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Move MostDerived and DerivedToFront to std.traits

Browse source 
Those two helpers are about type introspection and use
MetaList only coincidently. Such utilities are better fit
to std.traits
This commit is contained in:
Dicebot 2015-03-31 00:11:02 +03:00
parent 5cd03d229a
commit 3ca20b5ca4
2 changed files with 65 additions and 51 deletions
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56
std/meta/package.d
View file

@ -37,56 +37,10 @@ public import std.meta.predicates;
// shouldn't go into release // shouldn't go into release
public import std.meta.internal; public import std.meta.internal;
/** static import std.traits;
* Returns the type from TList that is the most derived from type T.
* If none are found, T is returned.
*/
template MostDerived(T, TList...)
{
static if (TList.length == 0)
alias MostDerived = T;
else static if (is(TList[0] : T))
alias MostDerived = MostDerived!(TList[0], TList[1 .. $]);
else
alias MostDerived = MostDerived!(T, TList[1 .. $]);
}
/// deprecated("Use std.traits.MostDerived instead")
unittest alias MostDerived = std.traits.MostDerived;
{
class A { }
class B : A { }
class C : B { }
alias Types = MetaList!(A, C, B);
MostDerived!(Object, Types) x; // x is declared as type C deprecated("Use std.traits.DerivedToFront instead")
static assert(is(typeof(x) == C)); alias DerivedToFront = std.traits.DerivedToFront;
}
/**
* Returns the list TList with the types sorted so that the most
* derived types come first.
*/
template DerivedToFront(TList...)
{
static if (TList.length == 0)
alias DerivedToFront = TList;
else
alias DerivedToFront =
MetaList!(MostDerived!(TList[0], TList[1 .. $]),
DerivedToFront!(ReplaceAll!(MostDerived!(TList[0], TList[1 .. $]),
TList[0],
TList[1 .. $])));
}
///
unittest
{
class A { }
class B : A { }
class C : B { }
alias Types = MetaList!(A, C, B);
alias TL = DerivedToFront!(Types);
static assert(is(TL == MetaList!(C, B, A)));
}

60
std/traits.d
View file

@ -6383,3 +6383,63 @@ unittest
static assert(is(typeof(a) == real)); static assert(is(typeof(a) == real));
static assert(is(typeof(b) == real)); static assert(is(typeof(b) == real));
} }
/**
* Returns the type from type list that is the most derived from type T.
* If none are found, T is returned.
*/
template MostDerived(T, TList...)
{
static if (TList.length == 0)
alias MostDerived = T;
else static if (is(TList[0] : T))
alias MostDerived = MostDerived!(TList[0], TList[1 .. $]);
else
alias MostDerived = MostDerived!(T, TList[1 .. $]);
}
///
unittest
{
import std.meta.list;
class A { }
class B : A { }
class C : B { }
alias Types = MetaList!(A, C, B);
MostDerived!(Object, Types) x; // x is declared as type C
static assert(is(typeof(x) == C));
}
/**
* Returns the type list based on TList with the types sorted so that
* the most derived types come first.
*/
template DerivedToFront(TList...)
{
import std.meta.list;
static if (TList.length == 0)
alias DerivedToFront = TList;
else
alias DerivedToFront =
MetaList!(MostDerived!(TList[0], TList[1 .. $]),
DerivedToFront!(ReplaceAll!(MostDerived!(TList[0], TList[1 .. $]),
TList[0],
TList[1 .. $])));
}
///
unittest
{
import std.meta.list;
class A { }
class B : A { }
class C : B { }
alias Types = MetaList!(A, C, B);
alias TL = DerivedToFront!(Types);
static assert(is(TL == MetaList!(C, B, A)));
}