LibGUI: Add FilteringProxyModel

This model does not support nested indices well, in that it flattens
them all out.
That's a FIXME for the future as it does its job for now.

4 files changed, 198 insertions, 2 deletions

diff --git a/Libraries/LibGUI/CMakeLists.txt b/Libraries/LibGUI/CMakeLists.txt
index 88ab51cffe..d7cace8e85 100644
--- a/Libraries/LibGUI/CMakeLists.txt
+++ b/Libraries/LibGUI/CMakeLists.txt
@@ -26,6 +26,7 @@ set(SOURCES
     Event.cpp
     FilePicker.cpp
     FileSystemModel.cpp
+    FilteringProxyModel.cpp
     FontDatabase.cpp
     Frame.cpp
     GroupBox.cpp
diff --git a/Libraries/LibGUI/FilteringProxyModel.cpp b/Libraries/LibGUI/FilteringProxyModel.cpp
new file mode 100644
index 0000000000..7d14b29a13
--- /dev/null
+++ b/Libraries/LibGUI/FilteringProxyModel.cpp
@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibGUI/FilteringProxyModel.h>
+
+namespace GUI {
+
+ModelIndex FilteringProxyModel::index(int row, int column, const ModelIndex& parent_index) const
+{
+    int parent_row = parent_index.row();
+    if (!parent_index.is_valid())
+        parent_row = 0;
+
+    return create_index(parent_row + row, column);
+}
+
+int FilteringProxyModel::row_count(const ModelIndex&) const
+{
+    return m_matching_indices.size();
+}
+
+int FilteringProxyModel::column_count(const ModelIndex& index) const
+{
+    if (!index.is_valid())
+        return {};
+
+    if ((size_t)index.row() > m_matching_indices.size() || index.row() < 0)
+        return 0;
+
+    return m_model.column_count(m_matching_indices[index.row()]);
+}
+
+Variant FilteringProxyModel::data(const ModelIndex& index, Role role) const
+{
+    if (!index.is_valid())
+        return {};
+
+    if ((size_t)index.row() > m_matching_indices.size() || index.row() < 0)
+        return 0;
+
+    return m_model.data(m_matching_indices[index.row()], role);
+}
+
+void FilteringProxyModel::update()
+{
+    m_model.update();
+    filter();
+    did_update();
+}
+
+void FilteringProxyModel::filter()
+{
+    m_matching_indices.clear();
+
+    Function<void(ModelIndex&)> add_matching = [&](ModelIndex& parent_index) {
+        for (auto i = 0; i < m_model.row_count(parent_index); ++i) {
+            auto index = m_model.index(i, 0, parent_index);
+            if (!index.is_valid())
+                continue;
+
+            auto filter_matches = m_model.data_matches(index, m_filter_term);
+            bool matches = filter_matches == TriState::True;
+            if (filter_matches == TriState::Unknown) {
+                auto data = m_model.data(index, Role::Display);
+                if (data.is_string() && data.as_string().contains(m_filter_term))
+                    matches = true;
+            }
+            if (matches)
+                m_matching_indices.append(index);
+
+            add_matching(index);
+        }
+    };
+
+    ModelIndex parent_index;
+    add_matching(parent_index);
+}
+
+void FilteringProxyModel::set_filter_term(const StringView& term)
+{
+    if (m_filter_term == term)
+        return;
+    m_filter_term = term;
+    update();
+}
+
+ModelIndex FilteringProxyModel::map(const ModelIndex& index) const
+{
+    if (!index.is_valid())
+        return {};
+
+    auto row = index.row();
+    if (m_matching_indices.size() > (size_t)row)
+        return m_matching_indices[row];
+
+    return {};
+}
+
+}
diff --git a/Libraries/LibGUI/FilteringProxyModel.h b/Libraries/LibGUI/FilteringProxyModel.h
new file mode 100644
index 0000000000..f5296c3e6b
--- /dev/null
+++ b/Libraries/LibGUI/FilteringProxyModel.h
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <AK/Optional.h>
+#include <AK/String.h>
+#include <LibGUI/Model.h>
+#include <LibGUI/TextBox.h>
+
+namespace GUI {
+
+class FilteringProxyModel final : public Model {
+public:
+    static NonnullRefPtr<FilteringProxyModel> construct(Model& model)
+    {
+        return adopt(*new FilteringProxyModel(model));
+    }
+
+    virtual ~FilteringProxyModel() override {};
+
+    virtual int row_count(const ModelIndex& = ModelIndex()) const override;
+    virtual int column_count(const ModelIndex& = ModelIndex()) const override;
+    virtual Variant data(const ModelIndex&, Role = Role::Display) const override;
+    virtual void update() override;
+    virtual ModelIndex index(int row, int column = 0, const ModelIndex& parent = ModelIndex()) const override;
+
+    void set_filter_term(const StringView& term);
+
+    ModelIndex map(const ModelIndex&) const;
+
+private:
+    void filter();
+    explicit FilteringProxyModel(Model& model)
+        : m_model(model)
+    {
+    }
+
+    Model& m_model;
+
+    // Maps row to actual model index.
+    Vector<ModelIndex> m_matching_indices;
+
+    String m_filter_term;
+};
+
+}
diff --git a/Libraries/LibGUI/Model.h b/Libraries/LibGUI/Model.h
index 29933023ba..d12a0f2afc 100644
--- a/Libraries/LibGUI/Model.h
+++ b/Libraries/LibGUI/Model.h
@@ -67,6 +67,7 @@ public:
         Font,
         DragData,
         TextAlignment,
+        Search,
         Custom = 0x100, // Applications are free to use roles above this number as they please
     };
 
@@ -76,12 +77,13 @@ public:
     virtual int column_count(const ModelIndex& = ModelIndex()) const = 0;
     virtual String column_name(int) const { return {}; }
     virtual Variant data(const ModelIndex&, Role = Role::Display) const = 0;
+    virtual TriState data_matches(const ModelIndex&, Variant) const { return TriState::Unknown; }
     virtual void update() = 0;
     virtual ModelIndex parent_index(const ModelIndex&) const { return {}; }
     virtual ModelIndex index(int row, int column = 0, const ModelIndex& = ModelIndex()) const { return create_index(row, column); }
     virtual ModelIndex sibling(int row, int column, const ModelIndex& parent) const;
     virtual bool is_editable(const ModelIndex&) const { return false; }
-    virtual void set_data(const ModelIndex&, const Variant&) {}
+    virtual void set_data(const ModelIndex&, const Variant&) { }
     virtual int tree_column() const { return 0; }
     virtual bool accepts_drag(const ModelIndex&, const StringView& data_type);
 
@@ -95,7 +97,7 @@ public:
 
     virtual int key_column() const { return -1; }
     virtual SortOrder sort_order() const { return SortOrder::None; }
-    virtual void set_key_column_and_sort_order(int, SortOrder) {}
+    virtual void set_key_column_and_sort_order(int, SortOrder) { }
 
     virtual StringView drag_data_type() const { return {}; }