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simplify ChooseResult implementation

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This commit is contained in:
John Colvin 2017-08-09 09:22:29 +01:00
parent d5f2228455
commit 397dbfd083
1 changed files with 6 additions and 32 deletions
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38
std/range/package.d
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@ -1374,8 +1374,6 @@ if (isInputRange!(Unqual!R1) && isInputRange!(Unqual!R2) &&
private struct ChooseResult(R1, R2) private struct ChooseResult(R1, R2)
{ {
import std.algorithm.comparison : max;
import std.algorithm.internal : addressOf;
import std.traits : hasElaborateCopyConstructor, hasElaborateDestructor; import std.traits : hasElaborateCopyConstructor, hasElaborateDestructor;
private union private union
@ -1389,48 +1387,24 @@ private struct ChooseResult(R1, R2)
auto ref ExtraArgs extraArgs) auto ref ExtraArgs extraArgs)
{ {
if (r.r1Chosen) if (r.r1Chosen)
{ return foo(r._r1, extraArgs);
ref getR1() @trusted { return r._r1; }
return foo(getR1(), extraArgs);
}
else else
{ return foo(r._r2, extraArgs);
ref getR2() @trusted { return r._r2; }
return foo(getR2(), extraArgs);
}
}
// have to do this in a constructor because otherwise
// the compiler thinks they're not initialised.
// Don't want to make the whole constructor @trusted
// because would hide @system code in R{1,2}.__ctor,
// hence this dummy constructor
private this(char dummy) @trusted
{
_r1 = R1.init;
_r2 = R2.init;
} }
this(bool r1Chosen, R1 r1, R2 r2) this(bool r1Chosen, R1 r1, R2 r2)
{ {
import std.conv : emplace; import std.conv : emplace;
this('\0'); _r1 = R1.init; // avoid uninitialised member errors
// This should be the only place r1Chosen is every assigned // This should be the only place r1Chosen is ever assigned
// independently // independently
this.r1Chosen = r1Chosen; this.r1Chosen = r1Chosen;
if (r1Chosen) if (r1Chosen)
{ emplace(&_r1, r1);
auto r1p = &_r1;
emplace(r1p, r1);
}
else else
{ emplace(&_r2, r2);
auto r2p = &_r2;
emplace(r2p, r2);
}
} }
// Carefully defined postblit to postblit the appropriate range // Carefully defined postblit to postblit the appropriate range