return nil
	}

	return r.execSeqs(data, off, litbuf, seqCount)
}

// seqCode is the kind of sequence codes we have to handle.
type seqCode int

const (
	seqLiteral seqCode = iota
	seqOffset
	seqMatch
)

// seqCodeInfoData is the information needed to set up seqTables and
// seqTableBits for a particular kind of sequence code.
type seqCodeInfoData struct {

		case OpPlus:
			b.WriteRune('+')
		case OpQuest:
			b.WriteRune('?')
		case OpRepeat:
			b.WriteRune('{')
			b.WriteString(strconv.Itoa(re.Min))
			if re.Max != re.Min {
				b.WriteRune(',')
				if re.Max >= 0 {
					b.WriteString(strconv.Itoa(re.Max))
				}
			}
			b.WriteRune('}')
		}
		if re.Flags&NonGreedy != 0 {
			b.WriteRune('?')
		}
	case OpConcat:

	metrics[name] = d
	metricsUnlock()
}

// statDep is a dependency on a group of statistics
// that a metric might have.
type statDep uint

const (
	heapStatsDep statDep = iota // corresponds to heapStatsAggregate
	sysStatsDep                 // corresponds to sysStatsAggregate
	cpuStatsDep                 // corresponds to cpuStatsAggregate
	gcStatsDep                  // corresponds to gcStatsAggregate

// The cached value is a uint32 in which the low bits
// are the "crash" and "all" settings and the remaining
// bits are the traceback value (0 off, 1 on, 2 include system).
const (
	tracebackCrash = 1 << iota
	tracebackAll
	tracebackShift = iota
)

var traceback_cache uint32 = 2 << tracebackShift
var traceback_env uint32

// gotraceback returns the current traceback settings.
//
// If level is 0, suppress all tracebacks.

//
// The Writer currently provides no support for sparse files.
type Format int

// Constants to identify various tar formats.
const (
	// Deliberately hide the meaning of constants from public API.
	_ Format = (1 << iota) / 4 // Sequence of 0, 0, 1, 2, 4, 8, etc...

	// FormatUnknown indicates that the format is unknown.
	FormatUnknown

	// The format of the original Unix V7 tar tool prior to standardization.
	formatV7

			year, month, day := t.Date()
			itoa(buf, year, 4)
			*buf = append(*buf, '/')
			itoa(buf, int(month), 2)
			*buf = append(*buf, '/')
			itoa(buf, day, 2)
			*buf = append(*buf, ' ')
		}
		if flag&(Ltime|Lmicroseconds) != 0 {
			hour, min, sec := t.Clock()
			itoa(buf, hour, 2)
			*buf = append(*buf, ':')
			itoa(buf, min, 2)
			*buf = append(*buf, ':')
			itoa(buf, sec, 2)
			if flag&Lmicroseconds != 0 {

	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	. "internal/types/errors"
)

// An operandMode specifies the (addressing) mode of an operand.
type operandMode byte

const (
	invalid   operandMode = iota // operand is invalid
	novalue                      // operand represents no value (result of a function call w/o result)
	builtin                      // operand is a built-in function

// BUG(r): There is no mechanism for full case folding, that is, for
// characters that involve multiple runes in the input or output.

// Indices into the Delta arrays inside CaseRanges for case mapping.
const (
	UpperCase = iota
	LowerCase
	TitleCase
	MaxCase
)

type d [MaxCase]rune // to make the CaseRanges text shorter

// If the Delta field of a [CaseRange] is UpperLower, it means

	// _Gscanwaiting -> _Gscanrunnable are actually okay because
	// they don't affect stack ownership.

	// _Gidle means this goroutine was just allocated and has not
	// yet been initialized.
	_Gidle = iota // 0

	// _Grunnable means this goroutine is on a run queue. It is
	// not currently executing user code. The stack is not owned.
	_Grunnable // 1

	// _Grunning means this goroutine may execute user code. The

	// i.e. struct fields and array elements, even with non-constant
	// indices: x is non-nil iff x.a.b[i].c is.

	type walkState int
	const (
		Work     walkState = iota // process nil checks and traverse to dominees
		ClearPtr                  // forget the fact that ptr is nil
	)

	type bp struct {
		block *Block // block, or nil in ClearPtr state