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| 1 | namespace Syntax.Trees is | |
| 2 | ||
| 3 | // A node that iterates a sequence: a `for` loop, or a `yield in` | |
| 4 | // that hands every element of one on. Compile-expressions resolves | |
| 5 | // the iterator surface (`$get_iterator`, `move_next`, `$get_current`) | |
| 6 | // once, here, and the IL pass drives those members directly. | |
| 7 | trait IteratorCarrier is | |
| 8 | // The sequence being iterated. Null where the parse failed. | |
| 9 | iterated: Expressions.Expression? | |
| 10 | ||
| 11 | // Null when `iterated` is already an iterator, in which case | |
| 12 | // move_next / read_current are driven on its value directly. | |
| 13 | read_iterator: Semantic.Symbols.Function?, | |
| 14 | = value | |
| 15 | ||
| 16 | read_current: Semantic.Symbols.Function?, | |
| 17 | = value | |
| 18 | ||
| 19 | move_next: Semantic.Symbols.Function?, | |
| 20 | = value | |
| 21 | ||
| 22 | // Inside a generator or async function the iterator has to | |
| 23 | // survive every suspension, so it lives in a frame field rather | |
| 24 | // than a CLR local, which MoveNext would reset on re-entry. | |
| 25 | // Allocated in compile-expressions rather than while emitting, | |
| 26 | // because the emitted assembly's rows are numbered before any | |
| 27 | // body is compiled and a field that appears after that has none. | |
| 28 | // Null outside a state machine. | |
| 29 | iterator_field: Semantic.Symbols.Field?, | |
| 30 | = value | |
| 31 | si | |
| 32 | si |