Add webserver_eval example

typon/trans/tests/webserver_eval.py

+# coding: utf-8
+# norun
+
+import sys
+from socket import socket, SOCK_STREAM, AF_INET6, SOL_SOCKET, SO_REUSEADDR
+from typon import fork
+from builtins import eval
+#fork = lambda x: x()
+
+BACKLOG = 1024
+PORT = 8000
+
+response_fmt = \
+    "HTTP/1.0 200 OK\r\n" \
+    "Content-type: text/plain\r\n" \
+    "Content-length: {}\r\n" \
+    "\r\n" \
+    "{}"
+
+def create_listening_socket(port):
+    sockfd = socket(AF_INET6, SOCK_STREAM)
+    sockfd.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
+    sockfd.bind(("", port))
+    sockfd.listen(BACKLOG)
+    return sockfd
+
+def handle_connection(connfd):
+    buf = connfd.recv(1024).decode("utf-8")
+    resp: str
+    if not buf.startswith("GET /eval?e="):
+        resp = "Expression missing"
+    else:
+        http_pos = buf.find("HTTP/1.1\r\n")
+        s = "str(" + buf[12:http_pos-1] + ")"
+        resp = eval(s, {"req": buf})
+    response = response_fmt.format(len(resp), resp)
+    connfd.send(response.encode("utf-8"))
+    connfd.close()
+
+def server_loop(sockfd):
+    while True:
+        connfd, _ = sockfd.accept()
+
+        fork(lambda: handle_connection(connfd))
+
+def server_loops(sockfd):
+    for i in range(20):
+        fork(lambda: server_loop(sockfd))
+
+if __name__ == "__main__":
+    print("Serving on port", PORT)
+    print()
+
+    sockfd = create_listening_socket(PORT)
+
+    server_loops(sockfd)