move http module to net.http

vlib/net/http/chunked/dechunk.v

@@ -0,0 +1,74 @@
+module chunked
+
+import strings
+// See: https://en.wikipedia.org/wiki/Chunked_transfer_encoding
+// /////////////////////////////////////////////////////////////
+// The chunk size is transferred as a hexadecimal number
+// followed by \r\n as a line separator,
+// followed by a chunk of data of the given size.
+// The end is marked with a chunk with size 0.
+struct ChunkScanner {
+mut:
+	pos  int
+	text string
+}
+
+fn (s mut ChunkScanner) read_chunk_size() int {
+	mut n := 0
+	for {
+		if s.pos >= s.text.len {
+			break
+		}
+		c := s.text[s.pos]
+		if !c.is_hex_digit() {
+			break
+		}
+		n = n<<4
+		n += int(unhex(c))
+		s.pos++
+	}
+	return n
+}
+
+fn unhex(c byte) byte {
+	if `0` <= c && c <= `9` {
+		return c - `0`
+	}
+	else if `a` <= c && c <= `f` {
+		return c - `a` + 10
+	}
+	else if `A` <= c && c <= `F` {
+		return c - `A` + 10
+	}
+	return 0
+}
+
+fn (s mut ChunkScanner) skip_crlf() {
+	s.pos += 2
+}
+
+fn (s mut ChunkScanner) read_chunk(chunksize int) string {
+	startpos := s.pos
+	s.pos += chunksize
+	return s.text[startpos..s.pos]
+}
+
+pub fn decode(text string) string {
+	mut sb := strings.new_builder(100)
+	mut cscanner := ChunkScanner{
+		pos: 0
+		text: text
+	}
+	for {
+		csize := cscanner.read_chunk_size()
+		if 0 == csize {
+			break
+		}
+		cscanner.skip_crlf()
+		sb.write(cscanner.read_chunk(csize))
+		cscanner.skip_crlf()
+	}
+	cscanner.skip_crlf()
+	return sb.str()
+}
+