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Implement ranges::istream_view #1334

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merged 9 commits into from
Oct 29, 2020
Merged

Implement ranges::istream_view #1334

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b8d3ca3
Implement ranges::istream_view
miscco Oct 1, 2020
d2554d1
Address review comments
miscco Oct 2, 2020
769bb06
No constexpr for you sir!
miscco Oct 2, 2020
7257687
Use istream rather than basic_istream<char>
miscco Oct 5, 2020
a978ef8
Casey's review comments
CaseyCarter Oct 12, 2020
fe4b53c
Merge branch 'main' into istream_view
CaseyCarter Oct 13, 2020
c617e60
default construct death_test_executive
CaseyCarter Oct 13, 2020
c550d44
Alphabetting is hard
CaseyCarter Oct 13, 2020
ff85a89
Apply suggestions from code review
StephanTLavavej Oct 27, 2020
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29 changes: 20 additions & 9 deletions stl/inc/ranges
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Original file line number Diff line number Diff line change
Expand Up @@ -657,7 +657,12 @@ namespace ranges {

_Iterator& operator++() {
#if _ITERATOR_DEBUG_LEVEL != 0
_STL_VERIFY(*this != default_sentinel, "cannot increment istream_view iterator at end of stream");
_STL_VERIFY(_Parent != nullptr,
"cannot increment default initialized istream_view iterator"); // Per LWG-XXXX
_STL_VERIFY(
_Parent->_Stream != nullptr, "cannot increment istream_view iterator with uninitialized stream");
_STL_VERIFY(!_Parent->_Stream_at_end(),
"cannot increment istream_view iterator at end of stream"); // Per LWG-XXXX
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#endif // _ITERATOR_DEBUG_LEVEL != 0
*_Parent->_Stream >> _Parent->_Val;
return *this;
Expand All @@ -667,14 +672,19 @@ namespace ranges {
++*this;
}

_Ty& operator*() const {
_NODISCARD _Ty& operator*() const noexcept /* strengthened */ {
#if _ITERATOR_DEBUG_LEVEL != 0
_STL_VERIFY(*this != default_sentinel, "cannot dereference istream_view iterator at end of stream");
_STL_VERIFY(_Parent != nullptr,
"cannot dereference default initialized istream_view iterator"); // Per LWG-XXXX
_STL_VERIFY(
_Parent->_Stream != nullptr, "cannot dereference istream_view iterator with uninitialized stream");
_STL_VERIFY(!_Parent->_Stream_at_end(),
"cannot dereference istream_view iterator at end of stream"); // Per LWG-XXXX
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#endif // _ITERATOR_DEBUG_LEVEL != 0
return _Parent->_Val;
}

friend bool operator==(const _Iterator& _Left, default_sentinel_t) {
_NODISCARD friend bool operator==(const _Iterator& _Left, default_sentinel_t) noexcept /* strengthened */ {
return _Left._Parent == nullptr || _Left._Parent->_Stream_at_end();
}
};
Expand All @@ -684,27 +694,28 @@ namespace ranges {

public:
basic_istream_view() = default;
constexpr explicit basic_istream_view(basic_istream<_Elem, _Traits>& _Stream_) noexcept // strengthened
constexpr explicit basic_istream_view(basic_istream<_Elem, _Traits>& _Stream_) noexcept(
is_nothrow_default_constructible_v<_Ty>) // strengthened
: _Stream{_STD addressof(_Stream_)} {}

constexpr auto begin() {
_NODISCARD constexpr auto begin() {
if (_Stream) {
*_Stream >> _Val;
}
return _Iterator{*this};
}

constexpr default_sentinel_t end() const noexcept {
_NODISCARD constexpr default_sentinel_t end() const noexcept {
return default_sentinel;
}

constexpr bool _Stream_at_end() const noexcept {
_NODISCARD constexpr bool _Stream_at_end() const noexcept {
return _Stream == nullptr || !*_Stream;
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}
};

template <class _Ty, class _Elem, class _Traits>
basic_istream_view<_Ty, _Elem, _Traits> istream_view(basic_istream<_Elem, _Traits>& _Stream) {
_NODISCARD basic_istream_view<_Ty, _Elem, _Traits> istream_view(basic_istream<_Elem, _Traits>& _Stream) {
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return basic_istream_view<_Ty, _Elem, _Traits>{_Stream};
}

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38 changes: 24 additions & 14 deletions tests/std/tests/P0896R4_views_istream/test.cpp
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Expand Up @@ -4,21 +4,21 @@
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <istream>
#include <ranges>
#include <sstream>

#include <range_algorithm_support.hpp>

using namespace std;

static constexpr int expected_empty[] = {-1, -1, -1, -1, -1};
static constexpr int expected_copied[] = {0, 1, 2, 3, -1};
constexpr int expected_empty[] = {-1, -1, -1, -1, -1};

struct streamable {
streamable() = default;
streamable(const int input) : _val(input) {}

friend basic_istream<char>& operator>>(basic_istream<char>& is, streamable& right) noexcept {
friend istream& operator>>(istream& is, streamable& right) noexcept {
is >> right._val;
return is;
}
Expand All @@ -42,17 +42,21 @@ bool test_one_type() {
static_assert(!ranges::common_range<R>);

// validate constructor
auto nonempty_stream = istringstream{"0"};
auto empty_intstream = istringstream{};
same_as<R> auto default_constructed = ranges::basic_istream_view<T, char>{};
same_as<R> auto empty_constructed = ranges::basic_istream_view<T, char>{empty_intstream};
same_as<R> auto value_constructed = ranges::basic_istream_view<T, char>{nonempty_stream};
auto nonempty_stream = istringstream{"0"};
auto empty_intstream = istringstream{};
same_as<R> auto default_constructed = basic_istream_view<T, char>{};
same_as<R> auto empty_constructed = basic_istream_view<T, char>{empty_intstream};
same_as<R> auto non_empty_constructed = basic_istream_view<T, char>{nonempty_stream};

// validate member begin
// NOTE: This moves the stream one element int front
// NOTE: begin() consumes the first token
assert(default_constructed.begin() == default_sentinel);
assert(empty_constructed.begin() == default_sentinel);
assert(value_constructed.begin() != default_sentinel);
assert(non_empty_constructed.begin() != default_sentinel);

// validate default constructed istream::iterator
const auto default_constructed_it = ranges::iterator_t<R>();
assert(default_constructed_it == default_sentinel);

// validate member end
static_assert(same_as<decltype(default_constructed.end()), default_sentinel_t>);
Expand All @@ -75,10 +79,16 @@ bool test_one_type() {
ranges::copy(empty_constructed, input_empty);
assert(ranges::equal(input_empty, expected_empty));

auto intstream = istringstream{"0 1 2 3"};
T input_value[] = {-1, -1, -1, -1, -1};
ranges::copy(ranges::basic_istream_view<T, char>{intstream}, input_value);
assert(ranges::equal(input_value, expected_copied));
const T expected[] = {0, 1, 2, 3, -1};
auto intstream = istringstream{"0 1 2 3"};
T input_value[] = {-1, -1, -1, -1, -1};
ranges::copy(basic_istream_view<T, char>{intstream}, input_value);
assert(ranges::equal(input_value, expected));

auto intstream_view = istringstream{"0 1 2 3"};
T input_value_view[] = {-1, -1, -1, -1, -1};
ranges::copy(ranges::istream_view<T, char>(intstream_view), input_value_view);
assert(ranges::equal(input_value_view, expected));

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return true;
}
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31 changes: 15 additions & 16 deletions tests/std/tests/P0896R4_views_istream_death/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13,28 +13,28 @@ using namespace std;

using iview = ranges::basic_istream_view<int, char>;

void test_predecrement_default_initialized() {
decltype(std::declval<iview>().begin()) it;
void test_preincrement_default_initialized() {
ranges::iterator_t<iview> it;
(void) ++it;
}

void test_postdecrement_default_initialized() {
decltype(std::declval<iview>().begin()) it;
void test_postincrement_default_initialized() {
ranges::iterator_t<iview> it;
(void) it++;
}

void test_dereference_default_initialized() {
decltype(std::declval<iview>().begin()) it;
ranges::iterator_t<iview> it;
(void) *it;
}

void test_predecrement_no_stream() {
void test_preincrement_no_stream() {
iview v;
auto it = v.begin();
(void) ++it;
}

void test_postdecrement_no_stream() {
void test_postincrement_no_stream() {
iview v;
auto it = v.begin();
(void) it++;
Expand All @@ -46,15 +46,14 @@ void test_dereference_no_stream() {
(void) *it;
}


void test_predecrement_end_of_stream() {
void test_preincrement_end_of_stream() {
istringstream stream;
iview view{stream};
auto it = view.begin();
(void) ++it;
}

void test_postdecrement_end_of_stream() {
void test_postincrement_end_of_stream() {
istringstream stream;
iview view{stream};
auto it = view.begin();
Expand All @@ -73,14 +72,14 @@ int main(int argc, char* argv[]) {

#if _ITERATOR_DEBUG_LEVEL != 0
exec.add_death_tests({
test_predecrement_default_initialized,
test_postdecrement_default_initialized,
test_preincrement_default_initialized,
test_postincrement_default_initialized,
test_dereference_default_initialized,
test_predecrement_no_stream,
test_postdecrement_no_stream,
test_preincrement_no_stream,
test_postincrement_no_stream,
test_dereference_no_stream,
test_predecrement_end_of_stream,
test_postdecrement_end_of_stream,
test_preincrement_end_of_stream,
test_postincrement_end_of_stream,
test_dereference_end_of_stream,
});
#endif // _ITERATOR_DEBUG_LEVEL != 0
Expand Down