Method Evaluate

Source/cmGeneratorExpressionNode.cxx:3459–3518

  int NumExpectedParameters() const override { return OneOrMoreParameters; }

  std::string Evaluate(
    std::vector<std::string> const& parameters, cm::GenEx::Evaluation* eval,
    GeneratorExpressionContent const* content,
    cmGeneratorExpressionDAGChecker* dagChecker) const override
  {
    using ForGenex = cmGeneratorExpressionDAGChecker::ForGenex;

    if (!eval->HeadTarget || !dagChecker ||
        !dagChecker->EvaluatingLinkLibraries(nullptr, ForGenex::LINK_GROUP)) {
      reportError(
        eval, content->GetOriginalExpression(),
        "$<LINK_GROUP:...> may only be used with binary targets "
        "to specify group of link libraries through 'LINK_LIBRARIES', "
        "'INTERFACE_LINK_LIBRARIES', and "
        "'INTERFACE_LINK_LIBRARIES_DIRECT' properties.");
      return std::string();
    }

    cmList list{ parameters.begin(), parameters.end() };
    if (list.empty()) {
      reportError(
        eval, content->GetOriginalExpression(),
        "$<LINK_GROUP:...> expects a feature name as first argument.");
      return std::string();
    }
    // $<LINK_GROUP:..> cannot be nested
    if (std::find_if(list.cbegin(), list.cend(),
                     [](std::string const& item) -> bool {
                       return cmHasPrefix(item, "<LINK_GROUP"_s);
                     }) != list.cend()) {
      reportError(eval, content->GetOriginalExpression(),
                  "$<LINK_GROUP:...> cannot be nested.");
      return std::string();
    }
    if (list.size() == 1) {
      // no libraries specified, ignore this genex
      return std::string();
    }

    static cmsys::RegularExpression featureNameValidator("^[A-Za-z0-9_]+$");
    auto const& feature = list.front();
    if (!featureNameValidator.find(feature)) {
      reportError(eval, content->GetOriginalExpression(),
                  cmStrCat("The feature name '", feature,
                           "' contains invalid characters."));
      return std::string();
    }

    auto const LG_BEGIN = cmStrCat(
      "<LINK_GROUP:", feature, ':',
      cmJoin(cmRange<decltype(list.cbegin())>(list.cbegin() + 1, list.cend()),
             "|"_s),
      '>');
    auto const LG_END = cmStrCat("</LINK_GROUP:", feature, '>');

    list.front() = LG_BEGIN;
    list.push_back(LG_END);