text: // Copyright (c) 2020 Can Boluk and contributors of the VTIL Project   
  // All rights reserved.   
  //    
  // Redistribution and use in source and binary forms, with or without   
  // modification, are permitted provided that the following conditions are met: 
  //    
  // 1. Redistributions of source code must retain the above copyright notice,   
  //    this list of conditions and the following disclaimer.   
  // 2. Redistributions in binary form must reproduce the above copyright   
  //    notice, this list of conditions and the following disclaimer in the   
  //    documentation and/or other materials provided with the distribution.   
  // 3. Neither the name of VTIL Project nor the names of its contributors
  //    may be used to endorse or promote products derived from this software 
  //    without specific prior written permission.   
  //    
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
  // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE   
  // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE  
  // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE   
  // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR   
  // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF   
  // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS   
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN   
  // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)   
  // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE  
  // POSSIBILITY OF SUCH DAMAGE.        
  //
  #pragma once
  #include <iterator>
  #include <limits>
  
  namespace vtil
  {
  	template<typename _value_type = size_t>
  	struct numeric_range
  	{
  		// Declare the iterator type.
  		//
  		struct iterator_end_tag_t {};
  		struct iterator
  		{
  			// Generic iterator typedefs.
  			//
  			using iterator_category = std::bidirectional_iterator_tag;
  			using value_type =        _value_type;
  			using difference_type =   size_t;
  			using pointer =           value_type*;
  			using reference =         value_type&;
  
  			// Range of iteration.
  			//
  			value_type at;
  			value_type limit;
  
  			// Default constructor.
  			//
  			iterator( value_type at, value_type limit = 0 ) :
  				at( at ), value_type( limit ) {}
  
  			// Support bidirectional iteration.
  			//
  			iterator& operator++() { at++; return *this; }
  			iterator& operator--() { at--; return *this; }
  
  			// Equality check against another iterator.
  			//
  			bool operator==( const iterator& other ) const 
  			{ 
  				return at == other.at && limit == other.limit;
  			}
  			bool operator!=( const iterator& other ) const 
  			{ 
  				return at != other.at || limit != other.limit;
  			}
  			
  			// Equality check against special end iterator.
  			//
  			bool operator==( iterator_end_tag_t ) const { return at == limit; }
  			bool operator!=( iterator_end_tag_t ) const { return at != limit; }
  
  			// Redirect dereferencing to container.
  			//
  			value_type operator*() { return at; }
  			value_type operator*() const { return at; }
  		};
  		using const_iterator = iterator;
  
  		// Beginning and the end of the range.
  		//
  		_value_type rng_begin;
  		_value_type rng_end;
  
  		// Generic container helpers.
  		//
  		size_t size() const { return rng_end - rng_begin; }
  		iterator begin() const { return { rng_begin, rng_end }; }
  		iterator_end_tag_t end() const { return {}; }
  		_value_type operator[]( size_t n ) const { return rng_begin + n; }
  	};
  
  	// Simple range creation wrapper.
  	//
  	static const numeric_range<>& iindices() 
  	{
  		static const numeric_range<> cnt = { 0, SIZE_MAX };
  		return cnt;
  	};
  	template<typename T>
  	static numeric_range<T> iiota( T x ) { return { x, std::numeric_limits<T>::max() }; }
  };