContext&);
/*
*/
    virtual void Insert(Glyph*, GlyphContext&);
    virtual void Remove(GlyphContext&);
protected:
    Glyph();
};
/*
*/
class Character : public Glyph {
public:
    Character(char);

    virtual void Draw(Window*, GlyphContext&);
private:
    char _charcode;
};
/*
*/
class GlyphContext {
public:
    GlyphContext();
    virtual ~GlyphContext();
/*
*/
    virtual void Next(int step = 1);
    virtual void Insert(int quantity = 1);
/*
*/
    virtual Font* GetFont();
    virtual void SetFont(Font*, int span = 1);
private:
    int _index;
    BTree* _fonts;
};
/*
*/
void dummy () {
/*
*/
GlyphContext gc;
Font* times12 = new Font("Times-Roman-12");
Font* timesItalic12 = new Font("Times-Italic-12");
// ...

gc.SetFont(times12, 6);
/*
*/
gc.Insert(6);
gc.SetFont(timesItalic12, 6);
/*
*/
}
/*
*/
class Row {
};
class Column {
};
/*
*/
const int NCHARCODES = 128;

class GlyphFactory {
public:
    GlyphFactory();
    virtual ~GlyphFactory();
/*
*/
    virtual Character* CreateCharacter(char);
    virtual Row* CreateRow();
    virtual Column* CreateColumn();
    // ...
private:
    Character* _character[NCHARCODES];
};
/*
*/
GlyphFactory::GlyphFactory () {
    for (int i = 0; i < NCHARCODES; ++i) {
         _character[i] = 0;
    }
}
/*
*/
Character* GlyphFactory::CreateCharacter (char c) {
    if (!_character[c]) {
        _character[c] = new Character(c);
    }

    return _character[c];
}
/*
*/
Row* GlyphFactory::CreateRow () {
    return new Row;
}
/*
*/
Column* GlyphFactory::CreateColumn () {
    return new Column;
}
/*
*/