1 files changed, 146 insertions, 0 deletions
diff --git a/sax/inc/sax_attributes.hh b/sax/inc/sax_attributes.hh
new file mode 100644
index 0000000..4ab1a44
--- /dev/null
+++ b/sax/inc/sax_attributes.hh
@@ -0,0 +1,146 @@
+#ifndef SAX_ATTRIBUTES_HH
+#define SAX_ATTRIBUTES_HH
+
+#include <iterator>
+#include <optional>
+#include <string_view>
+
+namespace modxml {
+namespace sax {
+
+struct Attribute {
+  std::string_view name;
+  std::string_view value;
+
+  Attribute(std::string_view name, std::string_view value);
+};
+
+/**
+ * A view of attributes, with utility functions.
+ */
+class Attributes {
+ public:
+  virtual ~Attributes() = default;
+
+  class iterator {
+   public:
+    using iterator_category = std::random_access_iterator_tag;
+    using difference_type = std::ptrdiff_t;
+    using element_type = Attribute;
+    using pointer = element_type const *;
+    using reference = element_type const &;
+
+    iterator()
+        : attributes_(nullptr), index_(0) {}
+    iterator(iterator const& it)
+        : attributes_(it.attributes_), index_(it.index_) {}
+    iterator& operator=(iterator const& it) {
+      attributes_ = it.attributes_;
+      index_ = it.index_;
+      return *this;
+    }
+
+    /**
+     * Comparing two iterators from different Attributes instances is undefined.
+     */
+    bool operator==(iterator const& it) const {
+      return index_ == it.index_;
+    }
+    std::strong_ordering operator<=>(iterator const& it) const {
+      return index_ <=> it.index_;
+    }
+
+    pointer operator->() const { return &attributes_->at(index_); }
+    reference operator*() const { return attributes_->at(index_); }
+    reference operator[](difference_type i) const {
+      return attributes_->at(index_ + i);
+    }
+
+    iterator& operator++() {
+      ++index_;
+      return *this;
+    }
+    iterator operator++(int) {
+      auto ret = *this;
+      ++index_;
+      return ret;
+    }
+    iterator& operator+=(difference_type i) {
+      index_ += i;
+      return *this;
+    }
+    iterator operator+(difference_type i) const {
+      return iterator(attributes_, index_ + i);
+    }
+    friend iterator operator+(difference_type i, iterator const &it) {
+      return iterator(it.attributes_, it.index_ + i);
+    }
+    iterator& operator--() {
+      --index_;
+      return *this;
+    }
+    iterator operator--(int) {
+      auto ret = *this;
+      --index_;
+      return ret;
+    }
+    iterator& operator-=(difference_type i) {
+      index_ -= i;
+      return *this;
+    }
+    difference_type operator-(iterator const& it) const {
+      return index_ - it.index_;
+    }
+    iterator operator-(difference_type i) const {
+      return iterator(attributes_, index_ - i);
+    }
+
+   protected:
+    iterator(Attributes const* attributes, std::size_t index)
+        : attributes_(attributes), index_(index) {}
+
+   private:
+    Attributes const* attributes_;
+    std::size_t index_;
+  };
+
+  static_assert(std::random_access_iterator<iterator>);
+
+  virtual iterator begin() const = 0;
+  virtual iterator end() const = 0;
+
+  virtual std::size_t size() const = 0;
+  /**
+   * name and value of attribute are valid as long as Attributes instance is.
+   */
+  virtual Attribute const& at(std::size_t index) const = 0;
+
+  Attribute const& operator[](std::size_t index) const { return at(index); }
+
+  /**
+   * Return the first attribute with name, if any.
+   */
+  virtual std::optional<std::string_view> find_first(
+      std::string_view name) const;
+
+  /**
+   * Return the last attribute with name, if any.
+   */
+  virtual std::optional<std::string_view> find_last(
+      std::string_view name) const;
+
+  /**
+   * Return the index of the attribute with name, starting with offset.
+   */
+  virtual std::optional<std::size_t> find(std::string_view name,
+                                          std::size_t index = 0) const;
+
+ protected:
+  Attributes() = default;
+};
+
+}  // namespace sax
+}  // namespace modxml
+
+
+#endif  // SAX_ATTRIBUTES_HH