Add the function of getting table hidden attributes.

include/xlnt/workbook/workbook.hpp

@@ -241,6 +241,13 @@ public:
     /// </summary>
     const worksheet sheet_by_id(std::size_t id) const;
 
+    /// <summary>
+    /// Returns the hidden identifier of the worksheet at the given index.
+    /// This will throw an exception if index is greater than or equal to the
+    /// number of sheets in this workbook.
+    /// </summary>
+    bool sheet_hidden_by_index(std::size_t index) const;
+
     /// <summary>
     /// Returns true if this workbook contains a sheet with the given title.
     /// </summary>

source/detail/implementations/workbook_impl.hpp

@@ -79,6 +79,7 @@ struct workbook_impl
         manifest_ = other.manifest_;
 
         sheet_title_rel_id_map_ = other.sheet_title_rel_id_map_;
+        sheet_hidden_ = other.sheet_hidden_;
         view_ = other.view_;
         code_name_ = other.code_name_;
         file_version_ = other.file_version_;
@@ -105,6 +106,7 @@ struct workbook_impl
             && extended_properties_ == other.extended_properties_
             && custom_properties_ == other.custom_properties_
             && sheet_title_rel_id_map_ == other.sheet_title_rel_id_map_
+            && sheet_hidden_ == other.sheet_hidden_
             && view_ == other.view_
             && code_name_ == other.code_name_
             && file_version_ == other.file_version_
@@ -134,6 +136,7 @@ struct workbook_impl
     std::vector<std::pair<std::string, variant>> custom_properties_;
 
     std::unordered_map<std::string, std::string> sheet_title_rel_id_map_;
+    std::vector<bool> sheet_hidden_;
 
     optional<workbook_view> view_;
     optional<std::string> code_name_;

source/detail/serialization/xlsx_consumer.cpp

@@ -1883,12 +1883,14 @@ void xlsx_consumer::read_office_document(const std::string &content_type) // CT_
                 expect_start_element(qn("spreadsheetml", "sheet"), xml::content::simple);
 
                 auto title = parser().attribute("name");
-                skip_attribute("state");
 
                 sheet_title_index_map_[title] = index++;
                 sheet_title_id_map_[title] = parser().attribute<std::size_t>("sheetId");
                 target_.d_->sheet_title_rel_id_map_[title] = parser().attribute(qn("r", "id"));
 
+                bool hidden = parser().attribute<std::string>("state", "") == "hidden";
+                target_.d_->sheet_hidden_.push_back(hidden);
+
                 expect_end_element(qn("spreadsheetml", "sheet"));
             }
         }

source/workbook/workbook.cpp

@@ -716,6 +716,16 @@ const worksheet workbook::sheet_by_id(std::size_t id) const
     throw key_not_found();
 }
 
+bool workbook::sheet_hidden_by_index(std::size_t index) const
+{
+    if (index >= d_->sheet_hidden_.size())
+    {
+        throw invalid_parameter();
+    }
+
+    return d_->sheet_hidden_.at(index);
+}
+
 worksheet workbook::active_sheet()
 {
     return sheet_by_index(d_->active_sheet_index_.is_set() ? d_->active_sheet_index_.get() : 0);

tests/worksheet/worksheet_test_suite.cpp

@@ -112,6 +112,7 @@ public:
         register_test(test_delete_columns);
         register_test(test_insert_too_many);
         register_test(test_insert_delete_moves_merges);
+        register_test(test_hidden_sheet);
     }
 
     void test_new_worksheet()
@@ -1582,5 +1583,12 @@ public:
             xlnt_assert_equals(merged, expected);
         }
     }
+
+    void test_hidden_sheet()
+    {
+        xlnt::workbook wb;
+        wb.load(path_helper::test_file("16_hidden_sheet.xlsx"));
+        xlnt_assert_equals(wb.sheet_hidden_by_index(1), true);
+    }
 };
 static worksheet_test_suite x;