Appearance
| 1 | namespace Semantic.Symbols is | |
| 2 | // Supplies the `<>` operator for an enum type. | |
| 3 | // | |
| 4 | // Enums order by their underlying integer, so the comparison is the | |
| 5 | // same opcode the numeric primitives use. It cannot be declared in | |
| 6 | // the runtime alongside those: each enum is its own type, so there | |
| 7 | // is nothing to hang a declaration on, and a declaration generic | |
| 8 | // enough to cover them all also covers structs, whose values those | |
| 9 | // opcodes cannot compare. | |
| 10 | // | |
| 11 | // Supplied as a member rather than as a global operator. The type is | |
| 12 | // the one place that belongs to the enum itself, so it needs no | |
| 13 | // decision about which of the two stores the innate operators occupy | |
| 14 | // — the namespace when the assembly declaring them is being built, | |
| 15 | // that assembly's reflected globals carrier otherwise — and it keeps | |
| 16 | // one operator per enum out of every candidate list in the program. | |
| 17 | // | |
| 18 | // A member is also the shape an interface is satisfied by, but this | |
| 19 | // is not yet enough to satisfy `Ghul.Comparable[E]`: the interface | |
| 20 | // is absent from an enum's ancestors, because a .NET enum carries | |
| 21 | // only the non-generic `IComparable`. | |
| 22 | class ENUM_ORDER_OPERATOR is | |
| 23 | register(owner: Classy) static is | |
| 24 | register(owner, IoC.CONTAINER.instance.innate_symbol_lookup.get_int_type()) | |
| 25 | si | |
| 26 | ||
| 27 | register(owner: Classy, int_type: Types.Type) static is | |
| 28 | let type = owner.type | |
| 29 | ||
| 30 | // An enum whose type is not built yet has nothing to compare | |
| 31 | // against; nothing reaches this today, and the check is here | |
| 32 | // so a caller that does gets no half-formed operator. | |
| 33 | if !type? then | |
| 34 | return | |
| 35 | fi | |
| 36 | ||
| 37 | let operator = | |
| 38 | INNATE_METHOD(owner.location, owner, "<>", owner, "compare.order") | |
| 39 | ||
| 40 | operator.argument_names = Collections.LIST[string](["other"]) | |
| 41 | operator.arguments = Collections.LIST[Types.Type]([type]) | |
| 42 | operator.return_type = int_type | |
| 43 | ||
| 44 | // The comparison lowers to an opcode and writes nothing. | |
| 45 | // Declared here rather than inferred: the store-free | |
| 46 | // analysis classifies a function by walking its body, and | |
| 47 | // this one is built as a symbol without one. | |
| 48 | operator.mark_declared_pure() | |
| 49 | ||
| 50 | owner.add_member(operator) | |
| 51 | si | |
| 52 | si | |
| 53 | si |