WIP

Author: Utkarsh-khambra

src/contour/Config.cpp

@@ -1924,6 +1924,7 @@ void loadConfigFromFile(Config& _config, FileSystem::path const& _fileName)
     }
 
     tryLoadValue(usedKeys, doc, "reflow_on_resize", _config.reflowOnResize);
+    tryLoadValue(usedKeys, doc, "expand_tabs", _config.expandTabs);
 
     if (auto profiles = doc["profiles"]; profiles)
     {

src/contour/Config.h

@@ -250,6 +250,7 @@ struct Config
     size_t ptyBufferObjectSize = 1024lu * 1024lu;
 
     bool reflowOnResize = true;
+    bool expandTabs = false;
 
     std::unordered_map<std::string, terminal::ColorPalette> colorschemes;
     std::unordered_map<std::string, TerminalProfile> profiles;

src/contour/TerminalSession.cpp

@@ -128,6 +128,7 @@ namespace
         settings.primaryScreen.allowReflowOnResize = config.reflowOnResize;
         settings.highlightDoubleClickedWord = profile.highlightDoubleClickedWord;
         settings.highlightTimeout = profile.highlightTimeout;
+        settings.expandTabs = config.expandTabs;
 
         return settings;
     }

src/vtbackend/CellFlags.h

@@ -44,6 +44,7 @@ enum class CellFlags : uint32_t
     Overline = (1 << 14),
     RapidBlinking = (1 << 15),
     CharacterProtected = (1 << 16), // Character is protected by selective erase operations.
+    Tab = (1 << 17),                // Cell is part of tab character.
 };
 
 constexpr CellFlags& operator|=(CellFlags& a, CellFlags b) noexcept

src/vtbackend/Grid.cpp

@@ -798,8 +798,7 @@ CellLocation Grid<Cell>::resize(PageSize newSize, CellLocation currentCursorPos,
                     flushLogicalLine();
                     if (line.isTrivialBuffer())
                     {
-                        auto& buffer = line.trivialBuffer();
-                        buffer.displayWidth = newColumnCount;
+                        line.trivialBuffer().resize(newColumnCount);
                         grownLines.emplace_back(line);
                     }
                     else

src/vtbackend/Line.cpp

@@ -34,7 +34,7 @@ typename Line<Cell>::InflatedBuffer Line<Cell>::reflow(ColumnCount newColumnCoun
     {
         switch (crispy::strongCompare(newColumnCount, ColumnCount::cast_from(trivialBuffer().text.size())))
         {
-            case Comparison::Greater: trivialBuffer().displayWidth = newColumnCount; return {};
+            case Comparison::Greater: trivialBuffer().resize(newColumnCount); return {};
             case Comparison::Equal: return {};
             case Comparison::Less:;
         }
@@ -99,8 +99,7 @@ inline void Line<Cell>::resize(ColumnCount count)
     {
         if (isTrivialBuffer())
         {
-            TrivialBuffer& buffer = trivialBuffer();
-            buffer.displayWidth = count;
+            trivialBuffer().resize(count);
             return;
         }
     }
@@ -168,7 +167,7 @@ InflatedLineBuffer<Cell> inflate(TrivialLineBuffer const& input)
     auto lastChar = char32_t { 0 };
     auto utf8DecoderState = unicode::utf8_decoder_state {};
     auto gapPending = 0;
-
+    size_t cellNr = 0;
     for (char const ch: input.text.view())
     {
         unicode::ConvertResult const r = unicode::from_utf8(utf8DecoderState, static_cast<uint8_t>(ch));
@@ -189,6 +188,7 @@ InflatedLineBuffer<Cell> inflate(TrivialLineBuffer const& input)
             columns.emplace_back(Cell {});
             columns.back().setHyperlink(input.hyperlink);
             columns.back().write(input.textAttributes, nextChar, static_cast<uint8_t>(charWidth));
+            columns.back().setTab(input.tabstops[cellNr]);
             gapPending = charWidth - 1;
         }
         else
@@ -207,6 +207,7 @@ InflatedLineBuffer<Cell> inflate(TrivialLineBuffer const& input)
             }
         }
         lastChar = nextChar;
+        ++cellNr;
     }
 
     while (gapPending > 0)
@@ -218,10 +219,31 @@ InflatedLineBuffer<Cell> inflate(TrivialLineBuffer const& input)
     assert(columns.size() == unbox<size_t>(input.usedColumns));
 
     while (columns.size() < unbox<size_t>(input.displayWidth))
+    {
         columns.emplace_back(Cell { input.fillAttributes });
+        columns.back().setTab(input.tabstops[cellNr]);
+        ++cellNr;
+    }
 
     return columns;
 }
+
+template <typename Cell>
+void Line<Cell>::setTab(ColumnOffset start, ColumnCount n, bool tab)
+{
+    if (isInflatedBuffer())
+    {
+        for (; n > ColumnCount(0); --n)
+            useCellAt(start++).setTab(tab);
+    }
+    else
+    {
+        auto& buffer = trivialBuffer();
+        for (; n > ColumnCount(0); --n)
+            buffer.tabstops[(start++).as<size_t>()] = true;
+        // assert(false);
+    }
+}
 } // end namespace terminal
 
 #include <vtbackend/cell/CompactCell.h>

src/vtbackend/Line.h

@@ -63,14 +63,20 @@ struct TrivialLineBuffer
 
     ColumnCount usedColumns {};
     crispy::BufferFragment<char> text {};
-
+    std::vector<bool> tabstops = std::vector<bool>(displayWidth.value, false);
     void reset(GraphicsAttributes attributes) noexcept
     {
         textAttributes = attributes;
         fillAttributes = attributes;
         hyperlink = {};
         usedColumns = {};
         text.reset();
+        tabstops.clear();
+    }
+    void resize(ColumnCount count)
+    {
+        displayWidth = count;
+        tabstops.resize(count.as<size_t>());
     }
 };
 
@@ -233,6 +239,15 @@ class Line
         return inflatedBuffer().at(unbox<size_t>(column)).empty();
     }
 
+    [[nodiscard]] bool hasTabstop(ColumnOffset column) const noexcept
+    {
+        Require(ColumnOffset(0) <= column);
+        Require(column <= ColumnOffset::cast_from(size()));
+        if (isInflatedBuffer())
+            return cells()[column.as<size_t>()].isTab();
+        return trivialBuffer().tabstops[column.as<size_t>()];
+    }
+
     [[nodiscard]] uint8_t cellWidthAt(ColumnOffset column) const noexcept
     {
 #if 0 // TODO: This optimization - but only when we return actual widths and not always 1.
@@ -257,6 +272,8 @@ class Line
     [[nodiscard]] bool wrappable() const noexcept { return isFlagEnabled(LineFlags::Wrappable); }
     void setWrappable(bool enable) { setFlag(LineFlags::Wrappable, enable); }
 
+    void setTab(ColumnOffset start, ColumnCount n, bool tab);
+
     [[nodiscard]] LineFlags wrappableFlag() const noexcept
     {
         return wrappable() ? LineFlags::Wrappable : LineFlags::None;

src/vtbackend/Screen.cpp

@@ -86,8 +86,6 @@ using std::vector;
 namespace terminal
 {
 
-auto constexpr inline TabWidth = ColumnCount(8);
-
 auto const inline VTCaptureBufferLog = logstore::Category("vt.ext.capturebuffer",
                                                           "Capture Buffer debug logging.",
                                                           logstore::Category::State::Disabled,
@@ -1464,9 +1462,12 @@ void Screen<Cell>::moveCursorToNextTab()
             ++i;
 
         auto const currentCursorColumn = logicalCursorPosition().column;
-
         if (i < _state.tabs.size())
-            moveCursorForward(boxed_cast<ColumnCount>(_state.tabs[i] - currentCursorColumn));
+        {
+            auto const cursorMoveAmount = boxed_cast<ColumnCount>(_state.tabs[i] - currentCursorColumn);
+            currentLine().setTab(currentCursorColumn, cursorMoveAmount, true);
+            moveCursorForward(cursorMoveAmount);
+        }
         else if (realCursorPosition().column < margin().horizontal.to)
             moveCursorForward(boxed_cast<ColumnCount>(margin().horizontal.to - currentCursorColumn));
         else
@@ -1480,6 +1481,7 @@ void Screen<Cell>::moveCursorToNextTab()
             auto const n =
                 min((TabWidth - boxed_cast<ColumnCount>(_cursor.position.column) % TabWidth),
                     _settings.pageSize.columns - boxed_cast<ColumnCount>(logicalCursorPosition().column));
+            currentLine().setTab(logicalCursorPosition().column, n, true);
             moveCursorForward(n);
         }
         else

src/vtbackend/Screen.h

@@ -73,6 +73,7 @@ class ScreenBase: public SequenceHandler
     [[nodiscard]] virtual Margin& margin() noexcept = 0;
     [[nodiscard]] virtual bool contains(CellLocation coord) const noexcept = 0;
     [[nodiscard]] virtual bool isCellEmpty(CellLocation position) const noexcept = 0;
+    [[nodiscard]] virtual bool hasTabstop(CellLocation position) const noexcept = 0;
     [[nodiscard]] virtual bool compareCellTextAt(CellLocation position, char codepoint) const noexcept = 0;
     [[nodiscard]] virtual std::string cellTextAt(CellLocation position) const noexcept = 0;
     [[nodiscard]] virtual std::string lineTextAt(LineOffset line) const noexcept = 0;
@@ -509,6 +510,10 @@ class Screen final: public ScreenBase, public capabilities::StaticDatabase
         return _grid.lineAt(position.line).cellEmptyAt(position.column);
     }
 
+    [[nodiscard]] bool hasTabstop(CellLocation position) const noexcept override
+    {
+        return _grid.lineAt(position.line).hasTabstop(position.column);
+    }
     [[nodiscard]] bool compareCellTextAt(CellLocation position, char codepoint) const noexcept override
     {
         auto const& cell = _grid.lineAt(position.line).inflatedBuffer().at(position.column.as<size_t>());

src/vtbackend/Settings.h

@@ -62,6 +62,7 @@ struct Settings
     std::chrono::milliseconds highlightTimeout = std::chrono::milliseconds { 150 };
     bool highlightDoubleClickedWord = true;
     // TODO: ^^^ make also use of it. probably rename to how VScode has named it.
+    bool expandTabs = false;
 
     struct PrimaryScreen
     {