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Fix issue 8085 #987

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merged 4 commits into from
Dec 17, 2012
Merged

Fix issue 8085 #987

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d489281
Rewrite joiner to not assume persistence of .front.
Oct 29, 2012
f83ad8a
Add unittest for new joiner.
Oct 29, 2012
e471f8e
Completely get rid of UTF-8 to workaround OSX/64 bug.
Dec 10, 2012
3a2377c
Replace joiner unittest with one that doesn't suffer from issue 9131.
Dec 17, 2012
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103 changes: 95 additions & 8 deletions std/algorithm.d
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Original file line number Diff line number Diff line change
Expand Up @@ -2803,17 +2803,16 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR))
private:
RoR _items;
ElementType!RoR _current;
bool _valid_current;
void prepare()
{
for (;; _items.popFront())
// Skip over empty subranges.
if (_items.empty) return;
while (_items.front.empty)
{
_items.popFront();
if (_items.empty) return;
if (!_items.front.empty) break;
}
_current = _items.front;
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We'd need to make this (provided we have forward iteration):

_current = _items.front.save;

To be able to make joiner a true forward range.

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Actually, that's not enough. If the subranges are themselves ranges of ranges, then their respective subranges may be consumed if the user iterates over the .save'd range.

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Ah... But now we're back to the square one argument: That is just the element type of the "RoR" that we are iterating over. They are just elements, but not part of our range interface. This "third level" range is just as irrelevant to us as the "second level" range is irrelevant to array.save.

We were tasked with transforming the RoR into a R. The fact that those elements are also themselves ranges is not our problem, and shouldn't be our problem. Maybe the user wanted to have a RoR whose elements are mutable char[], which are not meant to be duplicated. What do we know?

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You're right, the .save exposed by joiner only guarantees saving the state of the joined ranged itself, it says nothing about the state of the elements themselves. My bad.

_valid_current = true;
_items.popFront();
}
public:
this(RoR r)
Expand All @@ -2829,7 +2828,7 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR))
{
@property auto empty()
{
return !_valid_current || _current.empty;
return _items.empty;
}
}
@property auto ref front()
Expand All @@ -2841,7 +2840,12 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR))
{
assert(!_current.empty);
_current.popFront();
if (_current.empty) prepare();
if (_current.empty)
{
assert(!_items.empty);
_items.popFront();
prepare();
}
}
static if (isForwardRange!RoR && isForwardRange!(ElementType!RoR))
{
Expand All @@ -2850,7 +2854,6 @@ if (isInputRange!RoR && isInputRange!(ElementType!RoR))
Result copy;
copy._items = _items.save;
copy._current = _current.save;
copy._valid_current = _valid_current;
return copy;
}
}
Expand Down Expand Up @@ -2897,6 +2900,90 @@ unittest
assert(!equal(js2, js));
}

unittest
{
struct TransientRange
{
int[128] _buf;
int[][] _values;
this(int[][] values)
{
_values = values;
}
@property bool empty()
{
return _values.length == 0;
}
@property auto front()
{
foreach (i; 0 .. _values.front.length)
{
_buf[i] = _values[0][i];
}
return _buf[0 .. _values.front.length];
}
void popFront()
{
_values = _values[1 .. $];
}
}

auto rr = TransientRange([[1,2], [3,4,5], [], [6,7]]);

// Can't use array() or equal() directly because they fail with transient
// .front.
int[] result;
foreach (c; rr.joiner()) {
result ~= c;
}

assert(equal(result, [1,2,3,4,5,6,7]));
}

// Temporarily disable this unittest due to issue 9131 on OSX/64.
version = Issue9131;
version(Issue9131) {} else
unittest
{
struct TransientRange
{
dchar[128] _buf;
dstring[] _values;
this(dstring[] values)
{
_values = values;
}
@property bool empty()
{
return _values.length == 0;
}
@property auto front()
{
foreach (i; 0 .. _values.front.length)
{
_buf[i] = _values[0][i];
}
return _buf[0 .. _values.front.length];
}
void popFront()
{
_values = _values[1 .. $];
}
}

auto rr = TransientRange(["abc"d, "12"d, "def"d, "34"d]);

// Can't use array() or equal() directly because they fail with transient
// .front.
dchar[] result;
foreach (c; rr.joiner()) {
result ~= c;
}

assert(equal(result, "abc12def34"d),
"Unexpected result: '%s'"d.format(result));
}

// uniq
/**
Iterates unique consecutive elements of the given range (functionality
Expand Down