var boundary byte
	switch {
	case IsWordChar(r1):
		boundary = 1
	case r1 == '\n':
		op |= EmptyBeginLine
	case r1 < 0:
		op |= EmptyBeginText | EmptyBeginLine
	}
	switch {
	case IsWordChar(r2):
		boundary ^= 1
	case r2 == '\n':
		op |= EmptyEndLine
	case r2 < 0:
		op |= EmptyEndText | EmptyEndLine
	}
	if boundary != 0 { // IsWordChar(r1) != IsWordChar(r2)
		op ^= (EmptyWordBoundary | EmptyNoWordBoundary)

var sink any

func BenchmarkIsWordChar(b *testing.B) {
	const chars = "Don't communicate by sharing memory, share memory by communicating."
	for i := 0; i < b.N; i++ {
		for _, r := range chars {
			sink = IsWordChar(r)
		}
	}
	if sink == nil {
		b.Fatal("Benchmark did not run")
	}
	sink = nil

		op &^= syntax.EmptyEndLine
	}
	if op&syntax.EmptyEndText != 0 {
		if r2 >= 0 {
			return false
		}
		op &^= syntax.EmptyEndText
	}
	if op == 0 {
		return true
	}
	if syntax.IsWordChar(r1) != syntax.IsWordChar(r2) {
		op &^= syntax.EmptyWordBoundary
	} else {
		op &^= syntax.EmptyNoWordBoundary
	}
	return op == 0
}

// match runs the machine over the input starting at pos.

		{"InstMatch", Const, 0},
		{"InstNop", Const, 0},
		{"InstOp", Type, 0},
		{"InstRune", Const, 0},
		{"InstRune1", Const, 0},
		{"InstRuneAny", Const, 0},
		{"InstRuneAnyNotNL", Const, 0},
		{"IsWordChar", Func, 0},
		{"Literal", Const, 0},
		{"MatchNL", Const, 0},
		{"NonGreedy", Const, 0},
		{"OneLine", Const, 0},
		{"Op", Type, 0},
		{"OpAlternate", Const, 0},
		{"OpAnyChar", Const, 0},

pkg regexp/syntax, const WasDollar Flags
pkg regexp/syntax, func Compile(*Regexp) (*Prog, error)
pkg regexp/syntax, func EmptyOpContext(int32, int32) EmptyOp
pkg regexp/syntax, func IsWordChar(int32) bool
pkg regexp/syntax, func Parse(string, Flags) (*Regexp, error)
pkg regexp/syntax, method (*Error) Error() string
pkg regexp/syntax, method (*Inst) MatchEmptyWidth(int32, int32) bool