LibPDF: Break weird dependency cycle

Old situation:
Object.h defines Object
Object.h defines ArrayObject
ArrayObject requires the definition of Object
ArrayObject requires the definition of Value
Value.h defines Value
Value requires the definition of Object

Therefore, a file with the single line "#include <Value.h>" used to
raise compilation errors; certainly not something that one might expect
from a library.

This patch splits up the definitions in Object.h to break the cycle.
Now, Object.h only defines Object, Value.h still only defines Value (and
includes Object.h), and the new header ObjectDerivatives.h defines
ArrayObject (and includes both Object.h and Value.h).

8 files changed, 218 insertions, 200 deletions

diff --git a/Userland/Libraries/LibPDF/CMakeLists.txt b/Userland/Libraries/LibPDF/CMakeLists.txt
index c3a959e4b2..e0ec0d86d9 100644
--- a/Userland/Libraries/LibPDF/CMakeLists.txt
+++ b/Userland/Libraries/LibPDF/CMakeLists.txt
@@ -3,7 +3,7 @@ set(SOURCES
     CommonNames.cpp
     Document.cpp
     Filter.cpp
-    Object.cpp
+    ObjectDerivatives.cpp
     Parser.cpp
     Renderer.cpp
     Value.cpp
diff --git a/Userland/Libraries/LibPDF/ColorSpace.cpp b/Userland/Libraries/LibPDF/ColorSpace.cpp
index 1336eb6aa7..ccb487e20f 100644
--- a/Userland/Libraries/LibPDF/ColorSpace.cpp
+++ b/Userland/Libraries/LibPDF/ColorSpace.cpp
@@ -6,6 +6,7 @@
 
 #include <LibPDF/ColorSpace.h>
 #include <LibPDF/CommonNames.h>
+#include <LibPDF/ObjectDerivatives.h>
 
 namespace PDF {
 
diff --git a/Userland/Libraries/LibPDF/ColorSpace.h b/Userland/Libraries/LibPDF/ColorSpace.h
index 2a680ff5ff..c22ee7d36e 100644
--- a/Userland/Libraries/LibPDF/ColorSpace.h
+++ b/Userland/Libraries/LibPDF/ColorSpace.h
@@ -8,7 +8,6 @@
 
 #include <AK/FlyString.h>
 #include <LibGfx/Color.h>
-#include <LibPDF/Object.h>
 #include <LibPDF/Value.h>
 
 #define ENUMERATE_COLOR_SPACES(V) \
diff --git a/Userland/Libraries/LibPDF/Document.h b/Userland/Libraries/LibPDF/Document.h
index 6c885cfcf2..7a4fc14a6f 100644
--- a/Userland/Libraries/LibPDF/Document.h
+++ b/Userland/Libraries/LibPDF/Document.h
@@ -10,7 +10,7 @@
 #include <AK/HashMap.h>
 #include <AK/RefCounted.h>
 #include <LibGfx/Color.h>
-#include <LibPDF/Object.h>
+#include <LibPDF/ObjectDerivatives.h>
 #include <LibPDF/Parser.h>
 
 namespace PDF {
diff --git a/Userland/Libraries/LibPDF/Object.h b/Userland/Libraries/LibPDF/Object.h
index d7673e8ca5..f3d0fea884 100644
--- a/Userland/Libraries/LibPDF/Object.h
+++ b/Userland/Libraries/LibPDF/Object.h
@@ -9,7 +9,6 @@
 #include <AK/Debug.h>
 #include <AK/FlyString.h>
 #include <AK/Format.h>
-#include <AK/HashMap.h>
 #include <AK/RefCounted.h>
 #include <AK/SourceLocation.h>
 #include <LibPDF/Forward.h>
@@ -36,199 +35,6 @@ private:
     u32 m_generation_index { 0 };
 };
 
-class StringObject final : public Object {
-public:
-    StringObject(String string, bool is_binary)
-        : m_string(move(string))
-        , m_is_binary(is_binary)
-    {
-    }
-
-    ~StringObject() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE String const& string() const { return m_string; }
-    [[nodiscard]] ALWAYS_INLINE bool is_binary() const { return m_is_binary; }
-
-    ALWAYS_INLINE bool is_string() const override { return true; }
-    ALWAYS_INLINE const char* type_name() const override { return "string"; }
-    String to_string(int indent) const override;
-
-private:
-    String m_string;
-    bool m_is_binary;
-};
-
-class NameObject final : public Object {
-public:
-    explicit NameObject(FlyString name)
-        : m_name(move(name))
-    {
-    }
-
-    ~NameObject() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE FlyString const& name() const { return m_name; }
-
-    ALWAYS_INLINE bool is_name() const override { return true; }
-    ALWAYS_INLINE const char* type_name() const override { return "name"; }
-    String to_string(int indent) const override;
-
-private:
-    FlyString m_name;
-};
-
-class ArrayObject final : public Object {
-public:
-    explicit ArrayObject(Vector<Value> elements)
-        : m_elements(move(elements))
-    {
-    }
-
-    ~ArrayObject() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE size_t size() const { return m_elements.size(); }
-    [[nodiscard]] ALWAYS_INLINE Vector<Value> elements() const { return m_elements; }
-
-    ALWAYS_INLINE auto begin() const { return m_elements.begin(); }
-    ALWAYS_INLINE auto end() const { return m_elements.end(); }
-
-    ALWAYS_INLINE Value const& operator[](size_t index) const { return at(index); }
-    ALWAYS_INLINE Value const& at(size_t index) const { return m_elements[index]; }
-
-    NonnullRefPtr<Object> get_object_at(Document*, size_t index) const;
-
-#define DEFINE_INDEXER(class_name, snake_name) \
-    NonnullRefPtr<class_name> get_##snake_name##_at(Document*, size_t index) const;
-    ENUMERATE_OBJECT_TYPES(DEFINE_INDEXER)
-#undef DEFINE_INDEXER
-
-    ALWAYS_INLINE bool is_array() const override
-    {
-        return true;
-    }
-    ALWAYS_INLINE const char* type_name() const override { return "array"; }
-    String to_string(int indent) const override;
-
-private:
-    Vector<Value> m_elements;
-};
-
-class DictObject final : public Object {
-public:
-    explicit DictObject(HashMap<FlyString, Value> map)
-        : m_map(move(map))
-    {
-    }
-
-    ~DictObject() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE HashMap<FlyString, Value> const& map() const { return m_map; }
-
-    template<typename... Args>
-    bool contains(Args&&... keys) const { return (m_map.contains(keys) && ...); }
-
-    ALWAYS_INLINE Optional<Value> get(FlyString const& key) const { return m_map.get(key); }
-
-    Value get_value(FlyString const& key) const
-    {
-        auto value = get(key);
-        VERIFY(value.has_value());
-        return value.value();
-    }
-
-    NonnullRefPtr<Object> get_object(Document*, FlyString const& key) const;
-
-#define DEFINE_GETTER(class_name, snake_name) \
-    NonnullRefPtr<class_name> get_##snake_name(Document*, FlyString const& key) const;
-    ENUMERATE_OBJECT_TYPES(DEFINE_GETTER)
-#undef DEFINE_GETTER
-
-    ALWAYS_INLINE bool is_dict() const override
-    {
-        return true;
-    }
-    ALWAYS_INLINE const char* type_name() const override { return "dict"; }
-    String to_string(int indent) const override;
-
-private:
-    HashMap<FlyString, Value> m_map;
-};
-
-class StreamObject : public Object {
-public:
-    explicit StreamObject(NonnullRefPtr<DictObject> const& dict)
-        : m_dict(dict)
-    {
-    }
-
-    virtual ~StreamObject() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE NonnullRefPtr<DictObject> dict() const { return m_dict; }
-    [[nodiscard]] virtual ReadonlyBytes bytes() const = 0;
-
-    ALWAYS_INLINE bool is_stream() const override { return true; }
-    ALWAYS_INLINE const char* type_name() const override { return "stream"; }
-    String to_string(int indent) const override;
-
-private:
-    NonnullRefPtr<DictObject> m_dict;
-};
-
-class PlainTextStreamObject final : public StreamObject {
-public:
-    PlainTextStreamObject(NonnullRefPtr<DictObject> const& dict, ReadonlyBytes const& bytes)
-        : StreamObject(dict)
-        , m_bytes(bytes)
-    {
-    }
-
-    virtual ~PlainTextStreamObject() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE virtual ReadonlyBytes bytes() const override { return m_bytes; }
-
-private:
-    ReadonlyBytes m_bytes;
-};
-
-class EncodedStreamObject final : public StreamObject {
-public:
-    EncodedStreamObject(NonnullRefPtr<DictObject> const& dict, ByteBuffer&& buffer)
-        : StreamObject(dict)
-        , m_buffer(buffer)
-    {
-    }
-
-    virtual ~EncodedStreamObject() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE virtual ReadonlyBytes bytes() const override { return m_buffer.bytes(); }
-
-private:
-    ByteBuffer m_buffer;
-};
-
-class IndirectValue final : public Object {
-public:
-    IndirectValue(u32 index, u32 generation_index, Value const& value)
-        : m_index(index)
-        , m_value(value)
-    {
-        set_generation_index(generation_index);
-    }
-
-    ~IndirectValue() override = default;
-
-    [[nodiscard]] ALWAYS_INLINE u32 index() const { return m_index; }
-    [[nodiscard]] ALWAYS_INLINE Value const& value() const { return m_value; }
-
-    ALWAYS_INLINE bool is_indirect_value() const override { return true; }
-    ALWAYS_INLINE const char* type_name() const override { return "indirect_object"; }
-    String to_string(int indent) const override;
-
-private:
-    u32 m_index;
-    Value m_value;
-};
-
 template<IsObject To, IsObject From>
 [[nodiscard]] ALWAYS_INLINE static NonnullRefPtr<To> object_cast(NonnullRefPtr<From> obj
 #ifdef PDF_DEBUG
diff --git a/Userland/Libraries/LibPDF/Object.cpp b/Userland/Libraries/LibPDF/ObjectDerivatives.cpp
index c94f868a27..28e66fce08 100644
--- a/Userland/Libraries/LibPDF/Object.cpp
+++ b/Userland/Libraries/LibPDF/ObjectDerivatives.cpp
@@ -6,7 +6,7 @@
 
 #include <AK/Hex.h>
 #include <LibPDF/Document.h>
-#include <LibPDF/Object.h>
+#include <LibPDF/ObjectDerivatives.h>
 
 namespace PDF {
 
diff --git a/Userland/Libraries/LibPDF/ObjectDerivatives.h b/Userland/Libraries/LibPDF/ObjectDerivatives.h
new file mode 100644
index 0000000000..9c23023361
--- /dev/null
+++ b/Userland/Libraries/LibPDF/ObjectDerivatives.h
@@ -0,0 +1,213 @@
+/*
+ * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
+ * Copyright (c) 2021, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/FlyString.h>
+#include <AK/HashMap.h>
+#include <AK/RefCounted.h>
+#include <AK/SourceLocation.h>
+#include <LibPDF/Forward.h>
+#include <LibPDF/Object.h>
+#include <LibPDF/Value.h>
+
+namespace PDF {
+
+class StringObject final : public Object {
+public:
+    StringObject(String string, bool is_binary)
+        : m_string(move(string))
+        , m_is_binary(is_binary)
+    {
+    }
+
+    ~StringObject() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE String const& string() const { return m_string; }
+    [[nodiscard]] ALWAYS_INLINE bool is_binary() const { return m_is_binary; }
+
+    ALWAYS_INLINE bool is_string() const override { return true; }
+    ALWAYS_INLINE const char* type_name() const override { return "string"; }
+    String to_string(int indent) const override;
+
+private:
+    String m_string;
+    bool m_is_binary;
+};
+
+class NameObject final : public Object {
+public:
+    explicit NameObject(FlyString name)
+        : m_name(move(name))
+    {
+    }
+
+    ~NameObject() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE FlyString const& name() const { return m_name; }
+
+    ALWAYS_INLINE bool is_name() const override { return true; }
+    ALWAYS_INLINE const char* type_name() const override { return "name"; }
+    String to_string(int indent) const override;
+
+private:
+    FlyString m_name;
+};
+
+class ArrayObject final : public Object {
+public:
+    explicit ArrayObject(Vector<Value> elements)
+        : m_elements(move(elements))
+    {
+    }
+
+    ~ArrayObject() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE size_t size() const { return m_elements.size(); }
+    [[nodiscard]] ALWAYS_INLINE Vector<Value> elements() const { return m_elements; }
+
+    ALWAYS_INLINE auto begin() const { return m_elements.begin(); }
+    ALWAYS_INLINE auto end() const { return m_elements.end(); }
+
+    ALWAYS_INLINE Value const& operator[](size_t index) const { return at(index); }
+    ALWAYS_INLINE Value const& at(size_t index) const { return m_elements[index]; }
+
+    NonnullRefPtr<Object> get_object_at(Document*, size_t index) const;
+
+#define DEFINE_INDEXER(class_name, snake_name) \
+    NonnullRefPtr<class_name> get_##snake_name##_at(Document*, size_t index) const;
+    ENUMERATE_OBJECT_TYPES(DEFINE_INDEXER)
+#undef DEFINE_INDEXER
+
+    ALWAYS_INLINE bool is_array() const override
+    {
+        return true;
+    }
+    ALWAYS_INLINE const char* type_name() const override { return "array"; }
+    String to_string(int indent) const override;
+
+private:
+    Vector<Value> m_elements;
+};
+
+class DictObject final : public Object {
+public:
+    explicit DictObject(HashMap<FlyString, Value> map)
+        : m_map(move(map))
+    {
+    }
+
+    ~DictObject() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE HashMap<FlyString, Value> const& map() const { return m_map; }
+
+    template<typename... Args>
+    bool contains(Args&&... keys) const { return (m_map.contains(keys) && ...); }
+
+    ALWAYS_INLINE Optional<Value> get(FlyString const& key) const { return m_map.get(key); }
+
+    Value get_value(FlyString const& key) const
+    {
+        auto value = get(key);
+        VERIFY(value.has_value());
+        return value.value();
+    }
+
+    NonnullRefPtr<Object> get_object(Document*, FlyString const& key) const;
+
+#define DEFINE_GETTER(class_name, snake_name) \
+    NonnullRefPtr<class_name> get_##snake_name(Document*, FlyString const& key) const;
+    ENUMERATE_OBJECT_TYPES(DEFINE_GETTER)
+#undef DEFINE_GETTER
+
+    ALWAYS_INLINE bool is_dict() const override
+    {
+        return true;
+    }
+    ALWAYS_INLINE const char* type_name() const override { return "dict"; }
+    String to_string(int indent) const override;
+
+private:
+    HashMap<FlyString, Value> m_map;
+};
+
+class StreamObject : public Object {
+public:
+    explicit StreamObject(NonnullRefPtr<DictObject> const& dict)
+        : m_dict(dict)
+    {
+    }
+
+    virtual ~StreamObject() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE NonnullRefPtr<DictObject> dict() const { return m_dict; }
+    [[nodiscard]] virtual ReadonlyBytes bytes() const = 0;
+
+    ALWAYS_INLINE bool is_stream() const override { return true; }
+    ALWAYS_INLINE const char* type_name() const override { return "stream"; }
+    String to_string(int indent) const override;
+
+private:
+    NonnullRefPtr<DictObject> m_dict;
+};
+
+class PlainTextStreamObject final : public StreamObject {
+public:
+    PlainTextStreamObject(NonnullRefPtr<DictObject> const& dict, ReadonlyBytes const& bytes)
+        : StreamObject(dict)
+        , m_bytes(bytes)
+    {
+    }
+
+    virtual ~PlainTextStreamObject() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE virtual ReadonlyBytes bytes() const override { return m_bytes; }
+
+private:
+    ReadonlyBytes m_bytes;
+};
+
+class EncodedStreamObject final : public StreamObject {
+public:
+    EncodedStreamObject(NonnullRefPtr<DictObject> const& dict, ByteBuffer&& buffer)
+        : StreamObject(dict)
+        , m_buffer(buffer)
+    {
+    }
+
+    virtual ~EncodedStreamObject() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE virtual ReadonlyBytes bytes() const override { return m_buffer.bytes(); }
+
+private:
+    ByteBuffer m_buffer;
+};
+
+class IndirectValue final : public Object {
+public:
+    IndirectValue(u32 index, u32 generation_index, Value const& value)
+        : m_index(index)
+        , m_value(value)
+    {
+        set_generation_index(generation_index);
+    }
+
+    ~IndirectValue() override = default;
+
+    [[nodiscard]] ALWAYS_INLINE u32 index() const { return m_index; }
+    [[nodiscard]] ALWAYS_INLINE Value const& value() const { return m_value; }
+
+    ALWAYS_INLINE bool is_indirect_value() const override { return true; }
+    ALWAYS_INLINE const char* type_name() const override { return "indirect_object"; }
+    String to_string(int indent) const override;
+
+private:
+    u32 m_index;
+    Value m_value;
+};
+
+}
diff --git a/Userland/Libraries/LibPDF/Value.h b/Userland/Libraries/LibPDF/Value.h
index a8e8cd735e..2f6e0b1b63 100644
--- a/Userland/Libraries/LibPDF/Value.h
+++ b/Userland/Libraries/LibPDF/Value.h
@@ -10,11 +10,10 @@
 #include <AK/RefPtr.h>
 #include <AK/String.h>
 #include <LibPDF/Forward.h>
+#include <LibPDF/Object.h>
 
 namespace PDF {
 
-class Object;
-
 class Value {
 public:
     // We store refs as u32, with 18 bits for the index and 14 bits for the