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| 1 | namespace Syntax.Process is | |
| 2 | ||
| 3 | class YIELD_SCANNER: Visitor is | |
| 4 | _found: bool; | |
| 5 | ||
| 6 | init() is | |
| 7 | super.init(); | |
| 8 | si | |
| 9 | ||
| 10 | body_has_yield(body: Trees.Bodies.Body?) -> bool is | |
| 11 | if !body? then | |
| 12 | return false; | |
| 13 | fi | |
| 14 | ||
| 15 | _found = false; | |
| 16 | ||
| 17 | body.walk(self); | |
| 18 | ||
| 19 | return _found; | |
| 20 | si | |
| 21 | ||
| 22 | pre(`yield: Trees.Statements.YIELD) -> bool is | |
| 23 | _found = true; | |
| 24 | ||
| 25 | return true; | |
| 26 | si | |
| 27 | ||
| 28 | pre(function: Trees.Definitions.FUNCTION) -> bool => true; | |
| 29 | pre(function: Trees.Expressions.FUNCTION) -> bool => true; | |
| 30 | si | |
| 31 | ||
| 32 | // Scans a generator body for `for` loops. `let` bindings ARE | |
| 33 | // supported now (locals are lifted onto state-machine frame | |
| 34 | // fields via state_machine_field), but `for` lowers to a hidden | |
| 35 | // iterator TEMP that doesn't yet route through frame fields, so | |
| 36 | // the iterator gets re-created on every MoveNext re-entry. Until | |
| 37 | // TEMPs gain state-machine awareness, ask users to write the | |
| 38 | // expansion by hand: | |
| 39 | // | |
| 40 | // let it = xs.iterator; | |
| 41 | // while it.move_next() do | |
| 42 | // yield it.current; | |
| 43 | // od | |
| 44 | class GENERATOR_FOR_SCANNER: Visitor is | |
| 45 | _logger: Logging.Logger; | |
| 46 | ||
| 47 | init(logger: Logging.Logger) is | |
| 48 | super.init(); | |
| 49 | ||
| 50 | _logger = logger; | |
| 51 | si | |
| 52 | ||
| 53 | scan(body: Trees.Bodies.Body?) is | |
| 54 | if !body? then | |
| 55 | return; | |
| 56 | fi | |
| 57 | ||
| 58 | body.walk(self); | |
| 59 | si | |
| 60 | ||
| 61 | pre(`for: Trees.Statements.FOR) -> bool is | |
| 62 | _logger.error( | |
| 63 | `for.location, | |
| 64 | "for loop inside generator body is not yet supported" | |
| 65 | ); | |
| 66 | ||
| 67 | return false; | |
| 68 | si | |
| 69 | ||
| 70 | pre(function: Trees.Definitions.FUNCTION) -> bool => true; | |
| 71 | pre(function: Trees.Expressions.FUNCTION) -> bool => true; | |
| 72 | si | |
| 73 | ||
| 74 | // Scans a generator body for `yield` inside a `catch` or | |
| 75 | // `finally` HANDLER body. Yield in a try BODY is fine — | |
| 76 | // state-machine codegen handles it via per-region dispatch + the | |
| 77 | // `'.gen_state'` local + state-guarded finally. Handlers | |
| 78 | // (catch / finally) still need an AST-level rewrite (pend | |
| 79 | // exception, yield outside the handler, restore), so flag those | |
| 80 | // with a clean compile-time error. | |
| 81 | class YIELD_IN_TRY_SCANNER: HANDLER_DEPTH_SCANNER is | |
| 82 | init(logger: Logging.Logger) is | |
| 83 | super.init(logger); | |
| 84 | si | |
| 85 | ||
| 86 | pre(`yield: Trees.Statements.YIELD) -> bool is | |
| 87 | if handler_depth > 0 then | |
| 88 | logger.error(`yield.location, "yield inside a catch or finally handler is not yet supported"); | |
| 89 | fi | |
| 90 | return true; | |
| 91 | si | |
| 92 | si | |
| 93 | si |