Adding base_integrator and base_time_stepper

Signed-off-by: Sachin Pisal <[email protected]>

runtime/cudaq/base_integrator.h

@@ -0,0 +1,58 @@
+/****************************************************************-*- C++ -*-****
+ * Copyright (c) 2022 - 2025 NVIDIA Corporation & Affiliates.                  *
+ * All rights reserved.                                                        *
+ *                                                                             *
+ * This source code and the accompanying materials are made available under    *
+ * the terms of the Apache License 2.0 which accompanies this distribution.    *
+ ******************************************************************************/
+
+#pragma once
+
+#include <map>
+#include <vector>
+#include <memory>
+#include "schedule.h"
+#include "operators.h"
+
+namespace cudaq {
+template <typename TState>
+class BaseIntegrator {
+protected:
+    std::map<std::string, double> integrator_options;
+    TState state;
+    double t;
+    std::map<int, int> dimensions;
+    std::shared_ptr<Schedule> schedule;
+    std::shared_ptr<Operator> hamiltonian;
+    std::shared_ptr<BaseTimeStepper<Tstate>> stepper;
+    std::vector<std::shared_ptr<Operator>> collapse_operators;
+
+    virtual void post_init() = 0;
+
+public:
+    virtual ~BaseIntegrator() = default;
+
+    void set_state(const TState &initial_state, double t0 = 0.0) {
+        state = initial_state;
+        t = t0;
+    }
+
+    void set_system(
+        const std::map<int, int> &dimensions,
+        std::shared_ptr<Schedule> schedule,
+        std::shared_ptr<Operator> hamiltonian,
+        std::vector<std::shared_ptr<Operator>> collapse_operators = {}
+    ) {
+        this->dimensions = dimensions;
+        this->schedule = schedule;
+        this->hamiltonian = hamiltonian;
+        this->collapse_operators = collapse_operators;
+    }
+
+    virtual void integrate(double t) = 0;
+
+    std::pair<double, TState> get_state() const {
+        return {t, state};
+    }
+};
+}

runtime/cudaq/base_time_stepper.h

@@ -0,0 +1,19 @@
+/****************************************************************-*- C++ -*-****
+ * Copyright (c) 2022 - 2025 NVIDIA Corporation & Affiliates.                  *
+ * All rights reserved.                                                        *
+ *                                                                             *
+ * This source code and the accompanying materials are made available under    *
+ * the terms of the Apache License 2.0 which accompanies this distribution.    *
+ ******************************************************************************/
+
+#pragma once
+
+namespace cudaq {
+template <typename TState>
+class BaseTimeStepper {
+public:
+    virtual ~BaseTimeStepper() = default;
+
+    virtual void compute(TState &state, double t) = 0;
+};
+}