actionLine int // line of left delim starting action
	rangeDepth int
}

// A mode value is a set of flags (or 0). Modes control parser behavior.
type Mode uint

const (
	ParseComments Mode = 1 << iota // parse comments and add them to AST
	SkipFuncCheck                  // do not check that functions are defined
)

// Copy returns a copy of the [Tree]. Any parsing state is discarded.
func (t *Tree) Copy() *Tree {

// ending a given tag are *below* it on the stack, which is
// more work but forced on us by XML.
type stack struct {
	next *stack
	kind int
	name Name
	ok   bool
}

const (
	stkStart = iota
	stkNs
	stkEOF
)

func (d *Decoder) push(kind int) *stack {
	s := d.free
	if s != nil {
		d.free = s.next
	} else {
		s = new(stack)
	}
	s.next = d.stk
	s.kind = kind

}

// newFileKind describes the kind of file to newFile.
type newFileKind int

const (
	// kindNewFile means that the descriptor was passed to us via NewFile.
	kindNewFile newFileKind = iota
	// kindOpenFile means that the descriptor was opened using
	// Open, Create, or OpenFile.
	kindOpenFile
	// kindPipe means that the descriptor was opened using Pipe.
	kindPipe

	freg   int     // FP register index, used if kind == abiStepFloatReg
}

// abiStepKind is the "op-code" for an abiStep instruction.
type abiStepKind int

const (
	abiStepBad      abiStepKind = iota
	abiStepStack                // copy to/from stack
	abiStepIntReg               // copy to/from integer register
	abiStepPointer              // copy pointer to/from integer register

	val unsafe.Pointer // ptr to data (SendDir) or ptr to receive buffer (RecvDir)
}

// These values must match ../reflect/value.go:/SelectDir.
type selectDir int

const (
	_             selectDir = iota
	selectSend              // case Chan <- Send
	selectRecv              // case <-Chan:
	selectDefault           // default
)

//go:linkname reflect_rselect reflect.rselect

	//  of an assignment."
	//
	// Example:
	//  var x = _
	InvalidBlank

	// InvalidIota occurs when the predeclared identifier iota is used outside
	// of a constant declaration.
	//
	// Example:
	//  var x = iota
	InvalidIota

	// MissingInitBody occurs when an init function is missing its body.
	//
	// Example:
	//  func init()
	MissingInitBody

	GoTokens       = ScanIdents | ScanFloats | ScanChars | ScanStrings | ScanRawStrings | ScanComments | SkipComments
)

// The result of Scan is one of these tokens or a Unicode character.
const (
	EOF = -(iota + 1)
	Ident
	Int
	Float
	Char
	String
	RawString
	Comment

	// internal use only
	skipComment
)

var tokenString = map[rune]string{
	EOF:       "EOF",
	Ident:     "Ident",

		rst.backref(rst.demangleConst)
		return
	}

	if rst.str[0] == 'p' {
		rst.advance(1)
		rst.writeByte('_')
		return
	}

	typ := rst.str[0]

	const (
		invalid = iota
		signedInt
		unsignedInt
		boolean
		character
	)

	var kind int
	switch typ {
	case 'a', 's', 'l', 'x', 'n', 'i':
		kind = signedInt
	case 'h', 't', 'm', 'y', 'o', 'j':

		c.writeBytes(b[:sz])
		i = len(b[sz:]) / 2 // Greek modifiers are always of length 2.
	}

	for ; i < maxIgnorable && c.next(); i++ {
		switch r, _ := utf8.DecodeRune(c.src[c.pSrc:]); r {
		// Above and Iota Subscript
		case 0x0300, // U+0300 COMBINING GRAVE ACCENT
			0x0301, // U+0301 COMBINING ACUTE ACCENT
			0x0304, // U+0304 COMBINING MACRON
			0x0306, // U+0306 COMBINING BREVE
			0x0308, // U+0308 COMBINING DIAERESIS

// there may be control flow that could cause the benefit to be
// bypassed.
const (
	// Category 1 adjustments (see above)
	panicPathAdj scoreAdjustTyp = (1 << iota)
	initFuncAdj
	inLoopAdj

	// Category 2 adjustments (see above).
	passConstToIfAdj
	passConstToNestedIfAdj
	passConcreteToItfCallAdj
	passConcreteToNestedItfCallAdj
	passFuncToIndCallAdj