// An EmptyOp specifies a kind or mixture of zero-width assertions.
type EmptyOp uint8

const (
	EmptyBeginLine EmptyOp = 1 << iota
	EmptyEndLine
	EmptyBeginText
	EmptyEndText
	EmptyWordBoundary
	EmptyNoWordBoundary
)

// EmptyOpContext returns the zero-width assertions
// satisfied at the position between the runes r1 and r2.
// Passing r1 == -1 indicates that the position is
// at the beginning of the text.

	case OpBeginText:
		return c.empty(EmptyBeginText)
	case OpEndText:
		return c.empty(EmptyEndText)
	case OpWordBoundary:
		return c.empty(EmptyWordBoundary)
	case OpNoWordBoundary:
		return c.empty(EmptyNoWordBoundary)
	case OpCapture:
		bra := c.cap(uint32(re.Cap << 1))
		sub := c.compile(re.Sub[0])
		ket := c.cap(uint32(re.Cap<<1 | 1))
		return c.cat(c.cat(bra, sub), ket)
	case OpStar:

		}
		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.
// It reports whether a match was found.
// If so, m.matchcap holds the submatch information.

		{"Compile", Func, 0},
		{"DotNL", Const, 0},
		{"EmptyBeginLine", Const, 0},
		{"EmptyBeginText", Const, 0},
		{"EmptyEndLine", Const, 0},
		{"EmptyEndText", Const, 0},
		{"EmptyNoWordBoundary", Const, 0},
		{"EmptyOp", Type, 0},
		{"EmptyOpContext", Func, 0},
		{"EmptyWordBoundary", Const, 0},
		{"ErrInternalError", Const, 0},
		{"ErrInvalidCharClass", Const, 0},

pkg regexp/syntax, const EmptyBeginLine EmptyOp
pkg regexp/syntax, const EmptyBeginText EmptyOp
pkg regexp/syntax, const EmptyEndLine EmptyOp
pkg regexp/syntax, const EmptyEndText EmptyOp
pkg regexp/syntax, const EmptyNoWordBoundary EmptyOp
pkg regexp/syntax, const EmptyWordBoundary EmptyOp
pkg regexp/syntax, const ErrInternalError ErrorCode
pkg regexp/syntax, const ErrInvalidCharClass ErrorCode

pkg regexp/syntax, const EmptyBeginLine = 1
pkg regexp/syntax, const EmptyBeginText = 4
pkg regexp/syntax, const EmptyEndLine = 2
pkg regexp/syntax, const EmptyEndText = 8
pkg regexp/syntax, const EmptyNoWordBoundary = 32
pkg regexp/syntax, const EmptyWordBoundary = 16
pkg regexp/syntax, const ErrInternalError = "regexp/syntax: internal error"
pkg regexp/syntax, const ErrInvalidCharClass = "invalid character class"