diff options
Diffstat (limited to 'src/common')
| -rw-r--r-- | src/common/Utilities/Containers.h | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/src/common/Utilities/Containers.h b/src/common/Utilities/Containers.h index 3a5c3b1809..ca89e7de09 100644 --- a/src/common/Utilities/Containers.h +++ b/src/common/Utilities/Containers.h @@ -138,18 +138,28 @@ namespace Acore::Containers } /* - * Select a random element from a container. + * @brief Selects a random element from a container that matches the given predicate + * + * @param container Source container to select from + * @param predicate Unary predicate to filter elements + * @return Iterator to the randomly selected element, or end iterator if no elements match the predicate * * Note: container cannot be empty */ template<class C, class Predicate> - inline auto SelectRandomContainerElementIf(C const& container, Predicate&& predicate) -> typename std::add_const<decltype(*std::begin(container))>::type& + inline auto SelectRandomContainerElementIf(C const& container, Predicate&& predicate) -> decltype(std::begin(container)) { - C containerCopy; - std::copy_if(std::begin(container), std::end(container), std::inserter(containerCopy, std::end(containerCopy)), predicate); - auto it = std::begin(containerCopy); - std::advance(it, urand(0, uint32(std::size(containerCopy)) - 1)); - return *it; + std::vector<decltype(std::begin(container))> matchingElements; + + for (auto it = std::begin(container); it != std::end(container); ++it) + if (predicate(*it)) + matchingElements.push_back(it); + + if (matchingElements.empty()) + return std::end(container); + + auto randomIt = matchingElements[urand(0, matchingElements.size() - 1)]; + return randomIt; } /* |