1: #include <petsc/private/isimpl.h>

  3: PetscFunctionList ISList              = NULL;
  4: PetscBool         ISRegisterAllCalled = PETSC_FALSE;

  6: /*@
  7:   ISCreate - Create an index set object. `IS`, index sets, are PETSc objects used to do efficient indexing into other data structures such as `Vec` and `Mat`

  9:   Collective

 11:   Input Parameter:
 12: . comm - the MPI communicator

 14:   Output Parameter:
 15: . is - the new index set

 17:   Level: beginner

 19:   Notes:
 20:   When the communicator is not `MPI_COMM_SELF`, the operations on `is` are NOT
 21:   conceptually the same as `MPI_Group` operations. The `IS` are then
 22:   distributed sets of indices and thus certain operations on them are
 23:   collective.

 25: .seealso: [](sec_scatter), `IS`, `ISType()`, `ISSetType()`, `ISCreateGeneral()`, `ISCreateStride()`, `ISCreateBlock()`, `ISAllGather()`
 26: @*/
 27: PetscErrorCode ISCreate(MPI_Comm comm, IS *is)
 28: {
 29:   PetscFunctionBegin;
 30:   PetscAssertPointer(is, 2);
 31:   PetscCall(ISInitializePackage());

 33:   PetscCall(PetscHeaderCreate(*is, IS_CLASSID, "IS", "Index Set", "IS", comm, ISDestroy, ISView));
 34:   PetscCall(PetscLayoutCreate(comm, &(*is)->map));
 35:   (*is)->compressOutput = PETSC_TRUE;
 36:   PetscFunctionReturn(PETSC_SUCCESS);
 37: }

 39: /*@
 40:   ISSetType - Builds a index set, for a particular `ISType`

 42:   Collective

 44:   Input Parameters:
 45: + is     - The index set object
 46: - method - The name of the index set type

 48:   Options Database Key:
 49: . -is_type type - Sets the index set type; see `ISType`

 51:   Level: intermediate

 53:   Notes:
 54:   See `ISType` for available types (for instance, `ISGENERAL`, `ISSTRIDE`, or `ISBLOCK`).

 56:   Often convenience constructors such as `ISCreateGeneral()`, `ISCreateStride()` or  `ISCreateBlock()` can be used to construct the desired `IS` in one step

 58:   Use `ISDuplicate()` to make a duplicate

 60: .seealso: [](sec_scatter), `IS`, `ISGENERAL`, `ISBLOCK`, `ISGetType()`, `ISCreate()`, `ISCreateGeneral()`, `ISCreateStride()`, `ISCreateBlock()`
 61: @*/
 62: PetscErrorCode ISSetType(IS is, ISType method)
 63: {
 64:   PetscErrorCode (*r)(IS);
 65:   PetscBool match;

 67:   PetscFunctionBegin;
 69:   PetscCall(PetscObjectTypeCompare((PetscObject)is, method, &match));
 70:   if (match) PetscFunctionReturn(PETSC_SUCCESS);

 72:   PetscCall(ISRegisterAll());
 73:   PetscCall(PetscFunctionListFind(ISList, method, &r));
 74:   PetscCheck(r, PetscObjectComm((PetscObject)is), PETSC_ERR_ARG_UNKNOWN_TYPE, "Unknown IS type: %s", method);
 75:   PetscTryTypeMethod(is, destroy);
 76:   is->ops->destroy = NULL;

 78:   PetscCall((*r)(is));
 79:   PetscCall(PetscObjectChangeTypeName((PetscObject)is, method));
 80:   PetscFunctionReturn(PETSC_SUCCESS);
 81: }

 83: /*@
 84:   ISGetType - Gets the index set type name, `ISType`, (as a string) from the `IS`.

 86:   Not Collective

 88:   Input Parameter:
 89: . is - The index set

 91:   Output Parameter:
 92: . type - The index set type name

 94:   Level: intermediate

 96: .seealso: [](sec_scatter), `IS`, `ISType`, `ISSetType()`, `ISCreate()`
 97: @*/
 98: PetscErrorCode ISGetType(IS is, ISType *type)
 99: {
100:   PetscFunctionBegin;
102:   PetscAssertPointer(type, 2);
103:   if (!ISRegisterAllCalled) PetscCall(ISRegisterAll());
104:   *type = ((PetscObject)is)->type_name;
105:   PetscFunctionReturn(PETSC_SUCCESS);
106: }

108: /*@C
109:   ISRegister - Adds a new index set implementation

111:   Not Collective, No Fortran Support

113:   Input Parameters:
114: + sname    - The name of a new user-defined creation routine
115: - function - The creation routine itself

117:   Example Usage:
118: .vb
119:     ISRegister("my_is_name",  MyISCreate);
120: .ve

122:   Then, your vector type can be chosen with the procedural interface via
123: .vb
124:     ISCreate(MPI_Comm, IS *);
125:     ISSetType(IS,"my_is_name");
126: .ve
127:   or at runtime via the option
128: .vb
129:     -is_type my_is_name
130: .ve

132:   Level: developer

134:   Notes:
135:   `ISRegister()` may be called multiple times to add several user-defined vectors

137:   This is no `ISSetFromOptions()` and the current implementations do not have a way to dynamically determine type, so
138:   dynamic registration of custom `IS` types will be of limited use to users.

140: .seealso: [](sec_scatter), `IS`, `ISType`, `ISSetType()`, `ISRegisterAll()`, `ISRegisterDestroy()`
141: @*/
142: PetscErrorCode ISRegister(const char sname[], PetscErrorCode (*function)(IS))
143: {
144:   PetscFunctionBegin;
145:   PetscCall(ISInitializePackage());
146:   PetscCall(PetscFunctionListAdd(&ISList, sname, function));
147:   PetscFunctionReturn(PETSC_SUCCESS);
148: }