debian-packages/taggedalgebraic
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do implicit casting without std.conv.to

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John Colvin 2017-12-07 15:28:12 +00:00
parent 513729bf59
commit ffe296a96f
1 changed files with 26 additions and 7 deletions
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33
source/taggedalgebraic.d
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@ -1,6 +1,6 @@
/**
* Algebraic data type implementation based on a tagged union.
*
*
* Copyright: Copyright 2015-2016, Sönke Ludwig.
* License: $(WEB www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
* Authors: Sönke Ludwig
@ -144,10 +144,13 @@ struct TaggedAlgebraic(U) if (is(U == union) || is(U == struct))
final switch (m_kind) {
foreach (i, FT; FieldTypes) {
case __traits(getMember, Kind, fieldNames[i]):
static if (is(typeof(to!T(trustedGet!(fieldNames[i]))))) {
static if (is(typeof(trustedGet!(fieldNames[i])) : T))
return trustedGet!(fieldNames[i]);
else static if (is(typeof(to!T(trustedGet!(fieldNames[i]))))) {
return to!T(trustedGet!(fieldNames[i]));
} else {
assert(false, "Cannot cast a "~(cast(Kind)m_kind).to!string~" value ("~FT.stringof~") to "~T.stringof);
assert(false, "Cannot cast a " ~ m_kind.to!string
~ " value of type " ~ FT.stringof ~ " to " ~ T.stringof);
}
}
}
@ -162,10 +165,13 @@ struct TaggedAlgebraic(U) if (is(U == union) || is(U == struct))
final switch (m_kind) {
foreach (i, FT; FieldTypes) {
case __traits(getMember, Kind, fieldNames[i]):
static if (is(typeof(to!T(trustedGet!(fieldNames[i]))))) {
static if (is(typeof(trustedGet!(fieldNames[i])) : T))
return trustedGet!(fieldNames[i]);
else static if (is(typeof(to!T(trustedGet!(fieldNames[i]))))) {
return to!T(trustedGet!(fieldNames[i]));
} else {
assert(false, "Cannot cast a "~(cast(Kind)m_kind).to!string~" value ("~FT.stringof~") to "~T.stringof);
assert(false, "Cannot cast a " ~ m_kind.to!string
~ " value of type" ~ FT.stringof ~ " to " ~ T.stringof);
}
}
}
@ -232,7 +238,7 @@ unittest
Tagged taggedAny = taggedInt;
taggedAny = taggedString;
taggedAny = taggedFoo;
// Check type: Tagged.Kind is an enum
assert(taggedInt.kind == Tagged.Kind.i);
assert(taggedString.kind == Tagged.Kind.str);
@ -370,7 +376,7 @@ unittest {
static union U {
S s;
}
auto u = TaggedAlgebraic!U(S.init);
const uc = u;
immutable ui = cast(immutable)u;
@ -576,6 +582,19 @@ static if (__VERSION__ >= 2072) unittest { // default initialization
assert(ta.i == 42);
}
unittest
{
import std.meta : AliasSeq;
union U { int[int] a; }
foreach (TA; AliasSeq!(TaggedAlgebraic!U, const(TaggedAlgebraic!U)))
{
TA ta = [1 : 2];
assert(cast(int[int])ta == [1 : 2]);
}
}
/** Tests if the algebraic type stores a value of a certain data type.
*/