Improvements around collections and the use of them #314
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Largely this was copied from https://doc.rust-lang.org/stable/std/collections/index.html but with additional information for Subspace and/or C++ specific things or adjustments as needed.
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To do this, we just need an overload on operator== and operator<=> that compares between the numeric type and its primitive type, and whichi is not templated. Then we avoid ambiguous overload errors due to the compiler being able to convert in both directions.
And more docs for the collections namespace about it all.
This would introduce Slice invalidation, as the Slice shares the same length field as the Vec. Mutating the length of the Vec then changes the Slice too. This is only possible when you have a borrow checker to prevent the mutation.
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Beginning docs for #277 in the collections namespace here as well. |
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Implicit conversions back to primitive integers
A big pain when using std containers with subspace is converting explicitly back to primitive types.
But we really don't want subspace types to convert back to primitive types and fall out of subspace land, like adding a primitive to a subspace numeric should always result in a subspace numeric or a compile error (if the primitive is too big).
Getting this right required some serious heroics though where for every builtin binary operator that takes primitive types, we need to replace that with a function of our own if one of the two parameters is a subspace numeric. Then, either perform the action if it's valid, or delete the function if it's not, to avoid falling back to a conversion into a primitive type.
Slice invalidations
While writing docs we uncovered a bug which was caused by Vec returning a reference to itself for a Slice, but then the Slice shared the Vec's length field, so mutating the Vec also mutated the Slice. So Vec now converts to a Slice by constructing a Slice not just a reference.