QueryFocusStack Class Reference

#include "steam/mobject/session/query-focus-stack.hpp"

Description

A custom stack holding ScopePath »frames«.

It is utilised by the ScopeLocator to establish the current query focus location. Client code should access this mechanism through QueryFocus instances used as frontend. These QueryFocus objects incorporate a boost::intrusive_ptr, which stores the ref-count within the mentioned ScopePath frames located in the stack.

automatic cleanup of unused frames

The stack is aware of this ref-counting mechanism and will – on each access – automatically clean up any unused frames starting from stack top, until encountering the first frame still in use. This frame, by definition, is the current focus location. The stack ensures there is always at least one ScopePath frame, default-creating a new one if necessary.

See also

query-focus-stack-test.cpp

ScopeLocator

QueryFocus access point for client code

Definition at line 69 of file query-focus-stack.hpp.

Public Member Functions
void	clear ()
bool	empty () const
void	pop_unused ()
	investigate the stack top and discard any path frames which aren't referred anymore (as indicated by their ScopePath::use_count(). More...
ScopePath &	push (Scope const &)
	Open a new path frame, pushing down the current frame. More...
size_t	size () const
ScopePath &	top ()

Private Member Functions
void	openDefaultFrame ()
Private Member Functions inherited from NonCopyable
	NonCopyable (NonCopyable const &)=delete
NonCopyable &	operator= (NonCopyable const &)=delete

Private Attributes
std::list< ScopePath >	paths_

Member Function Documentation

push()

ScopePath & push

(

Scope const &

newStartPoint

)

Open a new path frame, pushing down the current frame.

The new frame tries to locate the given start scope and navigates to this position.

Note

EXCEPTION_STRONG guarantee

Returns

reference to the newly created path on top

Exceptions

error::Invalid

if newStartPoint isn't locatable

Definition at line 134 of file query-focus-stack.hpp.

References Scope::isRoot(), and ScopePath::isValid().

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top()

ScopePath & top

(

)

Returns

the topmost path frame actually in use

Note

may invoke pop_unused()

EXCEPTON_FREE ///////TODO prove!

Definition at line 150 of file query-focus-stack.hpp.

References QueryFocusStack::pop_unused().

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pop_unused()

void pop_unused

(

)

investigate the stack top and discard any path frames which aren't referred anymore (as indicated by their ScopePath::use_count().

After executing this function the topmost frame is either in use, or a new default frame has been created at the bottom of an empty stack.

Note

EXCEPTION_FREE ///////TODO prove!

Definition at line 170 of file query-focus-stack.hpp.

References QueryFocusStack::openDefaultFrame().

Referenced by QueryFocusStack::top().

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openDefaultFrame()

void openDefaultFrame ( )

private

open a default path frame at the bottom of an empty stack, locating to current model root

Note

EXCEPTION_FREE ///////TODO prove!

Definition at line 189 of file query-focus-stack.hpp.

Referenced by QueryFocusStack::pop_unused().

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The documentation for this class was generated from the following file:

• query-focus-stack.hpp