src/common/optional.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005 - 2019 Christian Schoenebeck                       *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the Free Software           *
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef __LS_OPTIONAL_H__
#define __LS_OPTIONAL_H__

#include "Exception.h"

namespace LinuxSampler {

    /**
     * Base class of template class optional, not meant to be instantiated
     * directly. It just provides the optional<T>::nothing member.
     */
    class optional_base {
        public:
            class nothing_t { public: nothing_t() {} };

            static const nothing_t nothing;
    };

    /**
     * This class can be used for any variable that might not have a value
     * set. E.g. as a return value type of a function, since in the case of
     * return values of functions it's often difficult to return a pointer
     * variable which might do the trick of an optional return value. It
     * behaves pretty much like a pointer though. That is, it can be checked
     * against NULL and the actual value can be dereferenced with the
     * typical C pointer dereference operators.
     */
    template<class T>
    class optional : public optional_base {
        public:
            optional() {
                initialized = false;
            }

            optional(T data) {
                this->data  = data;
                initialized = true;
            }

            optional(nothing_t) {
                initialized = false;
            }

            template <class T_inner>
            optional(T_inner data) {
                this->data  = T(data);
                initialized = true;
            }

            const T& get() const throw (Exception) {
                if (!initialized) throw Exception("optional variable not initialized");
                return data;
            }

            T& get() throw (Exception) {
                if (!initialized) throw Exception("optional variable not initialized");
                return data;
            }

            optional& operator =(const optional& arg) {
                this->data  = arg.data;
                initialized = arg.initialized;
                return *this;
            }

            optional& operator =(const T& arg) {
                this->data  = arg;
                initialized = true;
                return *this;
            }

            bool operator ==(const optional& o) const {
                if (!initialized || !o.initialized)
                    return initialized == o.initialized;
                return data == o.data;
            }

            bool operator !=(const optional& o) const {
                return !(*this == o);
            }

            const T& operator *() const throw (Exception) { return get(); }
            T&       operator *()       throw (Exception) { return get(); }

            const T* operator ->() const throw (Exception) {
                if (!initialized) throw Exception("optional variable not initialized");
                return &data;
            }

            T* operator ->() throw (Exception) {
                if (!initialized) throw Exception("optional variable not initialized");
                return &data;
            }

            operator bool()   const { return initialized; }
            bool operator !() const { return !initialized; }

        protected:
            T    data;
            bool initialized;
    };

} // namespace LinuxSampler

#endif // __LS_OPTIONAL_H__
1	schoenebeck	123	/***************************************************************************
2			* *
3			* LinuxSampler - modular, streaming capable sampler *
4			* *
5			* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6	schoenebeck	3514	* Copyright (C) 2005 - 2019 Christian Schoenebeck *
7	schoenebeck	123	* *
8			* This program is free software; you can redistribute it and/or modify *
9			* it under the terms of the GNU General Public License as published by *
10			* the Free Software Foundation; either version 2 of the License, or *
11			* (at your option) any later version. *
12			* *
13			* This program is distributed in the hope that it will be useful, *
14			* but WITHOUT ANY WARRANTY; without even the implied warranty of *
15			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16			* GNU General Public License for more details. *
17			* *
18			* You should have received a copy of the GNU General Public License *
19			* along with this program; if not, write to the Free Software *
20			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
21			* MA 02111-1307 USA *
22			***************************************************************************/
23
24			#ifndef __LS_OPTIONAL_H__
25			#define __LS_OPTIONAL_H__
26
27	schoenebeck	880	#include "Exception.h"
28	schoenebeck	123
29			namespace LinuxSampler {
30
31	schoenebeck	2121	/**
32			* Base class of template class optional, not meant to be instantiated
33			* directly. It just provides the optional<T>::nothing member.
34			*/
35	schoenebeck	123	class optional_base {
36			public:
37			class nothing_t { public: nothing_t() {} };
38
39			static const nothing_t nothing;
40			};
41
42	schoenebeck	2121	/**
43			* This class can be used for any variable that might not have a value
44			* set. E.g. as a return value type of a function, since in the case of
45			* return values of functions it's often difficult to return a pointer
46			* variable which might do the trick of an optional return value. It
47			* behaves pretty much like a pointer though. That is, it can be checked
48			* against NULL and the actual value can be dereferenced with the
49			* typical C pointer dereference operators.
50			*/
51	schoenebeck	123	template<class T>
52			class optional : public optional_base {
53			public:
54			optional() {
55			initialized = false;
56			}
57
58			optional(T data) {
59			this->data = data;
60			initialized = true;
61			}
62
63			optional(nothing_t) {
64			initialized = false;
65			}
66
67			template <class T_inner>
68			optional(T_inner data) {
69			this->data = T(data);
70			initialized = true;
71			}
72
73	schoenebeck	880	const T& get() const throw (Exception) {
74			if (!initialized) throw Exception("optional variable not initialized");
75	schoenebeck	123	return data;
76			}
77
78	schoenebeck	880	T& get() throw (Exception) {
79			if (!initialized) throw Exception("optional variable not initialized");
80	schoenebeck	123	return data;
81			}
82
83	schoenebeck	2121	optional& operator =(const optional& arg) {
84	schoenebeck	123	this->data = arg.data;
85	schoenebeck	2121	initialized = arg.initialized;
86	schoenebeck	810	return *this;
87	schoenebeck	123	}
88
89			optional& operator =(const T& arg) {
90			this->data = arg;
91			initialized = true;
92	schoenebeck	810	return *this;
93	schoenebeck	123	}
94
95	schoenebeck	3514	bool operator ==(const optional& o) const {
96			if (!initialized \|\| !o.initialized)
97			return initialized == o.initialized;
98			return data == o.data;
99			}
100
101			bool operator !=(const optional& o) const {
102			return !(*this == o);
103			}
104
105	schoenebeck	880	const T& operator *() const throw (Exception) { return get(); }
106			T& operator *() throw (Exception) { return get(); }
107	schoenebeck	123
108	schoenebeck	880	const T* operator ->() const throw (Exception) {
109			if (!initialized) throw Exception("optional variable not initialized");
110	schoenebeck	123	return &data;
111			}
112
113	schoenebeck	880	T* operator ->() throw (Exception) {
114			if (!initialized) throw Exception("optional variable not initialized");
115	schoenebeck	123	return &data;
116			}
117
118			operator bool() const { return initialized; }
119	senkov	134	bool operator !() const { return !initialized; }
120	schoenebeck	123
121			protected:
122			T data;
123			bool initialized;
124			};
125
126			} // namespace LinuxSampler
127
128			#endif // __LS_OPTIONAL_H__