*/
struct GNUNET_REGEX_Context
{
+ /**
+ * Unique state id.
+ */
unsigned int state_id;
+
+ /**
+ * Unique transition id.
+ */
unsigned int transition_id;
/**
- * DLL of GNUNET_REGEX_Automaton's used as a stack
+ * DLL of GNUNET_REGEX_Automaton's used as a stack.
*/
struct GNUNET_REGEX_Automaton *stack_head;
+
+ /**
+ * DLL of GNUNET_REGEX_Automaton's used as a stack.
+ */
struct GNUNET_REGEX_Automaton *stack_tail;
};
+/**
+ * Type of an automaton.
+ */
enum GNUNET_REGEX_automaton_type
{
NFA,
};
/**
- * Automaton representation
+ * Automaton representation.
*/
struct GNUNET_REGEX_Automaton
{
+ /**
+ * This is a linked list.
+ */
struct GNUNET_REGEX_Automaton *prev;
+
+ /**
+ * This is a linked list.
+ */
struct GNUNET_REGEX_Automaton *next;
+ /**
+ * First state of the automaton. This is mainly
+ * used for constructing an NFA, where each NFA
+ * itself consists of one or more NFAs linked
+ * together.
+ */
struct State *start;
+
+ /**
+ * End state of the automaton.
+ */
struct State *end;
+ /**
+ * Number of states in the automaton.
+ */
+ unsigned int state_count;
+
+ /**
+ * DLL of states.
+ */
struct State *states_head;
+
+ /**
+ * DLL of states
+ */
struct State *states_tail;
+ /**
+ * Type of the automaton.
+ */
enum GNUNET_REGEX_automaton_type type;
};
*/
struct State
{
+ /**
+ * This is a linked list.
+ */
struct State *prev;
+
+ /**
+ * This is a linked list.
+ */
struct State *next;
+ /**
+ * Unique state id.
+ */
unsigned int id;
+
+ /**
+ * If this is an accepting state or not.
+ */
int accepting;
+
+ /**
+ * Marking of the state. This is used for marking all visited
+ * states when traversing all states of an automaton and for
+ * cases where the state id cannot be used (dfa minimization).
+ */
int marked;
+
+ /**
+ * Human readable name of the automaton. Used for debugging
+ * and graph creation.
+ */
char *name;
+ /**
+ * Number of transitions from this state to other states.
+ */
+ unsigned int transition_count;
+
+ /**
+ * DLL of transitions.
+ */
struct Transition *transitions_head;
+
+ /**
+ * DLL of transitions.
+ */
struct Transition *transitions_tail;
+ /**
+ * Set of states on which this state is based on. Used when
+ * creating a DFA out of several NFA states.
+ */
struct StateSet *nfa_set;
};
*/
struct Transition
{
+ /**
+ * This is a linked list.
+ */
struct Transition *prev;
+
+ /**
+ * This is a linked list.
+ */
struct Transition *next;
+ /**
+ * Unique id of this transition.
+ */
unsigned int id;
+
+ /**
+ * Literal for this transition. This is basically the edge label for
+ * the graph.
+ */
char literal;
+
+ /**
+ * State to which this transition leads.
+ */
struct State *state;
};
/**
- * Set of states
+ * Set of states.
*/
struct StateSet
{
/**
- * Array of states
+ * Array of states.
*/
struct State **states;
+
+ /**
+ * Length of the 'states' array.
+ */
unsigned int len;
};
*
* @param ctx context
*/
-void
+static void
GNUNET_REGEX_context_init (struct GNUNET_REGEX_Context *ctx)
{
if (NULL == ctx)
ctx->stack_tail = NULL;
}
-void
+static void
debug_print_state (struct State *s)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
s->marked, s->accepting);
}
-void
+static void
debug_print_states (struct StateSet *sset)
{
struct State *s;
}
}
-void
+static void
debug_print_transitions (struct State *s)
{
struct Transition *t;
}
}
+/**
+ * Compare two states. Used for sorting.
+ *
+ * @param a first state
+ * @param b second state
+ *
+ * @return an integer less than, equal to, or greater than zero
+ * if the first argument is considered to be respectively
+ * less than, equal to, or greater than the second.
+ */
+static int
+state_compare (const void *a, const void *b)
+{
+ struct State **s1;
+ struct State **s2;
+
+ s1 = (struct State **) a;
+ s2 = (struct State **) b;
+
+ return (*s1)->id - (*s2)->id;
+}
+
/**
* Compare to state sets by comparing the id's of the states that are
- * contained in each set.
+ * contained in each set. Both sets are expected to be sorted by id!
*
* @param sset1 first state set
* @param sset2 second state set
*
- * @return 0 if they are equal, non 0 otherwise
+ * @return an integer less than, equal to, or greater than zero
+ * if the first argument is considered to be respectively
+ * less than, equal to, or greater than the second.
*/
-int
+static int
state_set_compare (struct StateSet *sset1, struct StateSet *sset2)
{
- struct State *s1;
- struct State *s2;
- int i1;
- int i2;
- int contains;
- int rslt;
+ int result;
+ int i;
- if (sset1->len < 1 || sset2->len < 1)
- return -1;
+ if (NULL == sset1 || NULL == sset2)
+ return 1;
- rslt = 0;
+ result = sset1->len - sset2->len;
- for (i1 = 0; i1 < sset1->len; i1++)
+ for (i = 0; i < sset1->len; i++)
{
- s1 = sset1->states[i1];
- contains = 0;
- for (i2 = 0; i2 < sset2->len; i2++)
- {
- s2 = sset2->states[i2];
- if (s1->id == s2->id)
- {
- contains = 1;
- break;
- }
- }
-
- if (0 == contains)
- {
- rslt = 1;
+ if (0 != result)
break;
- }
+
+ result = state_compare (&sset1->states[i], &sset2->states[i]);
}
- return rslt;
+ return result;
}
/**
*
* @return GNUNET_YES if 'set' contains 'elem, GNUNET_NO otherwise
*/
-int
+static int
state_set_contains (struct StateSet *set, struct State *elem)
{
struct State *s;
return GNUNET_NO;
}
+/**
+ * Clears the given StateSet 'set'
+ *
+ * @param set set to be cleared
+ */
+static void
+state_set_clear (struct StateSet *set)
+{
+ if (NULL != set)
+ {
+ if (NULL != set->states)
+ GNUNET_free (set->states);
+ GNUNET_free (set);
+ }
+}
+
/**
* Adds a transition from one state to another on 'literal'
*
* @param literal transition label
* @param to_state state to where the transition should point to
*/
-void
+static void
add_transition (struct GNUNET_REGEX_Context *ctx, struct State *from_state,
const char literal, struct State *to_state)
{
*
* @param a automaton to be cleared
*/
-void
+static void
automaton_fragment_clear (struct GNUNET_REGEX_Automaton *a)
{
+ if (NULL == a)
+ return;
+
a->start = NULL;
a->end = NULL;
a->states_head = NULL;
a->states_tail = NULL;
+ a->state_count = 0;
GNUNET_free (a);
}
*
* @param s state that should be destroyed
*/
-void
+static void
automaton_destroy_state (struct State *s)
{
struct Transition *t;
struct Transition *next_t;
+ if (NULL == s)
+ return;
+
if (NULL != s->name)
GNUNET_free (s->name);
t = next_t;
}
- if (NULL != s->nfa_set)
+ state_set_clear (s->nfa_set);
+
+ GNUNET_free (s);
+}
+
+/**
+ * Remove a state from the given automaton 'a'. Always use this function
+ * when altering the states of an automaton. Will also remove all transitions
+ * leading to this state, before destroying it.
+ *
+ * @param a automaton
+ * @param s state to remove
+ */
+static void
+automaton_remove_state (struct GNUNET_REGEX_Automaton *a, struct State *s)
+{
+ struct State *ss;
+ struct State *s_check;
+ struct Transition *t_check;
+
+ if (NULL == a || NULL == s)
+ return;
+
+ // remove state
+ ss = s;
+ GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s);
+ a->state_count--;
+
+ // remove all transitions leading to this state
+ for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
{
- if (s->nfa_set->len > 0)
- GNUNET_free (s->nfa_set->states);
- GNUNET_free (s->nfa_set);
+ for (t_check = s_check->transitions_head; NULL != t_check;
+ t_check = t_check->next)
+ {
+ if (t_check->state == ss)
+ {
+ GNUNET_CONTAINER_DLL_remove (s_check->transitions_head,
+ s_check->transitions_tail, t_check);
+ s_check->transition_count--;
+ }
+ }
}
- GNUNET_free (s);
+ automaton_destroy_state (ss);
+}
+
+/**
+ * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy 's2'.
+ *
+ * @param ctx context
+ * @param a automaton
+ * @param s1 first state
+ * @param s2 second state, will be destroyed
+ */
+static void
+automaton_merge_states (struct GNUNET_REGEX_Context *ctx,
+ struct GNUNET_REGEX_Automaton *a, struct State *s1,
+ struct State *s2)
+{
+ struct State *s_check;
+ struct Transition *t_check;
+ struct Transition *t;
+ char *new_name;
+
+ GNUNET_assert (NULL != ctx && NULL != a && NULL != s1 && NULL != s2);
+
+ // 1. Make all transitions pointing to s2 point to s1
+ for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
+ {
+ for (t_check = s_check->transitions_head; NULL != t_check;
+ t_check = t_check->next)
+ {
+ if (s_check != s1 && s2 == t_check->state)
+ t_check->state = s1;
+ }
+ }
+
+ // 2. Add all transitions from s2 to sX to s1
+ for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next)
+ {
+ for (t = s1->transitions_head; NULL != t; t = t->next)
+ {
+ if (t_check->literal != t->literal && NULL != t_check->state &&
+ t_check->state != t->state && t_check->state != s2)
+ {
+ add_transition (ctx, s1, t_check->literal, t_check->state);
+ }
+ }
+ }
+
+ // 3. Rename s1 to {s1,s2}
+ new_name = GNUNET_malloc (strlen (s1->name) + strlen (s2->name) + 1);
+ strncat (new_name, s1->name, strlen (s1->name));
+ strncat (new_name, s2->name, strlen (s2->name));
+ if (NULL != s1->name)
+ GNUNET_free (s1->name);
+ s1->name = new_name;
+
+ // remove state
+ s_check = s2;
+ GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s_check);
+ a->state_count--;
+ automaton_destroy_state (s_check);
+}
+
+/**
+ * Add a state to the automaton 'a', always use this function to
+ * alter the states DLL of the automaton.
+ *
+ * @param a automaton to add the state to
+ * @param s state that should be added
+ */
+static void
+automaton_add_state (struct GNUNET_REGEX_Automaton *a, struct State *s)
+{
+ GNUNET_CONTAINER_DLL_insert (a->states_head, a->states_tail, s);
+ a->state_count++;
}
/**
*
* @return new DFA state
*/
-struct State *
+static struct State *
dfa_state_create (struct GNUNET_REGEX_Context *ctx, struct StateSet *nfa_states)
{
struct State *s;
s->name = NULL;
if (NULL == nfa_states)
+ {
+ GNUNET_asprintf (&s->name, "s%i", s->id);
return s;
+ }
s->nfa_set = nfa_states;
return s;
}
-struct State *
+/**
+ * Move from the given state 's' to the next state on
+ * transition 'literal'
+ *
+ * @param s starting state
+ * @param literal edge label to follow
+ *
+ * @return new state or NULL, if transition on literal not possible
+ */
+static struct State *
dfa_move (struct State *s, const char literal)
{
struct Transition *t;
return new_s;
}
+/**
+ * Remove all unreachable states from DFA 'a'. Unreachable states
+ * are those states that are not reachable from the starting state.
+ *
+ * @param a DFA automaton
+ */
+static void
+dfa_remove_unreachable_states (struct GNUNET_REGEX_Automaton *a)
+{
+ struct State *stack[a->state_count];
+ int stack_len;
+ struct State *s;
+ struct Transition *t;
+
+ stack_len = 0;
+
+ // 1. unmark all states
+ for (s = a->states_head; NULL != s; s = s->next)
+ {
+ s->marked = 0;
+ }
+
+ // 2. traverse dfa from start state and mark all visited states
+ stack[stack_len] = a->start;
+ stack_len++;
+ while (stack_len > 0)
+ {
+ s = stack[stack_len - 1];
+ stack_len--;
+ s->marked = 1; // mark s as visited
+ for (t = s->transitions_head; NULL != t; t = t->next)
+ {
+ // add next states to stack
+ if (NULL != t->state && 0 == t->state->marked)
+ stack[++stack_len] = t->state;
+ }
+ }
+
+ // 3. delete all states that were not visited
+ for (s = a->states_head; NULL != s; s = s->next)
+ {
+ if (0 == s->marked)
+ automaton_remove_state (a, s);
+ }
+}
+
+/**
+ * Remove all dead states from the DFA 'a'. Dead states are those
+ * states that do not transition to any other state but themselfes.
+ *
+ * @param a DFA automaton
+ */
+static void
+dfa_remove_dead_states (struct GNUNET_REGEX_Automaton *a)
+{
+ struct State *s;
+ struct Transition *t;
+ int dead;
+
+ GNUNET_assert (DFA == a->type);
+
+ for (s = a->states_head; NULL != s; s = s->next)
+ {
+ if (s->accepting)
+ continue;
+
+ dead = 1;
+ for (t = s->transitions_head; NULL != t; t = t->next)
+ {
+ if (NULL != t->state && t->state != s)
+ {
+ dead = 0;
+ break;
+ }
+ }
+
+ if (0 == dead)
+ continue;
+
+ // state s is dead, remove it
+ automaton_remove_state (a, s);
+ }
+}
+
+/**
+ * Merge all non distinguishable states in the DFA 'a'
+ *
+ * @param ctx context
+ * @param a DFA automaton
+ */
+static void
+dfa_merge_nondistinguishable_states (struct GNUNET_REGEX_Context *ctx,
+ struct GNUNET_REGEX_Automaton *a)
+{
+ int i;
+ int table[a->state_count][a->state_count];
+ struct State *s1;
+ struct State *s2;
+ struct Transition *t1;
+ struct Transition *t2;
+ int change;
+
+ change = 1;
+ for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1;
+ i++, s1 = s1->next)
+ s1->marked = i;
+
+ // Mark all pairs of accepting/!accepting states
+ for (s1 = a->states_head; NULL != s1; s1 = s1->next)
+ {
+ for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next)
+ {
+ if ((s1->accepting && !s2->accepting) ||
+ (!s1->accepting && s2->accepting))
+ {
+ table[s1->marked][s2->marked] = 1;
+ }
+ else
+ table[s1->marked][s2->marked] = 0;
+ }
+ }
+
+ while (0 != change)
+ {
+ change = 0;
+ for (s1 = a->states_head; NULL != s1; s1 = s1->next)
+ {
+ for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next)
+ {
+ if (0 != table[s1->marked][s2->marked])
+ continue;
+
+ for (t1 = s1->transitions_head; NULL != t1; t1 = t1->next)
+ {
+ for (t2 = s2->transitions_head; NULL != t2; t2 = t2->next)
+ {
+ if (t1->literal == t2->literal && t1->state == t2->state &&
+ (0 != table[t1->state->marked][t2->state->marked] ||
+ 0 != table[t2->state->marked][t1->state->marked]))
+ {
+ table[s1->marked][s2->marked] = t1->literal;
+ change = 1;
+ }
+ else if (t1->literal != t2->literal && t1->state != t2->state)
+ {
+ table[s1->marked][s2->marked] = -1;
+ change = 1;
+ }
+ }
+ }
+ }
+ }
+ }
+
+ struct State *s2_next;
+
+ for (i = 0, s1 = a->states_head; NULL != s1; s1 = s1->next)
+ {
+ for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2_next)
+ {
+ s2_next = s2->next;
+ if (s1 != s2 && table[s1->marked][s2->marked] == 0)
+ automaton_merge_states (ctx, a, s1, s2);
+ }
+ }
+}
+
+/**
+ * Minimize the given DFA 'a' by removing all unreachable states,
+ * removing all dead states and merging all non distinguishable states
+ *
+ * @param ctx context
+ * @param a DFA automaton
+ */
+static void
+dfa_minimize (struct GNUNET_REGEX_Context *ctx,
+ struct GNUNET_REGEX_Automaton *a)
+{
+ if (NULL == a)
+ return;
+
+ GNUNET_assert (DFA == a->type);
+
+ // 1. remove unreachable states
+ dfa_remove_unreachable_states (a);
+
+ // 2. remove dead states
+ dfa_remove_dead_states (a);
+
+ // 3. Merge nondistinguishable states
+ dfa_merge_nondistinguishable_states (ctx, a);
+}
+
/**
* Creates a new NFA fragment. Needs to be cleared using automaton_fragment_clear.
*
*
* @return new NFA fragment
*/
-struct GNUNET_REGEX_Automaton *
+static struct GNUNET_REGEX_Automaton *
nfa_fragment_create (struct State *start, struct State *end)
{
struct GNUNET_REGEX_Automaton *n;
if (NULL == start && NULL == end)
return n;
- GNUNET_CONTAINER_DLL_insert (n->states_head, n->states_tail, end);
- GNUNET_CONTAINER_DLL_insert (n->states_head, n->states_tail, start);
+ automaton_add_state (n, end);
+ automaton_add_state (n, start);
+
+ n->start = start;
+ n->end = end;
+
+ return n;
+}
+
+/**
+ * Adds a list of states to the given automaton 'n'.
+ *
+ * @param n automaton to which the states should be added
+ * @param states_head head of the DLL of states
+ * @param states_tail tail of the DLL of states
+ */
+static void
+nfa_add_states (struct GNUNET_REGEX_Automaton *n, struct State *states_head,
+ struct State *states_tail)
+{
+ struct State *s;
+
+ if (NULL == n || NULL == states_head)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n");
+ return;
+ }
+
+ if (NULL == n->states_head)
+ {
+ n->states_head = states_head;
+ n->states_tail = states_tail;
+ return;
+ }
+
+ if (NULL != states_head)
+ {
+ n->states_tail->next = states_head;
+ n->states_tail = states_tail;
+ }
+
+ for (s = states_head; NULL != s; s = s->next)
+ n->state_count++;
+}
+
+/**
+ * Creates a new NFA state. Needs to be freed using automaton_destroy_state.
+ *
+ * @param ctx context
+ * @param accepting is it an accepting state or not
+ *
+ * @return new NFA state
+ */
+static struct State *
+nfa_state_create (struct GNUNET_REGEX_Context *ctx, int accepting)
+{
+ struct State *s;
+
+ s = GNUNET_malloc (sizeof (struct State));
+ s->id = ctx->state_id++;
+ s->accepting = accepting;
+ s->marked = 0;
+ s->name = NULL;
+ GNUNET_asprintf (&s->name, "s%i", s->id);
+
+ return s;
+}
+
+/**
+ * Calculates the NFA closure set for the given state.
+ *
+ * @param s starting point state
+ * @param literal transitioning literal on which to base the closure on,
+ * pass 0 for epsilon transition
+ *
+ * @return sorted nfa closure on 'literal' (epsilon closure if 'literal' is 0)
+ */
+static struct StateSet *
+nfa_closure_create (struct State *s, const char literal)
+{
+ struct StateSet *cls;
+ struct StateSet *cls_check;
+ struct State *clsstate;
+ struct State *currentstate;
+ struct Transition *ctran;
+
+ if (NULL == s)
+ return NULL;
+
+ cls = GNUNET_malloc (sizeof (struct StateSet));
+ cls_check = GNUNET_malloc (sizeof (struct StateSet));
+
+ // Add start state to closure only for epsilon closure
+ if (0 == literal)
+ GNUNET_array_append (cls->states, cls->len, s);
+
+ GNUNET_array_append (cls_check->states, cls_check->len, s);
+ while (cls_check->len > 0)
+ {
+ currentstate = cls_check->states[cls_check->len - 1];
+ GNUNET_array_grow (cls_check->states, cls_check->len, cls_check->len - 1);
+
+ for (ctran = currentstate->transitions_head; NULL != ctran;
+ ctran = ctran->next)
+ {
+ if (NULL != ctran->state && literal == ctran->literal)
+ {
+ clsstate = ctran->state;
+
+ if (NULL != clsstate &&
+ GNUNET_YES != state_set_contains (cls, clsstate))
+ {
+ GNUNET_array_append (cls->states, cls->len, clsstate);
+ GNUNET_array_append (cls_check->states, cls_check->len, clsstate);
+ }
+ }
+ }
+ }
+ GNUNET_assert (0 == cls_check->len);
+ GNUNET_free (cls_check);
- n->start = start;
- n->end = end;
+ if (cls->len > 1)
+ qsort (cls->states, cls->len, sizeof (struct State *), state_compare);
- return n;
+ return cls;
}
/**
- * Adds a list of states to the given automaton 'n'.
+ * Calculates the closure set for the given set of states.
*
- * @param n automaton to which the states should be added
- * @param states_head head of the DLL of states
- * @param states_tail tail of the DLL of states
+ * @param states list of states on which to base the closure on
+ * @param literal transitioning literal for which to base the closure on,
+ * pass 0 for epsilon transition
+ *
+ * @return sorted nfa closure on 'literal' (epsilon closure if 'literal' is 0)
*/
-void
-nfa_add_states (struct GNUNET_REGEX_Automaton *n, struct State *states_head,
- struct State *states_tail)
+static struct StateSet *
+nfa_closure_set_create (struct StateSet *states, const char literal)
{
- if (NULL == n || NULL == states_head)
- {
- GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n");
- return;
- }
+ struct State *s;
+ struct StateSet *sset;
+ struct StateSet *cls;
+ int i;
+ int j;
+ int k;
+ int contains;
- if (NULL == n->states_head)
- {
- n->states_head = states_head;
- n->states_tail = states_tail;
- return;
- }
+ if (NULL == states)
+ return NULL;
- if (NULL != states_head)
+ cls = GNUNET_malloc (sizeof (struct StateSet));
+
+ for (i = 0; i < states->len; i++)
{
- n->states_tail->next = states_head;
- n->states_tail = states_tail;
- }
-}
+ s = states->states[i];
+ sset = nfa_closure_create (s, literal);
-/**
- * Creates a new NFA state. Needs to be freed using automaton_destroy_state.
- *
- * @param ctx context
- * @param accepting is it an accepting state or not
- *
- * @return new NFA state
- */
-struct State *
-nfa_state_create (struct GNUNET_REGEX_Context *ctx, int accepting)
-{
- struct State *s;
+ for (j = 0; j < sset->len; j++)
+ {
+ contains = 0;
+ for (k = 0; k < cls->len; k++)
+ {
+ if (sset->states[j]->id == cls->states[k]->id)
+ {
+ contains = 1;
+ break;
+ }
+ }
+ if (!contains)
+ GNUNET_array_append (cls->states, cls->len, sset->states[j]);
+ }
+ state_set_clear (sset);
+ }
- s = GNUNET_malloc (sizeof (struct State));
- s->id = ctx->state_id++;
- s->accepting = accepting;
- s->marked = 0;
- s->name = NULL;
- GNUNET_asprintf (&s->name, "s%i", s->id);
+ if (cls->len > 1)
+ qsort (cls->states, cls->len, sizeof (struct State *), state_compare);
- return s;
+ return cls;
}
/**
*
* @param ctx context
*/
-void
+static void
nfa_add_concatenation (struct GNUNET_REGEX_Context *ctx)
{
struct GNUNET_REGEX_Automaton *a;
*
* @param ctx context
*/
-void
+static void
nfa_add_star_op (struct GNUNET_REGEX_Context *ctx)
{
struct GNUNET_REGEX_Automaton *a;
*
* @param ctx context
*/
-void
+static void
nfa_add_plus_op (struct GNUNET_REGEX_Context *ctx)
{
struct GNUNET_REGEX_Automaton *a;
GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a);
}
+/**
+ * Pops an NFA fragment (a) from the stack and adds a new fragment (a?)
+ *
+ * @param ctx context
+ */
+static void
+nfa_add_question_op (struct GNUNET_REGEX_Context *ctx)
+{
+ struct GNUNET_REGEX_Automaton *a;
+ struct GNUNET_REGEX_Automaton *new;
+ struct State *start;
+ struct State *end;
+
+ a = ctx->stack_tail;
+ GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
+
+ if (NULL == a)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "nfa_add_question_op failed, because there was no element on the stack");
+ return;
+ }
+
+ start = nfa_state_create (ctx, 0);
+ end = nfa_state_create (ctx, 1);
+
+ add_transition (ctx, start, 0, a->start);
+ add_transition (ctx, start, 0, end);
+ add_transition (ctx, a->end, 0, end);
+
+ a->end->accepting = 0;
+
+ new = nfa_fragment_create (start, end);
+ nfa_add_states (new, a->states_head, a->states_tail);
+ automaton_fragment_clear (a);
+
+ GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
+}
+
/**
* Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment
* that alternates between a and b (a|b)
*
* @param ctx context
*/
-void
+static void
nfa_add_alternation (struct GNUNET_REGEX_Context *ctx)
{
struct GNUNET_REGEX_Automaton *a;
* @param ctx context
* @param lit literal for nfa transition
*/
-void
+static void
nfa_add_literal (struct GNUNET_REGEX_Context *ctx, const char lit)
{
struct GNUNET_REGEX_Automaton *n;
GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, n);
}
-/**
- * Calculates the NFA closure set for the given state
- *
- * @param s starting point state
- * @param literal transitioning literal on which to base the closure on,
- * pass 0 for epsilon transition
- *
- * @return nfa closure on 'literal' (epsilon closure if 'literal' is 0)
- */
-struct StateSet *
-nfa_closure_create (struct State *s, const char literal)
-{
- struct StateSet *cls;
- struct StateSet *cls_check;
- struct State *clsstate;
- struct State *currentstate;
- struct Transition *ctran;
-
- if (NULL == s)
- return NULL;
-
- cls = GNUNET_malloc (sizeof (struct StateSet));
- cls_check = GNUNET_malloc (sizeof (struct StateSet));
-
- // Add start state to closure only for epsilon closure
- if (0 == literal)
- GNUNET_array_append (cls->states, cls->len, s);
-
- GNUNET_array_append (cls_check->states, cls_check->len, s);
- while (cls_check->len > 0)
- {
- currentstate = cls_check->states[cls_check->len - 1];
- GNUNET_array_grow (cls_check->states, cls_check->len, cls_check->len - 1);
-
- for (ctran = currentstate->transitions_head; NULL != ctran;
- ctran = ctran->next)
- {
- if (NULL != ctran->state && literal == ctran->literal)
- {
- clsstate = ctran->state;
-
- if (NULL != clsstate &&
- GNUNET_YES != state_set_contains (cls, clsstate))
- {
- GNUNET_array_append (cls->states, cls->len, clsstate);
- GNUNET_array_append (cls_check->states, cls_check->len, clsstate);
- }
- }
- }
- }
- GNUNET_assert (0 == cls_check->len);
- GNUNET_free (cls_check);
-
- return cls;
-}
-
-/**
- * Calculates the closure set for the given set of states.
- *
- * @param states list of states on which to base the closure on
- * @param literal transitioning literal for which to base the closure on,
- * pass 0 for epsilon transition
- *
- * @return nfa closure on 'literal' (epsilon closure if 'literal' is 0)
- */
-struct StateSet *
-nfa_closure_set_create (struct StateSet *states, const char literal)
-{
- struct State *s;
- struct StateSet *sset;
- struct StateSet *cls;
- int i;
- int j;
-
- if (NULL == states)
- return NULL;
-
- cls = GNUNET_malloc (sizeof (struct StateSet));
-
- for (i = 0; i < states->len; i++)
- {
- s = states->states[i];
- sset = nfa_closure_create (s, literal);
-
- for (j = 0; j < sset->len; j++)
- GNUNET_array_append (cls->states, cls->len, sset->states[j]);
-
- if (NULL != sset)
- {
- if (sset->len > 0)
- GNUNET_free (sset->states);
- GNUNET_free (sset);
- }
- }
-
- return cls;
-}
-
/**
* Construct an NFA by parsing the regex string of length 'len'.
*
}
nfa_add_plus_op (&ctx);
break;
+ case '?':
+ if (atomcount == 0)
+ {
+ error_msg = "Cannot append '?' to nothing";
+ goto error;
+ }
+ nfa_add_question_op (&ctx);
+ break;
case 92: /* escape: \ */
regexp++;
count++;
goto error;
}
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "Created NFA with %i States and a total of %i Transitions\n",
- ctx.state_id, ctx.transition_id);
-
return nfa;
error:
GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex\n");
if (NULL != error_msg)
GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "%s\n", error_msg);
- GNUNET_free (p);
+ if (NULL != p)
+ GNUNET_free (p);
while (NULL != ctx.stack_tail)
{
GNUNET_REGEX_automaton_destroy (ctx.stack_tail);
// Create NFA
nfa = GNUNET_REGEX_construct_nfa (regex, len);
+ if (NULL == nfa)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Could not create DFA, because NFA creation failed\n");
+ return NULL;
+ }
+
dfa = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
dfa->type = DFA;
dfa_stack = GNUNET_malloc (sizeof (struct StateSet));
nfa_set = nfa_closure_create (nfa->start, 0);
dfa->start = dfa_state_create (&ctx, nfa_set);
- GNUNET_CONTAINER_DLL_insert (dfa->states_head, dfa->states_tail, dfa->start);
+ automaton_add_state (dfa, dfa->start);
GNUNET_array_append (dfa_stack->states, dfa_stack->len, dfa->start);
+
+ // Create dfa states by combining nfa states
while (dfa_stack->len > 0)
{
dfa_state = dfa_stack->states[dfa_stack->len - 1];
{
tmp = nfa_closure_set_create (dfa_state->nfa_set, ctran->literal);
nfa_set = nfa_closure_set_create (tmp, 0);
- if (NULL != tmp)
- {
- if (tmp->len > 0)
- GNUNET_free (tmp->states);
- GNUNET_free (tmp);
- }
+ state_set_clear (tmp);
new_dfa_state = dfa_state_create (&ctx, nfa_set);
state_contains = NULL;
for (state_iter = dfa->states_head; NULL != state_iter;
if (NULL == state_contains)
{
- GNUNET_CONTAINER_DLL_insert_tail (dfa->states_head, dfa->states_tail,
- new_dfa_state);
+ automaton_add_state (dfa, new_dfa_state);
GNUNET_array_append (dfa_stack->states, dfa_stack->len,
new_dfa_state);
ctran->state = new_dfa_state;
GNUNET_free (dfa_stack);
GNUNET_REGEX_automaton_destroy (nfa);
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Created DFA with %i States\n",
- ctx.state_id);
+ dfa_minimize (&ctx, dfa);
return dfa;
}
fclose (p);
}
-int
+/**
+ * Evaluates the given string using the given DFA automaton
+ *
+ * @param a automaton, type must be DFA
+ * @param string string that should be evaluated
+ *
+ * @return 0 if string matches, non 0 otherwise
+ */
+static int
evaluate_dfa (struct GNUNET_REGEX_Automaton *a, const char *string)
{
const char *strp;
struct State *s;
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Evaluating '%s' using DFA\n", string);
+ if (DFA != a->type)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Tried to evaluate DFA, but NFA automaton given");
+ return -1;
+ }
s = a->start;
}
if (NULL != s && s->accepting)
- return GNUNET_YES;
+ return 0;
- return GNUNET_NO;
+ return 1;
}
-int
+/**
+ * Evaluates the given string using the given NFA automaton
+ *
+ * @param a automaton, type must be NFA
+ * @param string string that should be evaluated
+ *
+ * @return 0 if string matches, non 0 otherwise
+ */
+static int
evaluate_nfa (struct GNUNET_REGEX_Automaton *a, const char *string)
{
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Evaluating '%s' using NFA\n", string);
+ const char *strp;
+ struct State *s;
+ struct StateSet *sset;
+ struct StateSet *new_sset;
+ int i;
+ int result;
- return GNUNET_YES;
-}
+ if (NFA != a->type)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Tried to evaluate NFA, but DFA automaton given");
+ return -1;
+ }
+
+ result = 1;
+ strp = string;
+ sset = nfa_closure_create (a->start, 0);
+
+ for (strp = string; NULL != strp && *strp; strp++)
+ {
+ new_sset = nfa_closure_set_create (sset, *strp);
+ state_set_clear (sset);
+ sset = nfa_closure_set_create (new_sset, 0);
+ state_set_clear (new_sset);
+ }
+
+ for (i = 0; i < sset->len; i++)
+ {
+ s = sset->states[i];
+ if (NULL != s && s->accepting)
+ {
+ result = 0;
+ break;
+ }
+ }
+ state_set_clear (sset);
+ return result;
+}
/**
* Evaluates the given 'string' against the given compiled regex
* @param a automaton
* @param string string to check
*
- * @return GNUNET_YES if 'a' matches 'string', GNUNET_NO otherwise
+ * @return 0 if string matches, non 0 otherwise
*/
int
GNUNET_REGEX_eval (struct GNUNET_REGEX_Automaton *a, const char *string)
{
- int eval;
+ int result;
switch (a->type)
{
case DFA:
- eval = evaluate_dfa (a, string);
+ result = evaluate_dfa (a, string);
break;
case NFA:
- eval = evaluate_nfa (a, string);
+ result = evaluate_nfa (a, string);
break;
default:
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
"Evaluating regex failed, automaton has no type!\n");
- eval = GNUNET_SYSERR;
+ result = GNUNET_SYSERR;
break;
}
- return eval;
+ return result;
}
projects / oweals / gnunet.git / blobdiff