13 files changed, 468 insertions, 11 deletions
diff --git a/Applications/Spreadsheet/CMakeLists.txt b/Applications/Spreadsheet/CMakeLists.txt
index 5ec5efee9a..e3c4a0766d 100644
--- a/Applications/Spreadsheet/CMakeLists.txt
+++ b/Applications/Spreadsheet/CMakeLists.txt
@@ -1,6 +1,10 @@
 set(SOURCES
     Cell.cpp
     CellSyntaxHighlighter.cpp
+    CellType/Identity.cpp
+    CellType/Numeric.cpp
+    CellType/String.cpp
+    CellType/Type.cpp
     HelpWindow.cpp
     JSIntegration.cpp
     Spreadsheet.cpp
diff --git a/Applications/Spreadsheet/Cell.cpp b/Applications/Spreadsheet/Cell.cpp
index d44d02debf..d7beec0bb3 100644
--- a/Applications/Spreadsheet/Cell.cpp
+++ b/Applications/Spreadsheet/Cell.cpp
@@ -60,6 +60,45 @@ void Cell::set_data(JS::Value new_data)
     evaluated_data = move(new_data);
 }
 
+void Cell::set_type(const StringView& name)
+{
+    auto* cell_type = CellType::get_by_name(name);
+    if (cell_type) {
+        m_type = cell_type;
+        return;
+    }
+
+    ASSERT_NOT_REACHED();
+}
+
+void Cell::set_type_metadata(CellTypeMetadata&& metadata)
+{
+    m_type_metadata = move(metadata);
+}
+
+const CellType& Cell::type() const
+{
+    if (m_type)
+        return *m_type;
+
+    if (kind == LiteralString) {
+        if (data.to_int().has_value())
+            return *CellType::get_by_name("Numeric");
+    }
+
+    return *CellType::get_by_name("Identity");
+}
+
+String Cell::typed_display() const
+{
+    return type().display(const_cast<Cell&>(*this), m_type_metadata);
+}
+
+JS::Value Cell::typed_js_data() const
+{
+    return type().js_value(const_cast<Cell&>(*this), m_type_metadata);
+}
+
 void Cell::update_data()
 {
     TemporaryChange cell_change { sheet->current_evaluated_cell(), this };
diff --git a/Applications/Spreadsheet/Cell.h b/Applications/Spreadsheet/Cell.h
index 6fed58f4b9..f7dd3c71dd 100644
--- a/Applications/Spreadsheet/Cell.h
+++ b/Applications/Spreadsheet/Cell.h
@@ -26,6 +26,7 @@
 
 #pragma once
 
+#include "CellType/Type.h"
 #include "Forward.h"
 #include "JSIntegration.h"
 #include <AK/String.h>
@@ -57,6 +58,16 @@ struct Cell : public Weakable<Cell> {
     void set_data(String new_data);
     void set_data(JS::Value new_data);
 
+    void set_type(const StringView& name);
+    void set_type_metadata(CellTypeMetadata&&);
+
+    String typed_display() const;
+    JS::Value typed_js_data() const;
+
+    const CellType& type() const;
+    const CellTypeMetadata& type_metadata() const { return m_type_metadata; }
+    CellTypeMetadata& type_metadata() { return m_type_metadata; }
+
     String source() const;
 
     JS::Value js_data();
@@ -76,6 +87,8 @@ struct Cell : public Weakable<Cell> {
     Kind kind { LiteralString };
     WeakPtr<Sheet> sheet;
     Vector<WeakPtr<Cell>> referencing_cells;
+    const CellType* m_type { nullptr };
+    CellTypeMetadata m_type_metadata;
 
 private:
     void update_data();
diff --git a/Applications/Spreadsheet/CellType/Identity.cpp b/Applications/Spreadsheet/CellType/Identity.cpp
new file mode 100644
index 0000000000..eed7cb190c
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/Identity.cpp
@@ -0,0 +1,52 @@
+/*
+ * 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 "Identity.h"
+#include "../Cell.h"
+#include "../Spreadsheet.h"
+
+namespace Spreadsheet {
+
+IdentityCell::IdentityCell()
+    : CellType("Identity")
+{
+}
+
+IdentityCell::~IdentityCell()
+{
+}
+
+String IdentityCell::display(Cell& cell, const CellTypeMetadata&) const
+{
+    return cell.js_data().to_string_without_side_effects();
+}
+
+JS::Value IdentityCell::js_value(Cell& cell, const CellTypeMetadata&) const
+{
+    return cell.js_data();
+}
+
+}
diff --git a/Applications/Spreadsheet/CellType/Identity.h b/Applications/Spreadsheet/CellType/Identity.h
new file mode 100644
index 0000000000..09089153ec
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/Identity.h
@@ -0,0 +1,42 @@
+/*
+ * 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 "Type.h"
+
+namespace Spreadsheet {
+
+class IdentityCell : public CellType {
+
+public:
+    IdentityCell();
+    virtual ~IdentityCell() override;
+    virtual String display(Cell&, const CellTypeMetadata&) const override;
+    virtual JS::Value js_value(Cell&, const CellTypeMetadata&) const override;
+};
+
+}
diff --git a/Applications/Spreadsheet/CellType/Numeric.cpp b/Applications/Spreadsheet/CellType/Numeric.cpp
new file mode 100644
index 0000000000..4218e0d1b2
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/Numeric.cpp
@@ -0,0 +1,62 @@
+/*
+ * 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 "Numeric.h"
+#include "../Cell.h"
+#include "../Spreadsheet.h"
+
+namespace Spreadsheet {
+
+NumericCell::NumericCell()
+    : CellType("Numeric")
+{
+}
+
+NumericCell::~NumericCell()
+{
+}
+
+String NumericCell::display(Cell& cell, const CellTypeMetadata& metadata) const
+{
+    auto value = js_value(cell, metadata);
+    String string;
+    if (metadata.format.is_null())
+        string = value.to_string_without_side_effects();
+    else
+        string = String::format(metadata.format.characters(), value.to_double(cell.sheet->interpreter())); // FIXME: Somehow make this format less dependent on 'double'.
+
+    if (metadata.length >= 0)
+        return string.substring(0, metadata.length);
+
+    return string;
+}
+
+JS::Value NumericCell::js_value(Cell& cell, const CellTypeMetadata&) const
+{
+    return cell.js_data().to_number(cell.sheet->interpreter());
+}
+
+}
diff --git a/Applications/Spreadsheet/CellType/Numeric.h b/Applications/Spreadsheet/CellType/Numeric.h
new file mode 100644
index 0000000000..e0cd4a295a
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/Numeric.h
@@ -0,0 +1,42 @@
+/*
+ * 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 "Type.h"
+
+namespace Spreadsheet {
+
+class NumericCell : public CellType {
+
+public:
+    NumericCell();
+    virtual ~NumericCell() override;
+    virtual String display(Cell&, const CellTypeMetadata&) const override;
+    virtual JS::Value js_value(Cell&, const CellTypeMetadata&) const override;
+};
+
+}
diff --git a/Applications/Spreadsheet/CellType/String.cpp b/Applications/Spreadsheet/CellType/String.cpp
new file mode 100644
index 0000000000..e8b0ed61d2
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/String.cpp
@@ -0,0 +1,57 @@
+/*
+ * 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 "String.h"
+#include "../Cell.h"
+#include "../Spreadsheet.h"
+
+namespace Spreadsheet {
+
+StringCell::StringCell()
+    : CellType("String")
+{
+}
+
+StringCell::~StringCell()
+{
+}
+
+String StringCell::display(Cell& cell, const CellTypeMetadata& metadata) const
+{
+    auto string = cell.js_data().to_string_without_side_effects();
+    if (metadata.length >= 0)
+        return string.substring(0, metadata.length);
+
+    return string;
+}
+
+JS::Value StringCell::js_value(Cell& cell, const CellTypeMetadata& metadata) const
+{
+    auto string = display(cell, metadata);
+    return JS::js_string(cell.sheet->interpreter(), string);
+}
+
+}
diff --git a/Applications/Spreadsheet/CellType/String.h b/Applications/Spreadsheet/CellType/String.h
new file mode 100644
index 0000000000..e4ba28eb24
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/String.h
@@ -0,0 +1,42 @@
+/*
+ * 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 "Type.h"
+
+namespace Spreadsheet {
+
+class StringCell : public CellType {
+
+public:
+    StringCell();
+    virtual ~StringCell() override;
+    virtual String display(Cell&, const CellTypeMetadata&) const override;
+    virtual JS::Value js_value(Cell&, const CellTypeMetadata&) const override;
+};
+
+}
diff --git a/Applications/Spreadsheet/CellType/Type.cpp b/Applications/Spreadsheet/CellType/Type.cpp
new file mode 100644
index 0000000000..80933c1a3d
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/Type.cpp
@@ -0,0 +1,52 @@
+/*
+ * 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 "Type.h"
+#include "Identity.h"
+#include "Numeric.h"
+#include "String.h"
+#include <AK/HashMap.h>
+#include <AK/OwnPtr.h>
+
+static HashMap<String, Spreadsheet::CellType*> s_cell_types;
+static Spreadsheet::StringCell s_string_cell;
+static Spreadsheet::NumericCell s_numeric_cell;
+static Spreadsheet::IdentityCell s_identity_cell;
+
+namespace Spreadsheet {
+
+const CellType* CellType::get_by_name(const StringView& name)
+{
+    return s_cell_types.get(name).value_or(nullptr);
+}
+
+CellType::CellType(const StringView& name)
+{
+    ASSERT(!s_cell_types.contains(name));
+    s_cell_types.set(name, this);
+}
+
+}
diff --git a/Applications/Spreadsheet/CellType/Type.h b/Applications/Spreadsheet/CellType/Type.h
new file mode 100644
index 0000000000..7ed9dbe763
--- /dev/null
+++ b/Applications/Spreadsheet/CellType/Type.h
@@ -0,0 +1,53 @@
+/*
+ * 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 "../Forward.h"
+#include <AK/Forward.h>
+#include <AK/String.h>
+#include <LibJS/Forward.h>
+
+namespace Spreadsheet {
+
+struct CellTypeMetadata {
+    int length { -1 };
+    String format;
+};
+
+class CellType {
+public:
+    static const CellType* get_by_name(const StringView&);
+
+    virtual String display(Cell&, const CellTypeMetadata&) const = 0;
+    virtual JS::Value js_value(Cell&, const CellTypeMetadata&) const = 0;
+    virtual ~CellType() { }
+
+protected:
+    CellType(const StringView& name);
+};
+
+}
diff --git a/Applications/Spreadsheet/JSIntegration.cpp b/Applications/Spreadsheet/JSIntegration.cpp
index 830b664f6f..2431b5e409 100644
--- a/Applications/Spreadsheet/JSIntegration.cpp
+++ b/Applications/Spreadsheet/JSIntegration.cpp
@@ -49,7 +49,7 @@ JS::Value SheetGlobalObject::get(const JS::PropertyName& name, JS::Value receive
         if (auto pos = Sheet::parse_cell_name(name.as_string()); pos.has_value()) {
             auto& cell = m_sheet.ensure(pos.value());
             cell.reference_from(m_sheet.current_evaluated_cell());
-            return cell.js_data();
+            return cell.typed_js_data();
         }
     }
 
diff --git a/Applications/Spreadsheet/SpreadsheetModel.cpp b/Applications/Spreadsheet/SpreadsheetModel.cpp
index 2b92619784..c4c5c286a6 100644
--- a/Applications/Spreadsheet/SpreadsheetModel.cpp
+++ b/Applications/Spreadsheet/SpreadsheetModel.cpp
@@ -50,34 +50,33 @@ GUI::Variant SheetModel::data(const GUI::ModelIndex& index, GUI::ModelRole role)
         return {};
 
     if (role == GUI::ModelRole::Display) {
-        const auto* value = m_sheet->at({ m_sheet->column(index.column()), (size_t)index.row() });
-        if (!value)
+        const auto* cell = m_sheet->at({ m_sheet->column(index.column()), (size_t)index.row() });
+        if (!cell)
             return String::empty();
 
-        if (value->kind == Spreadsheet::Cell::Formula) {
-            if (auto object = as_error(value->evaluated_data)) {
+        if (cell->kind == Spreadsheet::Cell::Formula) {
+            if (auto object = as_error(cell->evaluated_data)) {
                 StringBuilder builder;
                 auto error = object->get("message").to_string_without_side_effects();
                 builder.append("Error: ");
                 builder.append(error);
                 return builder.to_string();
             }
-            return value->evaluated_data.is_empty() ? "" : value->evaluated_data.to_string_without_side_effects();
         }
 
-        return value->data;
+        return cell->typed_display();
     }
 
     if (role == GUI::ModelRole::TextAlignment)
         return {};
 
     if (role == GUI::ModelRole::ForegroundColor) {
-        const auto* value = m_sheet->at({ m_sheet->column(index.column()), (size_t)index.row() });
-        if (!value)
+        const auto* cell = m_sheet->at({ m_sheet->column(index.column()), (size_t)index.row() });
+        if (!cell)
             return {};
 
-        if (value->kind == Spreadsheet::Cell::Formula) {
-            if (as_error(value->evaluated_data))
+        if (cell->kind == Spreadsheet::Cell::Formula) {
+            if (as_error(cell->evaluated_data))
                 return Color(Color::Red);
         }