| 1 | // Copyright (c) Meta Platforms, Inc. and affiliates. |
| 2 | // |
| 3 | // This source code is licensed under the MIT license found in the |
| 4 | // LICENSE file in the root directory of this source tree. |
| 5 | |
| 6 | //! Aligns scopes of object method values to that of their enclosing object expressions. |
| 7 | //! To produce a well-formed JS program in Codegen, object methods and object expressions |
| 8 | //! must be in the same ReactiveBlock as object method definitions must be inlined. |
| 9 | //! |
| 10 | //! Ported from TypeScript `src/ReactiveScopes/AlignObjectMethodScopes.ts`. |
| 11 | |
| 12 | use rustc_hash::{FxHashMap, FxHashSet}; |
| 13 | use std::cmp; |
| 14 | |
| 15 | use react_compiler_hir::environment::Environment; |
| 16 | use react_compiler_hir::{ |
| 17 | EvaluationOrder, HirFunction, IdentifierId, InstructionValue, ObjectPropertyOrSpread, ScopeId, |
| 18 | }; |
| 19 | use react_compiler_utils::DisjointSet; |
| 20 | |
| 21 | // ============================================================================= |
| 22 | // findScopesToMerge |
| 23 | // ============================================================================= |
| 24 | |
| 25 | /// Identifies ObjectMethod lvalue identifiers and then finds ObjectExpression |
| 26 | /// instructions whose operands reference those methods. Returns a disjoint set |
| 27 | /// of scopes that must be merged. |
| 28 | fn find_scopes_to_merge(func: &HirFunction, env: &Environment) -> DisjointSet<ScopeId> { |
| 29 | let mut object_method_decls: FxHashSet<IdentifierId> = FxHashSet::default(); |
| 30 | let mut merged_scopes = DisjointSet::<ScopeId>::new(); |
| 31 | |
| 32 | for (_block_id, block) in &func.body.blocks { |
| 33 | for &instr_id in &block.instructions { |
| 34 | let instr = &func.instructions[instr_id.0 as usize]; |
| 35 | match &instr.value { |
| 36 | InstructionValue::ObjectMethod { .. } => { |
| 37 | object_method_decls.insert(instr.lvalue.identifier); |
| 38 | } |
| 39 | InstructionValue::ObjectExpression { properties, .. } => { |
| 40 | for prop_or_spread in properties { |
| 41 | let operand_place = match prop_or_spread { |
| 42 | ObjectPropertyOrSpread::Property(prop) => &prop.place, |
| 43 | ObjectPropertyOrSpread::Spread(spread) => &spread.place, |
| 44 | }; |
| 45 | if object_method_decls.contains(&operand_place.identifier) { |
| 46 | let operand_scope = |
| 47 | env.identifiers[operand_place.identifier.0 as usize].scope; |
| 48 | let lvalue_scope = |
| 49 | env.identifiers[instr.lvalue.identifier.0 as usize].scope; |
| 50 | |
| 51 | // TS: CompilerError.invariant(operandScope != null && lvalueScope != null, ...) |
| 52 | let operand_sid = operand_scope.expect( |
| 53 | "Internal error: Expected all ObjectExpressions and ObjectMethods to have non-null scope.", |
| 54 | ); |
| 55 | let lvalue_sid = lvalue_scope.expect( |
| 56 | "Internal error: Expected all ObjectExpressions and ObjectMethods to have non-null scope.", |
| 57 | ); |
| 58 | merged_scopes.union(&[operand_sid, lvalue_sid]); |
| 59 | } |
| 60 | } |
| 61 | } |
| 62 | _ => {} |
| 63 | } |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | merged_scopes |
| 68 | } |
| 69 | |
| 70 | // ============================================================================= |
| 71 | // Public API |
| 72 | // ============================================================================= |
| 73 | |
| 74 | /// Aligns object method scopes so that ObjectMethod values and their enclosing |
| 75 | /// ObjectExpression share the same scope. |
| 76 | /// |
| 77 | /// Corresponds to TS `alignObjectMethodScopes(fn: HIRFunction): void`. |
| 78 | pub fn align_object_method_scopes(func: &mut HirFunction, env: &mut Environment) { |
| 79 | // Handle inner functions first (TS recurses before processing the outer function) |
| 80 | for (_block_id, block) in &func.body.blocks { |
| 81 | for &instr_id in &block.instructions { |
| 82 | let instr = &func.instructions[instr_id.0 as usize]; |
| 83 | match &instr.value { |
| 84 | InstructionValue::FunctionExpression { lowered_func, .. } |
| 85 | | InstructionValue::ObjectMethod { lowered_func, .. } => { |
| 86 | let func_id = lowered_func.func; |
| 87 | let mut inner_func = std::mem::replace( |
| 88 | &mut env.functions[func_id.0 as usize], |
| 89 | react_compiler_ssa::enter_ssa::placeholder_function(), |
| 90 | ); |
| 91 | align_object_method_scopes(&mut inner_func, env); |
| 92 | env.functions[func_id.0 as usize] = inner_func; |
| 93 | } |
| 94 | _ => {} |
| 95 | } |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | let mut merged_scopes = find_scopes_to_merge(func, env); |
| 100 | |
| 101 | // Step 1: Merge affected scopes to their canonical root. |
| 102 | // Use a FxHashMap to accumulate min/max across all scopes mapping to the same root, |
| 103 | // matching TS behavior where root.range is updated in-place during iteration. |
| 104 | let mut range_updates: FxHashMap<ScopeId, (EvaluationOrder, EvaluationOrder)> = |
| 105 | FxHashMap::default(); |
| 106 | |
| 107 | merged_scopes.for_each(|scope_id, root_id| { |
| 108 | if scope_id == root_id { |
| 109 | return; |
| 110 | } |
| 111 | let scope_range = env.scopes[scope_id.0 as usize].range.clone(); |
| 112 | let root_range = env.scopes[root_id.0 as usize].range.clone(); |
| 113 | |
| 114 | let entry = range_updates |
| 115 | .entry(root_id) |
| 116 | .or_insert_with(|| (root_range.start, root_range.end)); |
| 117 | entry.0 = EvaluationOrder(cmp::min(entry.0.0, scope_range.start.0)); |
| 118 | entry.1 = EvaluationOrder(cmp::max(entry.1.0, scope_range.end.0)); |
| 119 | }); |
| 120 | |
| 121 | // Save original scope range IDs before updating |
| 122 | let original_range_ids: FxHashMap<ScopeId, react_compiler_hir::MutableRangeId> = range_updates |
| 123 | .keys() |
| 124 | .map(|&root_id| { |
| 125 | let range_id = env.scopes[root_id.0 as usize].range.id; |
| 126 | (root_id, range_id) |
| 127 | }) |
| 128 | .collect(); |
| 129 | |
| 130 | for (root_id, (new_start, new_end)) in &range_updates { |
| 131 | env.scopes[root_id.0 as usize].range.start = *new_start; |
| 132 | env.scopes[root_id.0 as usize].range.end = *new_end; |
| 133 | } |
| 134 | |
| 135 | // Sync identifier mutable_ranges that shared the old scope range. |
| 136 | // Uses MutableRangeId for exact identity matching instead of value comparison. |
| 137 | for ident in &mut env.identifiers { |
| 138 | if let Some(scope_id) = ident.scope { |
| 139 | if let Some(&orig_range_id) = original_range_ids.get(&scope_id) { |
| 140 | if ident.mutable_range.id == orig_range_id { |
| 141 | let new_range = &env.scopes[scope_id.0 as usize].range; |
| 142 | ident.mutable_range.start = new_range.start; |
| 143 | ident.mutable_range.end = new_range.end; |
| 144 | } |
| 145 | } |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | // Step 2: Repoint identifiers whose scopes were merged |
| 150 | // Build a map from old scope -> root scope for quick lookup |
| 151 | let mut scope_remap: FxHashMap<ScopeId, ScopeId> = FxHashMap::default(); |
| 152 | merged_scopes.for_each(|scope_id, root_id| { |
| 153 | if scope_id != root_id { |
| 154 | scope_remap.insert(scope_id, root_id); |
| 155 | } |
| 156 | }); |
| 157 | |
| 158 | for (_block_id, block) in &func.body.blocks { |
| 159 | for &instr_id in &block.instructions { |
| 160 | let lvalue_id = func.instructions[instr_id.0 as usize].lvalue.identifier; |
| 161 | |
| 162 | if let Some(current_scope) = env.identifiers[lvalue_id.0 as usize].scope { |
| 163 | if let Some(&root) = scope_remap.get(¤t_scope) { |
| 164 | env.identifiers[lvalue_id.0 as usize].scope = Some(root); |
| 165 | } |
| 166 | } |
| 167 | } |
| 168 | } |
| 169 | } |