changed get() and slicing

include/Accessor.hpp

@@ -84,6 +84,9 @@ namespace cytnx {
     Accessor(const Accessor &rhs);
     // copy assignment:
     Accessor &operator=(const Accessor &rhs);
+
+    // check equality
+    bool operator==(const Accessor &rhs) const;
     ///@endcond
 
     int type() const { return this->_type; }

include/Tensor.hpp

@@ -1008,10 +1008,13 @@ namespace cytnx {
     /**
     @brief get elements using Accessor (C++ API) / slices (python API)
     @param[in] accessors the Accessor (C++ API) / slices (python API) to get the elements.
+    @param[out] removed the indices that were removed from the original shape of the Tensor are
+    pushed to the end of this vector. Usually, an empty vector should be passed.
     @return [Tensor]
     @see \link cytnx::Accessor Accessor\endlink for cordinate with Accessor in C++ API.
     @note
-        1. the return will be a new Tensor instance, which not share memory with the current Tensor.
+        The return will be a new Tensor instance, which does not share memory with the current
+    Tensor.
 
     ## Equivalently:
         One can also using more intruisive way to get the slice using [] operator.
@@ -1026,9 +1029,16 @@ namespace cytnx {
     #### output>
     \verbinclude example/Tensor/get.py.out
     */
+    Tensor get(const std::vector<cytnx::Accessor> &accessors,
+               std::vector<cytnx_int64> &removed) const {
+      Tensor out;
+      out._impl = this->_impl->get(accessors, removed);
+      return out;
+    }
     Tensor get(const std::vector<cytnx::Accessor> &accessors) const {
       Tensor out;
-      out._impl = this->_impl->get(accessors);
+      std::vector<cytnx_int64> removed;
+      out._impl = this->_impl->get(accessors, removed);
       return out;
     }
 

include/UniTensor.hpp

@@ -684,12 +684,12 @@ namespace cytnx {
       if (this->is_diag()) {
         cytnx_error_msg(
           in.shape() != this->_block.shape(),
-          "[ERROR][DenseUniTensor] put_block, the input tensor shape does not match.%s", "\n");
+          "[ERROR][DenseUniTensor][put_block] the input tensor shape does not match.%s", "\n");
         this->_block = in.clone();
       } else {
         cytnx_error_msg(
           in.shape() != this->shape(),
-          "[ERROR][DenseUniTensor] put_block, the input tensor shape does not match.%s", "\n");
+          "[ERROR][DenseUniTensor][put_block] the input tensor shape does not match.%s", "\n");
         this->_block = in.clone();
       }
     }
@@ -711,12 +711,12 @@ namespace cytnx {
       if (this->is_diag()) {
         cytnx_error_msg(
           in.shape() != this->_block.shape(),
-          "[ERROR][DenseUniTensor] put_block, the input tensor shape does not match.%s", "\n");
+          "[ERROR][DenseUniTensor][put_block] the input tensor shape does not match.%s", "\n");
         this->_block = in;
       } else {
         cytnx_error_msg(
           in.shape() != this->shape(),
-          "[ERROR][DenseUniTensor] put_block, the input tensor shape does not match.%s", "\n");
+          "[ERROR][DenseUniTensor][put_block] the input tensor shape does not match.%s", "\n");
         this->_block = in;
       }
     }
@@ -731,16 +731,9 @@ namespace cytnx {
         true, "[ERROR][DenseUniTensor] try to put_block using qnum on a non-symmetry UniTensor%s",
         "\n");
     }
-    // this will only work on non-symm tensor (DenseUniTensor)
-    boost::intrusive_ptr<UniTensor_base> get(const std::vector<Accessor> &accessors) {
-      boost::intrusive_ptr<UniTensor_base> out(new DenseUniTensor());
-      out->Init_by_Tensor(this->_block.get(accessors), false, 0);  // wrapping around.
-      return out;
-    }
-    // this will only work on non-symm tensor (DenseUniTensor)
-    void set(const std::vector<Accessor> &accessors, const Tensor &rhs) {
-      this->_block.set(accessors, rhs);
-    }
+    // these two methods only work on non-symm tensor (DenseUniTensor)
+    boost::intrusive_ptr<UniTensor_base> get(const std::vector<Accessor> &accessors);
+    void set(const std::vector<Accessor> &accessors, const Tensor &rhs);
 
     void reshape_(const std::vector<cytnx_int64> &new_shape, const cytnx_uint64 &rowrank = 0);
     boost::intrusive_ptr<UniTensor_base> reshape(const std::vector<cytnx_int64> &new_shape,
@@ -1700,7 +1693,7 @@ namespace cytnx {
         true,
         "[ERROR] cannot perform elementwise arithmetic '+' between Scalar and BlockUniTensor.\n %s "
         "\n",
-        "This operation would destroy the block structure. [Suggest] Avoid or use get/set_block(s) "
+        "This operation would destroy the block structure. [Suggest] Avoid or use get/put_block(s) "
         "to do operation on blocks.");
     }
 
@@ -1713,15 +1706,15 @@ namespace cytnx {
         true,
         "[ERROR] cannot perform elementwise arithmetic '-' between Scalar and BlockUniTensor.\n %s "
         "\n",
-        "This operation would destroy the block structure. [Suggest] Avoid or use get/set_block(s) "
+        "This operation would destroy the block structure. [Suggest] Avoid or use get/put_block(s) "
         "to do operation on blocks.");
     }
     void lSub_(const Scalar &lhs) {
       cytnx_error_msg(
         true,
         "[ERROR] cannot perform elementwise arithmetic '-' between Scalar and BlockUniTensor.\n %s "
         "\n",
-        "This operation would destroy the block structure. [Suggest] Avoid or use get/set_block(s) "
+        "This operation would destroy the block structure. [Suggest] Avoid or use get/put_block(s) "
         "to do operation on blocks.");
     }
 
@@ -1733,7 +1726,7 @@ namespace cytnx {
         "[ERROR] cannot perform elementwise arithmetic '/' between Scalar and BlockUniTensor.\n %s "
         "\n",
         "This operation would cause division by zero on non-block elements. [Suggest] Avoid or use "
-        "get/set_block(s) to do operation on blocks.");
+        "get/put_block(s) to do operation on blocks.");
     }
     void from_(const boost::intrusive_ptr<UniTensor_base> &rhs, const bool &force,
                const cytnx_double &tol);
@@ -2490,7 +2483,7 @@ namespace cytnx {
                       "BlockFermionicUniTensor.\n %s "
                       "\n",
                       "This operation would destroy the block structure. [Suggest] Avoid or use "
-                      "get/set_block(s) to do operation on blocks.");
+                      "get/put_block(s) to do operation on blocks.");
     }
 
     void Mul_(const boost::intrusive_ptr<UniTensor_base> &rhs);
@@ -2503,15 +2496,15 @@ namespace cytnx {
                       "BlockFermionicUniTensor.\n %s "
                       "\n",
                       "This operation would destroy the block structure. [Suggest] Avoid or use "
-                      "get/set_block(s) to do operation on blocks.");
+                      "get/put_block(s) to do operation on blocks.");
     }
     void lSub_(const Scalar &lhs) {
       cytnx_error_msg(true,
                       "[ERROR] cannot perform elementwise arithmetic '-' between Scalar and "
                       "BlockFermionicUniTensor.\n %s "
                       "\n",
                       "This operation would destroy the block structure. [Suggest] Avoid or use "
-                      "get/set_block(s) to do operation on blocks.");
+                      "get/put_block(s) to do operation on blocks.");
     }
 
     void Div_(const boost::intrusive_ptr<UniTensor_base> &rhs);
@@ -2522,7 +2515,7 @@ namespace cytnx {
                       "BlockFermionicUniTensor.\n %s "
                       "\n",
                       "This operation would cause division by zero on non-block elements. "
-                      "[Suggest] Avoid or use get/set_block(s) to do operation on blocks.");
+                      "[Suggest] Avoid or use get/put_block(s) to do operation on blocks.");
     }
     void from_(const boost::intrusive_ptr<UniTensor_base> &rhs, const bool &force);
 
@@ -4280,11 +4273,69 @@ namespace cytnx {
       in.permute_(new_order);
       return *this;
     }
+
+    /**
+    @brief get elements using Accessor (C++ API) / slices (python API)
+    @param[in] accessors the Accessor (C++ API) / slices (python API) to get the elements.
+    @return [UniTensor]
+    @see Tensor::get, UniTensor::operator[]
+    @note
+      1. The return will be a new UniTensor instance, which does not share memory with the current
+         UniTensor.
+
+      2. Equivalently, one can also use the [] operator to access elements.
+
+      3. For diagonal UniTensors, the accessor list can have either one element (to address the
+         diagonal elements), or two elements (in this case, the output will be a non-diagonal
+         UniTensor).
+    */
     UniTensor get(const std::vector<Accessor> &accessors) const {
       UniTensor out;
       out._impl = this->_impl->get(accessors);
       return out;
     }
+
+    /**
+    @brief get elements using Accessor (C++ API) / slices (python API)
+    @see get()
+    */
+    UniTensor operator[](const std::vector<cytnx::Accessor> &accessors) const {
+      UniTensor out;
+      out._impl = this->_impl->get(accessors);
+      return out;
+    }
+    UniTensor operator[](const std::initializer_list<cytnx::Accessor> &accessors) const {
+      std::vector<cytnx::Accessor> acc_in = accessors;
+      return this->get(acc_in);
+    }
+    UniTensor operator[](const std::vector<cytnx_int64> &accessors) const {
+      std::vector<cytnx::Accessor> acc_in;
+      for (cytnx_int64 i = 0; i < accessors.size(); i++) {
+        acc_in.push_back(cytnx::Accessor(accessors[i]));
+      }
+      return this->get(acc_in);
+    }
+    UniTensor operator[](const std::initializer_list<cytnx_int64> &accessors) const {
+      std::vector<cytnx_int64> acc_in = accessors;
+      return (*this)[acc_in];
+    }
+
+    /**
+    @brief set elements using Accessor (C++ API) / slices (python API)
+    @param[in] accessors the Accessor (C++ API) / slices (python API) to set the elements.
+    @param[in] rhs the tensor containing the values to set.
+    @return [UniTensor]
+    @see Tensor::set, UniTensor::operator[], UniTensor::get
+    @note
+      1. The return will be a new UniTensor instance, which does not share memory with the current
+         UniTensor.
+
+      2. Equivalently, one can also use the [] operator to access elements.
+
+      3. For diagonal UniTensors, the accessor list can have either one element (to address the
+         diagonal elements; rhs must be one-dimensional), or two elements (in this case, the
+         output will be a non-diagonal UniTensor; rhs must be two-dimensional).
+    */
     UniTensor &set(const std::vector<Accessor> &accessors, const Tensor &rhs) {
       this->_impl->set(accessors, rhs);
       return *this;

include/backend/Tensor_impl.hpp

@@ -187,7 +187,12 @@ namespace cytnx {
       return this->_storage.at(RealRank);
     }
 
-    boost::intrusive_ptr<Tensor_impl> get(const std::vector<cytnx::Accessor> &accessors);
+    boost::intrusive_ptr<Tensor_impl> get(const std::vector<cytnx::Accessor> &accessors,
+                                          std::vector<cytnx_int64> &removed);
+    boost::intrusive_ptr<Tensor_impl> get(const std::vector<cytnx::Accessor> &accessors) {
+      std::vector<cytnx_int64> removed;
+      return this->get(accessors, removed);
+    }
     [[deprecated("Use Tensor_impl::get instead")]] boost::intrusive_ptr<Tensor_impl> get_deprecated(
       const std::vector<cytnx::Accessor> &accessors);
     void set(const std::vector<cytnx::Accessor> &accessors,