Make selection an exclusive range (#18106)

Selection is generally stored as an inclusive start and end. This PR
makes the end exclusive which now allows degenerate selections, namely
in mark mode. This also modifies mouse selection to round to the nearest
cell boundary (see #5099) and improves word boundaries to be a bit more
modern and make sense for degenerate selections (similar to #15787).

Closes #5099
Closes #13447
Closes #17892

## Detailed Description of the Pull Request / Additional comments
- Buffer, Viewport, and Point
- Introduced a few new functions here to find word boundaries, delimiter
class runs, and glyph boundaries.
- 📝These new functions should be able to replace a few other functions
(i.e. `GetWordStart` --> `GetWordStart2`). That migration is going to be
a part of #4423 to reduce the risk of breaking UIA.
- Viewport: added a few functions to handle navigating the _exclusive_
bounds (namely allowing RightExclusive as a position for buffer
coordinates). This is important for selection to be able to highlight
the entire line.
- 📝`BottomInclusiveRightExclusive()` will replace `EndExclusive` in the
UIA code
- Point: `iterate_rows_exclusive` is similar to `iterate_rows`, except
it has handling for RightExclusive
- Renderer
- Use `iterate_rows_exclusive` for proper handling (this actually fixed
a lot of our issues)
- Remove some workarounds in `_drawHighlighted` (this is a boundary
where we got inclusive coords and made them exclusive, but now we don't
need that!)
- Terminal
   - fix selection marker rendering
- `_ConvertToBufferCell()`: add a param to allow for RightExclusive or
clamp it to RightInclusive (original behavior). Both are useful!
- Use new `GetWordStart2` and `GetWordEnd2` to improve word boundaries
and make them feel right now that the selection an exclusive range.
- Convert a few `IsInBounds` --> `IsInExclusiveBounds` for safety and
correctness
   - Add `TriggerSelection` to `SelectNewRegion`
- 📝 We normally called `TriggerSelection` in a different layer, but it
turns out, UIA's `Select` function wouldn't actually update the
renderer. Whoops! This fixes that.
- TermControl
- `_getTerminalPosition` now has a new param to round to the nearest
cell (see #5099)
- UIA
- `TermControlUIAProvider::GetSelectionRange` no need to convert from
inclusive range to exclusive range anymore!
- `TextBuffer::GetPlainText` now works on an exclusive range, so no need
to convert the range anymore!

## Validation Steps Performed
This fundamental change impacts a lot of scenarios:
- ✅Rendering selections
- ✅Selection markers
- ✅Copy text
- ✅Session restore
- ✅Mark mode navigation (i.e. character, word, line, buffer)
- ✅Mouse selection (i.e. click+drag, shift+click, multi-click,
alt+click)
- ✅Hyperlinks (interaction and rendering)
- ✅Accessibility (i.e. get selection, movement, text extraction,
selecting text)
- [ ] Prev/Next Command/Output (untested)
- ✅Unit tests

## Follow-ups
- Refs #4423
- Now that selection and UIA are both exclusive ranges, it should be a
lot easier to deduplicate code between selection and UIA. We should be
able to remove `EndExclusive` as well when we do that. This'll also be
an opportunity to modernize that code and use more `til` classes.

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

@@ -163,6 +163,7 @@ CBN
 cbt
 Ccc
 CCCBB
+CCCDDD
 cch
 CCHAR
 CCmd
@@ -369,6 +370,7 @@ DColor
 dcommon
 DComposition
 dde
+DDDCCC
 DDESHARE
 DDevice
 DEADCHAR

src/buffer/out/Row.cpp

@@ -80,19 +80,20 @@ constexpr OutIt copy_n_small(InIt first, Diff count, OutIt dest)
     return dest;
 }
 
-CharToColumnMapper::CharToColumnMapper(const wchar_t* chars, const uint16_t* charOffsets, ptrdiff_t lastCharOffset, til::CoordType currentColumn) noexcept :
+CharToColumnMapper::CharToColumnMapper(const wchar_t* chars, const uint16_t* charOffsets, ptrdiff_t charsLength, til::CoordType currentColumn, til::CoordType columnCount) noexcept :
     _chars{ chars },
     _charOffsets{ charOffsets },
-    _lastCharOffset{ lastCharOffset },
-    _currentColumn{ currentColumn }
+    _charsLength{ charsLength },
+    _currentColumn{ currentColumn },
+    _columnCount{ columnCount }
 {
 }
 
 // If given a position (`offset`) inside the ROW's text, this function will return the corresponding column.
 // This function in particular returns the glyph's first column.
 til::CoordType CharToColumnMapper::GetLeadingColumnAt(ptrdiff_t targetOffset) noexcept
 {
-    targetOffset = clamp(targetOffset, 0, _lastCharOffset);
+    targetOffset = clamp(targetOffset, 0, _charsLength);
 
     // This code needs to fulfill two conditions on top of the obvious (a forward/backward search):
     // A: We never want to stop on a column that is marked with CharOffsetsTrailer (= "GetLeadingColumn").
@@ -130,10 +131,14 @@ til::CoordType CharToColumnMapper::GetLeadingColumnAt(ptrdiff_t targetOffset) no
 til::CoordType CharToColumnMapper::GetTrailingColumnAt(ptrdiff_t offset) noexcept
 {
     auto col = GetLeadingColumnAt(offset);
-    // This loop is a little redundant with the forward search loop in GetLeadingColumnAt()
-    // but it's realistically not worth caring about this. This code is not a bottleneck.
-    for (; WI_IsFlagSet(_charOffsets[col + 1], CharOffsetsTrailer); ++col)
+
+    if (col < _columnCount)
     {
+        // This loop is a little redundant with the forward search loop in GetLeadingColumnAt()
+        // but it's realistically not worth caring about this. This code is not a bottleneck.
+        for (; WI_IsFlagSet(_charOffsets[col + 1], CharOffsetsTrailer); ++col)
+        {
+        }
     }
     return col;
 }
@@ -1114,6 +1119,9 @@ std::wstring_view ROW::GetText() const noexcept
     return { _chars.data(), width };
 }
 
+// Arguments:
+// - columnBegin: inclusive
+// - columnEnd: exclusive
 std::wstring_view ROW::GetText(til::CoordType columnBegin, til::CoordType columnEnd) const noexcept
 {
     const auto columns = GetReadableColumnCount();
@@ -1219,15 +1227,15 @@ T ROW::_adjustForward(T column) const noexcept
 }
 
 // Creates a CharToColumnMapper given an offset into _chars.data().
-// In other words, for a 120 column ROW with just ASCII text, the offset should be [0,120).
+// In other words, for a 120 column ROW with just ASCII text, the offset should be [0,120].
 CharToColumnMapper ROW::_createCharToColumnMapper(ptrdiff_t offset) const noexcept
 {
     const auto charsSize = _charSize();
-    const auto lastChar = gsl::narrow_cast<ptrdiff_t>(charsSize - 1);
+    const auto lastChar = gsl::narrow_cast<ptrdiff_t>(charsSize);
     // We can sort of guess what column belongs to what offset because BMP glyphs are very common and
     // UTF-16 stores them in 1 char. In other words, usually a ROW will have N chars for N columns.
     const auto guessedColumn = gsl::narrow_cast<til::CoordType>(clamp(offset, 0, _columnCount));
-    return CharToColumnMapper{ _chars.data(), _charOffsets.data(), lastChar, guessedColumn };
+    return CharToColumnMapper{ _chars.data(), _charOffsets.data(), lastChar, guessedColumn, _columnCount };
 }
 
 const std::optional<ScrollbarData>& ROW::GetScrollbarData() const noexcept

src/buffer/out/Row.hpp

@@ -71,7 +71,7 @@ struct RowCopyTextFromState
 // into a ROW's text this class can tell you what cell that pointer belongs to.
 struct CharToColumnMapper
 {
-    CharToColumnMapper(const wchar_t* chars, const uint16_t* charOffsets, ptrdiff_t lastCharOffset, til::CoordType currentColumn) noexcept;
+    CharToColumnMapper(const wchar_t* chars, const uint16_t* charOffsets, ptrdiff_t lastCharOffset, til::CoordType currentColumn, til::CoordType columnCount) noexcept;
 
     til::CoordType GetLeadingColumnAt(ptrdiff_t targetOffset) noexcept;
     til::CoordType GetTrailingColumnAt(ptrdiff_t offset) noexcept;
@@ -85,8 +85,9 @@ struct CharToColumnMapper
 
     const wchar_t* _chars;
     const uint16_t* _charOffsets;
-    ptrdiff_t _lastCharOffset;
+    ptrdiff_t _charsLength;
     til::CoordType _currentColumn;
+    til::CoordType _columnCount;
 };
 
 class ROW final

src/buffer/out/UTextAdapter.cpp

@@ -411,16 +411,13 @@ Microsoft::Console::ICU::unique_uregex Microsoft::Console::ICU::CreateRegex(cons
     return unique_uregex{ re };
 }
 
-// Returns an inclusive point range given a text start and end position.
+// Returns a half-open [beg,end) range given a text start and end position.
 // This function is designed to be used with uregex_start64/uregex_end64.
 til::point_span Microsoft::Console::ICU::BufferRangeFromMatch(UText* ut, URegularExpression* re)
 {
     UErrorCode status = U_ZERO_ERROR;
     const auto nativeIndexBeg = uregex_start64(re, 0, &status);
-    auto nativeIndexEnd = uregex_end64(re, 0, &status);
-
-    // The parameters are given as a half-open [beg,end) range, but the point_span we return in closed [beg,end].
-    nativeIndexEnd--;
+    const auto nativeIndexEnd = uregex_end64(re, 0, &status);
 
     const auto& textBuffer = *static_cast<const TextBuffer*>(ut->context);
     til::point_span ret;
@@ -439,7 +436,7 @@ til::point_span Microsoft::Console::ICU::BufferRangeFromMatch(UText* ut, URegula
     if (utextAccess(ut, nativeIndexEnd, true))
     {
         const auto y = accessCurrentRow(ut);
-        ret.end.x = textBuffer.GetRowByOffset(y).GetTrailingColumnAtCharOffset(ut->chunkOffset);
+        ret.end.x = textBuffer.GetRowByOffset(y).GetLeadingColumnAtCharOffset(ut->chunkOffset);
         ret.end.y = y;
     }
     else