package fmt

import (
	"errors"
	"io"
	"math"
	"os"
	"reflect"
	"strconv"
	"sync"
	"unicode/utf8"
)

// ScanState represents the scanner state passed to custom scanners.
// Scanners may do rune-at-a-time scanning or ask the ScanState
// to discover the next space-delimited token.
type ScanState interface {
	// ReadRune reads the next rune (Unicode code point) from the input.

	case '-':
		neg = true
	case '+':
		// nothing to do
	default:
		r.UnreadByte()
	}
	return
}

// byteReader is a local wrapper around fmt.ScanState;
// it implements the ByteReader interface.
type byteReader struct {
	fmt.ScanState
}

func (r byteReader) ReadByte() (byte, error) {
	ch, size, err := r.ReadRune()
	if size != 1 && err == nil {
		err = fmt.Errorf("invalid rune %#U", ch)
	}

// [fmt.Scan] for floating point values, which are:
// 'b' (binary), 'e', 'E', 'f', 'F', 'g' and 'G'.
// Scan doesn't handle ±Inf.
func (z *Float) Scan(s fmt.ScanState, ch rune) error {
	s.SkipSpace()
	_, _, err := z.scan(byteReader{s}, 0)
	return err

var _ fmt.Scanner = &ratZero // *Rat must implement fmt.Scanner

// Scan is a support routine for fmt.Scanner. It accepts the formats
// 'e', 'E', 'f', 'F', 'g', 'G', and 'v'. All formats are equivalent.
func (z *Rat) Scan(s fmt.ScanState, ch rune) error {
	tok, err := s.Token(true, ratTok)
	if err != nil {
		return err
	}
	if !strings.ContainsRune("efgEFGv", ch) {
		return errors.New("Rat.Scan: invalid verb")
	}

		{"Fscan", Func, 0},
		{"Fscanf", Func, 0},
		{"Fscanln", Func, 0},
		{"GoStringer", Type, 0},
		{"Print", Func, 0},
		{"Printf", Func, 0},
		{"Println", Func, 0},
		{"Scan", Func, 0},
		{"ScanState", Type, 0},
		{"Scanf", Func, 0},
		{"Scanln", Func, 0},
		{"Scanner", Type, 0},
		{"Sprint", Func, 0},
		{"Sprintf", Func, 0},
		{"Sprintln", Func, 0},
		{"Sscan", Func, 0},