On 7 January 2011 10:20, Raphael Langella <[email protected]> wrote:
> for (m_tabs_it = m_tabs.begin(); m_tabs_it != m_tabs.end(); ++m_tabs_it)
>
> m_tabs is a std::map. It works fine when it's empty, but as soon as there is
> an element, gdb crashes at the beginning of the second iteration, when it
> tries to increment the iterator (m_tabs_it). Here is the error:
That line looks fine as far as it goes, but:
for (m_tabs_it = m_tabs.begin(); m_tabs_it != m_tabs.end(); ++m_tabs_it)
{
delete (*m_tabs_it).second;
m_tabs.erase(m_tabs_it);
m_layers[LAYER_NORMAL].m_regions.pop_back();
}
...after m_tabs.erase(m_tabs_it) the iterator is invalidated and can't
be incremented to get to the next element. As it stands you are
accessing deleted memory. You need something like this:
m_tabs_it = m_tabs.begin();
std::map<int, TabbedRegion*>::iterator next;
while (m_tabs_it != m_tabs.end())
{
next = m_tabs_it++;
delete m_tabs_it->second;
m_tabs.erase(m_tabs_it);
m_layers[LAYER_NORMAL].m_regions.pop_back();
m_tabs_it = next;
}
However, since you are going through and deleting everything anyway,
you may want to do something more STL-stylie, eg:
struct ClearTabs {
public:
ClearTabs(std::vector<Region*> ®ions): m_regions(regions) {}
void operator()(std::map<int, TabbedRegion*>::value_type &value)
{
delete value.second;
m_regions.pop_back();
}
private:
std::vector<Region*> &m_regions;
};
bool TilesFramework::layout_statcol(bool show_gold_turns)
{
std::for_each(m_tabs.begin(), m_tabs.end(),
ClearTabs(m_layers[LAYER_NORMAL].m_regions));
m_tabs.clear();
....
You could probably simplify that significantly if there are no subtle
interactions between the regions and the tabs (i.e. do the deletion
and popping separately).
Also, from a very quick look there doesn't seem to be any good reason
for m_tabs_it to be a member variable. It should probably be replaced
by local variables everywhere it is used in the class. Apologies if
I've missed something subtle.
Cheers,
Duane.
--
"I never could learn to drink that blood and call it wine" - Bob Dylan
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