StableSidemap Class — react Architecture

Source Code

compiler/packages/babel-plugin-react-compiler/src/Inference/InferReactivePlaces.ts lines 43–126

class StableSidemap {
  map: Map<IdentifierId, {isStable: boolean}> = new Map();
  env: Environment;

  constructor(env: Environment) {
    this.env = env;
  }

  handleInstruction(instr: Instruction): void {
    const {value, lvalue} = instr;

    switch (value.kind) {
      case 'CallExpression':
      case 'MethodCall': {
        /**
         * Sources of stability are known hook calls
         */
        if (evaluatesToStableTypeOrContainer(this.env, instr)) {
          if (isStableType(lvalue.identifier)) {
            this.map.set(lvalue.identifier.id, {
              isStable: true,
            });
          } else {
            this.map.set(lvalue.identifier.id, {
              isStable: false,
            });
          }
        }
        break;
      }

      case 'Destructure':
      case 'PropertyLoad': {
        /**
         * PropertyLoads may from stable containers may also produce stable
         * values. ComputedLoads are technically safe for now (as all stable
         * containers have differently-typed elements), but are not handled as
         * they should be rare anyways.
         */
        const source =
          value.kind === 'Destructure'
            ? value.value.identifier.id
            : value.object.identifier.id;
        const entry = this.map.get(source);
        if (entry) {
          for (const lvalue of eachInstructionLValue(instr)) {
            if (isStableTypeContainer(lvalue.identifier)) {
              this.map.set(lvalue.identifier.id, {
                isStable: false,
              });
            } else if (isStableType(lvalue.identifier)) {
              this.map.set(lvalue.identifier.id, {
                isStable: true,
              });
            }
          }
        }
        break;
      }

      case 'StoreLocal': {
        const entry = this.map.get(value.value.identifier.id);
        if (entry) {
          this.map.set(lvalue.identifier.id, entry);
          this.map.set(value.lvalue.place.identifier.id, entry);
        }
        break;
      }

      case 'LoadLocal': {
        const entry = this.map.get(value.place.identifier.id);
        if (entry) {
          this.map.set(lvalue.identifier.id, entry);
        }
        break;
      }
    }
  }

  isStable(id: IdentifierId): boolean {
    const entry = this.map.get(id);