feat(calculator): initial version.

calculator.py

@@ -0,0 +1,43 @@
+
+class Calculator:
+    def __init__(self, client):
+        self.client = client
+
+    def calc(self, operation):
+        fixed_operation = self.fix_operation(operation)
+        self.client.connect()
+        self.client.send(
+            fixed_operation
+        )
+        response = self.client.getText(512)
+        self.client.close()
+        result = Result(response)
+        # if result.has_error():
+        #     raise Exception(result.get_content())
+        return result.get_content()
+
+    def fix_operation(self, operation):
+        if not operation:
+            return '\n'
+        if operation[-1] != '\n':
+            return operation + '\n'
+        return operation
+
+class Result:
+    ok = 'OK'
+    error = 'ERROR'
+    separator = ':'
+
+    def __init__(self, response_text):
+        self.response = response_text
+        self.splited_response = self.response.split(self.separator)
+
+    def has_error(self):
+        if not self.splited_response[0] == self.ok:
+            return True
+        return False
+
+    def get_content(self):
+        return self.separator.join(
+            self.splited_response[1:]
+        )

client_jorobany.py

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+import socket
+
+class ClientJorobany:
+    def __init__(self, host, port):
+        self.host = host
+        self.port = port
+
+    def connect(self):
+        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.socket.connect((self.host, self.port))
+
+    def getText(self, buffersize):
+        binaryText = self.socket.recv(buffersize)
+        if binaryText:
+            return binaryText.decode('utf-8')
+        return ''
+
+    def send(self, data):
+        self.socket.sendall(data.encode())
+
+    def close(self):
+        self.socket.close()

exercise.py

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+from calculator import Calculator
+from client_jorobany import ClientJorobany
+
+host = 'localhost'
+port = 65517
+
+operation = '2+3'
+expected_result = '5\n'
+
+client = ClientJorobany(host, port)
+calculator = Calculator(client)
+result = calculator.calc(operation)
+assert result == expected_result

server.py

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+import socket
+import threading
+import re
+
+# protocolo
+# operacion: valor + operando + valor\n
+# OK:<resultado>\n
+# ERROR:<mensaje>\n
+
+def validate_pdu(pdu):
+    return re.match(r'\d+\s*[-+*/]\s*\d+', pdu) != None
+
+def handle_connection(conn):
+    try:
+        r = conn.makefile('rw')
+        while True:
+            frame = r.readline()
+            pdu = frame.split()
+            command = ''.join(pdu)
+
+            print('got %s' % (frame))
+            if validate_pdu(command):
+                try:
+                    r.writelines(["OK:%s\n" % (eval(command))])
+                except:
+                    r.writelines(["ERR:exception\n"])
+            else:
+                r.writelines(["ERROR:😒yntax error\n"])
+            r.flush()
+    except:
+        pass
+    conn.close()
+
+
+# MAIN
+
+PORT=65517
+with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    s.bind(('', PORT))
+    s.listen(12)
+    while True:
+        conn, addr = s.accept()
+        print('Connected by', addr)
+        t = threading.Thread(target=handle_connection, args=(conn,))
+        t.start()

socket_excercise.py

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+import socket
+
+class ClientJorobany:
+    def __init__(self, host, port):
+        self.host = host
+        self.port = port
+
+    def connect(self):
+        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.socket.connect((self.host, self.port))
+
+    def getText(self, buffersize):
+        binaryText = self.socket.recv(buffersize)
+        if binaryText:
+            return binaryText.decode('utf-8')
+        return ''
+
+    def send(self, data):
+        self.socket.sendall(data)
+
+    def close(self):
+        self.socket.close()
+
+# c = ClientJorobany('mob.bit4bit.in', 65303)
+# c.connect()
+# print(c.getText(512))
+# c.close()

user_calculator.py

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+from calculator import Calculator
+from client_jorobany import ClientJorobany
+
+host = 'localhost'
+port = 65517
+
+client = ClientJorobany(host, port)
+calculator = Calculator(client)
+
+def sanitize_result(result):
+    target = '\n'
+    if result and result[-1] == target:
+        return result[:-1]
+    return result
+
+input_message = "Ingrese operacion (q para salir): "
+
+user_input = input(input_message);
+while not user_input == 'q':
+    result = calculator.calc(user_input)
+    print(sanitize_result(result))
+    user_input = input(input_message)