Parser idea

.gitignore

@@ -63,3 +63,8 @@ pip-wheel-metadata/
 
 # Docs
 _build/
+
+# ply
+lextab.py
+parsetab.py
+parser.out

mypy.ini

@@ -16,6 +16,9 @@ ignore_missing_imports = True
 [mypy-uvloop]
 ignore_missing_imports = True
 
+[mypy-ply.*]
+ignore_missing_imports = True
+
 # disable mypy completely for now
 [mypy-tests.*]
 ignore_errors = True

setup.py

@@ -2,7 +2,7 @@
 
 import setuptools  # type: ignore
 
-install_requires = ["aioredis"]
+install_requires = ["aioredis", "ply"]
 
 with open("README.md", "r", encoding="utf-8") as fh:
     long_description = fh.read()

yarpc/parser.py

@@ -0,0 +1,163 @@
+from enum import Enum
+from typing import Union
+
+import ply.lex as lex
+import ply.yacc as yacc
+
+
+class SyntaxError(Exception):
+    def __init__(self, text: str):
+        self.text = text
+
+
+class Action(Enum):
+    CONNECT = "REQUEST"
+    PING = "PING"
+    INFO = "INFO"
+    REQUEST = "REQUEST"
+    RESPOND = "RESPOND"
+
+
+class Query:
+    def __init__(
+        self,
+        action: Action,
+        parameter: str = None,
+        destination: Union[int, str] = "ALL",
+    ):
+        self.action = action
+        self.parameter = parameter
+        if parameter:
+            self.clean_parameter = parameter.replace("'", "\\'")
+        self.destination = destination
+
+    @property
+    def has_parameter(self) -> bool:
+        return self.parameter is not None
+
+    def __str__(self) -> str:
+        if not self.has_parameter:
+            return f"{self.action};"
+        else:
+            return f"{self.action} '{self.clean_parameter}' TO {self.destination};"
+
+
+tokens = (
+    "SEMICOLON",
+    "ALL",
+    "TO",
+    "STRING",
+    "INTEGER",
+    "PING",
+    "INFO",
+    "REQUEST",
+    "RESPOND",
+    "CONNECT",
+)
+
+# very basic integers
+t_INTEGER = r"\d+"
+
+# our actions
+t_PING = r"PING"
+t_INFO = r"INFO"
+t_REQUEST = r"REQUEST|REQ"
+t_RESPOND = r"RESPOND|RESP"
+t_CONNECT = r"CONNECT|CONN"
+
+t_SEMICOLON = r";"
+t_TO = r"TO|FROM"
+t_ALL = r"ALL"
+t_ignore_WS = r"\s+"
+
+
+def t_STRING(t: lex.LexToken) -> lex.LexToken:
+    r'("(?:\\"|.)*?"|\'(?:\\\'|.)*?\')'
+
+    # make multiple quotes possible like this
+    t.value = t.value[1:-1]
+    t.value = bytes(t.value, "utf-8").decode("unicode_escape")
+
+    return t
+
+
+def t_error(t: lex.LexToken) -> None:
+    print("Illegal character '%s'" % t.value[0])
+    t.lexer.skip(1)
+
+
+lex.lex(optimize=1)
+
+
+def p_query(p: yacc.YaccProduction) -> None:
+    """
+    query : action_noargs SEMICOLON
+          | action_args STRING SEMICOLON
+          | action_args STRING TO destination SEMICOLON
+    """
+    nargs = len(p) - 2  # minus [0] and ;
+    if nargs == 1:  # action_noargs
+        p[0] = Query(action=p[1])
+    elif nargs == 2:  # action_args STRING
+        p[0] = Query(action=p[1], parameter=p[2])
+    elif nargs == 4:  # action_args STRING TO destination
+        p[0] = Query(action=p[1], parameter=p[2], destination=p[4])
+
+
+# def p_action(p):
+#    """
+#    action : PING
+#           | INFO
+#           | REQUEST
+#           | RESPOND
+#           | CONNECT
+#    """
+#    p[0] = p[1]
+
+
+def p_action_no_args(p: yacc.YaccProduction) -> None:
+    """
+    action_noargs : PING
+                  | INFO
+                  | CONNECT
+    """
+    p[0] = p[1]
+
+
+def p_action_args(p: yacc.YaccProduction) -> None:
+    """
+    action_args : REQUEST
+                | RESPOND
+    """
+    p[0] = p[1]
+
+
+def p_destination(p: yacc.YaccProduction) -> None:
+    """
+    destination : INTEGER
+                | ALL
+    """
+    p[0] = p[1]
+
+
+def p_error(p: yacc.YaccProduction) -> None:
+    if not p:  # missing ;
+        raise SyntaxError("Missing ; after query")
+    raise SyntaxError("Syntax error at '%s'" % p.value)
+
+
+parser = yacc.yacc()
+
+if __name__ == "__main__":
+    while True:
+        try:
+            s = input("yarpc > ")
+        except (EOFError, KeyboardInterrupt):
+            break
+        if not s:
+            continue
+        try:
+            r = parser.parse(s)
+        except SyntaxError as e:
+            print(e.text)
+        print(r)