// license that can be found in the LICENSE file.

package strings

import (
	"errors"
	"io"
	"unicode/utf8"
)

// A Reader implements the [io.Reader], [io.ReaderAt], [io.ByteReader], [io.ByteScanner],
// [io.RuneReader], [io.RuneScanner], [io.Seeker], and [io.WriterTo] interfaces by reading
// from a string.
// The zero value for Reader operates like a Reader of an empty string.
type Reader struct {
	s        string

// “0b” or “0B” selects base 2; a “0”, “0o”, or “0O” prefix selects
// base 8, and a “0x” or “0X” prefix selects base 16. Otherwise the selected
// base is 10.
func (z *Int) scan(r io.ByteScanner, base int) (*Int, int, error) {
	// determine sign
	neg, err := scanSign(r)
	if err != nil {
		return nil, 0, err
	}

	// determine mantissa
	z.abs, base, _, err = z.abs.scan(r, base, false)

}

// scan is like Parse but reads the longest possible prefix representing a valid
// floating point number from an io.ByteScanner rather than a string. It serves
// as the implementation of Parse. It does not recognize ±Inf and does not expect
// EOF at the end.
func (z *Float) scan(r io.ByteScanner, base int) (f *Float, b int, err error) {
	prec := z.prec
	if prec == 0 {
		prec = 64
	}

// processing. A [Reader] that does not implement  ByteReader
// can be wrapped using bufio.NewReader to add this method.
type ByteReader interface {
	ReadByte() (byte, error)
}

// ByteScanner is the interface that adds the UnreadByte method to the
// basic ReadByte method.
//
// UnreadByte causes the next call to ReadByte to return the last byte read.

//	sign     = "+" | "-" .
//	digits   = digit { [ '_' ] digit } .
//	digit    = "0" ... "9" .
//
// A base 2 exponent is only permitted if base2ok is set.
func scanExponent(r io.ByteScanner, base2ok, sepOk bool) (exp int64, base int, err error) {
	// one char look-ahead
	ch, err := r.ReadByte()
	if err != nil {
		if err == io.EOF {
			err = nil
		}
		return 0, 10, err
	}

// is set, only), and -count is the number of fractional digits found.
// In this case, the actual value of the scanned number is res * b**count.
func (z nat) scan(r io.ByteScanner, base int, fracOk bool) (res nat, b, count int, err error) {
	// reject invalid bases
	baseOk := base == 0 ||
		!fracOk && 2 <= base && base <= MaxBase ||
		fracOk && (base == 2 || base == 8 || base == 10 || base == 16)

func (z *Int) SetString(s string, base int) (*Int, bool) {
	return z.setFromScanner(strings.NewReader(s), base)
}

// setFromScanner implements SetString given an io.ByteScanner.
// For documentation see comments of SetString.
func (z *Int) setFromScanner(r io.ByteScanner, base int) (*Int, bool) {
	if _, _, err := z.scan(r, base); err != nil {
		return nil, false
	}
	// entire content must have been consumed

		{"(*SectionReader).Read", Method, 0},
		{"(*SectionReader).ReadAt", Method, 0},
		{"(*SectionReader).Seek", Method, 0},
		{"(*SectionReader).Size", Method, 0},
		{"ByteReader", Type, 0},
		{"ByteScanner", Type, 0},
		{"ByteWriter", Type, 1},
		{"Closer", Type, 0},
		{"Copy", Func, 0},
		{"CopyBuffer", Func, 5},
		{"CopyN", Func, 0},
		{"Discard", Var, 16},
		{"EOF", Var, 0},

pkg io, type ByteReader interface { ReadByte }
pkg io, type ByteReader interface, ReadByte() (uint8, error)
pkg io, type ByteScanner interface { ReadByte, UnreadByte }
pkg io, type ByteScanner interface, ReadByte() (uint8, error)
pkg io, type ByteScanner interface, UnreadByte() error
pkg io, type Closer interface { Close }
pkg io, type Closer interface, Close() error
pkg io, type LimitedReader struct