Simple script emulator

examples/smart_contracts/simple_script.py

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+from eopsin.prelude import *
+
+
+@dataclass()
+class RequireSignature(PlutusData):
+    CONSTR_ID = 0
+    vkeyhash: bytes  # this is either a PubKeyHash or a VerificationKeyHash
+
+
+@dataclass()
+class RequireAllOf(PlutusData):
+    CONSTR_ID = 1
+    scripts: List[Datum]  # "Script"
+
+
+@dataclass()
+class RequireAnyOf(PlutusData):
+    CONSTR_ID = 2
+    scripts: List[Datum]  # "Script"
+
+
+@dataclass()
+class RequireMOf(PlutusData):
+    CONSTR_ID = 3
+    num: int
+    scripts: List[Datum]  # "Script"
+
+
+@dataclass()
+class RequireBefore(PlutusData):
+    CONSTR_ID = 4
+    unixtimestamp: int
+
+
+@dataclass()
+class RequireAfter(PlutusData):
+    CONSTR_ID = 5
+    unixtimestamp: int
+
+
+Script = Union[
+    RequireSignature,
+    RequireMOf,
+    RequireAnyOf,
+    RequireAllOf,
+    RequireAfter,
+    RequireBefore,
+]
+
+
+def validate_script(
+    script_raw: Datum, signatories: List[bytes], valid_range: POSIXTimeRange
+) -> bool:
+    script: Script = script_raw  # cast to Script in the type system to avoid recursive type definition
+    if isinstance(script, RequireSignature):
+        res = script.vkeyhash in signatories
+    elif isinstance(script, RequireAllOf):
+        res = all(
+            [validate_script(s, signatories, valid_range) for s in script.scripts]
+        )
+    elif isinstance(script, RequireAnyOf):
+        res = any(
+            [validate_script(s, signatories, valid_range) for s in script.scripts]
+        )
+    elif isinstance(script, RequireMOf):
+        res = (
+            sum(
+                [
+                    1 if validate_script(s, signatories, valid_range) else 0
+                    for s in script.scripts
+                ]
+            )
+            >= script.num
+        )
+    elif isinstance(script, RequireBefore):
+        upper_bound = valid_range.upper_bound
+        upper_limit = upper_bound.limit
+        if isinstance(upper_limit, FinitePOSIXTime):
+            upper_closed = upper_bound.closed
+            if isinstance(upper_closed, TrueData):
+                res = upper_limit.time <= script.unixtimestamp
+            else:
+                res = upper_limit.time < script.unixtimestamp
+        elif isinstance(upper_limit, PosInfPOSIXTime):
+            res = False
+        elif isinstance(upper_limit, NegInfPOSIXTime):
+            res = True
+    elif isinstance(script, RequireAfter):
+        lower_bound = valid_range.lower_bound
+        lower_limit = lower_bound.limit
+        if isinstance(lower_limit, FinitePOSIXTime):
+            lower_closed = lower_bound.closed
+            if isinstance(lower_closed, TrueData):
+                res = lower_limit.time >= script.unixtimestamp
+            else:
+                res = lower_limit.time > script.unixtimestamp
+        elif isinstance(lower_limit, PosInfPOSIXTime):
+            res = True
+        elif isinstance(lower_limit, NegInfPOSIXTime):
+            res = False
+    else:
+        assert False, "Invalid simple script passed"
+    return res
+
+
+# to fully emulate simple script behaviour, compile with --force-three-params
+# the script is a contract parameter, pass it into the build command
+def validator(
+    script: Script, datum: None, redeemer: None, context: ScriptContext
+) -> None:
+    assert validate_script(
+        script, context.tx_info.signatories, context.tx_info.valid_range
+    ), "Simple Script validation failed!"