Function castOptional

src/cpp-syntax-utils.ts:231–253

(expr: Expression, target: Type, source: Type)

 * Conversions between optionals.
 */
export function castOptional(expr: Expression, target: Type, source: Type): Expression {
  // Use helper when there is template type.
  if (source.category == 'template' || target.category == 'template') {
    if (source.isOptional) {
      return new CustomExpression(target, (ctx) => {
        return `compilets::GetOptionalValue(${expr.print(ctx)})`;
      });
    }
  }
  // Convert undefined to std::nullopt.
  if (source.category == 'undefined' && target.isStdOptional()) {
    if (target.isProperty)
      return expr;
    return new CustomExpression(target, (ctx) => 'std::nullopt');
  }
  // Get the optional value first before converting to other types.
  if (source.isStdOptional() && !target.isStdOptional()) {
    return new CustomExpression(source.noOptional(), (ctx) => {
      return `${printExpressionValue(expr, ctx)}.value()`;
    });
  }
  return expr;
}