OpenGATE Contents | GATE development concepts: Enumerators

Container content iteration

Problem description

Iterating the elements of containers is very different depending on the implementation details of container itself.

In C, we use indexes, pointers and other native structures to access collections of items.

This leads to inflexibility when one container is replaced with another one.

Solution

All containers shall provide one generic interface that allows to iterate elements with only one API.

The GATE framework provides the gate_enumerator_t type that fulfills this requirement.

C Example

 1#include <gate/arrays.h>
 2
 3static gate_int32_t sum_int_array(gate_array_t const* arr)
 4{
 5  int sum = 0;
 6  gate_enumerator_t e;
 7  gate_int32_t const* ptr_item;
 8
 9  gate_array_enumerate(arr, &e);
10
11  while(gate_enumerator_valid(&e))
12  {
13    ptr_item = (gate_int32_t const*)gate_enumerator_get(&e);
14    sum += *ptr_item;
15    gate_enumerator_next(&e);
16  }
17  return sum;
18}

C++ Example

 1#include "gate/arrays.hpp"
 2
 3using namespace gate;
 4
 5static int32_t sum_int_array(Array<int32_t> const& arr)
 6{
 7  int32_t sum = 0;
 8  Enumerator<int32_t const> e = arr.enumerate();
 9  for(; e.valid(); e.next())
10  {
11    sum += *e;
12  }
13  return sum;
14}