89 lines
4.0 KiB
Plaintext
89 lines
4.0 KiB
Plaintext
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/* -*-c++-*- */
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/* osgEarth - Geospatial SDK for OpenSceneGraph
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* Copyright 2020 Pelican Mapping
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* http://osgearth.org
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*
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* osgEarth is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>
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*/
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#pragma once
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namespace osgEarth
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{
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/**
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* A template for defining "optional" class members. An optional member has a default value
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* and a flag indicating whether the member is "set".
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* This is used extensively in osgEarth's Config subsystem.
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*/
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template<typename T> struct optional {
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optional() { }
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optional(const optional<T>& rhs) : _set(rhs._set), _value(rhs._value), _defaultValue(rhs._defaultValue) { }
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optional<T>& operator = (const optional<T>& rhs) { _set=rhs._set; _value=rhs._value; _defaultValue=rhs._defaultValue; return *this; }
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optional(const T& defaultValue) : _value(defaultValue), _defaultValue(defaultValue) { }
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const T& operator =(const T& value) { _set=true; _value=value; return _value; }
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bool operator ==(const optional<T>& rhs) const { return _set && rhs._set && _value==rhs._value; }
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bool operator !=(const optional<T>& rhs) const { return !( (*this)==rhs); }
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bool operator ==(const T& value) const { return _value==value; }
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bool operator !=(const T& value) const { return _value!=value; }
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bool operator > (const T& value) const { return _value>value; }
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bool operator >=(const T& value) const { return _value>=value; }
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bool operator < (const T& value) const { return _value<value; }
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bool operator <=(const T& value) const { return _value<=value; }
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bool isSetTo(const T& value) const { return _set && _value==value; } // differs from == in that the value must be explicity set
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bool isSet() const { return _set; }
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void unset() { _set = false; _value=_defaultValue; }
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void clear() { unset(); }
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const T& get() const { return value(); }
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const T& value() const { return _value; }
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const T& defaultValue() const { return _defaultValue; }
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const T& getOrUse(const T& fallback) const { return _set ? _value : fallback; }
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// gets a mutable reference, automatically setting
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T& mutable_value() { _set = true; return _value; }
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T& edit() { return mutable_value(); }
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// sets a default value (without altering a set value)
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void setDefault(T defValue) { _defaultValue = defValue; if (!_set) _value = defValue; }
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// gets the const value.
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operator const T*() const { return &_value; }
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// gets the const value.
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const T* operator ->() const { return &_value; }
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public: // deprecated methods
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// sets a default value and usets the variable
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//[[deprecated("Use setDefault or OE_OPTION(type,name,default) instead")]]
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void init(T defValue) { _value = defValue; _defaultValue = defValue; unset(); }
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//[[deprecated("Use mutable_value() or edit() instead")]]
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T* operator ->() { _set = true; return &_value; }
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private:
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bool _set = false;
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T _value;
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T _defaultValue;
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typedef T* optional::*unspecified_bool_type;
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public:
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operator unspecified_bool_type() const { return 0; }
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};
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}
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