xLnt. shared string performance optimization.

include/xlnt/cell/rich_text.hpp

@@ -130,4 +130,18 @@ private:
     std::vector<rich_text_run> runs_;
 };
 
+class XLNT_API rich_text_hash 
+{
+public:
+	std::size_t operator()(const rich_text& k) const
+	{
+		std::size_t res = 0;
+
+		for (auto r : k.runs())
+			res ^= std::hash<std::string>()(r.first);
+
+		return res;
+	}
+};
+
 } // namespace xlnt

include/xlnt/workbook/workbook.hpp

@@ -31,8 +31,10 @@
 #include <unordered_map>
 #include <utility>
 #include <vector>
+#include <map>
 
 #include <xlnt/xlnt_config.hpp>
+#include <xlnt/cell/rich_text.hpp>
 
 namespace xlnt {
 
@@ -704,17 +706,27 @@ public:
     /// </summary>
     std::size_t add_shared_string(const rich_text &shared, bool allow_duplicates = false);
 
-    /// <summary>
-    /// Returns a reference to the shared strings being used by cells
-    /// in this workbook.
-    /// </summary>
-    std::vector<rich_text> &shared_strings();
+	/// <summary>
+	/// Returns a reference to the shared string ordered by id
+	/// </summary>
+	const std::map<std::size_t, rich_text> &workbook::shared_strings_by_id() const;
+
+	/// <summary>
+	/// Returns a reference to the shared string related to the specified index
+	/// </summary>
+	const rich_text& workbook::shared_strings(std::size_t index) const;
 
     /// <summary>
     /// Returns a reference to the shared strings being used by cells
     /// in this workbook.
     /// </summary>
-    const std::vector<rich_text> &shared_strings() const;
+    std::unordered_map<rich_text, std::size_t, rich_text_hash> &shared_strings();
+
+    /// <summary>
+    /// Returns a reference to the shared strings being used by cells
+    /// in this workbook.
+    /// </summary>
+    const std::unordered_map<rich_text, std::size_t, rich_text_hash> &shared_strings() const;
 
     // Thumbnail
 

source/cell/cell.cpp

@@ -642,7 +642,7 @@ XLNT_API rich_text cell::value() const
 {
     if (data_type() == cell::type::shared_string)
     {
-        return workbook().shared_strings().at(static_cast<std::size_t>(d_->value_numeric_));
+		return workbook().shared_strings(static_cast<std::size_t>(d_->value_numeric_));
     }
 
     return d_->value_text_;

source/cell/rich_text_run.cpp

@@ -27,7 +27,10 @@ namespace xlnt {
 
 bool rich_text_run::operator<(const rich_text_run &other) const
 {
-	return first < other.first && second < other.second;
+	if (first != other.first)
+		return first < other.first;
+
+	return second < other.second;
 }
 
 bool rich_text_run::operator==(const rich_text_run &other) const

source/detail/implementations/workbook_impl.hpp

@@ -53,7 +53,8 @@ struct workbook_impl
     workbook_impl(const workbook_impl &other)
         : active_sheet_index_(other.active_sheet_index_),
           worksheets_(other.worksheets_),
-          shared_strings_(other.shared_strings_),
+          shared_strings_ids_(other.shared_strings_ids_),
+		  shared_strings_values_(other.shared_strings_values_),
           stylesheet_(other.stylesheet_),
           manifest_(other.manifest_),
           theme_(other.theme_),
@@ -71,8 +72,8 @@ struct workbook_impl
         active_sheet_index_ = other.active_sheet_index_;
         worksheets_.clear();
         std::copy(other.worksheets_.begin(), other.worksheets_.end(), back_inserter(worksheets_));
-        shared_strings_.clear();
-        std::copy(other.shared_strings_.begin(), other.shared_strings_.end(), std::back_inserter(shared_strings_));
+		shared_strings_ids_ = other.shared_strings_ids_;
+		shared_strings_values_ = other.shared_strings_values_;
 		theme_ = other.theme_;
         manifest_ = other.manifest_;
 
@@ -91,7 +92,8 @@ struct workbook_impl
     optional<std::size_t> active_sheet_index_;
 
     std::list<worksheet_impl> worksheets_;
-    std::vector<rich_text> shared_strings_;
+    std::unordered_map<rich_text, std::size_t, rich_text_hash> shared_strings_ids_;
+	std::map<std::size_t, rich_text> shared_strings_values_;
 
     optional<stylesheet> stylesheet_;
 

source/detail/serialization/xlsx_consumer.cpp

@@ -1675,18 +1675,17 @@ void xlsx_consumer::read_shared_string_table()
         unique_count = parser().attribute<std::size_t>("uniqueCount");
     }
 
-    auto &strings = target_.shared_strings();
-
     while (in_element(qn("spreadsheetml", "sst")))
     {
         expect_start_element(qn("spreadsheetml", "si"), xml::content::complex);
-        strings.push_back(read_rich_text(qn("spreadsheetml", "si")));
+		auto rt = read_rich_text(qn("spreadsheetml", "si"));
+		target_.add_shared_string(rt);
         expect_end_element(qn("spreadsheetml", "si"));
     }
 
     expect_end_element(qn("spreadsheetml", "sst"));
 
-    if (has_unique_count && unique_count != strings.size())
+    if (has_unique_count && unique_count != target_.shared_strings().size())
     {
         throw invalid_file("sizes don't match");
     }

source/detail/serialization/xlsx_producer.cpp

@@ -818,20 +818,20 @@ void xlsx_producer::write_shared_string_table(const relationship & /*rel*/)
 #pragma clang diagnostic pop
 
     write_attribute("count", string_count);
-    write_attribute("uniqueCount", source_.shared_strings().size());
+    write_attribute("uniqueCount", source_.shared_strings_by_id().size());
 
     auto has_trailing_whitespace = [](const std::string &s)
     {
         return !s.empty() && (s.front() == ' ' || s.back() == ' ');
     };
 
-    for (const auto &string : source_.shared_strings())
+    for (const auto &string : source_.shared_strings_by_id())
     {
-        if (string.runs().size() == 1 && !string.runs().at(0).second.is_set())
+        if (string.second.runs().size() == 1 && !string.second.runs().at(0).second.is_set())
         {
             write_start_element(xmlns, "si");
             write_start_element(xmlns, "t");
-            write_characters(string.plain_text(), has_trailing_whitespace(string.plain_text()));
+            write_characters(string.second.plain_text(), has_trailing_whitespace(string.second.plain_text()));
             write_end_element(xmlns, "t");
             write_end_element(xmlns, "si");
 
@@ -840,7 +840,7 @@ void xlsx_producer::write_shared_string_table(const relationship & /*rel*/)
 
         write_start_element(xmlns, "si");
 
-        for (const auto &run : string.runs())
+        for (const auto &run : string.second.runs())
         {
             write_start_element(xmlns, "r");
 

source/workbook/workbook.cpp

@@ -1251,39 +1251,47 @@ const manifest &workbook::manifest() const
     return d_->manifest_;
 }
 
-std::vector<rich_text> &workbook::shared_strings()
+const std::map<std::size_t, rich_text> &workbook::shared_strings_by_id() const
 {
-    return d_->shared_strings_;
+	return d_->shared_strings_values_;
 }
 
-const std::vector<rich_text> &workbook::shared_strings() const
+const rich_text& workbook::shared_strings(std::size_t index) const
 {
-    return d_->shared_strings_;
+	auto it = d_->shared_strings_values_.find(index);
+	if (it != d_->shared_strings_values_.end())
+		return it->second;
+
+	static rich_text empty;
+	return empty;
+}
+
+std::unordered_map<rich_text, std::size_t, rich_text_hash> &workbook::shared_strings()
+{
+    return d_->shared_strings_ids_;
+}
+
+const std::unordered_map<rich_text, std::size_t, rich_text_hash> &workbook::shared_strings() const
+{
+    return d_->shared_strings_ids_;
 }
 
 std::size_t workbook::add_shared_string(const rich_text &shared, bool allow_duplicates)
 {
     register_workbook_part(relationship_type::shared_string_table);
 
-    auto index = std::size_t(0);
-
     if (!allow_duplicates)
     {
-        // TODO: inefficient, use a set or something?
-        for (auto &s : d_->shared_strings_)
-        {
-            if (s == shared)
-            {
-                return index;
-            }
-
-            ++index;
-        }
+		auto it = d_->shared_strings_ids_.find(shared);
+		if (it != d_->shared_strings_ids_.end())
+			return it->second;
     }
 
-    d_->shared_strings_.push_back(shared);
+	auto sz = d_->shared_strings_ids_.size();
+    d_->shared_strings_ids_[shared] = sz;
+	d_->shared_strings_values_[sz] = shared;
 
-    return index;
+    return sz;
 }
 
 bool workbook::contains(const std::string &sheet_title) const