75 lines
1.3 KiB
V
75 lines
1.3 KiB
V
module chunked
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import strings
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// See: https://en.wikipedia.org/wiki/Chunked_transfer_encoding
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// /////////////////////////////////////////////////////////////
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// The chunk size is transferred as a hexadecimal number
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// followed by \r\n as a line separator,
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// followed by a chunk of data of the given size.
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// The end is marked with a chunk with size 0.
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struct ChunkScanner {
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mut:
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pos int
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text string
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}
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fn (s mut ChunkScanner) read_chunk_size() int {
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mut n := 0
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for {
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if s.pos >= s.text.len {
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break
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}
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c := s.text[s.pos]
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if !c.is_hex_digit() {
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break
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}
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n = n<<4
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n += int(unhex(c))
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s.pos++
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}
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return n
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}
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fn unhex(c byte) byte {
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if `0` <= c && c <= `9` {
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return c - `0`
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}
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else if `a` <= c && c <= `f` {
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return c - `a` + 10
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}
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else if `A` <= c && c <= `F` {
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return c - `A` + 10
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}
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return 0
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}
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fn (s mut ChunkScanner) skip_crlf() {
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s.pos += 2
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}
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fn (s mut ChunkScanner) read_chunk(chunksize int) string {
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startpos := s.pos
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s.pos += chunksize
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return s.text[startpos..s.pos]
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}
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pub fn decode(text string) string {
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mut sb := strings.new_builder(100)
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mut cscanner := ChunkScanner{
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pos: 0
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text: text
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}
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for {
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csize := cscanner.read_chunk_size()
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if 0 == csize {
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break
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}
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cscanner.skip_crlf()
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sb.write(cscanner.read_chunk(csize))
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cscanner.skip_crlf()
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}
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cscanner.skip_crlf()
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return sb.str()
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}
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