Add support for the DECST8C escape sequence (#16534)

## Summary of the Pull Request

This PR adds support for the `DECST8C` escape sequence, which resets the
tab stops to every 8 columns.

## Detailed Description of the Pull Request / Additional comments

This is actually a private parameter variant of the ANSI `CTC` sequence
(Cursor Tabulation Control), which accepts a selective parameter which
specifies the type of tab operation to be performed. But the DEC variant
only defines a single parameter value (5), which resets all tab stops.
It also considers an omitted parameter to be the equivalent of 5, so we
support that too.

## Validation Steps Performed

I've extended the existing tab stop tests in `ScreenBufferTests` with
some basic coverage of this sequence.

I've also manually verified that the `DECTABSR` script in #14984 now
passes the `DECST8C` portion of the test.

## PR Checklist
- [x] Closes #16533
- [x] Tests added/passed

.github/actions/spelling/expect/expect.txt

@@ -443,6 +443,7 @@ DECSLPP
 DECSLRM
 DECSMKR
 DECSR
+DECST
 DECSTBM
 DECSTGLT
 DECSTR

src/host/ut_host/ScreenBufferTests.cpp

@@ -604,6 +604,16 @@ void ScreenBufferTests::TestResetClearTabStops()
     stateMachine.ProcessString(resetToInitialState);
     expectedStops = { 8, 16, 24, 32, 40, 48, 56, 64, 72 };
     VERIFY_ARE_EQUAL(expectedStops, _GetTabStops(screenInfo));
+
+    Log::Comment(L"DECST8C with 5 parameter resets tabs to defaults.");
+    stateMachine.ProcessString(clearTabStops);
+    stateMachine.ProcessString(L"\033[?5W");
+    VERIFY_ARE_EQUAL(expectedStops, _GetTabStops(screenInfo));
+
+    Log::Comment(L"DECST8C with omitted parameter resets tabs to defaults.");
+    stateMachine.ProcessString(clearTabStops);
+    stateMachine.ProcessString(L"\033[?W");
+    VERIFY_ARE_EQUAL(expectedStops, _GetTabStops(screenInfo));
 }
 
 void ScreenBufferTests::TestAddTabStop()

src/terminal/adapter/DispatchTypes.hpp

@@ -565,6 +565,11 @@ namespace Microsoft::Console::VirtualTerminal::DispatchTypes
         ClearAllColumns = 3
     };
 
+    enum TabSetType : VTInt
+    {
+        SetEvery8Columns = 5
+    };
+
     enum WindowManipulationType : VTInt
     {
         Invalid = 0,

src/terminal/adapter/ITermDispatch.hpp

@@ -68,6 +68,7 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
     virtual bool ForwardTab(const VTInt numTabs) = 0; // CHT, HT
     virtual bool BackwardsTab(const VTInt numTabs) = 0; // CBT
     virtual bool TabClear(const DispatchTypes::TabClearType clearType) = 0; // TBC
+    virtual bool TabSet(const VTParameter setType) = 0; // DECST8C
     virtual bool SetColorTableEntry(const size_t tableIndex, const DWORD color) = 0; // OSCColorTable
     virtual bool SetDefaultForeground(const DWORD color) = 0; // OSCDefaultForeground
     virtual bool SetDefaultBackground(const DWORD color) = 0; // OSCDefaultBackground

src/terminal/adapter/adaptDispatch.cpp

@@ -2822,16 +2822,23 @@ void AdaptDispatch::_ClearAllTabStops() noexcept
 }
 
 // Routine Description:
-// - Clears all tab stops and sets the _initDefaultTabStops flag to indicate
+// - DECST8C - If the parameter is SetEvery8Columns or is omitted, then this
+//    clears all tab stops and sets the _initDefaultTabStops flag to indicate
 //    that the default positions should be reinitialized when needed.
 // Arguments:
-// - <none>
+// - setType - only SetEvery8Columns is supported
 // Return value:
-// - <none>
-void AdaptDispatch::_ResetTabStops() noexcept
+// - True if handled successfully. False otherwise.
+bool AdaptDispatch::TabSet(const VTParameter setType) noexcept
 {
-    _tabStopColumns.clear();
-    _initDefaultTabStops = true;
+    constexpr auto SetEvery8Columns = DispatchTypes::TabSetType::SetEvery8Columns;
+    if (setType.value_or(SetEvery8Columns) == SetEvery8Columns)
+    {
+        _tabStopColumns.clear();
+        _initDefaultTabStops = true;
+        return true;
+    }
+    return false;
 }
 
 // Routine Description:
@@ -3105,7 +3112,7 @@ bool AdaptDispatch::HardReset()
     _api.GetTextBuffer().GetCursor().SetBlinkingAllowed(true);
 
     // Delete all current tab stops and reapply
-    _ResetTabStops();
+    TabSet(DispatchTypes::TabSetType::SetEvery8Columns);
 
     // Clear the soft font in the renderer and delete the font buffer.
     _renderer.UpdateSoftFont({}, {}, false);

src/terminal/adapter/adaptDispatch.hpp

@@ -105,6 +105,7 @@ namespace Microsoft::Console::VirtualTerminal
         bool ForwardTab(const VTInt numTabs) override; // CHT, HT
         bool BackwardsTab(const VTInt numTabs) override; // CBT
         bool TabClear(const DispatchTypes::TabClearType clearType) override; // TBC
+        bool TabSet(const VTParameter setType) noexcept override; // DECST8C
         bool DesignateCodingSystem(const VTID codingSystem) override; // DOCS
         bool Designate94Charset(const VTInt gsetNumber, const VTID charset) override; // SCS
         bool Designate96Charset(const VTInt gsetNumber, const VTID charset) override; // SCS
@@ -251,7 +252,6 @@ namespace Microsoft::Console::VirtualTerminal
 
         void _ClearSingleTabStop();
         void _ClearAllTabStops() noexcept;
-        void _ResetTabStops() noexcept;
         void _InitTabStopsForWidth(const VTInt width);
 
         StringHandler _RestoreColorTable();
@@ -271,7 +271,7 @@ namespace Microsoft::Console::VirtualTerminal
         StringHandler _CreateDrcsPassthroughHandler(const DispatchTypes::DrcsCharsetSize charsetSize);
         StringHandler _CreatePassthroughHandler();
 
-        std::vector<bool> _tabStopColumns;
+        std::vector<uint8_t> _tabStopColumns;
         bool _initDefaultTabStops = true;
 
         ITerminalApi& _api;

src/terminal/adapter/termDispatch.hpp

@@ -61,6 +61,7 @@ class Microsoft::Console::VirtualTerminal::TermDispatch : public Microsoft::Cons
     bool ForwardTab(const VTInt /*numTabs*/) override { return false; } // CHT, HT
     bool BackwardsTab(const VTInt /*numTabs*/) override { return false; } // CBT
     bool TabClear(const DispatchTypes::TabClearType /*clearType*/) override { return false; } // TBC
+    bool TabSet(const VTParameter /*setType*/) override { return false; } // DECST8C
     bool SetColorTableEntry(const size_t /*tableIndex*/, const DWORD /*color*/) override { return false; } // OSCColorTable
     bool SetDefaultForeground(const DWORD /*color*/) override { return false; } // OSCDefaultForeground
     bool SetDefaultBackground(const DWORD /*color*/) override { return false; } // OSCDefaultBackground

src/terminal/parser/OutputStateMachineEngine.cpp

@@ -566,6 +566,11 @@ bool OutputStateMachineEngine::ActionCsiDispatch(const VTID id, const VTParamete
             return _dispatch->TabClear(clearType);
         });
         break;
+    case CsiActionCodes::DECST8C_SetTabEvery8Columns:
+        success = parameters.for_each([&](const auto setType) {
+            return _dispatch->TabSet(setType);
+        });
+        break;
     case CsiActionCodes::ECH_EraseCharacters:
         success = _dispatch->EraseCharacters(parameters.at(0));
         break;

src/terminal/parser/OutputStateMachineEngine.hpp

@@ -121,6 +121,7 @@ namespace Microsoft::Console::VirtualTerminal
             DCH_DeleteCharacter = VTID("P"),
             SU_ScrollUp = VTID("S"),
             SD_ScrollDown = VTID("T"),
+            DECST8C_SetTabEvery8Columns = VTID("?W"),
             ECH_EraseCharacters = VTID("X"),
             CBT_CursorBackTab = VTID("Z"),
             HPA_HorizontalPositionAbsolute = VTID("`"),