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vladchicos 2021-08-10 08:13:34 +03:00
parent cba0b3f813
commit bbfe30a671
1 changed files with 18 additions and 9 deletions
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27
std/algorithm/iteration.d
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@ -2908,6 +2908,11 @@ is propagated if no separator is specified.
See_also: See_also:
$(REF chain, std,range), which chains a sequence of ranges with compatible elements $(REF chain, std,range), which chains a sequence of ranges with compatible elements
into a single range. into a single range.
Note:
When both outer and inner ranges of `RoR` are bidirectional and the joiner is
iterated from the back to the front, the separator will still be consumed from
front to back, even if it is a bidirectional range too.
*/ */
auto joiner(RoR, Separator)(RoR r, Separator sep) auto joiner(RoR, Separator)(RoR r, Separator sep)
if (isInputRange!RoR && isInputRange!(ElementType!RoR) if (isInputRange!RoR && isInputRange!(ElementType!RoR)
@ -3006,8 +3011,10 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR)
private void useSeparator() private void useSeparator()
{ {
// Separator must always come after an item. // Separator must always come after an item.
assert(_currentSep.empty && !_items.empty, assert(_currentSep.empty,
"joiner: internal error"); "Attempting to reset a non-empty separator");
assert(!_items.empty,
"Attempting to use a separator in an empty joiner");
_items.popFront(); _items.popFront();
// If there are no more items, we're done, since separators are not // If there are no more items, we're done, since separators are not
@ -3058,12 +3065,13 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR)
_current = _items.front; _current = _items.front;
static if (isBidirectional) static if (isBidirectional)
{
_currentBack = _items.back.save; _currentBack = _items.back.save;
static if (isBidirectional)
{
if (_currentBack.empty) if (_currentBack.empty)
{ {
// No data in the currentBack item - toggle to use
// the separator
inputEndsWithEmpty = true; inputEndsWithEmpty = true;
} }
} }
@ -3073,9 +3081,8 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR)
// No data in the current item - toggle to use the separator // No data in the current item - toggle to use the separator
inputStartsWithEmpty = true; inputStartsWithEmpty = true;
//A range with a single element which is empty will always // If RoR contains a single empty element,
// return an empty Result // the returned Result will always be empty
import std.range : dropOne; import std.range : dropOne;
static if (hasLength!RoR) static if (hasLength!RoR)
{ {
@ -3186,8 +3193,10 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR)
private void useBackSeparator() private void useBackSeparator()
{ {
// Separator must always come after an item. // Separator must always come after an item.
assert(_currentBackSep.empty && !_items.empty, assert(_currentBackSep.empty,
"joiner: internal error"); "Attempting to reset a non-empty separator");
assert(!_items.empty,
"Attempting to use a separator in an empty joiner");
_items.popBack(); _items.popBack();
// If there are no more items, we're done, since separators are not // If there are no more items, we're done, since separators are not