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A stripped down version of std.typecons.Tuple
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alias Identity(alias A) = A; | |
template AliasSeq(TList...) | |
{ | |
alias AliasSeq = TList; | |
} | |
template staticMap(alias F, T...) | |
{ | |
static if (T.length == 0) | |
{ | |
alias staticMap = AliasSeq!(); | |
} | |
else static if (T.length == 1) | |
{ | |
alias staticMap = AliasSeq!(F!(T[0])); | |
} | |
else | |
{ | |
alias staticMap = | |
AliasSeq!( | |
staticMap!(F, T[ 0 .. $/2]), | |
staticMap!(F, T[$/2 .. $ ])); | |
} | |
} | |
template Tuple(Specs...) | |
{ | |
// Parse (type,name) pairs (FieldSpecs) out of the specified | |
// arguments. Some fields would have name, others not. | |
template parseSpecs(Specs...) | |
{ | |
static if (Specs.length == 0) | |
{ | |
alias parseSpecs = AliasSeq!(); | |
} | |
else static if (is(Specs[0])) | |
{ | |
static if (is(typeof(Specs[1]) : string)) | |
{ | |
alias parseSpecs = | |
AliasSeq!(FieldSpec!(Specs[0 .. 2]), | |
parseSpecs!(Specs[2 .. $])); | |
} | |
else | |
{ | |
alias parseSpecs = | |
AliasSeq!(FieldSpec!(Specs[0]), | |
parseSpecs!(Specs[1 .. $])); | |
} | |
} | |
else | |
{ | |
static assert(0, "Attempted to instantiate Tuple with an " | |
~"invalid argument: "~ Specs[0].stringof); | |
} | |
} | |
template FieldSpec(T, string s = "") | |
{ | |
alias Type = T; | |
alias name = s; | |
} | |
alias fieldSpecs = parseSpecs!Specs; | |
static string injectNamedFields() | |
{ | |
string decl = ""; | |
static foreach (i, val; fieldSpecs) | |
{{ | |
immutable si = i.stringof; | |
decl ~= "alias _" ~ si ~ " = Identity!(expand[" ~ si ~ "]); "; | |
if (val.name.length != 0) | |
{ | |
decl ~= "alias " ~ val.name ~ " = _" ~ si ~ "; "; | |
} | |
}} | |
return decl; | |
} | |
struct Tuple | |
{ | |
alias extractType(alias spec) = spec.Type; | |
alias Types = staticMap!(extractType, fieldSpecs); | |
Types expand; | |
pragma(msg, "Injected Fields: ", injectNamedFields); | |
pragma(msg, "Types: ", Types); | |
mixin(injectNamedFields()); | |
static if (is(Specs)) | |
{ | |
// This is mostly to make t[n] work. | |
alias expand this; | |
} | |
else | |
{ | |
@property | |
ref inout(Tuple!Types) _Tuple_super() inout @trusted | |
{ | |
foreach (i, _; Types) // Rely on the field layout | |
{ | |
static assert(typeof(return).init.tupleof[i].offsetof == | |
expand[i].offsetof); | |
} | |
return *cast(typeof(return)*) &(expand[0]); | |
} | |
// This is mostly to make t[n] work. | |
alias _Tuple_super this; | |
//alias expand this; | |
} | |
static if (Types.length > 0) | |
{ | |
this(Types values) | |
{ | |
expand[] = values[]; | |
} | |
} | |
} | |
} | |
@safe unittest | |
{ | |
alias point = Tuple!(int, "x", int, "y"); | |
static assert(point(2, 2)[0] == 2); | |
} | |
@safe unittest | |
{ | |
auto t1 = Tuple!(int, "x", string, "y")(1, "a"); | |
void foo(Tuple!(int, string) t2) {} | |
foo(t1); | |
} |
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