add extract_pair_dimension and extract_pair for fortran module

fortran/lammps.f90

@@ -113,6 +113,8 @@ MODULE LIBLAMMPS
     PROCEDURE :: get_mpi_comm           => lmp_get_mpi_comm
     PROCEDURE :: extract_setting        => lmp_extract_setting
     PROCEDURE :: extract_global         => lmp_extract_global
+    PROCEDURE :: extract_pair_dimension => lmp_extract_pair_dimension
+    PROCEDURE :: extract_pair           => lmp_extract_pair
     PROCEDURE, PRIVATE :: lmp_map_atom_int
     PROCEDURE, PRIVATE :: lmp_map_atom_big
     GENERIC :: map_atom               => lmp_map_atom_int, lmp_map_atom_big
@@ -511,6 +513,20 @@ MODULE LIBLAMMPS
       TYPE(c_ptr) :: lammps_extract_global
     END FUNCTION lammps_extract_global
 
+    FUNCTION lammps_extract_pair_dimension(handle,name) BIND(C)
+      IMPORT :: c_ptr, c_int
+      IMPLICIT NONE
+      TYPE(c_ptr), INTENT(IN), VALUE :: handle, name
+      INTEGER(c_int) :: lammps_extract_pair_dimension
+    END FUNCTION lammps_extract_pair_dimension
+
+    FUNCTION lammps_extract_pair(handle, name) BIND(C)
+      IMPORT :: c_ptr
+      IMPLICIT NONE
+      TYPE(c_ptr), INTENT(IN), VALUE :: handle, name
+      TYPE(c_ptr) :: lammps_extract_pair
+    END FUNCTION lammps_extract_pair
+
     FUNCTION lammps_map_atom(handle, tag) BIND(C)
       IMPORT :: c_ptr, c_int
       IMPLICIT NONE
@@ -1333,6 +1349,55 @@ CONTAINS
     END SELECT
   END FUNCTION
 
+  ! equivalent function to lammps_extract_pair_dimension
+  FUNCTION lmp_extract_pair_dimension(self, name) RESULT(dim)
+    CLASS(lammps), INTENT(IN), TARGET :: self
+    CHARACTER(LEN=*), INTENT(IN) :: name
+    INTEGER(c_int) :: dim
+    TYPE(c_ptr) :: Cname
+
+    Cname = f2c_string(name)
+    dim = lammps_extract_pair_dimension(self%handle, Cname)
+    CALL lammps_free(Cname)
+  END FUNCTION
+
+  ! equivalent function to lammps_extract_pair
+  ! the assignment is actually overloaded so as to bind the pointers to
+  ! lammps data based on the information available from LAMMPS
+  FUNCTION lmp_extract_pair(self, name) RESULT(pair_data)
+    CLASS(lammps), INTENT(IN), TARGET :: self
+    CHARACTER(LEN=*), INTENT(IN) :: name
+    TYPE(lammps_data) :: pair_data
+    INTEGER(c_int) :: dim
+    TYPE(c_ptr) :: Cname, Cptr
+    INTEGER(c_size_t) :: length
+
+    ! Determine extracted arrays length and dimension
+    length = lmp_extract_setting(self, 'ntypes') + 1
+
+    Cname = f2c_string(name)
+    dim = lammps_extract_pair_dimension(self%handle, Cname)
+      ! above could be c_null_ptr in place of self%handle...doesn't matter
+    Cptr = lammps_extract_pair(self%handle, Cname)
+    CALL lammps_free(Cname)
+
+    pair_data%lammps_instance => self
+    SELECT CASE (dim)
+      CASE (0)
+        pair_data%datatype = DATA_DOUBLE
+        CALL C_F_POINTER(Cptr, pair_data%r64)
+      CASE (1)
+        pair_data%datatype = DATA_DOUBLE_1D
+        CALL C_F_POINTER(Cptr, pair_data%r64_vec, [length])
+      CASE (2)
+        pair_data%datatype = DATA_DOUBLE_2D
+        CALL C_F_POINTER(Cptr, pair_data%r64_mat, [length, length])
+      CASE (-1)
+        CALL lmp_error(self, LMP_ERROR_ALL + LMP_ERROR_WORLD, &
+          'Unknown property ' // name // ' in extract_pair')
+    END SELECT
+  END FUNCTION
+
   ! equivalent function to lammps_map_atom (for 32-bit integer tags)
   INTEGER FUNCTION lmp_map_atom_int(self, id)
     CLASS(lammps), INTENT(IN) :: self