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Consistent constants #419

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Consistent constants #419

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0f872c8
Forest: remove useless alias
Joseph-Edwards Apr 23, 2026
1d1298f
Misc: convert to int with const ref
Joseph-Edwards Apr 23, 2026
a3a8c93
Use from_int function more
Joseph-Edwards Apr 23, 2026
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6 changes: 1 addition & 5 deletions src/forest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,6 @@ Constructs a forest with *n* nodes, that is initialised so that the
parents,
std::vector<int_or_unsigned_constant<node_type>> const&
labels) {
using node_type = node_type;
return make<Forest>(to_ints<node_type>(parents),
to_ints<node_type>(labels));
}),
Expand Down Expand Up @@ -156,10 +155,7 @@ the same state as if it had just been constructed as ``Forest(n)``.
"label",
[](Forest const& self,
node_type i) -> int_or_unsigned_constant<node_type> {
if (self.label(i) != UNDEFINED) {
return {self.label(i)};
}
return {UNDEFINED};
return from_int(self.label(i));
},
py::arg("i"),
R"pbdoc(
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2 changes: 1 addition & 1 deletion src/main.hpp
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Expand Up @@ -100,7 +100,7 @@ namespace libsemigroups {
int_or_unsigned_constant<Int>>;

template <typename Int>
Int to_int(int_or_constant<Int> val) {
Int to_int(int_or_constant<Int> const& val) {
if (std::holds_alternative<Int>(val)) {
return std::get<0>(val);
} else if (std::holds_alternative<Undefined>(val)) {
Expand Down
11 changes: 2 additions & 9 deletions src/transf.cpp
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Expand Up @@ -111,11 +111,7 @@ the image of the point ``i`` under the {0} is ``imgs[i]``.
// corresponds to a std::out_of_range for things like list(a) to
// work.
try {
auto result = a.at(b);
if (result != UNDEFINED) {
return {result};
}
return {UNDEFINED};
return from_int(a.at(b));
} catch (LibsemigroupsException const& e) {
throw std::out_of_range(formatted_error_message(e));
}
Expand Down Expand Up @@ -171,10 +167,7 @@ definition, which is equal to the size of :any:`{0}.images`.
auto r = rx::iterator_range(self.begin(), self.end())
| rx::transform(
[](auto val) -> int_or_unsigned_constant<Scalar> {
if (val != UNDEFINED) {
return {val};
}
return {UNDEFINED};
return from_int(val);
});
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@Joseph-Edwards Joseph-Edwards Apr 23, 2026

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It's possible to remove this lambda all together, with something like

static_cast<int_or_constant<Scalar> (*)(Scalar)>(from_int)

but this felt a bit unwieldy to me, so I opted to keep the lambda.

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@james-d-mitchell james-d-mitchell Apr 24, 2026

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And you can't just replace the lambda with from_int ?

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@Joseph-Edwards Joseph-Edwards Apr 24, 2026

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Unfortunately not; transform is unable to infer the type of from_int. I think this is because from_int is an overloaded function template. Something like this seems to work:

auto r = rx::iterator_range(self.begin(), self.end())
         | rx::transform<int_or_constant<Scalar> (*)(Scalar)>(
             &from_int);

Should we go with that instead?

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@james-d-mitchell james-d-mitchell Apr 24, 2026

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Nah, the lambda is better. Sorry for the noise.

return py::make_iterator(rx::begin(r), rx::end(r));
},
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