LibGUI: Give GTextDocument access to the GTextEditor during commands

It's useful for the GTextDocument to have access to the initiating
GTextEditor widget during the initial execution of a command.

Since commands are executed via calls to GUndoCommand::redo(), we do
this by wrapping the invocation of redo() in a new helper called
GTextDocumentUndoCommand::execute_from(GTextDocument::Client).

This is then used to fetch the current auto-indentation feature state
and the soft tab width, both used by text insertion.

Libraries/LibGUI/GTextDocument.cpp

@@ -27,6 +27,7 @@
 #include <AK/StringBuilder.h>
 #include <LibCore/CTimer.h>
 #include <LibGUI/GTextDocument.h>
+#include <LibGUI/GTextEditor.h>
 #include <ctype.h>
 
 GTextDocument::GTextDocument(Client* client)
@@ -427,7 +428,7 @@ InsertTextCommand::InsertTextCommand(GTextDocument& document, const String& text
 
 void InsertTextCommand::redo()
 {
-    auto new_cursor = m_document.insert_at(m_range.start(), m_text);
+    auto new_cursor = m_document.insert_at(m_range.start(), m_text, m_client);
     // NOTE: We don't know where the range ends until after doing redo().
     //       This is okay since we always do redo() after adding this to the undo stack.
     m_range.set_end(new_cursor);
@@ -464,26 +465,25 @@ void GTextDocument::update_undo_timer()
     m_undo_stack.finalize_current_combo();
 }
 
-GTextPosition GTextDocument::insert_at(const GTextPosition& position, const StringView& text)
+GTextPosition GTextDocument::insert_at(const GTextPosition& position, const StringView& text, const Client* client)
 {
     GTextPosition cursor = position;
     for (size_t i = 0; i < text.length(); ++i)
-        cursor = insert_at(cursor, text[i]);
+        cursor = insert_at(cursor, text[i], client);
     return cursor;
 }
 
-GTextPosition GTextDocument::insert_at(const GTextPosition& position, char ch)
+GTextPosition GTextDocument::insert_at(const GTextPosition& position, char ch, const Client* client)
 {
-    // FIXME: We need these from GTextEditor!
+    bool automatic_indentation_enabled = client ? client->is_automatic_indentation_enabled() : false;
-    bool m_automatic_indentation_enabled = true;
+    size_t m_soft_tab_width = client ? client->soft_tab_width() : 4;
-    size_t m_soft_tab_width = 4;
 
     bool at_head = position.column() == 0;
     bool at_tail = position.column() == line(position.line()).length();
     if (ch == '\n') {
         if (at_tail || at_head) {
             String new_line_contents;
-            if (m_automatic_indentation_enabled && at_tail) {
+            if (automatic_indentation_enabled && at_tail) {
                 size_t leading_spaces = 0;
                 auto& old_line = lines()[position.line()];
                 for (size_t i = 0; i < old_line.length(); ++i) {

Libraries/LibGUI/GTextDocument.h

@@ -40,6 +40,7 @@
 class GTextEditor;
 class GTextDocument;
 class GTextDocumentLine;
+class GTextDocumentUndoCommand;
 
 struct GTextDocumentSpan {
     GTextRange range;
@@ -50,37 +51,6 @@ struct GTextDocumentSpan {
     void* data { nullptr };
 };
 
-class GTextDocumentUndoCommand : public GCommand {
-public:
-    GTextDocumentUndoCommand(GTextDocument&);
-    virtual ~GTextDocumentUndoCommand();
-
-protected:
-    GTextDocument& m_document;
-};
-
-class InsertTextCommand : public GTextDocumentUndoCommand {
-public:
-    InsertTextCommand(GTextDocument&, const String&, const GTextPosition&);
-    virtual void undo() override;
-    virtual void redo() override;
-
-private:
-    String m_text;
-    GTextRange m_range;
-};
-
-class RemoveTextCommand : public GTextDocumentUndoCommand {
-public:
-    RemoveTextCommand(GTextDocument&, const String&, const GTextRange&);
-    virtual void undo() override;
-    virtual void redo() override;
-
-private:
-    String m_text;
-    GTextRange m_range;
-};
-
 class GTextDocument : public RefCounted<GTextDocument> {
 public:
     enum class SearchShouldWrap {
@@ -98,6 +68,9 @@ public:
         virtual void document_did_change() = 0;
         virtual void document_did_set_text() = 0;
         virtual void document_did_set_cursor(const GTextPosition&) = 0;
+
+        virtual bool is_automatic_indentation_enabled() const = 0;
+        virtual int soft_tab_width() const = 0;
     };
 
     static NonnullRefPtr<GTextDocument> create(Client* client = nullptr)
@@ -157,8 +130,8 @@ public:
     void notify_did_change();
     void set_all_cursors(const GTextPosition&);
 
-    GTextPosition insert_at(const GTextPosition&, char);
+    GTextPosition insert_at(const GTextPosition&, char, const Client* = nullptr);
-    GTextPosition insert_at(const GTextPosition&, const StringView&);
+    GTextPosition insert_at(const GTextPosition&, const StringView&, const Client* = nullptr);
     void remove(const GTextRange&);
 
 private:
@@ -201,3 +174,42 @@ private:
     // NOTE: This vector is null terminated.
     Vector<char> m_text;
 };
+
+class GTextDocumentUndoCommand : public GCommand {
+public:
+    GTextDocumentUndoCommand(GTextDocument&);
+    virtual ~GTextDocumentUndoCommand();
+
+    void execute_from(const GTextDocument::Client& client)
+    {
+        m_client = &client;
+        redo();
+        m_client = nullptr;
+    }
+
+protected:
+    GTextDocument& m_document;
+    const GTextDocument::Client* m_client { nullptr };
+};
+
+class InsertTextCommand : public GTextDocumentUndoCommand {
+public:
+    InsertTextCommand(GTextDocument&, const String&, const GTextPosition&);
+    virtual void undo() override;
+    virtual void redo() override;
+
+private:
+    String m_text;
+    GTextRange m_range;
+};
+
+class RemoveTextCommand : public GTextDocumentUndoCommand {
+public:
+    RemoveTextCommand(GTextDocument&, const String&, const GTextRange&);
+    virtual void undo() override;
+    virtual void redo() override;
+
+private:
+    String m_text;
+    GTextRange m_range;
+};

Libraries/LibGUI/GTextEditor.h

@@ -60,9 +60,11 @@ public:
     bool is_readonly() const { return m_readonly; }
     void set_readonly(bool);
 
-    bool is_automatic_indentation_enabled() const { return m_automatic_indentation_enabled; }
+    virtual bool is_automatic_indentation_enabled() const final { return m_automatic_indentation_enabled; }
     void set_automatic_indentation_enabled(bool enabled) { m_automatic_indentation_enabled = enabled; }
 
+    virtual int soft_tab_width() const final { return m_soft_tab_width; }
+
     bool is_line_wrapping_enabled() const { return m_line_wrapping_enabled; }
     void set_line_wrapping_enabled(bool);
 
@@ -202,7 +204,7 @@ private:
     inline void execute(Args&&... args)
     {
         auto command = make<T>(*m_document, forward<Args>(args)...);
-        command->redo();
+        command->execute_from(*this);
         m_document->add_to_undo_stack(move(command));
     }