xref: /petsc/src/sys/objects/olist.c (revision 95452b02e12c0ee11232c7ff2b24b568a8e07e43)

/*
         Provides a general mechanism to maintain a linked list of PETSc objects.
     This is used to allow PETSc objects to carry a list of "composed" objects
*/
#include <petscsys.h>

struct _n_PetscObjectList {
  char            name[256];
  PetscBool       skipdereference;      /* when the PetscObjectList is destroyed do not call PetscObjectDereference() on this object */
  PetscObject     obj;
  PetscObjectList next;
};

/*@C
     PetscObjectListRemoveReference - Calls PetscObjectDereference() on an object in the list immediately but keeps a pointer to the object in the list.

    Input Parameters:
+     fl - the object list
-     name - the name to use for the object

    Level: developer

       Notes:
    Use PetscObjectListAdd(PetscObjectList,const char name[],NULL) to truly remove the object from the list

              Use this routine ONLY if you know that the object referenced will remain in existence until the pointing object is destroyed

      Developer Note: this is to handle some cases that otherwise would result in having circular references so reference counts never got to zero

.seealso: PetscObjectListDestroy(), PetscObjectListFind(), PetscObjectListDuplicate(), PetscObjectListReverseFind(), PetscObjectListDuplicate(), PetscObjectListAdd()

@*/
PetscErrorCode  PetscObjectListRemoveReference(PetscObjectList *fl,const char name[])
{
  PetscObjectList nlist;
  PetscErrorCode  ierr;
  PetscBool       match;

  PetscFunctionBegin;
  nlist = *fl;
  while (nlist) {
    ierr = PetscStrcmp(name,nlist->name,&match);CHKERRQ(ierr);
    if (match) { /* found it in the list */
      if (!nlist->skipdereference) {
        ierr = PetscObjectDereference(nlist->obj);CHKERRQ(ierr);
      }
      nlist->skipdereference = PETSC_TRUE;
      PetscFunctionReturn(0);
    }
    nlist = nlist->next;
  }
  PetscFunctionReturn(0);
}

/*@C
     PetscObjectListAdd - Adds a new object to an PetscObjectList

    Input Parameters:
+     fl - the object list
.     name - the name to use for the object
-     obj - the object to attach

    Level: developer

       Notes:
    Replaces item if it is already in list. Removes item if you pass in a NULL object.

        Use PetscObjectListFind() or PetscObjectListReverseFind() to get the object back

.seealso: PetscObjectListDestroy(), PetscObjectListFind(), PetscObjectListDuplicate(), PetscObjectListReverseFind(), PetscObjectListDuplicate()

@*/
PetscErrorCode  PetscObjectListAdd(PetscObjectList *fl,const char name[],PetscObject obj)
{
  PetscObjectList olist,nlist,prev;
  PetscErrorCode  ierr;
  PetscBool       match;

  PetscFunctionBegin;
  if (!obj) { /* this means remove from list if it is there */
    nlist = *fl; prev = 0;
    while (nlist) {
      ierr = PetscStrcmp(name,nlist->name,&match);CHKERRQ(ierr);
      if (match) {  /* found it already in the list */
        /* Remove it first to prevent circular derefs */
        if (prev) prev->next = nlist->next;
        else if (nlist->next) *fl = nlist->next;
        else *fl = 0;
        if (!nlist->skipdereference) {
          ierr = PetscObjectDereference(nlist->obj);CHKERRQ(ierr);
        }
        ierr = PetscFree(nlist);CHKERRQ(ierr);
        PetscFunctionReturn(0);
      }
      prev  = nlist;
      nlist = nlist->next;
    }
    PetscFunctionReturn(0); /* did not find it to remove */
  }
  /* look for it already in list */
  nlist = *fl;
  while (nlist) {
    ierr = PetscStrcmp(name,nlist->name,&match);CHKERRQ(ierr);
    if (match) {  /* found it in the list */
      ierr = PetscObjectReference(obj);CHKERRQ(ierr);
      if (!nlist->skipdereference) {
        ierr = PetscObjectDereference(nlist->obj);CHKERRQ(ierr);
      }
      nlist->skipdereference = PETSC_FALSE;
      nlist->obj             = obj;
      PetscFunctionReturn(0);
    }
    nlist = nlist->next;
  }

  /* add it to list, because it was not already there */
  ierr        = PetscNew(&olist);CHKERRQ(ierr);
  olist->next = 0;
  olist->obj  = obj;

  ierr = PetscObjectReference(obj);CHKERRQ(ierr);
  ierr = PetscStrcpy(olist->name,name);CHKERRQ(ierr);

  if (!*fl) *fl = olist;
  else { /* go to end of list */
    nlist = *fl;
    while (nlist->next) {
      nlist = nlist->next;
    }
    nlist->next = olist;
  }
  PetscFunctionReturn(0);
}

/*@C
    PetscObjectListDestroy - Destroy a list of objects

    Input Parameter:
.   ifl   - pointer to list

    Level: developer

.seealso: PetscObjectListAdd(), PetscObjectListFind(), PetscObjectListDuplicate(), PetscObjectListReverseFind(), PetscObjectListDuplicate()

@*/
PetscErrorCode  PetscObjectListDestroy(PetscObjectList *ifl)
{
  PetscObjectList tmp,fl = *ifl;
  PetscErrorCode  ierr;

  PetscFunctionBegin;
  while (fl) {
    tmp = fl->next;
    if (!fl->skipdereference) {
      ierr = PetscObjectDereference(fl->obj);CHKERRQ(ierr);
    }
    ierr = PetscFree(fl);CHKERRQ(ierr);
    fl   = tmp;
  }
  *ifl = NULL;
  PetscFunctionReturn(0);
}


/*@C
    PetscObjectListFind - givn a name, find the matching object

    Input Parameters:
+   fl   - pointer to list
-   name - name string

    Output Parameters:
.   ob - the PETSc object

    Level: developer

    Notes:
    The name must have been registered with the PetscObjectListAdd() before calling this routine.

    The reference count of the object is not increased

.seealso: PetscObjectListDestroy(), PetscObjectListAdd(), PetscObjectListDuplicate(), PetscObjectListReverseFind(), PetscObjectListDuplicate()

@*/
PetscErrorCode  PetscObjectListFind(PetscObjectList fl,const char name[],PetscObject *obj)
{
  PetscErrorCode ierr;
  PetscBool      match;

  PetscFunctionBegin;
  *obj = 0;
  while (fl) {
    ierr = PetscStrcmp(name,fl->name,&match);CHKERRQ(ierr);
    if (match) {
      *obj = fl->obj;
      break;
    }
    fl = fl->next;
  }
  PetscFunctionReturn(0);
}

/*@C
    PetscObjectListReverseFind - given a object, find the matching name if it exists

    Input Parameters:
+   fl   - pointer to list
-   ob - the PETSc object

    Output Parameters:
+  name - name string
-  skipdereference - if the object is list but does not have the increased reference count for a circular dependency

    Level: developer

    Notes:
    The name must have been registered with the PetscObjectListAdd() before calling this routine.

    The reference count of the object is not increased

.seealso: PetscObjectListDestroy(), PetscObjectListAdd(), PetscObjectListDuplicate(), PetscObjectListFind(), PetscObjectListDuplicate()

@*/
PetscErrorCode  PetscObjectListReverseFind(PetscObjectList fl,PetscObject obj,char **name,PetscBool *skipdereference)
{
  PetscFunctionBegin;
  *name = 0;
  while (fl) {
    if (fl->obj == obj) {
      *name = fl->name;
      if (skipdereference) *skipdereference = fl->skipdereference;
      break;
    }
    fl = fl->next;
  }
  PetscFunctionReturn(0);
}

/*@C
    PetscObjectListDuplicate - Creates a new list from a give object list.

    Input Parameters:
.   fl   - pointer to list

    Output Parameters:
.   nl - the new list (should point to 0 to start, otherwise appends)

    Level: developer

.seealso: PetscObjectListDestroy(), PetscObjectListAdd(), PetscObjectListReverseFind(), PetscObjectListFind(), PetscObjectListDuplicate()

@*/
PetscErrorCode  PetscObjectListDuplicate(PetscObjectList fl,PetscObjectList *nl)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  while (fl) {
    ierr = PetscObjectListAdd(nl,fl->name,fl->obj);CHKERRQ(ierr);
    fl   = fl->next;
  }
  PetscFunctionReturn(0);
}