memio - string.go

     1  package memio
     2  
     3  import (
     4  	"io"
     5  	"unicode/utf8"
     6  )
     7  
     8  // String grants a string Read-Only methods.
     9  type String string
    10  
    11  // Read satisfies the io.Reader interface
    12  func (s *String) Read(p []byte) (int, error) {
    13  	if len(p) == 0 {
    14  		return 0, nil
    15  	}
    16  	if len(*s) == 0 {
    17  		return 0, io.EOF
    18  	}
    19  	n := copy(p, *s)
    20  	*s = (*s)[n:]
    21  	return n, nil
    22  }
    23  
    24  // WriteTo satisfies the io.WriterTo interface
    25  func (s *String) WriteTo(w io.Writer) (int64, error) {
    26  	if len(*s) == 0 {
    27  		return 0, io.EOF
    28  	}
    29  	n, err := io.WriteString(w, string(*s))
    30  	*s = (*s)[n:]
    31  	return int64(n), err
    32  }
    33  
    34  // ReadByte satisfies the io.ByteReader interface
    35  func (s *String) ReadByte() (byte, error) {
    36  	if len(*s) == 0 {
    37  		return 0, io.EOF
    38  	}
    39  	b := (*s)[0]
    40  	*s = (*s)[1:]
    41  	return b, nil
    42  }
    43  
    44  // ReadRune satisfies the io.RuneReader interface
    45  func (s *String) ReadRune() (rune, int, error) {
    46  	if len(*s) == 0 {
    47  		return 0, 0, io.EOF
    48  	}
    49  	r, n := utf8.DecodeRuneInString(string(*s))
    50  	*s = (*s)[n:]
    51  	return r, n, nil
    52  }
    53  
    54  // Peek reads the next n bytes without advancing the position
    55  func (s *String) Peek(n int) ([]byte, error) {
    56  	if n > len(*s) {
    57  		return []byte(*s), io.EOF
    58  	}
    59  	return []byte((*s)[:n]), nil
    60  }
    61  
    62  // Close satisfies the io.Closer interface
    63  func (s *String) Close() error {
    64  	*s = ""
    65  	return nil
    66  }