mirrors/phobos
1
0
Fork 0
mirror of https://github.com/dlang/phobos.git synced 2025-05-03 16:40:48 +03:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

Tweak min and max for yet more efficiency

Browse source 
I checked the generated assembly code, and it looks pretty damn good. I've not been able to achieve any better anyways.
This commit is contained in:
monarch dodra 2014-03-27 13:34:01 +01:00 • committed by monarchdodra
parent bfcd33a627
commit a4e448be50
1 changed files with 66 additions and 54 deletions
Download patch file Download diff file Expand all files Collapse all files

120
std/algorithm.d
View file

@ -7052,9 +7052,13 @@ unittest
// MinType // MinType
private template MinType(T...) private template MinType(T...)
if (T.length >= 2) if (T.length >= 1)
{ {
static if (T.length == 2) static if (T.length == 1)
{
alias MinType = T[0];
}
else static if (T.length == 2)
{ {
static if (!is(typeof(T[0].min))) static if (!is(typeof(T[0].min)))
alias MinType = CommonType!T; alias MinType = CommonType!T;
@ -7074,44 +7078,46 @@ private template MinType(T...)
} }
else else
{ {
alias MinType = MinType!(T[0 .. $/2], MinType!(T[$/2 .. $])); alias MinType = MinType!(MinType!(T[0 .. ($+1)/2]), MinType!(T[($+1)/2 .. $]));
} }
} }
// min // min
/** /**
Returns the minimum of the passed-in values. The type of the result is Returns the minimum of the passed-in values.
computed by using $(XREF traits, CommonType).
*/ */
MinType!T min(T...)(T args) MinType!T min(T...)(T args)
if (T.length >= 2) if (T.length >= 2)
{ {
static if (T.length == 2) //Get "a"
static if (T.length <= 2)
alias args[0] a;
else
auto a = min(args[0 .. ($+1)/2]);
alias typeof(a) T0;
//Get "b"
static if (T.length <= 3)
alias args[$-1] b;
else
auto b = min(args[($+1)/2 .. $]);
alias typeof(b) T1;
static assert (is(typeof(a < b)),
algoFormat("Invalid arguments: Cannot compare types %s and %s.", T0.stringof, T1.stringof));
//Do the "min" proper with a and b
static if (isIntegral!T0 && isIntegral!T1 &&
(mostNegative!T0 < 0) != (mostNegative!T1 < 0))
{ {
alias T0 = T[0]; static if (mostNegative!T0 < 0)
alias T1 = T[1]; immutable chooseB = b < a && a > 0;
alias a = args[0];
alias b = args[1];
static assert (is(typeof(a < b)),
algoFormat("Invalid arguments: Cannot compare types %s and %s.", T0.stringof, T1.stringof));
static if (isIntegral!T0 && isIntegral!T1 &&
(mostNegative!T0 < 0) != (mostNegative!T1 < 0))
{
static if (mostNegative!T0 < 0)
immutable chooseB = b < a && a > 0;
else
immutable chooseB = b < a || b < 0;
}
else else
immutable chooseB = b < a; immutable chooseB = b < a || b < 0;
return cast(typeof(return)) (chooseB ? b : a);
} }
else else
{ immutable chooseB = b < a;
return min(args[0 .. $/2], min(args[$/2 .. $])); return cast(typeof(return)) (chooseB ? b : a);
}
} }
unittest unittest
@ -7147,9 +7153,13 @@ unittest
// MaxType // MaxType
private template MaxType(T...) private template MaxType(T...)
if (T.length >= 2) if (T.length >= 1)
{ {
static if (T.length == 2) static if (T.length == 1)
{
alias MaxType = T[0];
}
else static if (T.length == 2)
{ {
static if (!is(typeof(T[0].min))) static if (!is(typeof(T[0].min)))
alias MaxType = CommonType!T; alias MaxType = CommonType!T;
@ -7160,44 +7170,46 @@ private template MaxType(T...)
} }
else else
{ {
alias MaxType = MaxType!(T[0 .. $/2], MaxType!(T[$/2 .. $])); alias MaxType = MaxType!(MaxType!(T[0 .. ($+1)/2]), MaxType!(T[($+1)/2 .. $]));
} }
} }
// max // max
/** /**
Returns the maximum of the passed-in values. The type of the result is Returns the maximum of the passed-in values.
computed by using $(XREF traits, CommonType).
*/ */
MaxType!T max(T...)(T args) MaxType!T max(T...)(T args)
if (T.length >= 2) if (T.length >= 2)
{ {
static if (T.length == 2) //Get "a"
static if (T.length <= 2)
alias args[0] a;
else
auto a = max(args[0 .. ($+1)/2]);
alias typeof(a) T0;
//Get "b"
static if (T.length <= 3)
alias args[$-1] b;
else
auto b = max(args[($+1)/2 .. $]);
alias typeof(b) T1;
static assert (is(typeof(a < b)),
algoFormat("Invalid arguments: Cannot compare types %s and %s.", T0.stringof, T1.stringof));
//Do the "max" proper with a and b
static if (isIntegral!T0 && isIntegral!T1 &&
(mostNegative!T0 < 0) != (mostNegative!T1 < 0))
{ {
alias T0 = T[0]; static if (mostNegative!T0 < 0)
alias T1 = T[1]; immutable chooseB = b > a || a < 0;
alias a = args[0];
alias b = args[1];
static assert (is(typeof(a < b)),
algoFormat("Invalid arguments: Cannot compare types %s and %s.", T0.stringof, T1.stringof));
static if (isIntegral!T0 && isIntegral!T1 &&
(mostNegative!T0 < 0) != (mostNegative!T1 < 0))
{
static if (mostNegative!T0 < 0)
immutable chooseB = b > a || a < 0;
else
immutable chooseB = b > a && b > 0;
}
else else
immutable chooseB = b > a; immutable chooseB = b > a && b > 0;
return cast(typeof(return)) (chooseB ? b : a);
} }
else else
{ immutable chooseB = b > a;
return max(args[0 .. $/2], max(args[$/2 .. $])); return cast(typeof(return)) (chooseB ? b : a);
}
} }
/// ///