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sumtype: extract common code from get and tryGet

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This commit is contained in:
Paul Backus 2025-02-24 14:17:12 -05:00
parent 688ecf2089
commit 7e34f06d83
1 changed files with 60 additions and 92 deletions
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152
std/sumtype.d
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@ -2766,54 +2766,12 @@ template get(T)
auto ref T get(Self)(auto ref Self self)
if (isSumType!Self)
{
import std.typecons : No;
static if (__traits(isRef, self))
return self.match!getLvalue;
return self.match!(getLvalue!(No.try_, T));
else
return self.match!getRvalue;
}
// Helpers to avoid redundant template instantiations
ref T getLvalue(Value)(ref Value value)
{
static if (is(Value == T))
{
return value;
}
else
{
assert(false,
"Tried to get `" ~ T.stringof ~ "`" ~
" but found `" ~ Value.stringof ~ "`"
);
}
}
T getRvalue(Value)(ref Value value)
{
static if (is(Value == T))
{
import core.lifetime : move;
// Move if possible; otherwise fall back to copy
static if (is(typeof(move(value))))
{
static if (isCopyable!Value)
// Workaround for https://issues.dlang.org/show_bug.cgi?id=21542
return __ctfe ? value : move(value);
else
return move(value);
}
else
return value;
}
else
{
assert(false,
"Tried to get `" ~ T.stringof ~ "`" ~
" but found `" ~ Value.stringof ~ "`"
);
}
return self.match!(getRvalue!(No.try_, T));
}
}
@ -2918,54 +2876,12 @@ template tryGet(T)
auto ref T tryGet(Self)(auto ref Self self)
if (isSumType!Self)
{
import std.typecons : Yes;
static if (__traits(isRef, self))
return self.match!tryGetLvalue;
return self.match!(getLvalue!(Yes.try_, T));
else
return self.match!tryGetRvalue;
}
// Helpers to avoid redundant template instantiations
ref T tryGetLvalue(Value)(ref Value value)
{
static if (is(Value == T))
{
return value;
}
else
{
throw new MatchException(
"Tried to get `" ~ T.stringof ~ "`" ~
" but found `" ~ Value.stringof ~ "`"
);
}
}
T tryGetRvalue(Value)(ref Value value)
{
static if (is(Value == T))
{
import core.lifetime : move;
// Move if possible; otherwise fall back to copy
static if (is(typeof(move(value))))
{
static if (isCopyable!Value)
// Workaround for https://issues.dlang.org/show_bug.cgi?id=21542
return __ctfe ? value : move(value);
else
return move(value);
}
else
return value;
}
else
{
throw new MatchException(
"Tried to get `" ~ T.stringof ~ "`" ~
" but found `" ~ Value.stringof ~ "`"
);
}
return self.match!(getRvalue!(Yes.try_, T));
}
}
@ -3071,6 +2987,58 @@ version (D_Exceptions)
assert(ctResult == ElaborateCopy());
}
private enum failedGetMessage(Expected, Actual) =
"Tried to get `" ~ Expected.stringof ~ "`" ~
" but found `" ~ Actual.stringof ~ "`";
private template getLvalue(Flag!"try_" try_, T)
{
ref T getLvalue(Value)(ref Value value)
{
static if (is(Value == T))
{
return value;
}
else
{
static if (try_)
throw new MatchException(failedGetMessage!(T, Value));
else
assert(false, failedGetMessage!(T, Value));
}
}
}
private template getRvalue(Flag!"try_" try_, T)
{
T getRvalue(Value)(ref Value value)
{
static if (is(Value == T))
{
import core.lifetime : move;
// Move if possible; otherwise fall back to copy
static if (is(typeof(move(value))))
{
static if (isCopyable!Value)
// Workaround for https://issues.dlang.org/show_bug.cgi?id=21542
return __ctfe ? value : move(value);
else
return move(value);
}
else
return value;
}
else
{
static if (try_)
throw new MatchException(failedGetMessage!(T, Value));
else
assert(false, failedGetMessage!(T, Value));
}
}
}
private void destroyIfOwner(T)(ref T value)
{
static if (hasElaborateDestructor!T)