// writeEncodedTextToFile encodes the text in the passed file under the tree
// it was called on, and writes out the encoded bits to the passed file. Is called
// by EncodeText. Returns a non-nil error on failure, nil otherwise.
func (t *huffNode) writeEncodedText(fromFile string,
toFile *os.File) (err error, length uint64) {
toEncode, err := ioutil.ReadFile(fromFile)
if err != nil {
return err, 0
}
bitReps := t.getByteMap()
bw, err := bitIO.NewWriterOnFile(toFile)
if err != nil {
return err, 0
}
// Write 'em
length = 0
for _, char := range toEncode {
length++
bitRep := bitReps[char]
for _, bit := range bitRep {
err = bw.WriteBit(byte(bit - '0'))
if err != nil {
return err, 0
}
}
}
_, err = bw.CloseAndReturnFile()
return err, length
}
// writeToFile writes the tree out to the passed os.File.
// Will be called by EncodeText to write the tree out to the beginning
// of the encoded file.
func (t *huffNode) writeToFile(f *os.File) (err error) {
// First, get the map of byte->string of 0s and 1s (character->binary representation)
var bytes map[byte]string = t.getByteMap()
// Then, write the number of bytes we have in the tree
err = binary.Write(f, endianness, int8(len(bytes)-1))
if err != nil {
return err
}
// Now for each byte, we write:
// - The byte
// - The length of its binary (as a uint16)
// - The binary
for char, repString := range bytes {
// First the character
_, err = f.Write([]byte{char})
if err != nil {
return err
}
// Now the length of the binary
err = binary.Write(f, endianness, int8(len(repString)))
if err != nil {
return err
}
// And the actual bits
bw, err := bitIO.NewWriterOnFile(f)
if err != nil {
return err
}
for _, c := range repString {
err = bw.WriteBit(byte(c - '0')) // WriteBit() wants a byte, we have runes
if err != nil {
return err
}
}
f, err = bw.CloseAndReturnFile()
if err != nil {
return err
}
}
return nil
}
