sloonz / go-qprintable

Quoted-printable encoding (RFC 2045) implementation for Go

qprintable

-- import "github.com/sloonz/go-qprintable"

Package qprintable implements quoted-printable encoding as specified by RFC 2045. It is strict on ouput, generous on input.

Quoting RFC 2045:

The Quoted-Printable encoding is intended to represent data that
largely consists of octets that correspond to printable characters in
the US-ASCII character set.  It encodes the data in such a way that
the resulting octets are unlikely to be modified by mail transport.
If the data being encoded are mostly US-ASCII text, the encoded form
of the data remains largely recognizable by humans.  A body which is
entirely US-ASCII may also be encoded in Quoted-Printable to ensure
the integrity of the data should the message pass through a
character-translating, and/or line-wrapping gateway.

Usage

var BinaryEncoding = &Encoding{false, ""}

In binary encoding, CR and LF characters are treated like other control characters sequence and are escaped.

var MacTextEncoding = &Encoding{true, "\r"}

A text encoding has to convert its input in the canonical form (as defined by RFC 2045) : native ends of line (CR for MacTextEncoding, LF for UnixTextEncoding, CRLF for WindowsTextEncoding) are converted into CRLF sequences. Non-native EOL sequences (for example, CR on UnixTextEncoding) are treated as control characters and escaped.

In the decoding process, CRLF sequences are converted to native ends of line.

var UnixTextEncoding = &Encoding{true, "\n"}

var WindowsTextEncoding = &Encoding{true, "\r\n"}

func NewDecoder

func NewDecoder(enc *Encoding, r io.Reader) io.Reader

Returns a new decoder. Data will be read from r, and decoded according to enc.

func NewEncoder

func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser

Returns a new encoder. Any data passed to Write will be encoded according to enc and then written to w.

Data passed to Write must be in its canonical form. The canonical form depends on the encoding:

for binary encoding, anything goes.

for text encodings, there shouldn't be any CR or LF characters other than the one used for end-of-line representation, that is, LF on Unix, CR on old Mac, CR+LF on Windows.

It is the responsibility of the caller to ensure that the input stream is in its canonical form. Any CR of LF character which is not part of an end-of-line representation will be quoted.

This returns a WriteCloser, but Close has no effect for encoding other than WindowsEncoding.

For WindowsEncoding, any trailing CR will not be written unless you call this function. However, note that for a text conforming to windows canonical form, this should never happen. So this function is useful only for invalid WindowsEncoding text streams, you can safely ignore it in all other cases.

func NewEncoderWithEOL

func NewEncoderWithEOL(eol string, enc *Encoding, w io.Writer) io.WriteCloser

Returns an encoder where the line-endings of the resulting stream is not the standard value (CRLF)

Standard requires CRLF line endings, but there are some variants out there (like Maildir) which requires LF line endings.

type Encoding

type Encoding struct {
}

func DetectEncoding

func DetectEncoding(data string) *Encoding

Try to detect encoding of string: strings with no \r will be Unix, strings with \r and no \n will be Mac, strings with count(\r\n) == count(\r) == count(\n) will be Windows, other strings will be binary