examples: add vanilla_http_server - a fast, multi-threaded, non-blocking, port and host reuse, thread-safe, epoll server (#23094)

examples/vanilla_http_server/src/request_parser.v

@@ -0,0 +1,71 @@
+module main
+
+struct Slice {
+	start int
+	len   int
+}
+
+struct HttpRequest {
+mut:
+	buffer  []u8
+	method  Slice
+	path    Slice
+	version Slice
+}
+
+@[direct_array_access]
+fn parse_request_line(mut req HttpRequest) ! {
+	mut i := 0
+	// Parse HTTP method
+	for i < req.buffer.len && req.buffer[i] != ` ` {
+		i++
+	}
+	req.method = Slice{
+		start: 0
+		len:   i
+	}
+	i++
+
+	// Parse path
+	mut path_start := i
+	for i < req.buffer.len && req.buffer[i] != ` ` {
+		i++
+	}
+	req.path = Slice{
+		start: path_start
+		len:   i - path_start
+	}
+	i++
+
+	// Parse HTTP version
+	mut version_start := i
+	for i < req.buffer.len && req.buffer[i] != `\r` {
+		i++
+	}
+	req.version = Slice{
+		start: version_start
+		len:   i - version_start
+	}
+
+	// Move to the end of the request line
+	if i + 1 < req.buffer.len && req.buffer[i] == `\r` && req.buffer[i + 1] == `\n` {
+		i += 2
+	} else {
+		return error('Invalid HTTP request line')
+	}
+}
+
+fn decode_http_request(buffer []u8) !HttpRequest {
+	mut req := HttpRequest{
+		buffer: buffer
+	}
+
+	parse_request_line(mut req)!
+
+	return req
+}
+
+// Helper function to convert Slice to string for debugging
+fn slice_to_string(buffer []u8, s Slice) string {
+	return buffer[s.start..s.start + s.len].bytestr()
+}