Sorting

Sorting — Sorting.

Synopsis


#include <libhrel/relation.h>


            HRelationSort;
HRelation*  h_relation_sort                 (HRelation *relation,
                                             GCompareDataFunc compare_func,
                                             gpointer user_data);
HRelation*  h_relation_sort_by_attrs        (HRelation *relation,
                                             ...);
HRelation*  h_relation_sort_by_attrs_l      (HRelation *relation,
                                             GSList *list);

Object Hierarchy


  GObject
   +----HRelation
         +----HRelationSort

Description

Strictly speaking, tuples in a relation are by definition unordered. While HRelationSort is a HRelation due to inheritance, it does not represent a relation.

Details

HRelationSort

typedef struct _HRelationSort HRelationSort;

A HRelation representing a "sorted relation".

h_relation_sort ()

HRelation*  h_relation_sort                 (HRelation *relation,
                                             GCompareDataFunc compare_func,
                                             gpointer user_data);

Creates a sorted relation.

`relation` :	a relation to sort
`compare_func` :	function to compare a pair of tuples in `relation`
`user_data` :	Custom data passed to `compare_func`
Returns :	sorted relation

h_relation_sort_by_attrs ()

HRelation*  h_relation_sort_by_attrs        (HRelation *relation,
                                             ...);

Creates a relation sorted by attributes. Each pair of tuples are compared attribute by attribute in the order listed.

`relation` :	relation to sort
`...` :	name of first attribute, followed by the second and so on, then a `NULL`
Returns :	sorted relation

h_relation_sort_by_attrs_l ()

HRelation*  h_relation_sort_by_attrs_l      (HRelation *relation,
                                             GSList *list);

A variation of h_relation_sort_by_attrs(), taking a GSList for the attribute name list.

`relation` :	relation to sort
`list` :	list of attribute names
Returns :	sorted relation