Add document undo history tests

src/document/document.cpp

@@ -231,4 +231,91 @@ pp::foundation::Status CanvasDocument::set_active_frame(std::size_t index) noexc
     return pp::foundation::Status::success();
 }
 
+pp::foundation::Result<DocumentHistory> DocumentHistory::create(
+    CanvasDocument initial_document,
+    std::size_t max_entries)
+{
+    if (max_entries < min_document_history_entries) {
+        return pp::foundation::Result<DocumentHistory>::failure(
+            pp::foundation::Status::invalid_argument("document history must keep at least two entries"));
+    }
+
+    if (max_entries > max_document_history_entries) {
+        return pp::foundation::Result<DocumentHistory>::failure(
+            pp::foundation::Status::out_of_range("document history entry limit exceeds the configured limit"));
+    }
+
+    DocumentHistory history;
+    history.max_entries_ = max_entries;
+    history.entries_.reserve(max_entries);
+    history.entries_.push_back(initial_document);
+    return pp::foundation::Result<DocumentHistory>::success(history);
+}
+
+const CanvasDocument& DocumentHistory::current() const noexcept
+{
+    return entries_[current_index_];
+}
+
+std::size_t DocumentHistory::size() const noexcept
+{
+    return entries_.size();
+}
+
+std::size_t DocumentHistory::current_index() const noexcept
+{
+    return current_index_;
+}
+
+bool DocumentHistory::can_undo() const noexcept
+{
+    return current_index_ > 0;
+}
+
+bool DocumentHistory::can_redo() const noexcept
+{
+    return current_index_ + 1U < entries_.size();
+}
+
+pp::foundation::Status DocumentHistory::apply(CanvasDocument next_document)
+{
+    if (entries_.empty()) {
+        return pp::foundation::Status::invalid_argument("document history is not initialized");
+    }
+
+    if (can_redo()) {
+        entries_.erase(entries_.begin() + static_cast<std::ptrdiff_t>(current_index_ + 1U), entries_.end());
+    }
+
+    entries_.push_back(next_document);
+    if (entries_.size() > max_entries_) {
+        entries_.erase(entries_.begin());
+    } else {
+        ++current_index_;
+    }
+
+    current_index_ = entries_.size() - 1U;
+    return pp::foundation::Status::success();
+}
+
+pp::foundation::Status DocumentHistory::undo() noexcept
+{
+    if (!can_undo()) {
+        return pp::foundation::Status::out_of_range("document history has no undo entry");
+    }
+
+    --current_index_;
+    return pp::foundation::Status::success();
+}
+
+pp::foundation::Status DocumentHistory::redo() noexcept
+{
+    if (!can_redo()) {
+        return pp::foundation::Status::out_of_range("document history has no redo entry");
+    }
+
+    ++current_index_;
+    return pp::foundation::Status::success();
+}
+
 }

src/document/document.h

@@ -15,6 +15,8 @@ constexpr std::uint32_t max_canvas_dimension = 131072;
 constexpr std::uint32_t max_layer_count = 1024;
 constexpr std::uint32_t max_frame_count = 100000;
 constexpr std::uint32_t min_frame_duration_ms = 1;
+constexpr std::size_t min_document_history_entries = 2;
+constexpr std::size_t max_document_history_entries = 10000;
 
 struct DocumentConfig {
     std::uint32_t width = 0;
@@ -64,4 +66,26 @@ private:
     std::vector<AnimationFrame> frames_;
 };
 
+class DocumentHistory {
+public:
+    [[nodiscard]] static pp::foundation::Result<DocumentHistory> create(
+        CanvasDocument initial_document,
+        std::size_t max_entries = 256);
+
+    [[nodiscard]] const CanvasDocument& current() const noexcept;
+    [[nodiscard]] std::size_t size() const noexcept;
+    [[nodiscard]] std::size_t current_index() const noexcept;
+    [[nodiscard]] bool can_undo() const noexcept;
+    [[nodiscard]] bool can_redo() const noexcept;
+
+    [[nodiscard]] pp::foundation::Status apply(CanvasDocument next_document);
+    [[nodiscard]] pp::foundation::Status undo() noexcept;
+    [[nodiscard]] pp::foundation::Status redo() noexcept;
+
+private:
+    std::size_t max_entries_ = 0;
+    std::size_t current_index_ = 0;
+    std::vector<CanvasDocument> entries_;
+};
+
 }