Add min/max algorithms

This commit is contained in:
Eugen Wissner 2018-04-22 12:08:33 +02:00
parent e8222123e6
commit 86053de8c9
2 changed files with 196 additions and 0 deletions
source/tanya/algorithm

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@ -0,0 +1,195 @@
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Algorithms for comparing values.
*
* Copyright: Eugene Wissner 2018.
* License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
* Mozilla Public License, v. 2.0).
* Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
* Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/algorithm/comparison.d,
* tanya/algorithm/comparison.d)
*/
module tanya.algorithm.comparison;
import tanya.meta.trait;
import tanya.range.array;
import tanya.range.primitive;
/**
* Finds the smallest element in the argument list or a range.
*
* The function should take at least one argument.
*
* If a range is passed, $(D_PSYMBOL min) returns a range of the same type,
* whose front element is the smallest in the range. If more than one element
* fulfills this condition, the front of the returned range points to
* the first one found.
* If $(D_PARAM range) is empty, the original range is returned.
*
* Params:
* Args = Types of the arguments. All arguments should have the same type.
* Range = Forward range type.
* args = Argument list.
* range = Forward range.
*
* Returns: The smallest element.
*/
Args[0] min(Args...)(Args args)
if (Args.length > 0 && isOrderingComparable!(Args[0]) && allSameType!Args)
{
return min!Args(args);
}
/// ditto
ref Args[0] min(Args...)(ref Args args)
if (Args.length > 0 && isOrderingComparable!(Args[0]) && allSameType!Args)
{
auto actual = (() @trusted => &args[0])();
foreach (arg; args[1 .. $])
{
if (arg < *actual)
{
actual = (() @trusted => &arg)();
}
}
return *actual;
}
@nogc nothrow pure @safe unittest
{
assert(min(1) == 1);
static assert(!is(typeof(min(1, 1UL))));
}
/// ditto
Range min(Range)(Range range)
if (isForwardRange!Range && isOrderingComparable!(ElementType!Range))
{
if (range.empty)
{
return range;
}
auto actual = range.save;
range.popFront();
for (; !range.empty; range.popFront())
{
if (range.front < actual.front)
{
actual = range.save;
}
}
return actual;
}
///
@nogc nothrow pure @safe unittest
{
assert(min(1, 2) == 1);
assert(min(3, 2) == 2);
assert(min(3, 1, 2) == 1);
int[4] range = [3, 1, 1, 2];
auto minElement = min(range[]);
assert(minElement.front == 1);
assert(minElement.length == 3);
}
@nogc nothrow pure @safe unittest
{
assert(min(cast(ubyte[]) []).empty);
}
/**
* Finds the largest element in the argument list or a range.
*
* The function should take at least one argument.
*
* If a range is passed, $(D_PSYMBOL max) returns a range of the same type,
* whose front element is the largest in the range. If more than one element
* fulfills this condition, the front of the returned range points to
* the first one found.
* If $(D_PARAM range) is empty, the original range is returned.
*
* Params:
* Args = Types of the arguments. All arguments should have the same type.
* Range = Forward range type.
* args = Argument list.
* range = Forward range.
*
* Returns: The largest element.
*/
Args[0] max(Args...)(Args args)
if (Args.length > 0 && isOrderingComparable!(Args[0]) && allSameType!Args)
{
return max!Args(args);
}
/// ditto
ref Args[0] max(Args...)(ref Args args)
if (Args.length > 0 && isOrderingComparable!(Args[0]) && allSameType!Args)
{
auto actual = (() @trusted => &args[0])();
foreach (arg; args[1 .. $])
{
if (arg > *actual)
{
actual = (() @trusted => &arg)();
}
}
return *actual;
}
@nogc nothrow pure @safe unittest
{
assert(max(1) == 1);
static assert(!is(typeof(max(1, 1UL))));
}
/// ditto
Range max(Range)(Range range)
if (isForwardRange!Range && isOrderingComparable!(ElementType!Range))
{
if (range.empty)
{
return range;
}
auto actual = range.save;
range.popFront();
for (; !range.empty; range.popFront())
{
if (range.front > actual.front)
{
actual = range.save;
}
}
return actual;
}
///
@nogc nothrow pure @safe unittest
{
assert(max(1, 2) == 2);
assert(max(3, 2) == 3);
assert(max(1, 3, 2) == 3);
int[4] range = [1, 5, 5, 2];
auto maxElement = max(range[]);
assert(maxElement.front == 5);
assert(maxElement.length == 3);
}
@nogc nothrow pure @safe unittest
{
assert(max(cast(ubyte[]) []).empty);
}

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@ -14,4 +14,5 @@
*/ */
module tanya.algorithm; module tanya.algorithm;
public import tanya.algorithm.comparison;
public import tanya.algorithm.mutation; public import tanya.algorithm.mutation;