From 031019926557d9752cabf9c39ede765975b111eb Mon Sep 17 00:00:00 2001
From: HGSilveri <henrique.silverio@tecnico.ulisboa.pt>
Date: Fri, 15 Nov 2024 16:13:21 +0100
Subject: [PATCH] Define the EmulatorBackend ABC

---
 pulser-core/pulser/backend/abc.py | 42 ++++++++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 6 deletions(-)

diff --git a/pulser-core/pulser/backend/abc.py b/pulser-core/pulser/backend/abc.py
index 8c1ec754..13264a0f 100644
--- a/pulser-core/pulser/backend/abc.py
+++ b/pulser-core/pulser/backend/abc.py
@@ -14,32 +14,38 @@
 """Base class for the backend interface."""
 from __future__ import annotations
 
-import typing
 from abc import ABC, abstractmethod
+from collections.abc import Sequence
+from typing import ClassVar
 
+import pulser
+from pulser.backend.config import EmulationConfig
 from pulser.backend.results import Results
 from pulser.devices import Device
-from pulser.sequence import Sequence
 
 
 class Backend(ABC):
     """The backend abstract base class."""
 
-    def __init__(self, sequence: Sequence, mimic_qpu: bool = False) -> None:
+    def __init__(
+        self, sequence: pulser.Sequence, mimic_qpu: bool = False
+    ) -> None:
         """Starts a new backend instance."""
         self.validate_sequence(sequence, mimic_qpu=mimic_qpu)
         self._sequence = sequence
         self._mimic_qpu = bool(mimic_qpu)
 
     @abstractmethod
-    def run(self) -> Results | typing.Sequence[Results]:
+    def run(self) -> Results | Sequence[Results]:
         """Executes the sequence on the backend."""
         pass
 
     @staticmethod
-    def validate_sequence(sequence: Sequence, mimic_qpu: bool = False) -> None:
+    def validate_sequence(
+        sequence: pulser.Sequence, mimic_qpu: bool = False
+    ) -> None:
         """Validates a sequence prior to submission."""
-        if not isinstance(sequence, Sequence):
+        if not isinstance(sequence, pulser.Sequence):
             raise TypeError(
                 "'sequence' should be a `Sequence` instance"
                 f", not {type(sequence)}."
@@ -68,3 +74,27 @@ def validate_sequence(sequence: Sequence, mimic_qpu: bool = False) -> None:
                 "the register's layout must be one of the layouts available "
                 f"in '{device.name}.calibrated_register_layouts'."
             )
+
+
+class EmulatorBackend(Backend):
+    """The emulator backend parent class."""
+
+    default_config: ClassVar[EmulationConfig]
+
+    def __init__(
+        self,
+        sequence: pulser.Sequence,
+        config: EmulationConfig | None = None,
+        mimic_qpu: bool = False,
+    ) -> None:
+        """Initializes the backend."""
+        super().__init__(sequence, mimic_qpu=mimic_qpu)
+        config = config or self.default_config
+        if not isinstance(config, EmulationConfig):
+            raise TypeError(
+                "'config' must be an instance of 'EmulationConfig', "
+                f"not {type(config)}."
+            )
+        self._config = config
+        # See the BackendConfig definition to see how this would work
+        self._config = type(self.default_config)(**config._backend_options)