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Hi. Would it make sense to add an array search builtin accessible via (for
example) std::reverse_lookup?

template <typename ArrayType, size_t ArraySize, typename Compare>
constexpr ArrayType* reverse_lookup(ArrayType(&array)[ArraySize], Compare&&
compare)
{
        return SOME_BUILTIN_REVERSE_LOOKUP(array, compare);
}

(returns pointer to the first found element, nullptr otherwise)

The purpose is (hopefully) optimization because manually implemented linear
search seems ineffective, and binary search requires sorting which is not
guaranteed. Another possibility would be similar constexpr
lower_bound/upper_bound-alike binary search functions expected to fail
loudly if the array is not appropriately sorted.

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<div dir=3D"ltr"><div>Hi. Would it make sense to add an array search builti=
n accessible via (for example) std::reverse_lookup?<span style=3D"color: #0=
00;" class=3D"styled-by-prettify"><br></span></div><div><br></div><div><div=
 style=3D"background-color: #FAFAFA; border-color: #BBB; border-style: soli=
d; border-width: 1px; word-wrap: break-word;" class=3D"prettyprint"><code c=
lass=3D"prettyprint"><div class=3D"subprettyprint"><span style=3D"color: #0=
08;" class=3D"styled-by-prettify">template</span><span style=3D"color: #000=
;" class=3D"styled-by-prettify"> </span><span style=3D"color: #660;" class=
=3D"styled-by-prettify">&lt;</span><span style=3D"color: #008;" class=3D"st=
yled-by-prettify">typename</span><span style=3D"color: #000;" class=3D"styl=
ed-by-prettify"> </span><span style=3D"color: #606;" class=3D"styled-by-pre=
ttify">ArrayType</span><span style=3D"color: #660;" class=3D"styled-by-pret=
tify">,</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> si=
ze_t </span><span style=3D"color: #606;" class=3D"styled-by-prettify">Array=
Size</span><span style=3D"color: #660;" class=3D"styled-by-prettify">,</spa=
n><span style=3D"color: #000;" class=3D"styled-by-prettify"> </span><span s=
tyle=3D"color: #008;" class=3D"styled-by-prettify">typename</span><span sty=
le=3D"color: #000;" class=3D"styled-by-prettify"> </span><span style=3D"col=
or: #606;" class=3D"styled-by-prettify">Compare</span><span style=3D"color:=
 #660;" class=3D"styled-by-prettify">&gt;</span><span style=3D"color: #000;=
" class=3D"styled-by-prettify"><br></span><span style=3D"color: #008;" clas=
s=3D"styled-by-prettify">constexpr</span><span style=3D"color: #000;" class=
=3D"styled-by-prettify"> </span><span style=3D"color: #606;" class=3D"style=
d-by-prettify">ArrayType</span><span style=3D"color: #660;" class=3D"styled=
-by-prettify">*</span><span style=3D"color: #000;" class=3D"styled-by-prett=
ify"> reverse_lookup</span><span style=3D"color: #660;" class=3D"styled-by-=
prettify">(</span><span style=3D"color: #606;" class=3D"styled-by-prettify"=
>ArrayType</span><span style=3D"color: #660;" class=3D"styled-by-prettify">=
(&amp;</span><span style=3D"color: #000;" class=3D"styled-by-prettify">arra=
y</span><span style=3D"color: #660;" class=3D"styled-by-prettify">)[</span>=
<span style=3D"color: #606;" class=3D"styled-by-prettify">ArraySize</span><=
span style=3D"color: #660;" class=3D"styled-by-prettify">],</span><span sty=
le=3D"color: #000;" class=3D"styled-by-prettify"> </span><span style=3D"col=
or: #606;" class=3D"styled-by-prettify">Compare</span><span style=3D"color:=
 #660;" class=3D"styled-by-prettify">&amp;&amp;</span><span style=3D"color:=
 #000;" class=3D"styled-by-prettify"> compare</span><span style=3D"color: #=
660;" class=3D"styled-by-prettify">)</span><span style=3D"color: #000;" cla=
ss=3D"styled-by-prettify"><br></span><span style=3D"color: #660;" class=3D"=
styled-by-prettify">{</span><span style=3D"color: #000;" class=3D"styled-by=
-prettify"><br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 </span><span style=3D"color: #00=
8;" class=3D"styled-by-prettify">return</span><span style=3D"color: #000;" =
class=3D"styled-by-prettify"> SOME_BUILTIN_REVERSE_LOOKUP</span><span style=
=3D"color: #660;" class=3D"styled-by-prettify">(</span><span style=3D"color=
: #000;" class=3D"styled-by-prettify">array</span><span style=3D"color: #66=
0;" class=3D"styled-by-prettify">,</span><span style=3D"color: #000;" class=
=3D"styled-by-prettify"> compare</span><span style=3D"color: #660;" class=
=3D"styled-by-prettify">);</span><span style=3D"color: #000;" class=3D"styl=
ed-by-prettify"><br></span><span style=3D"color: #660;" class=3D"styled-by-=
prettify">}</span></div></code></div><br>(returns pointer to the first foun=
d element, nullptr otherwise)</div><div><br></div><div>The purpose is (hope=
fully) optimization because manually implemented linear search seems ineffe=
ctive, and binary search requires sorting which is not guaranteed. Another =
possibility would be similar constexpr lower_bound/upper_bound-alike binary=
 search functions expected to fail loudly if the array is not appropriately=
 sorted.</div></div>

<p></p>

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