corelib/include/ebcl/Algorithms.hh

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2017-11-08 09:07:04 +01:00
/******************************************************************************/
/* VARIOUS ALGORITHMS *********************************************************/
/******************************************************************************/
#ifndef _H_EBCL_ALGORITHMS
#define _H_EBCL_ALGORITHMS
#include <ebcl/Types.hh>
#include <ebcl/Arrays.hh>
namespace ebcl {
/*= VISITOR ==================================================================*/
/* Helper for the visitor algorithm. Provides the various types used internally
* as well as means to create and dereference values for the stack.
*
* The template's default implementation are not functional. It is specialised
* later for references and non-references.
*/
template<
typename T_Ref ,
bool IsRef = std::is_reference< T_Ref >::value
> struct T_VisitorHelper_
{
using T_Opt = void; // Optional value type
using T_StackRef = void; // Stack reference type
static T_StackRef mkext( T_Ref ) noexcept; // Create stack reference
static T_Ref deref( T_StackRef ) noexcept; // Dereference stack entry
};
template<
// Node type
typename T_Node ,
// Node reference type; by default, use values for arithmetic types and
// pointers, and references for other types
typename R_Node = std::conditional_t<
std::is_arithmetic< T_Node >::value || std::is_pointer< T_Node >::value ,
T_Node , T_Node& >
> class T_Visitor
{
private:
using Helper_ = T_VisitorHelper_< R_Node >;
public:
// Optional value
using T_OptNode = typename Helper_::T_Opt;
// Node browser. Returns the Nth child of the specified node, or null
// if there are no children left.
using F_NodeBrowser = std::function< T_OptNode( R_Node , uint32_t ) >;
// Node action. Second parameter indicates whether the action is
// being called before (false) or after (true) visiting the children.
using F_NodeAction = std::function< bool( R_Node , bool ) >;
private:
using T_StackRef_ = typename Helper_::T_StackRef;
// State of a stack entry
enum E_State_ {
BEFORE , // Must enter the node
CHILDREN , // Going through children
AFTER // Must exit the node
};
struct T_NodeRef_ {
T_StackRef_ node;
uint32_t child;
E_State_ state{ BEFORE };
explicit T_NodeRef_( R_Node node ) noexcept
: node( Helper_::mkext( node ) ) , child( 0 ) {}
explicit T_NodeRef_( R_Node node , uint32_t child ) noexcept
: node( Helper_::mkext( node ) ) , child( child ) {}
};
F_NodeBrowser nodeBrowser_;
T_AutoArray< T_NodeRef_ , 8 > stack_;
public:
T_Visitor( ) = delete;
T_Visitor( T_Visitor const& ) = default;
T_Visitor( T_Visitor&& ) noexcept = default;
explicit T_Visitor( F_NodeBrowser browser ) noexcept;
void visit( R_Node root , F_NodeAction action );
};
} // namespace
#endif // _H_EBCL_ALGORITHMS
#include <ebcl/inline/Algorithms.hh>