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//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
#ifndef Patternist_XsdStateMachine_H
#define Patternist_XsdStateMachine_H
#include "qnamepool_p.h"
#include <QtCore/QHash>
#include <QtCore/QSet>
#include <QtCore/QTextStream>
class QIODevice;
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
namespace QPatternist
{
/**
* @short A state machine used for evaluation.
*
* @ingroup Patternist_schema
* @author Tobias Koenig <tobias.koenig@nokia.com>
*/
template <typename TransitionType>
class XsdStateMachine
{
public:
typedef qint32 StateId;
/**
* Describes the type of state.
*/
enum StateType
{
StartState, ///< The state the machine will start with.
StartEndState, ///< The state the machine will start with, can be end state as well.
InternalState, ///< Any state that is not start or end state.
EndState ///< Any state where the machine is allowed to stop.
};
/**
* Creates a new state machine object.
*/
XsdStateMachine();
/**
* Creates a new state machine object.
*
* The name pool to use for accessing object names.
*/
XsdStateMachine(const NamePool::Ptr &namePool);
/**
* Adds a new state of the given @p type to the state machine.
*
* @return The id of the new state.
*/
StateId addState(StateType type);
/**
* Adds a new @p transition to the state machine.
*
* @param start The start state.
* @param transition The transition to come from the start to the end state.
* @param end The end state.
*/
void addTransition(StateId start, TransitionType transition, StateId end);
/**
* Adds a new epsilon @p transition to the state machine.
*
* @param start The start state.
* @param end The end state.
*/
void addEpsilonTransition(StateId start, StateId end);
/**
* Resets the machine to the start state.
*/
void reset();
/**
* Removes all states and transitions from the state machine.
*/
void clear();
/**
* Continues execution of the machine with the given input @p transition.
*
* @return @c true if the transition was successfull, @c false otherwise.
*/
bool proceed(TransitionType transition);
/**
* Returns the list of transitions that are reachable from the current
* state.
*/
QList<TransitionType> possibleTransitions() const;
/**
* Continues execution of the machine with the given @p input.
*
* @note To use this method, inputEqualsTransition must be implemented
* to find the right transition to use.
*
* @return @c true if the transition was successfull, @c false otherwise.
*/
template <typename InputType>
bool proceed(InputType input);
/**
* Returns whether the given @p input matches the given @p transition.
*/
template <typename InputType>
bool inputEqualsTransition(InputType input, TransitionType transition) const;
/**
* Returns whether the machine is in an allowed end state.
*/
bool inEndState() const;
/**
* Returns the last transition that was taken.
*/
TransitionType lastTransition() const;
/**
* Returns the start state of the machine.
*/
StateId startState() const;
/**
* This method should be redefined by template specialization for every
* concret TransitionType.
*/
QString transitionTypeToString(TransitionType type) const;
/**
* Outputs the state machine in DOT format to the given
* output @p device.
*/
bool outputGraph(QIODevice *device, const QString &graphName) const;
/**
* Returns a DFA that is equal to the NFA of the state machine.
*/
XsdStateMachine<TransitionType> toDFA() const;
/**
* Returns the information of all states of the state machine.
*/
QHash<StateId, StateType> states() const;
/**
* Returns the information of all transitions of the state machine.
*
* The implementation is inlined in order to workaround a compiler
* bug on Symbian/winscw.
*/
QHash<StateId, QHash<TransitionType, QVector<StateId> > > transitions() const
{
return m_transitions;
}
private:
/**
* Returns the DFA state for the given @p nfaStat from the given @p stateTable.
* If there is no corresponding DFA state yet, a new one is created.
*/
StateId dfaStateForNfaState(QSet<StateId> nfaState, QList< QPair< QSet<StateId>, StateId> > &stateTable, XsdStateMachine<TransitionType> &dfa) const;
/**
* Returns the set of all states that can be reached from the set of @p input states
* by the epsilon transition.
*
* The implementation is inlined in order to workaround a compiler
* bug on Symbian/winscw.
*/
QSet<StateId> epsilonClosure(const QSet<StateId> &input) const
{
// every state can reach itself by epsilon transition, so include the input states
// in the result as well
QSet<StateId> result = input;
// add the input states to the list of to be processed states
QList<StateId> workStates = input.toList();
while (!workStates.isEmpty()) { // while there are states to be processed left...
// dequeue one state from list
const StateId state = workStates.takeFirst();
// get the list of states that can be reached by the epsilon transition
// from the current 'state'
const QVector<StateId> targetStates = m_epsilonTransitions.value(state);
for (int i = 0; i < targetStates.count(); ++i) {
// if we have this target state not in our result set yet...
if (!result.contains(targetStates.at(i))) {
// ... add it to the result set
result.insert(targetStates.at(i));
// add the target state to the list of to be processed states as well,
// as we want to have the epsilon transitions not only for the first
// level of following states
workStates.append(targetStates.at(i));
}
}
}
return result;
}
/**
* Returns the set of all states that can be reached from the set of given @p states
* by the given @p input.
*
* The implementation is inlined in order to workaround a compiler
* bug on Symbian/winscw.
*/
QSet<StateId> move(const QSet<StateId> &states, TransitionType input) const
{
QSet<StateId> result;
QSetIterator<StateId> it(states);
while (it.hasNext()) { // iterate over all given states
const StateId state = it.next();
// get the transition table for the current state
const QHash<TransitionType, QVector<StateId> > transitions = m_transitions.value(state);
// get the target states for the given input
const QVector<StateId> targetStates = transitions.value(input);
// add all target states to the result
for (int i = 0; i < targetStates.size(); ++i)
result.insert(targetStates.at(i));
}
return result;
}
NamePool::Ptr m_namePool;
QHash<StateId, StateType> m_states;
QHash<StateId, QHash<TransitionType, QVector<StateId> > > m_transitions;
QHash<StateId, QVector<StateId> > m_epsilonTransitions;
StateId m_currentState;
qint32 m_counter;
TransitionType m_lastTransition;
};
#include "qxsdstatemachine.cpp"
}
QT_END_NAMESPACE
QT_END_HEADER
#endif