#include "diff.h" #include #include #include namespace pt = boost::property_tree; Diff::Diff() { } Diff::Diff(const std::string& old_version, const std::string& new_version) { create(old_version, new_version); } std::string Diff::apply(const std::string& old_version) const { std::string result{old_version}; result.erase(m_pos0, m_pos1 - m_pos0); result.insert(m_pos0, m_data); return result; } void Diff::create(const std::string& old_version, const std::string& new_version) { auto front_mismatch{std::mismatch(old_version.cbegin(), old_version.cend(), new_version.cbegin(), new_version.cend())}; std::string::difference_type old_pos0 {front_mismatch.first - old_version.cbegin()}; auto& new_pos0 {old_pos0}; // equal if (old_pos0 == old_version.size() && new_pos0 == new_version.size()) { m_pos0 = 0; m_pos1 = 0; m_data.clear(); return; } // append at end if (old_pos0 == old_version.size()) { m_pos0 = old_pos0; m_pos1 = old_pos0; m_data = new_version.substr(new_pos0); return; } // remove from end if (new_pos0 == new_version.size()) { m_pos0 = old_pos0; m_pos1 = old_version.size(); m_data.clear(); return; } auto back_mismatch{std::mismatch(old_version.crbegin(), old_version.crend(), new_version.crbegin(), new_version.crend())}; // i.e. the indices starting from which we can assume equality size_t old_pos1 {old_version.size() - (back_mismatch.first - old_version.crbegin())}; size_t new_pos1 {new_version.size() - (back_mismatch.second - new_version.crbegin())}; // complete equality is already handled above // insert at start if (old_pos1 == 0) { m_pos0 = 0; m_pos1 = 0; m_data = new_version.substr(0, new_pos1); return; } // remove from start if (new_pos1 == 0) { m_pos0 = 0; m_pos1 = old_pos1; m_data.clear(); return; } // insert in the middle if (old_pos0 == old_pos1) { m_pos0 = old_pos0; m_pos1 = old_pos0; m_data = new_version.substr(new_pos0, new_pos1 - new_pos0); return; } // remove from the middle if (new_pos0 == new_pos1) { m_pos0 = old_pos0; m_pos1 = old_pos1; m_data.clear(); return; } // last resort: remove and add in the middle m_pos0 = old_pos0; m_pos1 = old_pos1; m_data = new_version.substr(old_pos0, new_pos1 - new_pos0); } Diff::Diff(const std::string& xml) { create(xml); } void Diff::create(const std::string& xml) { pt::ptree tree; std::istringstream ss{xml}; pt::read_xml(ss, tree, pt::xml_parser::no_comments | pt::xml_parser::trim_whitespace); m_pos0 = tree.get("diff.start"); m_pos1 = tree.get("diff.end"); if (m_pos0 > m_pos1) throw std::runtime_error("Bad range in diff"); m_data = tree.get("diff.data"); } boost::property_tree::ptree Diff::get_structure() const { pt::ptree ptree; ptree.put("diff.start", std::to_string(m_pos0)); ptree.put("diff.end", std::to_string(m_pos1)); ptree.put("diff.data", m_data); return ptree; } std::string Diff::get_xml() const { pt::ptree ptree{get_structure()}; std::ostringstream oss; // write_xml_element instead of write_xml to omit header //pt::xml_parser::write_xml(oss, xml); pt::xml_parser::write_xml_element(oss, {}, ptree, -1, boost::property_tree::xml_writer_settings{}); return oss.str(); } extern "C" { const char* diff_create(const char* old_version, const char* new_version) { Diff diff{old_version, new_version}; return strdup(diff.get_xml().c_str()); } const char* diff_apply(const char* old_version, const char* diff) { Diff d{diff}; return strdup(d.apply(old_version).c_str()); } }