implement a strategy pattern into dsl example

logging mode switched to DEBUG.

examples/dsl/__main__.py

@@ -1,6 +1,8 @@
 import argparse
 import logging
 import time
+from abc import ABC, abstractmethod
+from enum import IntEnum
 
 from pyparsing import (
     Combine,
@@ -10,24 +12,88 @@ from pyparsing import (
     Suppress,
     Word,
     alphanums,
-    alphas,
     nums,
 )
 
 import voicemeeterlib
 
-logging.basicConfig(level=logging.INFO)
+logging.basicConfig(level=logging.DEBUG)
+logger = logging.getLogger(__name__)
+
+
 argparser = argparse.ArgumentParser(description="creates a basic dsl")
 argparser.add_argument("-i", action="store_true")
 args = argparser.parse_args()
 
 
+ParamKinds = IntEnum(
+    "ParamKinds",
+    "bool float string",
+)
+
+
+class Strategy(ABC):
+    def __init__(self, target, param, val):
+        self.target = target
+        self.param = param
+        self.val = val
+
+    @abstractmethod
+    def run(self):
+        pass
+
+
+class BoolStrategy(Strategy):
+    def run(self):
+        setattr(self.target, self.param, self.strtobool(self.val))
+
+    def strtobool(self, val):
+        """Convert a string representation of truth to it's numeric form."""
+
+        val = val.lower()
+        if val in ("y", "yes", "t", "true", "on", "1"):
+            return 1
+        elif val in ("n", "no", "f", "false", "off", "0"):
+            return 0
+        else:
+            raise ValueError("invalid truth value %r" % (val,))
+
+
+class FloatStrategy(Strategy):
+    def run(self):
+        setattr(self.target, self.param, float(self.val))
+
+
+class StringStrategy(Strategy):
+    def run(self):
+        setattr(self.target, self.param, " ".join(self.val))
+
+
+class Context:
+    def __init__(self, strategy: Strategy) -> None:
+        self._strategy = strategy
+
+    @property
+    def strategy(self) -> Strategy:
+        return self._strategy
+
+    @strategy.setter
+    def strategy(self, strategy: Strategy) -> None:
+        self._strategy = strategy
+
+    def run(self):
+        self.strategy.run()
+
+
 class Parser:
+    IS_STRING = ("label",)
+
     def __init__(self, vm):
+        self.logger = logger.getChild(self.__class__.__name__)
         self.vm = vm
         self.kls = Group(OneOrMore(Word(alphanums)))
         self.token = Suppress("->")
-        self.param = Word(alphanums)
+        self.param = Group(OneOrMore(Word(alphanums)))
         self.value = Combine(
             Optional("-") + Word(nums) + Optional(".") + Optional(Word(nums))
         ) | Group(OneOrMore(Word(alphanums)))
@@ -39,27 +105,64 @@ class Parser:
             + Optional(self.value)
         )
 
-    def parse(self, cmds):
+    def converter(self, cmds):
+        """determines the kind of parameter from the parsed string"""
+
         res = list()
-
         for cmd in cmds:
-            if len(self.event.parseString(cmd)) == 2:
+            self.logger.debug(f"running command: {cmd}")
-                kls, param = self.event.parseString(cmd)
+            match cmd_parsed := self.event.parseString(cmd):
-                target = getattr(self.vm, kls[0])[int(kls[-1])]
+                case [[kls, index], [param]]:
+                    target = getattr(self.vm, kls)[int(index)]
                     res.append(getattr(target, param))
-            elif len(self.event.parseString(cmd)) == 3:
+                case [[kls, index], [param], val] if param in self.IS_STRING:
-                kls, param, val = self.event.parseString(cmd)
+                    target = getattr(self.vm, kls)[int(index)]
-                target = getattr(self.vm, kls[0])[int(kls[-1])]
+                    context = self._get_context(ParamKinds.string, target, param, val)
-                if "".join(val) in ["off", "on"]:
+                    context.run()
-                    setattr(target, param, bool(["off", "on"].index("".join(val))))
+                case [[kls, index], [param], [val] | val]:
-                elif param in ["gain", "comp", "gate", "limit", "audibility"]:
+                    target = getattr(self.vm, kls)[int(index)]
-                    setattr(target, param, float("".join(val)))
+                    try:
-                elif param in ["label"]:
+                        context = self._get_context(ParamKinds.bool, target, param, val)
-                    setattr(target, param, " ".join(val))
+                        context.run()
-
+                    except ValueError as e:
+                        self.logger.error(f"{e}... switching to float strategy")
+                        context.strategy = FloatStrategy(target, param, val)
+                        context.run()
+                case [
+                    [kls, index],
+                    [secondary, param],
+                    [val] | val,
+                ]:
+                    primary = getattr(self.vm, kls)[int(index)]
+                    target = getattr(primary, secondary)
+                    try:
+                        context = self._get_context(ParamKinds.bool, target, param, val)
+                        context.run()
+                    except ValueError as e:
+                        self.logger.error(f"{e}... switching to float strategy")
+                        context.strategy = FloatStrategy(target, param, val)
+                        context.run()
+                case _:
+                    self.logger.error(
+                        f"unable to determine the kind of parameter from {cmd_parsed}"
+                    )
             time.sleep(0.05)
         return res
 
+    def _get_context(self, kind, *args):
+        """
+        determines a strategy for a kind of parameter and passes it to the context.
+        """
+
+        match kind:
+            case ParamKinds.bool:
+                context = Context(BoolStrategy(*args))
+            case ParamKinds.float:
+                context = Context(FloatStrategy(*args))
+            case ParamKinds.string:
+                context = Context(StringStrategy(*args))
+        return context
+
 
 def interactive_mode(parser):
     while cmd := input("Please enter command (Press <Enter> to exit)\n"):
@@ -70,25 +173,23 @@ def interactive_mode(parser):
 def main():
     # fmt: off
     cmds = (
-        "strip 0 -> mute -> on", "strip 0 -> mute", "bus 0 -> mute -> on",
+        "strip 0 -> mute -> true", "strip 0 -> mute", "bus 0 -> mute -> true",
-        "strip 0 -> mute -> off", "bus 0 -> mute -> on", "strip 3 -> solo -> on",
+        "strip 0 -> mute -> false", "bus 0 -> mute -> true", "strip 3 -> solo -> true",
-        "strip 3 -> solo -> off", "strip 1 -> A1 -> on", "strip 1 -> A1",
+        "strip 3 -> solo -> false", "strip 1 -> A1 -> true", "strip 1 -> A1",
-        "strip 1 -> A1 -> off", "strip 1 -> A1", "bus 3 -> eq -> on",
+        "strip 1 -> A1 -> false", "strip 1 -> A1", "strip 3 -> eq on -> true",
-        "bus 3 -> eq -> off", "strip 4 -> gain -> 1.2", "strip 0 -> gain -> -8.2",
+        "bus 3 -> eq on -> false", "strip 4 -> gain -> 1.2", "strip 0 -> gain -> -8.2",
         "strip 0 -> gain", "strip 1 -> label -> rode podmic", "strip 2 -> limit -> -28",
-        "strip 2 -> limit",
+        "strip 2 -> limit", "strip 3 -> comp knob -> 3.8"
     )
     # fmt: on
 
-    KIND_ID = "banana"
+    with voicemeeterlib.api("potato") as vm:
-
-    with voicemeeterlib.api(KIND_ID) as vm:
         parser = Parser(vm)
         if args.i:
             interactive_mode(parser)
             return
 
-        if res := parser.parse(cmds):
+        if res := parser.converter(cmds):
             print(res)