From d7c95b78ee7db87fb050048691f17afc9256c3e4 Mon Sep 17 00:00:00 2001
From: KowerKoint <kowerkoint@gmail.com>
Date: Tue, 30 Jan 2024 11:18:36 +0900
Subject: [PATCH] implement circuit base

---
 qulacs/CMakeLists.txt      |  1 +
 qulacs/all.hpp             |  3 +++
 qulacs/circuit/circuit.cpp | 43 ++++++++++++++++++++++++++++++++++++++
 qulacs/circuit/circuit.hpp | 40 +++++++++++++++++++++++++++++++++++
 4 files changed, 87 insertions(+)
 create mode 100644 qulacs/circuit/circuit.cpp
 create mode 100644 qulacs/circuit/circuit.hpp

diff --git a/qulacs/CMakeLists.txt b/qulacs/CMakeLists.txt
index 97d765d5..c60405fb 100644
--- a/qulacs/CMakeLists.txt
+++ b/qulacs/CMakeLists.txt
@@ -1,6 +1,7 @@
 cmake_minimum_required(VERSION 3.21)
 
 target_sources(qulacs PRIVATE
+    circuit/circuit.cpp
     gate/gate_npair_qubit.cpp
     gate/gate_one_control_one_target.cpp
     gate/gate_one_qubit.cpp
diff --git a/qulacs/all.hpp b/qulacs/all.hpp
index 2aa0bc49..7de1c32e 100644
--- a/qulacs/all.hpp
+++ b/qulacs/all.hpp
@@ -1,3 +1,6 @@
+#pragma once
+
+#include "circuit/circuit.hpp"
 #include "gate/constant.hpp"
 #include "gate/gate.hpp"
 #include "gate/gate_npair_qubit.hpp"
diff --git a/qulacs/circuit/circuit.cpp b/qulacs/circuit/circuit.cpp
new file mode 100644
index 00000000..4d1779ce
--- /dev/null
+++ b/qulacs/circuit/circuit.cpp
@@ -0,0 +1,43 @@
+#include "circuit.hpp"
+
+#include <ranges>
+
+namespace qulacs {
+void Circuit::add_gate(const Gate& gate) {
+    check_gate_is_valid(gate);
+    _gate_list.push_back(gate);
+}
+
+void Circuit::update_quantum_state(StateVector& state) const {
+    for (const auto& gate : _gate_list) {
+        gate->update_quantum_state(state);
+    }
+}
+
+Circuit Circuit::copy() const {
+    Circuit ccircuit(_n_qubits);
+    for (const auto& gate : _gate_list) {
+        ccircuit.add_gate(gate->copy());
+    }
+    return ccircuit;
+}
+
+Circuit Circuit::get_inverse() const {
+    Circuit icircuit(_n_qubits);
+    for (const auto& gate : _gate_list | std::views::reverse) {
+        icircuit.add_gate(gate->get_inverse());
+    }
+    return icircuit;
+}
+
+void Circuit::check_gate_is_valid(const Gate& gate) const {
+    auto targets = gate->get_target_qubit_list();
+    auto controls = gate->get_control_qubit_list();
+    bool valid = true;
+    if (!targets.empty()) valid &= *std::max_element(targets.begin(), targets.end()) < _n_qubits;
+    if (!controls.empty()) valid &= *std::max_element(controls.begin(), controls.end()) < _n_qubits;
+    if (!valid) {
+        throw std::runtime_error("Gate to be added to the circuit has invalid qubit range");
+    }
+}
+}  // namespace qulacs
diff --git a/qulacs/circuit/circuit.hpp b/qulacs/circuit/circuit.hpp
new file mode 100644
index 00000000..def15206
--- /dev/null
+++ b/qulacs/circuit/circuit.hpp
@@ -0,0 +1,40 @@
+#pragma once
+
+#include "../gate/gate.hpp"
+#include "../types.hpp"
+
+namespace qulacs {
+class Circuit {
+public:
+    explicit Circuit(UINT n_qubits) : _n_qubits(n_qubits) {}
+
+    [[nodiscard]] inline UINT n_qubits() const { return _n_qubits; }
+    [[nodiscard]] inline const std::vector<Gate>& gate_list() const { return _gate_list; }
+    [[nodiscard]] inline const Gate& get(UINT idx) const {
+        if (idx >= _gate_list.size()) {
+            throw std::runtime_error("Circuit::get(UINT): index out of bounds");
+        }
+        return _gate_list[idx];
+    }
+    [[nodiscard]] inline Gate& get(UINT idx) {
+        if (idx >= _gate_list.size()) {
+            throw std::runtime_error("Circuit::get(UINT): index out of bounds");
+        }
+        return _gate_list[idx];
+    }
+
+    void add_gate(const Gate& gate);
+
+    void update_quantum_state(StateVector& state) const;
+
+    Circuit copy() const;
+    Circuit get_inverse() const;
+
+private:
+    UINT _n_qubits;
+
+    std::vector<Gate> _gate_list;
+
+    void check_gate_is_valid(const Gate& gate) const;
+};
+}  // namespace qulacs