Filters: add an expand_tabulation filter

src/display_buffer.hh

@@ -40,6 +40,7 @@ struct DisplayAtom
     Color          fg_color;
     Color          bg_color;
     Attribute      attribute;
+    BufferString   replacement_text;
 
     DisplayAtom(BufferIterator begin, BufferIterator end,
                 Color fg_color = Color::Default,

src/filters.cc

@@ -52,4 +52,28 @@ void colorize_cplusplus(DisplayBuffer& display_buffer)
     colorize_regex(display_buffer, types_keywords, Color::Green);
 }
 
+void expand_tabulations(DisplayBuffer& display_buffer)
+{
+    const int tabstop = 8;
+    for (auto atom_it = display_buffer.begin();
+         atom_it != display_buffer.end(); ++atom_it)
+    {
+        for (BufferIterator it = atom_it->begin; it != atom_it->end; ++it)
+        {
+            if (*it == '\t')
+            {
+                if (it != atom_it->begin)
+                    atom_it = display_buffer.split(atom_it, it) + 1;
+
+                if (it+1 != atom_it->end)
+                    atom_it = display_buffer.split(atom_it, it+1);
+
+                BufferCoord pos = it.buffer().line_and_column_at(it);
+                int count = tabstop - (pos.column % tabstop);
+                atom_it->replacement_text = std::string(count, ' ');
+            }
+        }
+    }
+}
+
 }

src/filters.hh

@@ -11,6 +11,8 @@ void colorize_regex(DisplayBuffer& display_buffer,
                     const boost::regex& ex, Color color);
 
 void colorize_cplusplus(DisplayBuffer& display_buffer);
+void colorize_cplusplus(DisplayBuffer& display_buffer);
+void expand_tabulations(DisplayBuffer& display_buffer);
 
 }
 

src/main.cc

@@ -85,7 +85,8 @@ void draw_window(Window& window)
     WindowCoord position;
     for (const DisplayAtom& atom : window.display_buffer())
     {
-        const std::string content = window.buffer().string(atom.begin, atom.end);
+        const std::string content = atom.replacement_text.empty() ?
+            window.buffer().string(atom.begin, atom.end) : atom.replacement_text;
 
         set_attribute(A_UNDERLINE, atom.attribute & Underline);
         set_attribute(A_REVERSE, atom.attribute & Reverse);

src/window.cc

@@ -112,6 +112,7 @@ Window::Window(Buffer& buffer)
 {
     m_selections.push_back(Selection(buffer.begin(), buffer.begin()));
     m_filters.push_back(colorize_cplusplus);
+    m_filters.push_back(expand_tabulations);
     m_filters.push_back(HighlightSelections(*this));
 }