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std.traits: add examples

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wolframw 2022-01-26 22:39:39 +01:00 • committed by The Dlang Bot
parent e7724164b2
commit ebccda03e1
1 changed files with 88 additions and 2 deletions
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90
std/traits.d
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@ -5195,16 +5195,54 @@ enum isAssignable(Lhs, Rhs = Lhs) = isRvalueAssignable!(Lhs, Rhs) && isLvalueAss
/**
Returns `true` iff an rvalue of type `Rhs` can be assigned to a variable of
type `Lhs`
type `Lhs`.
*/
enum isRvalueAssignable(Lhs, Rhs = Lhs) = __traits(compiles, { lvalueOf!Lhs = rvalueOf!Rhs; });
///
@safe unittest
{
struct S1
{
void opAssign(S1);
}
struct S2
{
void opAssign(ref S2);
}
static assert( isRvalueAssignable!(long, int));
static assert(!isRvalueAssignable!(int, long));
static assert( isRvalueAssignable!S1);
static assert(!isRvalueAssignable!S2);
}
/**
Returns `true` iff an lvalue of type `Rhs` can be assigned to a variable of
type `Lhs`
type `Lhs`.
*/
enum isLvalueAssignable(Lhs, Rhs = Lhs) = __traits(compiles, { lvalueOf!Lhs = lvalueOf!Rhs; });
///
@safe unittest
{
struct S1
{
void opAssign(S1);
}
struct S2
{
void opAssign(ref S2);
}
static assert( isLvalueAssignable!(long, int));
static assert(!isLvalueAssignable!(int, long));
static assert( isLvalueAssignable!S1);
static assert( isLvalueAssignable!S2);
}
@safe unittest
{
static assert(!isAssignable!(immutable int, int));
@ -7000,6 +7038,18 @@ enum bool isArray(T) = isStaticArray!T || isDynamicArray!T;
*/
enum bool isAssociativeArray(T) = __traits(isAssociativeArray, T);
///
@safe unittest
{
struct S;
static assert( isAssociativeArray!(int[string]));
static assert( isAssociativeArray!(S[S]));
static assert(!isAssociativeArray!(string[]));
static assert(!isAssociativeArray!S);
static assert(!isAssociativeArray!(int[4]));
}
@safe unittest
{
struct Foo
@ -7055,6 +7105,7 @@ enum bool isBuiltinType(T) = is(BuiltinTypeOf!T) && !isAggregateType!T;
*/
enum bool isSIMDVector(T) = is(T : __vector(V[N]), V, size_t N);
///
@safe unittest
{
static if (is(__vector(float[4])))
@ -7072,6 +7123,20 @@ enum bool isSIMDVector(T) = is(T : __vector(V[N]), V, size_t N);
*/
enum bool isPointer(T) = is(T == U*, U) && __traits(isScalar, T);
///
@safe unittest
{
void fun();
static assert( isPointer!(int*));
static assert( isPointer!(int function()));
static assert(!isPointer!int);
static assert(!isPointer!string);
static assert(!isPointer!(typeof(null)));
static assert(!isPointer!(typeof(fun)));
static assert(!isPointer!(int delegate()));
}
@safe unittest
{
static foreach (T; AliasSeq!(int*, void*, char[]*))
@ -8841,6 +8906,27 @@ enum bool allSameType(Ts...) =
*/
enum ifTestable(T, alias pred = a => a) = __traits(compiles, { if (pred(T.init)) {} });
///
@safe unittest
{
class C;
struct S1;
struct S2
{
T opCast(T)() const;
}
static assert( ifTestable!bool);
static assert( ifTestable!int);
static assert( ifTestable!(S1*));
static assert( ifTestable!(typeof(null)));
static assert( ifTestable!(int[]));
static assert( ifTestable!(int[string]));
static assert( ifTestable!S2);
static assert( ifTestable!C);
static assert(!ifTestable!S1);
}
@safe unittest
{
import std.meta : AliasSeq, allSatisfy;