| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | */ |
| 7 | |
| 8 | import { |
| 9 | IdentifierId, |
| 10 | InstructionId, |
| 11 | Place, |
| 12 | PrunedReactiveScopeBlock, |
| 13 | ReactiveFunction, |
| 14 | isPrimitiveType, |
| 15 | isUseRefType, |
| 16 | Identifier, |
| 17 | } from '../HIR/HIR'; |
| 18 | import {ReactiveFunctionVisitor, visitReactiveFunction} from './visitors'; |
| 19 | |
| 20 | class Visitor extends ReactiveFunctionVisitor<Set<IdentifierId>> { |
| 21 | /* |
| 22 | * Visitors don't visit lvalues as places by default, but we want to visit all places to |
| 23 | * check for reactivity |
| 24 | */ |
| 25 | override visitLValue( |
| 26 | id: InstructionId, |
| 27 | lvalue: Place, |
| 28 | state: Set<IdentifierId>, |
| 29 | ): void { |
| 30 | this.visitPlace(id, lvalue, state); |
| 31 | } |
| 32 | |
| 33 | /* |
| 34 | * This visitor only infers data dependencies and does not account for control dependencies |
| 35 | * where a variable may be assigned a different value based on some conditional, eg via two |
| 36 | * different paths of an if statement. |
| 37 | */ |
| 38 | override visitPlace( |
| 39 | _id: InstructionId, |
| 40 | place: Place, |
| 41 | state: Set<IdentifierId>, |
| 42 | ): void { |
| 43 | if (place.reactive) { |
| 44 | state.add(place.identifier.id); |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | override visitPrunedScope( |
| 49 | scopeBlock: PrunedReactiveScopeBlock, |
| 50 | state: Set<IdentifierId>, |
| 51 | ): void { |
| 52 | this.traversePrunedScope(scopeBlock, state); |
| 53 | |
| 54 | for (const [id, decl] of scopeBlock.scope.declarations) { |
| 55 | if ( |
| 56 | !isPrimitiveType(decl.identifier) && |
| 57 | !isStableRefType(decl.identifier, state) |
| 58 | ) { |
| 59 | state.add(id); |
| 60 | } |
| 61 | } |
| 62 | } |
| 63 | } |
| 64 | function isStableRefType( |
| 65 | identifier: Identifier, |
| 66 | reactiveIdentifiers: Set<IdentifierId>, |
| 67 | ): boolean { |
| 68 | return isUseRefType(identifier) && !reactiveIdentifiers.has(identifier.id); |
| 69 | } |
| 70 | /* |
| 71 | * Computes a set of identifiers which are reactive, using the analysis previously performed |
| 72 | * in `InferReactivePlaces`. |
| 73 | */ |
| 74 | export function collectReactiveIdentifiers( |
| 75 | fn: ReactiveFunction, |
| 76 | ): Set<IdentifierId> { |
| 77 | const visitor = new Visitor(); |
| 78 | const state = new Set<IdentifierId>(); |
| 79 | visitReactiveFunction(fn, visitor, state); |
| 80 | |
| 81 | return state; |
| 82 | } |