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Telegram/ThirdParty/range-v3/test/view/take_while.cpp

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+// Range v3 library
+//
+//  Copyright Eric Niebler 2014-present
+//
+//  Use, modification and distribution is subject to the
+//  Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//
+// Project home: https://github.com/ericniebler/range-v3
+
+#include <vector>
+#include <range/v3/core.hpp>
+#include <range/v3/view/iota.hpp>
+#include <range/v3/view/generate.hpp>
+#include <range/v3/view/take_while.hpp>
+#include <range/v3/utility/copy.hpp>
+#include "../simple_test.hpp"
+#include "../test_utils.hpp"
+
+struct my_data
+{
+    int i;
+};
+
+bool operator==(my_data left, my_data right)
+{
+    return left.i == right.i;
+}
+
+int main()
+{
+    using namespace ranges;
+    auto rng0 = views::iota(10) | views::take_while([](int i) { return i != 25; });
+    ::check_equal(rng0, {10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24});
+    CPP_assert(view_<decltype(rng0)>);
+    CPP_assert(!common_range<decltype(rng0)>);
+    CPP_assert(random_access_iterator<decltype(rng0.begin())>);
+
+    std::vector<int> vi{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+    auto rng1 = vi | views::take_while([](int i) { return i != 50; });
+    CPP_assert(view_<decltype(rng1)>);
+    CPP_assert(random_access_range<decltype(rng1)>);
+    ::check_equal(rng1, {0, 1, 2, 3, 4, 5, 6, 7, 8, 9});
+
+    // Check with a mutable predicate
+    int rgi[] = {0,1,2,3,4,5,6,7,8,9};
+    int cnt = 0;
+    auto mutable_only = views::take_while(rgi, [cnt](int) mutable { return ++cnt <= 5;});
+    ::check_equal(mutable_only, {0,1,2,3,4});
+    CPP_assert(view_<decltype(mutable_only)>);
+    CPP_assert(!view_<decltype(mutable_only) const>);
+
+    {
+        auto ns = views::generate([]() mutable {
+            static int N;
+            return ++N;
+        });
+        auto rng = ns | views::take_while([](int i) { return i < 5; });
+        ::check_equal(rng, {1,2,3,4});
+    }
+
+    {
+        auto ns = views::generate([]() mutable {
+            static int N;
+            return ++N;
+        });
+        auto rng = ns | views::take_while([](int i) mutable { return i < 5; });
+        ::check_equal(rng, {1,2,3,4});
+    }
+
+    {
+        auto rng = debug_input_view<int const>{rgi} | views::take_while([](int i) {
+            return i != 5;
+        });
+        ::check_equal(rng, {0,1,2,3,4});
+    }
+
+    {
+        auto ns = views::generate([]() {
+            static int N;
+            return my_data{++N};
+        });
+        auto rng = ns | views::take_while([](int i) { return i < 5; },
+                                         &my_data::i);
+        ::check_equal(rng, std::vector<my_data>{{1},{2},{3},{4}});
+    }
+
+    return test_result();
+}