WIP

Author: Utkarsh-khambra

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/Line.cpp

@@ -101,6 +101,7 @@ inline void Line<Cell>::resize(ColumnCount count)
         {
             TrivialBuffer& buffer = trivialBuffer();
             buffer.displayWidth = count;
+            buffer.tabstops.resize(count.as<size_t>());
             return;
         }
     }
@@ -168,7 +169,7 @@ 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 +190,7 @@ 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 +209,7 @@ InflatedLineBuffer<Cell> inflate(TrivialLineBuffer const& input)
             }
         }
         lastChar = nextChar;
+        ++cellNr;
     }
 
     while (gapPending > 0)
@@ -218,10 +221,31 @@ 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 +63,15 @@ 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();
     }
 };
 
@@ -233,6 +234,15 @@ 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 +267,8 @@ 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;
@@ -315,7 +327,18 @@ class Line
         return !std::holds_alternative<TrivialBuffer>(storage_);
     }
 
-    void setBuffer(Storage buffer) noexcept { storage_ = std::move(buffer); }
+    void setBuffer(Storage buffer) noexcept
+    {
+        if (isTrivialBuffer())
+            std::get<TrivialBuffer>(buffer).tabstops = std::move(trivialBuffer().tabstops);
+        else
+        {
+            size_t cellNr = 0;
+            for (auto const& cell: cells())
+                std::get<TrivialBuffer>(buffer).tabstops[cellNr++] = cell.isTab();
+        }
+        storage_ = std::move(buffer);
+    }
 
     // Tests if the given text can be matched in this line at the exact given start column.
     [[nodiscard]] bool matchTextAt(std::u32string_view text, ColumnOffset startColumn) const noexcept

src/vtbackend/Screen.cpp

@@ -86,7 +86,7 @@ using std::vector;
 namespace terminal
 {
 
-auto constexpr inline TabWidth = ColumnCount(8);
+extern auto const TabWidth = ColumnCount(8);
 
 auto const inline VTCaptureBufferLog = logstore::Category("vt.ext.capturebuffer",
                                                           "Capture Buffer debug logging.",
@@ -1464,9 +1464,12 @@ void Screen<Cell>::moveCursorToNextTab()
             ++i;
 
         auto const currentCursorColumn = logicalCursorPosition().column;
-
+        auto const cursorMoveAmount = boxed_cast<ColumnCount>(_state.tabs[i] - currentCursorColumn);
         if (i < _state.tabs.size())
-            moveCursorForward(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 +1483,7 @@ 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/Terminal.cpp

@@ -38,6 +38,8 @@
 #include <utility>
 #include <variant>
 
+#include "fmt/core.h"
+
 using crispy::Size;
 
 using namespace std;
@@ -48,7 +50,8 @@ using std::move;
 
 namespace terminal
 {
-
+// inline constexpr auto TabWidth = ColumnCount(8);
+extern const ColumnCount TabWidth;
 namespace // {{{ helpers
 {
     constexpr size_t MaxColorPaletteSaveStackSize = 10;
@@ -786,7 +789,28 @@ bool Terminal::sendMouseMoveEvent(Modifier modifier,
     {
         if (currentScreen().isCellEmpty(relativePos) && !currentScreen().compareCellTextAt(relativePos, 0x20))
         {
-            relativePos.column = ColumnOffset { 0 } + *(_settings.pageSize.columns - 1);
+            if (currentScreen().hasTabstop(relativePos))
+            {
+                if (!_state.tabs.empty())
+                {
+                    auto tab = std::upper_bound(_state.tabs.begin(), _state.tabs.end(), relativePos.column);
+                    relativePos.column = (tab == _state.tabs.end())
+                                             ? ColumnOffset::cast_from(_settings.pageSize.columns - 1)
+                                             : *tab;
+                }
+                else
+                {
+                    auto const n =
+                        min((TabWidth - boxed_cast<ColumnCount>(relativePos.column) % TabWidth),
+                            _settings.pageSize.columns - boxed_cast<ColumnCount>(relativePos.column));
+                    relativePos.column += n;
+                }
+            }
+            else
+            {
+                fmt::print("Why here?\n");
+                relativePos.column = ColumnOffset::cast_from(_settings.pageSize.columns - 1);
+            }
         }
         changed = true;
         selector()->extend(relativePos);
@@ -1139,10 +1163,11 @@ namespace
                 text += '\n';
                 currentLine.clear();
             }
-            if (cell.empty())
+            if (cell.isTab())
+            {
                 currentLine += ' ';
-            else
-                currentLine += cell.toUtf8();
+            }
+            currentLine += cell.toUtf8();
             lastColumn = pos.column;
         }
 

src/vtbackend/cell/CellConcept.h

@@ -99,6 +99,9 @@ concept CellConcept = requires(T t, T const& u)
 
     { u.hyperlink() } -> std::same_as<HyperlinkId>;
     t.setHyperlink(HyperlinkId{});
+
+		t.setTab(bool{});
+		{ u.isTab() } noexcept -> std::same_as<bool>;
 };
 
 

src/vtbackend/cell/CompactCell.h

@@ -127,6 +127,7 @@ class CRISPY_PACKED CompactCell
     void setForegroundColor(Color color) noexcept;
     [[nodiscard]] Color backgroundColor() const noexcept;
     void setBackgroundColor(Color color) noexcept;
+    void setTab(bool tab) noexcept;
 
     [[nodiscard]] std::shared_ptr<ImageFragment> imageFragment() const noexcept;
     void setImageFragment(std::shared_ptr<RasterizedImage> rasterizedImage, CellLocation offset);
@@ -139,6 +140,7 @@ class CRISPY_PACKED CompactCell
     void setHyperlink(HyperlinkId hyperlink);
 
     [[nodiscard]] bool empty() const noexcept;
+    [[nodiscard]] bool isTab() const noexcept;
 
     void setGraphicsRendition(GraphicsRendition sgr) noexcept;
 
@@ -408,6 +410,14 @@ inline void CompactCell::setBackgroundColor(Color color) noexcept
     _backgroundColor = color;
 }
 
+inline void CompactCell::setTab(bool tab) noexcept
+{
+    if (tab)
+        extra().flags |= CellFlags::Tab;
+    else
+        extra().flags &= ~CellFlags::Tab;
+}
+
 inline Color CompactCell::underlineColor() const noexcept
 {
     if (!_extra)
@@ -460,6 +470,10 @@ inline bool CompactCell::empty() const noexcept
     return CellUtil::empty(*this);
 }
 
+inline bool CompactCell::isTab() const noexcept
+{
+    return _extra && _extra->flags & CellFlags::Tab;
+}
 inline void CompactCell::setGraphicsRendition(GraphicsRendition sgr) noexcept
 {
     CellUtil::applyGraphicsRendition(sgr, *this);

src/vtbackend/cell/SimpleCell.h

@@ -73,6 +73,7 @@ class SimpleCell
     void setForegroundColor(Color color) noexcept;
     void setBackgroundColor(Color color) noexcept;
     void setUnderlineColor(Color color) noexcept;
+    void setTab(bool tab) noexcept;
     [[nodiscard]] Color foregroundColor() const noexcept;
     [[nodiscard]] Color backgroundColor() const noexcept;
     [[nodiscard]] Color underlineColor() const noexcept;
@@ -84,6 +85,7 @@ class SimpleCell
     void setHyperlink(HyperlinkId hyperlink) noexcept;
 
     [[nodiscard]] bool empty() const noexcept { return CellUtil::empty(*this); }
+    [[nodiscard]] bool isTab() const noexcept { return _flags & CellFlags::Tab; }
 
   private:
     std::u32string _codepoints {};
@@ -123,7 +125,6 @@ inline void SimpleCell::write(GraphicsAttributes sgr, char32_t codepoint, uint8_
     _graphicsAttributes = sgr;
     _codepoints.clear();
     _codepoints.push_back(codepoint);
-
     _width = width;
 }
 
@@ -238,6 +239,14 @@ inline void SimpleCell::setUnderlineColor(Color color) noexcept
     _graphicsAttributes.underlineColor = color;
 }
 
+inline void SimpleCell::setTab(bool tab) noexcept
+{
+    if (tab)
+        _flags |= CellFlags::Tab;
+    else
+        _flags &= ~CellFlags::Tab;
+}
+
 inline Color SimpleCell::foregroundColor() const noexcept
 {
     return _graphicsAttributes.foregroundColor;