scram::core::Pdag

PDAG is a propositional directed acyclic graph. More...

#include <pdag.h>

Inherits from boost::noncopyable

Public Classes

	Name
class	NodeIndexGenerator <br>Generator of unique indices for graph nodes.
class	NullGateRegistrar <br>Registers pass-through or Null logic gates belonging to the graph.
struct	Substitution <br>Non-declarative substitutions.

Public Types

	Name
enum	NodeMark { kGateMark, kVisit, kCount, kOptiValue, kDescendant, kAncestor, kOrder}<br>Various kinds of marks applied to the nodes.
template <typename T > <br>using ext::index_map< kVariableStartIndex, T >	IndexMap <br>Sequential mapping of Variable indices to other data of type T.

Public Functions

	Name
bool	complement() const
bool &	complement()
	Pdag()<br>Constructs a graph with no root gate ready for general purpose (test) Boolean formulas.
	Pdag(const mef::Gate & root, bool ccf =false, const mef::Model * model =nullptr)<br>Constructs a PDAG starting from the top gate of a fault tree.
const std::vector< Substitution > &	substitutions() const
bool	coherent() const
void	coherent(bool flag)
bool	normal() const
void	normal(bool flag)
const GatePtr &	root()
const Gate &	root() const
void	root(const GatePtr & gate)<br>Sets the root gate.
const ConstantPtr &	constant() const
bool	HasConstants() const
bool	HasNullGates() const
bool	IsTrivial() const
bool	IsTrivial()<br>Attempts to make the graph trivial if possible.
const IndexMap< const mef::BasicEvent * > &	basic_events() const
void	Print()<br>Prints the PDAG in the Aralia format.
void	Log()<br>Writes PDAG properties into logs.
void	RemoveNullGates()<br>Removes gates of Null logic with a single argument (maybe constant).
template <NodeMark Mark> <br>void	Clear()<br>Clears marks from graph nodes.
template <NodeMark Mark> <br>void	Clear(const GatePtr & gate)<br>Determines the proper "clear" state for the graph node mark, and set the clear mark to nodes starting from the given gate.

Public Attributes

	Name
const int	kVariableStartIndex <br>The shift value for mapping.

Detailed Description

cpp

class scram::core::Pdag;

PDAG is a propositional directed acyclic graph.

Precondition: There are no shared pointers to any other graph gate except for the root gate of the graph upon graph transformations. Extra reference count will prevent automatic deletion of the node and management of the structure of the graph. Moreover, the graph may become a multi-root graph, which is not the assumption of all the other preprocessing and analysis algorithms.

This class provides a simpler representation of a fault tree that takes into account the indices of events instead of IDs and pointers. This graph can also be called an indexed fault tree.

This class is designed to help preprocessing and other graph transformation functions.

Public Types Documentation

enum NodeMark

Enumerator	Value	Description
kGateMark		General graph traversal (dirty upon traversal end!).
kVisit		General visit times for graph nodes.
kCount
kOptiValue
kDescendant
kAncestor
kOrder

Various kinds of marks applied to the nodes.

using IndexMap

cpp

template <typename T >
using scram::core::Pdag::IndexMap =  ext::index_map<kVariableStartIndex, T>;

Sequential mapping of Variable indices to other data of type T.

Public Functions Documentation

function complement

cpp

inline bool complement() const

Return: true if graph = ~root.

function complement

cpp

inline bool & complement()

function Pdag

cpp

Pdag()

Constructs a graph with no root gate ready for general purpose (test) Boolean formulas.

function Pdag

cpp

explicit Pdag(
    const mef::Gate & root,
    bool ccf =false,
    const mef::Model * model =nullptr
)

Constructs a PDAG starting from the top gate of a fault tree.

Parameters:

root The top gate of the fault tree.
ccf Incorporation of CCF gates and events for CCF groups.
model The Model containing substitutions if any.

Precondition: No new Variable nodes are introduced after the construction.

Postcondition:

All declarative substitutions are applied, and all non-declarative substitutions are collected for application.
The PDAG is stable as long as the argument fault tree and its underlying containers are stable. If the fault tree has been manipulated (event addition, etc.), its PDAG representation is not guaranteed to be the same.
The index assignment for variables is special: index in [kVariableStartIndex, num of vars + kVariableStartIndex). This indexing technique helps preprocessing and analysis algorithms optimize their work with basic events.
All Gate indices >= (num of vars + kVariableStartIndex).

Upon construction, features of the fault tree are recorded to help preprocessing and analysis functions.

function substitutions

cpp

inline const std::vector< Substitution > & substitutions() const

Return: Non-declarative substitutions to be applied by analysis.

function coherent

cpp

inline bool coherent() const

Return: true if the fault tree is coherent.

function coherent

cpp

inline void coherent(
    bool flag
)

Parameters:

flag true if fault tree doesn't contain non-coherent gates.

function normal

cpp

inline bool normal() const

Return: true if all gates of the fault tree are normalized AND/OR.

function normal

cpp

inline void normal(
    bool flag
)

Parameters:

flag true if the graph has been normalized.

function root

cpp

inline const GatePtr & root()

Return: The shared pointer to current root gate of the graph. nullptr iff the graph has been constructed root-less.

function root

cpp

inline const Gate & root() const

Return: The current root gate of the graph.

Precondition: The graph has been constructed with a root gate.

function root

cpp

inline void root(
    const GatePtr & gate
)

Sets the root gate.

Parameters:

gate Replacement root gate.

This function is helpful for transformations.

function constant

cpp

inline const ConstantPtr & constant() const

Return: The single Boolean constant for the whole graph.

function HasConstants

cpp

inline bool HasConstants() const

Return: true if the graph contains pass-through gates with a constant.

function HasNullGates

cpp

inline bool HasNullGates() const

Return: true if the graph has at least one pass-through logic gate.

function IsTrivial

cpp

inline bool IsTrivial() const

Return: true if the graph represents a trivial Boolean function; that is, graph = Constant or graph = Variable. The only gate is the root pass-through to the simple arg.

Note: The root gate may be swapped with a new one.

function IsTrivial

cpp

bool IsTrivial()

Attempts to make the graph trivial if possible.

Return: true if the graph is trivial or made trivial.

function basic_events

cpp

inline const IndexMap< const mef::BasicEvent * > & basic_events() const

Return: Original basic event as initialized in this indexed fault tree. The Variable indices map directly to the original basic events.

Precondition: No new Variable nodes are introduced after the construction.

function Print

cpp

void Print()

Prints the PDAG in the Aralia format.

Warning: Node visits are used.

This is a helper for logging and debugging. The output is the standard error.

function Log

cpp

void Log()

Writes PDAG properties into logs.

Warning: Gate marks are manipulated.

Precondition:

The graph is valid and well formed.
Logging cutoff level is Debug 4 or higher.

Postcondition: Gate marks are clear.

function RemoveNullGates

cpp

void RemoveNullGates()

Removes gates of Null logic with a single argument (maybe constant).

Warning: Gate marks will get cleared by this function.

Postcondition:

If there's still a Null logic gate, then it's the root of the graph with a single variable/constant, and no further processing is required.
If there's still a constant, it belongs to the root gate, and the whole graph is constant, so no further processing is required.

That one child arg is transferred to the parent gate, and the original argument gate is removed from the parent gate.

All Boolean constants from the PDAG are removed according to the Boolean logic of the gates upon passing these args to parent gates.

function Clear

cpp

template <NodeMark Mark>
inline void Clear()

Clears marks from graph nodes.

Template Parameters:

Mark The kind of the mark.

function Clear

cpp

template <NodeMark Mark>
void Clear(
    const GatePtr & gate
)

Determines the proper "clear" state for the graph node mark, and set the clear mark to nodes starting from the given gate.

Parameters:

gate The root gate to start the traversal and cleaning.

Template Parameters:

Mark The kind of the mark.

Precondition: The gate marks are usable for traversal (clear, continuous, etc.).

Public Attributes Documentation

variable kVariableStartIndex

cpp

static const int kVariableStartIndex = 2;

The shift value for mapping.

Updated on 2025-11-11 at 16:51:08 +0000

scram::core::Pdag ​

Public Classes ​

Public Types ​

Public Functions ​

Public Attributes ​

Detailed Description ​

Public Types Documentation ​

enum NodeMark ​

using IndexMap ​

Public Functions Documentation ​

function complement ​

function complement ​

function Pdag ​

function Pdag ​

function substitutions ​

function coherent ​

function coherent ​

function normal ​

function normal ​

function root ​

function root ​

function root ​

function constant ​

function HasConstants ​

function HasNullGates ​

function IsTrivial ​

function IsTrivial ​

function basic_events ​

function Print ​

function Log ​

function RemoveNullGates ​

function Clear ​

function Clear ​

Public Attributes Documentation ​

variable kVariableStartIndex ​

scram::core::Pdag

Public Classes

Public Types

Public Functions

Public Attributes

Detailed Description

Public Types Documentation

enum NodeMark

using IndexMap

Public Functions Documentation

function complement

function complement

function Pdag

function Pdag

function substitutions

function coherent

function coherent

function normal

function normal

function root

function root

function root

function constant

function HasConstants

function HasNullGates

function IsTrivial

function IsTrivial

function basic_events

function Print

function Log

function RemoveNullGates

function Clear

function Clear

Public Attributes Documentation

variable kVariableStartIndex