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/* 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 that modify its arguments.
*
* Copyright: Eugene Wissner 2017.
* 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/mutation.d,
* tanya/algorithm/mutation.d)
*/
module tanya.algorithm.mutation;
import tanya.memory.op;
import tanya.meta.trait;
/**
* Moves $(D_PARAM source) into $(D_PARAM target) assuming that
* $(D_PARAM target) isn't initialized.
*
* Moving the $(D_PARAM source) copies it into the $(D_PARAM target) and places
* the $(D_PARAM source) into a valid but unspecified state, which means that
* after moving $(D_PARAM source) can be destroyed or assigned a new value, but
* accessing it yields an unspecified value. No postblits or destructors are
* called. If the $(D_PARAM target) should be destroyed before, use
* $(D_PSYMBOL move).
*
* $(D_PARAM source) and $(D_PARAM target) must be different objects.
*
* Params:
* T = Object type.
* source = Source object.
* target = Target object.
*
* See_Also: $(D_PSYMBOL move),
* $(D_PSYMBOL hasElaborateCopyConstructor),
* $(D_PSYMBOL hasElaborateDestructor).
*
* Precondition: `&source !is &target`.
*/
void moveEmplace(T)(ref T source, ref T target) @system
in
{
assert(&source !is &target, "Source and target must be different");
}
body
{
static if (is(T == struct))
{
copy((&source)[0 .. 1], (&target)[0 .. 1]);
static if (hasElaborateCopyConstructor!T || hasElaborateDestructor!T)
{
static const T init = T.init;
static if (isNested!T)
{
// Don't override the context pointer.
enum size_t size = T.sizeof - (void*).sizeof;
copy((cast(void*) &init)[0 .. size], (&source)[0 .. 1]);
}
else
{
copy((&init)[0 .. 1], (&source)[0 .. 1]);
}
}
}
else
{
target = source;
}
}
///
@nogc nothrow pure @system unittest
{
static struct S
{
int member = 5;
this(this) @nogc nothrow pure @safe
{
assert(false);
}
}
S source, target = void;
moveEmplace(source, target);
assert(target.member == 5);
int x1 = 5, x2;
moveEmplace(x1, x2);
assert(x2 == 5);
}
/**
* Moves $(D_PARAM source) into $(D_PARAM target) assuming that
* $(D_PARAM target) isn't initialized.
*
* Moving the $(D_PARAM source) copies it into the $(D_PARAM target) and places
* the $(D_PARAM source) into a valid but unspecified state, which means that
* after moving $(D_PARAM source) can be destroyed or assigned a new value, but
* accessing it yields an unspecified value. $(D_PARAM target) is destroyed before
* the new value is assigned. If $(D_PARAM target) isn't initialized and
* therefore shouldn't be destroyed, $(D_PSYMBOL moveEmplace) can be used.
*
* If $(D_PARAM target) isn't specified, $(D_PSYMBOL move) returns the source
* as rvalue without calling its copy constructor or destructor.
*
* $(D_PARAM source) and $(D_PARAM target) are the same object,
* $(D_PSYMBOL move) does nothing.
*
* Params:
* T = Object type.
* source = Source object.
* target = Target object.
*
* See_Also: $(D_PSYMBOL moveEmplace).
*/
void move(T)(ref T source, ref T target)
{
if ((() @trusted => &source is &target)())
{
return;
}
static if (hasElaborateDestructor!T)
{
target.__xdtor();
}
(() @trusted => moveEmplace(source, target))();
}
/// ditto
T move(T)(ref T source)
{
T target = void;
(() @trusted => moveEmplace(source, target))();
return target;
}
///
@nogc nothrow pure @safe unittest
{
static struct S
{
int member = 5;
this(this) @nogc nothrow pure @safe
{
assert(false);
}
}
S source, target = void;
move(source, target);
assert(target.member == 5);
assert(move(target).member == 5);
int x1 = 5, x2;
move(x1, x2);
assert(x2 == 5);
assert(move(x2) == 5);
}
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