valueBlockResultToSequence() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/BuildReactiveFunction.ts lines 152–197

  valueBlockResultToSequence(
    result: {
      block: BlockId;
      value: ReactiveValue;
      place: Place;
      id: InstructionId;
    },
    loc: SourceLocation,
  ): ReactiveSequenceValue {
    // Collect all instructions from potentially nested SequenceExpressions
    const instructions: Array<ReactiveInstruction> = [];
    let innerValue: ReactiveValue = result.value;

    // Flatten nested SequenceExpressions
    while (innerValue.kind === 'SequenceExpression') {
      instructions.push(...innerValue.instructions);
      innerValue = innerValue.value;
    }

    /*
     * Only add the final instruction if the innermost value is not just a LoadLocal
     * of the same place we're storing to (which would be a no-op).
     * This happens when MaybeThrow blocks cause the sequence to already contain
     * all the necessary instructions.
     */
    const isLoadOfSamePlace =
      innerValue.kind === 'LoadLocal' &&
      innerValue.place.identifier.id === result.place.identifier.id;

    if (!isLoadOfSamePlace) {
      instructions.push({
        id: result.id,
        lvalue: result.place,
        value: innerValue,
        loc,
      });
    }

    return {
      kind: 'SequenceExpression',
      instructions,
      id: result.id,
      value: {kind: 'Primitive', value: undefined, loc},
      loc,
    };
  }