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optimize Slice.opEquals #4645

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optimize Slice.opEquals #4645

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45 changes: 27 additions & 18 deletions std/experimental/ndslice/slice.d
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Original file line number Diff line number Diff line change
Expand Up @@ -1726,8 +1726,9 @@ struct Slice(size_t _N, _Range)
bool opEquals(size_t NR, RangeR)(auto ref Slice!(NR, RangeR) rslice)
if (Slice!(NR, RangeR).PureN == PureN)
{
if (this._lengths != rslice._lengths)
return false;
foreach (i; Iota!(0, PureN))
if (this._lengths[i] != rslice._lengths[i])
return false;
static if (
!hasReference!(typeof(this))
&& !hasReference!(typeof(rslice))
Expand All @@ -1737,17 +1738,27 @@ struct Slice(size_t _N, _Range)
if (this._strides == rslice._strides && this._ptr == rslice._ptr)
return true;
}
return opEqualsImpl(this, rslice);
foreach (i; Iota!(0, PureN))
if (this._lengths[i] == 0)
return true;
import std.experimental.ndslice.selection : unpack;
return opEqualsImpl(this.unpack, rslice.unpack);
}

///ditto
bool opEquals(T)(T[] rarrary)
{
if (this.length != rarrary.length)
auto slice = this;
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@JackStouffer JackStouffer Jul 25, 2016 •
edited
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What's the reasoning behind this? Why not just use this?

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@9il 9il Jul 25, 2016 •
edited
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slice.popFront; will change the slice

if (slice.length != rarrary.length)
return false;
foreach (i, ref e; rarrary)
if (e != this[i])
if (rarrary.length) do
{
if (slice.front != rarrary.front)
return false;
slice.popFront;
rarrary.popFront;
}
while (rarrary.length);
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@Hackerpilot Hackerpilot Jul 25, 2016 •
edited
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Is this change also part of one of the other pull requests?

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@9il 9il Jul 25, 2016

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Oops, yes. Thank you! it is part of #4647

return true;
}

Expand Down Expand Up @@ -2765,28 +2776,26 @@ unittest
}

private bool opEqualsImpl
(size_t NL, RangeL, size_t NR, RangeR)(
auto ref Slice!(NL, RangeL) ls,
auto ref Slice!(NR, RangeR) rs)
in
{
assert(ls._lengths == rs._lengths);
}
body
(size_t N, RangeL, RangeR)(
Slice!(N, RangeL) ls,
Slice!(N, RangeR) rs)
{
foreach (i; 0 .. ls.length)
do
{
static if (Slice!(NL, RangeL).PureN == 1)
static if (Slice!(N, RangeL).PureN == 1)
{
if (ls[i] != rs[i])
if (ls.front != rs.front)
return false;
}
else
{
if (!opEqualsImpl(ls[i], rs[i]))
if (!opEqualsImpl(ls.front, rs.front))
return false;
}
rs.popFront;
ls.popFront;
}
while (ls.length);
return true;
}

Expand Down