1 // Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information. 2 3 #if !defined(CPPLINQ_LINQ_SELECT_HPP) 4 #define CPPLINQ_LINQ_SELECT_HPP 5 #pragma once 6 7 #include <cstddef> 8 9 namespace cpplinq 10 { 11 template <class Collection, class Selector> 12 class linq_select 13 { 14 typedef typename Collection::cursor 15 inner_cursor; 16 public: 17 struct cursor { 18 typedef typename util::result_of<Selector(typename inner_cursor::element_type)>::type 19 reference_type; 20 typedef typename std::remove_reference<reference_type>::type 21 element_type; 22 typedef typename inner_cursor::cursor_category 23 cursor_category; 24 25 cursor(const inner_cursor& cur, Selector sel) : cur(cur), sel(std::move(sel)) {} 26 27 void forget() { cur.forget(); } 28 bool empty() const { return cur.empty(); } 29 void inc() { cur.inc(); } 30 reference_type get() const { return sel(cur.get()); } 31 32 bool atbegin() const { return cur.atbegin(); } 33 void dec() { cur.dec(); } 34 35 void skip(std::size_t n) { cur.skip(n); } 36 std::size_t position() const { return cur.position(); } 37 std::size_t size() const { return cur.size(); } 38 private: 39 inner_cursor cur; 40 Selector sel; 41 }; 42 43 linq_select(const Collection& c, Selector sel) : c(c), sel(sel) {} 44 45 cursor get_cursor() const { return cursor(c.get_cursor(), sel); } 46 47 private: 48 Collection c; 49 Selector sel; 50 }; 51 52 } 53 54 #endif // defined(CPPLINQ_LINQ_SELECT_HPP) 55
