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Merge pull request #6776 from n8sh/issue-19412

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std.algorithm.cmp with default ordering can use memcmp for all size 1 unsigned types (instead of just char)
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Sebastian Wilzbach 2019-04-12 19:30:03 +02:00 • committed by GitHub
commit 3144226824
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1 changed files with 29 additions and 50 deletions
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79
std/algorithm/comparison.d
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@ -619,7 +619,19 @@ Note:
auto cmp(R1, R2)(R1 r1, R2 r2) auto cmp(R1, R2)(R1 r1, R2 r2)
if (isInputRange!R1 && isInputRange!R2) if (isInputRange!R1 && isInputRange!R2)
{ {
static if (!(isSomeString!R1 && isSomeString!R2)) alias E1 = ElementEncodingType!R1;
alias E2 = ElementEncodingType!R2;
static if (isDynamicArray!R1 && isDynamicArray!R2
&& __traits(isUnsigned, E1) && __traits(isUnsigned, E2)
&& E1.sizeof == 1 && E2.sizeof == 1
&& (is(Unqual!E1 == char) == is(Unqual!E2 == char))) // Both or neither must auto-decode.
{
// dstrcmp algorithm is correct for both ubyte[] and for char[].
import core.internal.string : dstrcmp;
return dstrcmp(cast(const char[]) r1, cast(const char[]) r2);
}
else static if (!(isSomeString!R1 && isSomeString!R2))
{ {
for (;; r1.popFront(), r2.popFront()) for (;; r1.popFront(), r2.popFront())
{ {
@ -644,66 +656,33 @@ if (isInputRange!R1 && isInputRange!R2)
} }
else else
{ {
import core.stdc.string : memcmp;
import std.utf : decode;
// For speed only
static int threeWay(size_t a, size_t b)
{
static if (size_t.sizeof == int.sizeof)
return a - b;
else
// Faster than return b < a ? 1 : a < b ? -1 : 0;
return (a > b) - (a < b);
}
// For speed only
// @@@BUG@@@ overloading should be allowed for nested functions
static int threeWayInt(int a, int b)
{
return a - b;
}
static if (typeof(r1[0]).sizeof == typeof(r2[0]).sizeof) static if (typeof(r1[0]).sizeof == typeof(r2[0]).sizeof)
{ {
static if (typeof(r1[0]).sizeof == 1) return () @trusted
{ {
immutable len = min(r1.length, r2.length); auto p1 = r1.ptr, p2 = r2.ptr,
int result = __ctfe ? pEnd = p1 + min(r1.length, r2.length);
{ for (; p1 != pEnd; ++p1, ++p2)
foreach (i; 0 .. len)
{
if (r1[i] != r2[i])
return threeWayInt(r1[i], r2[i]);
}
return 0;
}()
: () @trusted { return memcmp(r1.ptr, r2.ptr, len); }();
if (result) return result;
return threeWay(r1.length, r2.length);
}
else
{
return () @trusted
{ {
auto p1 = r1.ptr, p2 = r2.ptr, if (*p1 != *p2) return cast(int) *p1 - cast(int) *p2;
pEnd = p1 + min(r1.length, r2.length); }
for (; p1 != pEnd; ++p1, ++p2) static if (typeof(r1[0]).sizeof >= 2 && size_t.sizeof <= uint.sizeof)
{ return cast(int) r1.length - cast(int) r2.length;
if (*p1 != *p2) return threeWayInt(int(*p1), int(*p2)); else
} return int(r1.length > r2.length) - int(r1.length < r2.length);
return threeWay(r1.length, r2.length); }();
}();
}
} }
else else
{ {
import std.utf : decode;
for (size_t i1, i2;;) for (size_t i1, i2;;)
{ {
if (i1 == r1.length) return threeWay(i2, r2.length); if (i1 == r1.length) return -int(i2 < r2.length);
if (i2 == r2.length) return threeWay(r1.length, i1); if (i2 == r2.length) return int(1);
immutable c1 = decode(r1, i1), immutable c1 = decode(r1, i1),
c2 = decode(r2, i2); c2 = decode(r2, i2);
if (c1 != c2) return threeWayInt(int(c1), int(c2)); if (c1 != c2) return cast(int) c1 - cast(int) c2;
} }
} }
} }