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3 (C) 2012 Christian Grothoff (and other contributing authors)
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21 * @file src/regex/regex.c
22 * @brief library to create automatons from regular expressions
23 * @author Maximilian Szengel
26 #include "gnunet_container_lib.h"
27 #include "gnunet_crypto_lib.h"
28 #include "gnunet_regex_lib.h"
31 #define initial_bits 10
34 * Context that contains an id counter for states and transitions as well as a
35 * DLL of automatons used as a stack for NFA construction.
37 struct GNUNET_REGEX_Context
42 unsigned int state_id;
45 * Unique transition id.
47 unsigned int transition_id;
50 * Unique SCC (Strongly Connected Component) id.
55 * DLL of GNUNET_REGEX_Automaton's used as a stack.
57 struct GNUNET_REGEX_Automaton *stack_head;
60 * DLL of GNUNET_REGEX_Automaton's used as a stack.
62 struct GNUNET_REGEX_Automaton *stack_tail;
66 * Type of an automaton.
68 enum GNUNET_REGEX_automaton_type
75 * Automaton representation.
77 struct GNUNET_REGEX_Automaton
80 * This is a linked list.
82 struct GNUNET_REGEX_Automaton *prev;
85 * This is a linked list.
87 struct GNUNET_REGEX_Automaton *next;
90 * First state of the automaton. This is mainly used for constructing an NFA,
91 * where each NFA itself consists of one or more NFAs linked together.
93 struct GNUNET_REGEX_State *start;
96 * End state of the automaton.
98 struct GNUNET_REGEX_State *end;
101 * Number of states in the automaton.
103 unsigned int state_count;
108 struct GNUNET_REGEX_State *states_head;
113 struct GNUNET_REGEX_State *states_tail;
116 * Type of the automaton.
118 enum GNUNET_REGEX_automaton_type type;
122 * A state. Can be used in DFA and NFA automatons.
124 struct GNUNET_REGEX_State
127 * This is a linked list.
129 struct GNUNET_REGEX_State *prev;
132 * This is a linked list.
134 struct GNUNET_REGEX_State *next;
142 * If this is an accepting state or not.
147 * Marking of the state. This is used for marking all visited states when
148 * traversing all states of an automaton and for cases where the state id
149 * cannot be used (dfa minimization).
154 * Marking the state as contained. This is used for checking, if the state is
155 * contained in a set in constant time
160 * Marking the state as part of an SCC (Strongly Connected Component). All
161 * states with the same scc_id are part of the same SCC. scc_id is 0, if state
162 * is not a part of any SCC.
167 * Used for SCC detection.
172 * Used for SCC detection.
177 * Human readable name of the automaton. Used for debugging and graph
185 GNUNET_HashCode hash;
188 * Proof for this state.
193 * Number of transitions from this state to other states.
195 unsigned int transition_count;
198 * DLL of transitions.
200 struct Transition *transitions_head;
203 * DLL of transitions.
205 struct Transition *transitions_tail;
208 * Set of states on which this state is based on. Used when creating a DFA out
209 * of several NFA states.
211 struct GNUNET_REGEX_StateSet *nfa_set;
215 * Transition between two states. Each state can have 0-n transitions. If label
216 * is 0, this is considered to be an epsilon transition.
221 * This is a linked list.
223 struct Transition *prev;
226 * This is a linked list.
228 struct Transition *next;
231 * Unique id of this transition.
236 * Label for this transition. This is basically the edge label for the graph.
241 * State to which this transition leads.
243 struct GNUNET_REGEX_State *to_state;
246 * State from which this transition origins.
248 struct GNUNET_REGEX_State *from_state;
251 * Mark this transition. For example when reversing the automaton.
259 struct GNUNET_REGEX_StateSet
264 struct GNUNET_REGEX_State **states;
267 * Length of the 'states' array.
273 * Debug helper functions
276 debug_print_transitions (struct GNUNET_REGEX_State *);
279 debug_print_state (struct GNUNET_REGEX_State *s)
283 if (NULL == s->proof)
288 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
289 "State %i: %s marked: %i accepting: %i scc_id: %i transitions: %i proof: %s\n",
290 s->id, s->name, s->marked, s->accepting, s->scc_id,
291 s->transition_count, proof);
293 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transitions:\n");
294 debug_print_transitions (s);
298 debug_print_states (struct GNUNET_REGEX_Automaton *a)
300 struct GNUNET_REGEX_State *s;
302 for (s = a->states_head; NULL != s; s = s->next)
303 debug_print_state (s);
307 debug_print_transition (struct Transition *t)
321 if (NULL == t->to_state)
324 to_state = t->to_state->name;
326 if (NULL == t->from_state)
329 from_state = t->from_state->name;
331 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transition %i: From %s on %c to %s\n",
332 t->id, from_state, label, to_state);
336 debug_print_transitions (struct GNUNET_REGEX_State *s)
338 struct Transition *t;
340 for (t = s->transitions_head; NULL != t; t = t->next)
341 debug_print_transition (t);
345 * Recursive function doing DFS with 'v' as a start, detecting all SCCs inside
346 * the subgraph reachable from 'v'. Used with scc_tarjan function to detect all
347 * SCCs inside an automaton.
350 * @param v start vertex
351 * @param index current index
352 * @param stack stack for saving all SCCs
353 * @param stack_size current size of the stack
356 scc_tarjan_strongconnect (struct GNUNET_REGEX_Context *ctx,
357 struct GNUNET_REGEX_State *v, int *index,
358 struct GNUNET_REGEX_State **stack,
359 unsigned int *stack_size)
361 struct GNUNET_REGEX_State *w;
362 struct Transition *t;
367 stack[(*stack_size)++] = v;
370 for (t = v->transitions_head; NULL != t; t = t->next)
373 if (NULL != w && w->index < 0)
375 scc_tarjan_strongconnect (ctx, w, index, stack, stack_size);
376 v->lowlink = (v->lowlink > w->lowlink) ? w->lowlink : v->lowlink;
378 else if (0 != w->contained)
379 v->lowlink = (v->lowlink > w->index) ? w->index : v->lowlink;
382 if (v->lowlink == v->index)
384 w = stack[--(*stack_size)];
392 w->scc_id = ctx->scc_id;
393 w = stack[--(*stack_size)];
396 w->scc_id = ctx->scc_id;
402 * Detect all SCCs (Strongly Connected Components) inside the given automaton.
403 * SCCs will be marked using the scc_id on each state.
409 scc_tarjan (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *a)
412 struct GNUNET_REGEX_State *v;
413 struct GNUNET_REGEX_State *stack[a->state_count];
414 unsigned int stack_size;
416 for (v = a->states_head; NULL != v; v = v->next)
426 for (v = a->states_head; NULL != v; v = v->next)
429 scc_tarjan_strongconnect (ctx, v, &index, stack, &stack_size);
434 * Adds a transition from one state to another on 'label'. Does not add
438 * @param from_state starting state for the transition
439 * @param label transition label
440 * @param to_state state to where the transition should point to
443 state_add_transition (struct GNUNET_REGEX_Context *ctx,
444 struct GNUNET_REGEX_State *from_state, const char label,
445 struct GNUNET_REGEX_State *to_state)
448 struct Transition *t;
450 if (NULL == from_state)
452 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n");
456 // Do not add duplicate state transitions
458 for (t = from_state->transitions_head; NULL != t; t = t->next)
460 if (t->to_state == to_state && t->label == label &&
461 t->from_state == from_state)
471 t = GNUNET_malloc (sizeof (struct Transition));
472 t->id = ctx->transition_id++;
474 t->to_state = to_state;
475 t->from_state = from_state;
477 // Add outgoing transition to 'from_state'
478 from_state->transition_count++;
479 GNUNET_CONTAINER_DLL_insert (from_state->transitions_head,
480 from_state->transitions_tail, t);
484 * Compare two states. Used for sorting.
486 * @param a first state
487 * @param b second state
489 * @return an integer less than, equal to, or greater than zero
490 * if the first argument is considered to be respectively
491 * less than, equal to, or greater than the second.
494 state_compare (const void *a, const void *b)
496 struct GNUNET_REGEX_State **s1;
497 struct GNUNET_REGEX_State **s2;
499 s1 = (struct GNUNET_REGEX_State **) a;
500 s2 = (struct GNUNET_REGEX_State **) b;
502 return (*s1)->id - (*s2)->id;
506 * Get all edges leaving state 's'.
509 * @param edges all edges leaving 's'.
511 * @return number of edges.
514 state_get_edges (struct GNUNET_REGEX_State *s, struct GNUNET_REGEX_Edge *edges)
516 struct Transition *t;
524 for (t = s->transitions_head; NULL != t; t = t->next)
526 if (NULL != t->to_state)
528 edges[count].label = &t->label;
529 edges[count].destination = t->to_state->hash;
537 * Compare to state sets by comparing the id's of the states that are contained
538 * in each set. Both sets are expected to be sorted by id!
540 * @param sset1 first state set
541 * @param sset2 second state set
543 * @return an integer less than, equal to, or greater than zero
544 * if the first argument is considered to be respectively
545 * less than, equal to, or greater than the second.
548 state_set_compare (struct GNUNET_REGEX_StateSet *sset1,
549 struct GNUNET_REGEX_StateSet *sset2)
554 if (NULL == sset1 || NULL == sset2)
557 result = sset1->len - sset2->len;
559 for (i = 0; i < sset1->len; i++)
564 result = state_compare (&sset1->states[i], &sset2->states[i]);
570 * Clears the given StateSet 'set'
572 * @param set set to be cleared
575 state_set_clear (struct GNUNET_REGEX_StateSet *set)
579 GNUNET_free_non_null (set->states);
585 * Clears an automaton fragment. Does not destroy the states inside the
588 * @param a automaton to be cleared
591 automaton_fragment_clear (struct GNUNET_REGEX_Automaton *a)
598 a->states_head = NULL;
599 a->states_tail = NULL;
605 * Frees the memory used by State 's'
607 * @param s state that should be destroyed
610 automaton_destroy_state (struct GNUNET_REGEX_State *s)
612 struct Transition *t;
613 struct Transition *next_t;
618 GNUNET_free_non_null (s->name);
619 GNUNET_free_non_null (s->proof);
621 for (t = s->transitions_head; NULL != t; t = next_t)
624 GNUNET_CONTAINER_DLL_remove (s->transitions_head, s->transitions_tail, t);
628 state_set_clear (s->nfa_set);
634 * Remove a state from the given automaton 'a'. Always use this function when
635 * altering the states of an automaton. Will also remove all transitions leading
636 * to this state, before destroying it.
639 * @param s state to remove
642 automaton_remove_state (struct GNUNET_REGEX_Automaton *a,
643 struct GNUNET_REGEX_State *s)
645 struct GNUNET_REGEX_State *ss;
646 struct GNUNET_REGEX_State *s_check;
647 struct Transition *t_check;
649 if (NULL == a || NULL == s)
654 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s);
657 // remove all transitions leading to this state
658 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
660 for (t_check = s_check->transitions_head; NULL != t_check;
661 t_check = t_check->next)
663 if (t_check->to_state == ss)
665 GNUNET_CONTAINER_DLL_remove (s_check->transitions_head,
666 s_check->transitions_tail, t_check);
667 s_check->transition_count--;
672 automaton_destroy_state (ss);
676 * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy
681 * @param s1 first state
682 * @param s2 second state, will be destroyed
685 automaton_merge_states (struct GNUNET_REGEX_Context *ctx,
686 struct GNUNET_REGEX_Automaton *a,
687 struct GNUNET_REGEX_State *s1,
688 struct GNUNET_REGEX_State *s2)
690 struct GNUNET_REGEX_State *s_check;
691 struct Transition *t_check;
694 GNUNET_assert (NULL != ctx && NULL != a && NULL != s1 && NULL != s2);
699 // 1. Make all transitions pointing to s2 point to s1
700 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
702 for (t_check = s_check->transitions_head; NULL != t_check;
703 t_check = t_check->next)
705 if (s2 == t_check->to_state)
706 t_check->to_state = s1;
710 // 2. Add all transitions from s2 to sX to s1
711 for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next)
713 if (t_check->to_state != s1)
714 state_add_transition (ctx, s1, t_check->label, t_check->to_state);
717 // 3. Rename s1 to {s1,s2}
718 new_name = GNUNET_strdup (s1->name);
719 GNUNET_free_non_null (s1->name);
720 GNUNET_asprintf (&s1->name, "{%s,%s}", new_name, s2->name);
721 GNUNET_free (new_name);
724 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s2);
726 automaton_destroy_state (s2);
730 * Add a state to the automaton 'a', always use this function to alter the
731 * states DLL of the automaton.
733 * @param a automaton to add the state to
734 * @param s state that should be added
737 automaton_add_state (struct GNUNET_REGEX_Automaton *a,
738 struct GNUNET_REGEX_State *s)
740 GNUNET_CONTAINER_DLL_insert (a->states_head, a->states_tail, s);
745 * Function that is called with each state, when traversing an automaton.
750 typedef void (*GNUNET_REGEX_traverse_action) (void *cls,
751 struct GNUNET_REGEX_State * s);
754 * Traverses all states that are reachable from state 's'. Expects the states to
755 * be unmarked (s->marked == GNUNET_NO). Performs 'action' on each visited
758 * @param cls closure.
759 * @param s start state.
760 * @param action action to be performed on each state.
763 automaton_state_traverse (void *cls, struct GNUNET_REGEX_State *s,
764 GNUNET_REGEX_traverse_action action)
766 struct Transition *t;
768 if (GNUNET_NO == s->marked)
770 s->marked = GNUNET_YES;
775 for (t = s->transitions_head; NULL != t; t = t->next)
776 automaton_state_traverse (cls, t->to_state, action);
781 * Traverses the given automaton from it's start state, visiting all reachable
782 * states and calling 'action' on each one of them.
784 * @param cls closure.
785 * @param a automaton.
786 * @param action action to be performed on each state.
789 automaton_traverse (void *cls, struct GNUNET_REGEX_Automaton *a,
790 GNUNET_REGEX_traverse_action action)
792 struct GNUNET_REGEX_State *s;
794 for (s = a->states_head; NULL != s; s = s->next)
795 s->marked = GNUNET_NO;
797 automaton_state_traverse (cls, a->start, action);
801 * Create proofs for all states in the given automaton. Implementation of the
802 * algorithms descriped in chapter 3.2.1 of "Automata Theory, Languages, and
803 * Computation 3rd Edition" by Hopcroft, Motwani and Ullman.
805 * @param a automaton.
808 automaton_create_proofs (struct GNUNET_REGEX_Automaton *a)
810 struct GNUNET_REGEX_State *s;
811 struct Transition *t;
816 struct GNUNET_REGEX_State *states[a->state_count];
817 char *R_last[a->state_count][a->state_count];
818 char *R_cur[a->state_count][a->state_count];
825 for (i = 0, s = a->states_head; NULL != s; s = s->next, i++)
832 for (i = 0; i < n; i++)
834 for (j = 0; j < n; j++)
838 for (t = states[i]->transitions_head; NULL != t; t = t->next)
840 if (t->to_state == states[j])
842 if (NULL == R_last[i][j])
843 GNUNET_asprintf (&R_last[i][j], "%c", t->label);
847 GNUNET_asprintf (&R_last[i][j], "%s|%c", R_last[i][j], t->label);
853 if (NULL != R_last[i][j] && 1 < strlen (R_last[i][j]))
856 GNUNET_asprintf (&R_last[i][j], "(%s)", R_last[i][j]);
862 if (NULL == R_last[i][j])
863 GNUNET_asprintf (&R_last[i][j], "");
869 for (k = 0; k < n; k++)
871 for (i = 0; i < n; i++)
873 for (j = 0; j < n; j++)
877 if (NULL == R_last[i][k] || NULL == R_last[k][j])
879 if (NULL != R_last[i][j])
880 R_cur[i][j] = GNUNET_strdup (R_last[i][j]);
884 // R(k)ij = R(k-1)ij + R(k-1)ik (R(k-1)kk)* R(k-1)kj
886 snprintf (NULL, 0, "(%s|%s(%s)*%s)", R_last[i][j], R_last[i][k],
887 R_last[k][k], R_last[k][j]) + 1;
888 char *left = GNUNET_malloc (length);
889 char *right = GNUNET_malloc (length);
891 if (NULL != R_last[i][j])
892 strcat (left, R_last[i][j]);
894 if (NULL != R_last[i][k])
895 strcat (right, R_last[i][k]);
897 if (NULL != R_last[k][k] && 0 != strcmp (R_last[k][k], ""))
900 strcat (right, R_last[k][k]);
901 strcat (right, ")*");
904 if (NULL != R_last[k][j])
905 strcat (right, R_last[k][j]);
907 if (0 == strcmp (left, right) || 0 == strcmp (left, "") ||
908 0 == strcmp (right, ""))
910 if (0 == strcmp (left, ""))
911 GNUNET_asprintf (&R_cur[i][j], "%s", right);
913 GNUNET_asprintf (&R_cur[i][j], "%s", left);
916 GNUNET_asprintf (&R_cur[i][j], "(%s|%s)", left, right);
918 GNUNET_free_non_null (left);
919 GNUNET_free_non_null (right);
924 for (i = 0; i < n; i++)
926 for (j = 0; j < n; j++)
928 GNUNET_free_non_null (R_last[i][j]);
930 if (NULL != R_cur[i][j])
932 R_last[i][j] = GNUNET_strdup (R_cur[i][j]);
933 GNUNET_free (R_cur[i][j]);
940 // assign proofs and hashes
941 for (i = 0; i < n; i++)
943 states[i]->proof = GNUNET_strdup (R_last[a->start->marked][i]);
944 GNUNET_CRYPTO_hash (states[i]->proof, strlen (states[i]->proof),
949 for (i = 0; i < n; i++)
951 for (j = 0; j < n; j++)
952 GNUNET_free_non_null (R_last[i][j]);
957 * Creates a new DFA state based on a set of NFA states. Needs to be freed using
958 * automaton_destroy_state.
961 * @param nfa_states set of NFA states on which the DFA should be based on
963 * @return new DFA state
965 static struct GNUNET_REGEX_State *
966 dfa_state_create (struct GNUNET_REGEX_Context *ctx,
967 struct GNUNET_REGEX_StateSet *nfa_states)
969 struct GNUNET_REGEX_State *s;
972 struct GNUNET_REGEX_State *cstate;
973 struct Transition *ctran;
975 struct Transition *t;
978 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
979 s->id = ctx->state_id++;
989 if (NULL == nfa_states)
991 GNUNET_asprintf (&s->name, "s%i", s->id);
995 s->nfa_set = nfa_states;
997 if (nfa_states->len < 1)
1000 // Create a name based on 'sset'
1001 s->name = GNUNET_malloc (sizeof (char) * 2);
1002 strcat (s->name, "{");
1005 for (i = 0; i < nfa_states->len; i++)
1007 cstate = nfa_states->states[i];
1008 GNUNET_asprintf (&name, "%i,", cstate->id);
1012 len = strlen (s->name) + strlen (name) + 1;
1013 s->name = GNUNET_realloc (s->name, len);
1014 strcat (s->name, name);
1019 // Add a transition for each distinct label to NULL state
1020 for (ctran = cstate->transitions_head; NULL != ctran; ctran = ctran->next)
1022 if (0 != ctran->label)
1026 for (t = s->transitions_head; NULL != t; t = t->next)
1028 if (t->label == ctran->label)
1036 state_add_transition (ctx, s, ctran->label, NULL);
1040 // If the nfa_states contain an accepting state, the new dfa state is also
1042 if (cstate->accepting)
1046 s->name[strlen (s->name) - 1] = '}';
1052 * Move from the given state 's' to the next state on transition 'label'
1054 * @param s starting state
1055 * @param label edge label to follow
1057 * @return new state or NULL, if transition on label not possible
1059 static struct GNUNET_REGEX_State *
1060 dfa_move (struct GNUNET_REGEX_State *s, const char label)
1062 struct Transition *t;
1063 struct GNUNET_REGEX_State *new_s;
1070 for (t = s->transitions_head; NULL != t; t = t->next)
1072 if (label == t->label)
1074 new_s = t->to_state;
1083 * Remove all unreachable states from DFA 'a'. Unreachable states are those
1084 * states that are not reachable from the starting state.
1086 * @param a DFA automaton
1089 dfa_remove_unreachable_states (struct GNUNET_REGEX_Automaton *a)
1091 struct GNUNET_REGEX_State *s;
1092 struct GNUNET_REGEX_State *s_next;
1094 // 1. unmark all states
1095 for (s = a->states_head; NULL != s; s = s->next)
1096 s->marked = GNUNET_NO;
1098 // 2. traverse dfa from start state and mark all visited states
1099 automaton_traverse (NULL, a, NULL);
1101 // 3. delete all states that were not visited
1102 for (s = a->states_head; NULL != s; s = s_next)
1105 if (GNUNET_NO == s->marked)
1106 automaton_remove_state (a, s);
1111 * Remove all dead states from the DFA 'a'. Dead states are those states that do
1112 * not transition to any other state but themselfes.
1114 * @param a DFA automaton
1117 dfa_remove_dead_states (struct GNUNET_REGEX_Automaton *a)
1119 struct GNUNET_REGEX_State *s;
1120 struct Transition *t;
1123 GNUNET_assert (DFA == a->type);
1125 for (s = a->states_head; NULL != s; s = s->next)
1131 for (t = s->transitions_head; NULL != t; t = t->next)
1133 if (NULL != t->to_state && t->to_state != s)
1143 // state s is dead, remove it
1144 automaton_remove_state (a, s);
1149 * Merge all non distinguishable states in the DFA 'a'
1151 * @param ctx context
1152 * @param a DFA automaton
1155 dfa_merge_nondistinguishable_states (struct GNUNET_REGEX_Context *ctx,
1156 struct GNUNET_REGEX_Automaton *a)
1159 int table[a->state_count][a->state_count];
1160 struct GNUNET_REGEX_State *s1;
1161 struct GNUNET_REGEX_State *s2;
1162 struct Transition *t1;
1163 struct Transition *t2;
1164 struct GNUNET_REGEX_State *s1_next;
1165 struct GNUNET_REGEX_State *s2_next;
1167 int num_equal_edges;
1169 for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1;
1175 // Mark all pairs of accepting/!accepting states
1176 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1178 for (s2 = a->states_head; NULL != s2; s2 = s2->next)
1180 table[s1->marked][s2->marked] = 0;
1182 if ((s1->accepting && !s2->accepting) ||
1183 (!s1->accepting && s2->accepting))
1185 table[s1->marked][s2->marked] = 1;
1190 // Find all equal states
1195 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1197 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next)
1199 if (0 != table[s1->marked][s2->marked])
1202 num_equal_edges = 0;
1203 for (t1 = s1->transitions_head; NULL != t1; t1 = t1->next)
1205 for (t2 = s2->transitions_head; NULL != t2; t2 = t2->next)
1207 if (t1->label == t2->label)
1210 if (0 != table[t1->to_state->marked][t2->to_state->marked] ||
1211 0 != table[t2->to_state->marked][t1->to_state->marked])
1213 table[s1->marked][s2->marked] = t1->label != 0 ? t1->label : 1;
1219 if (num_equal_edges != s1->transition_count ||
1220 num_equal_edges != s2->transition_count)
1222 // Make sure ALL edges of possible equal states are the same
1223 table[s1->marked][s2->marked] = -2;
1229 // Merge states that are equal
1230 for (s1 = a->states_head; NULL != s1; s1 = s1_next)
1233 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2_next)
1236 if (table[s1->marked][s2->marked] == 0)
1237 automaton_merge_states (ctx, a, s1, s2);
1243 * Minimize the given DFA 'a' by removing all unreachable states, removing all
1244 * dead states and merging all non distinguishable states
1246 * @param ctx context
1247 * @param a DFA automaton
1250 dfa_minimize (struct GNUNET_REGEX_Context *ctx,
1251 struct GNUNET_REGEX_Automaton *a)
1256 GNUNET_assert (DFA == a->type);
1258 // 1. remove unreachable states
1259 dfa_remove_unreachable_states (a);
1261 // 2. remove dead states
1262 dfa_remove_dead_states (a);
1264 // 3. Merge nondistinguishable states
1265 dfa_merge_nondistinguishable_states (ctx, a);
1269 * Creates a new NFA fragment. Needs to be cleared using
1270 * automaton_fragment_clear.
1272 * @param start starting state
1273 * @param end end state
1275 * @return new NFA fragment
1277 static struct GNUNET_REGEX_Automaton *
1278 nfa_fragment_create (struct GNUNET_REGEX_State *start,
1279 struct GNUNET_REGEX_State *end)
1281 struct GNUNET_REGEX_Automaton *n;
1283 n = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
1289 if (NULL == start && NULL == end)
1292 automaton_add_state (n, end);
1293 automaton_add_state (n, start);
1302 * Adds a list of states to the given automaton 'n'.
1304 * @param n automaton to which the states should be added
1305 * @param states_head head of the DLL of states
1306 * @param states_tail tail of the DLL of states
1309 nfa_add_states (struct GNUNET_REGEX_Automaton *n,
1310 struct GNUNET_REGEX_State *states_head,
1311 struct GNUNET_REGEX_State *states_tail)
1313 struct GNUNET_REGEX_State *s;
1315 if (NULL == n || NULL == states_head)
1317 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n");
1321 if (NULL == n->states_head)
1323 n->states_head = states_head;
1324 n->states_tail = states_tail;
1328 if (NULL != states_head)
1330 n->states_tail->next = states_head;
1331 n->states_tail = states_tail;
1334 for (s = states_head; NULL != s; s = s->next)
1339 * Creates a new NFA state. Needs to be freed using automaton_destroy_state.
1341 * @param ctx context
1342 * @param accepting is it an accepting state or not
1344 * @return new NFA state
1346 static struct GNUNET_REGEX_State *
1347 nfa_state_create (struct GNUNET_REGEX_Context *ctx, int accepting)
1349 struct GNUNET_REGEX_State *s;
1351 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
1352 s->id = ctx->state_id++;
1353 s->accepting = accepting;
1360 GNUNET_asprintf (&s->name, "s%i", s->id);
1366 * Calculates the NFA closure set for the given state.
1368 * @param nfa the NFA containing 's'
1369 * @param s starting point state
1370 * @param label transitioning label on which to base the closure on,
1371 * pass 0 for epsilon transition
1373 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0)
1375 static struct GNUNET_REGEX_StateSet *
1376 nfa_closure_create (struct GNUNET_REGEX_Automaton *nfa,
1377 struct GNUNET_REGEX_State *s, const char label)
1379 struct GNUNET_REGEX_StateSet *cls;
1380 struct GNUNET_REGEX_StateSet *cls_check;
1381 struct GNUNET_REGEX_State *clsstate;
1382 struct GNUNET_REGEX_State *currentstate;
1383 struct Transition *ctran;
1388 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1389 cls_check = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1391 for (clsstate = nfa->states_head; NULL != clsstate; clsstate = clsstate->next)
1392 clsstate->contained = 0;
1394 // Add start state to closure only for epsilon closure
1396 GNUNET_array_append (cls->states, cls->len, s);
1398 GNUNET_array_append (cls_check->states, cls_check->len, s);
1399 while (cls_check->len > 0)
1401 currentstate = cls_check->states[cls_check->len - 1];
1402 GNUNET_array_grow (cls_check->states, cls_check->len, cls_check->len - 1);
1404 for (ctran = currentstate->transitions_head; NULL != ctran;
1405 ctran = ctran->next)
1407 if (NULL != ctran->to_state && label == ctran->label)
1409 clsstate = ctran->to_state;
1411 if (NULL != clsstate && 0 == clsstate->contained)
1413 GNUNET_array_append (cls->states, cls->len, clsstate);
1414 GNUNET_array_append (cls_check->states, cls_check->len, clsstate);
1415 clsstate->contained = 1;
1420 GNUNET_assert (0 == cls_check->len);
1421 GNUNET_free (cls_check);
1424 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
1431 * Calculates the closure set for the given set of states.
1433 * @param nfa the NFA containing 's'
1434 * @param states list of states on which to base the closure on
1435 * @param label transitioning label for which to base the closure on,
1436 * pass 0 for epsilon transition
1438 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0)
1440 static struct GNUNET_REGEX_StateSet *
1441 nfa_closure_set_create (struct GNUNET_REGEX_Automaton *nfa,
1442 struct GNUNET_REGEX_StateSet *states, const char label)
1444 struct GNUNET_REGEX_State *s;
1445 struct GNUNET_REGEX_StateSet *sset;
1446 struct GNUNET_REGEX_StateSet *cls;
1455 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1457 for (i = 0; i < states->len; i++)
1459 s = states->states[i];
1460 sset = nfa_closure_create (nfa, s, label);
1462 for (j = 0; j < sset->len; j++)
1465 for (k = 0; k < cls->len; k++)
1467 if (sset->states[j]->id == cls->states[k]->id)
1474 GNUNET_array_append (cls->states, cls->len, sset->states[j]);
1476 state_set_clear (sset);
1480 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
1487 * Pops two NFA fragments (a, b) from the stack and concatenates them (ab)
1489 * @param ctx context
1492 nfa_add_concatenation (struct GNUNET_REGEX_Context *ctx)
1494 struct GNUNET_REGEX_Automaton *a;
1495 struct GNUNET_REGEX_Automaton *b;
1496 struct GNUNET_REGEX_Automaton *new;
1498 b = ctx->stack_tail;
1499 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
1500 a = ctx->stack_tail;
1501 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1503 state_add_transition (ctx, a->end, 0, b->start);
1504 a->end->accepting = 0;
1505 b->end->accepting = 1;
1507 new = nfa_fragment_create (NULL, NULL);
1508 nfa_add_states (new, a->states_head, a->states_tail);
1509 nfa_add_states (new, b->states_head, b->states_tail);
1510 new->start = a->start;
1512 automaton_fragment_clear (a);
1513 automaton_fragment_clear (b);
1515 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
1519 * Pops a NFA fragment from the stack (a) and adds a new fragment (a*)
1521 * @param ctx context
1524 nfa_add_star_op (struct GNUNET_REGEX_Context *ctx)
1526 struct GNUNET_REGEX_Automaton *a;
1527 struct GNUNET_REGEX_Automaton *new;
1528 struct GNUNET_REGEX_State *start;
1529 struct GNUNET_REGEX_State *end;
1531 a = ctx->stack_tail;
1532 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1536 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1537 "nfa_add_star_op failed, because there was no element on the stack");
1541 start = nfa_state_create (ctx, 0);
1542 end = nfa_state_create (ctx, 1);
1544 state_add_transition (ctx, start, 0, a->start);
1545 state_add_transition (ctx, start, 0, end);
1546 state_add_transition (ctx, a->end, 0, a->start);
1547 state_add_transition (ctx, a->end, 0, end);
1549 a->end->accepting = 0;
1552 new = nfa_fragment_create (start, end);
1553 nfa_add_states (new, a->states_head, a->states_tail);
1554 automaton_fragment_clear (a);
1556 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
1560 * Pops an NFA fragment (a) from the stack and adds a new fragment (a+)
1562 * @param ctx context
1565 nfa_add_plus_op (struct GNUNET_REGEX_Context *ctx)
1567 struct GNUNET_REGEX_Automaton *a;
1569 a = ctx->stack_tail;
1570 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1572 state_add_transition (ctx, a->end, 0, a->start);
1574 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a);
1578 * Pops an NFA fragment (a) from the stack and adds a new fragment (a?)
1580 * @param ctx context
1583 nfa_add_question_op (struct GNUNET_REGEX_Context *ctx)
1585 struct GNUNET_REGEX_Automaton *a;
1586 struct GNUNET_REGEX_Automaton *new;
1587 struct GNUNET_REGEX_State *start;
1588 struct GNUNET_REGEX_State *end;
1590 a = ctx->stack_tail;
1591 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1595 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1596 "nfa_add_question_op failed, because there was no element on the stack");
1600 start = nfa_state_create (ctx, 0);
1601 end = nfa_state_create (ctx, 1);
1603 state_add_transition (ctx, start, 0, a->start);
1604 state_add_transition (ctx, start, 0, end);
1605 state_add_transition (ctx, a->end, 0, end);
1607 a->end->accepting = 0;
1609 new = nfa_fragment_create (start, end);
1610 nfa_add_states (new, a->states_head, a->states_tail);
1611 automaton_fragment_clear (a);
1613 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
1617 * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment that
1618 * alternates between a and b (a|b)
1620 * @param ctx context
1623 nfa_add_alternation (struct GNUNET_REGEX_Context *ctx)
1625 struct GNUNET_REGEX_Automaton *a;
1626 struct GNUNET_REGEX_Automaton *b;
1627 struct GNUNET_REGEX_Automaton *new;
1628 struct GNUNET_REGEX_State *start;
1629 struct GNUNET_REGEX_State *end;
1631 b = ctx->stack_tail;
1632 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
1633 a = ctx->stack_tail;
1634 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1636 start = nfa_state_create (ctx, 0);
1637 end = nfa_state_create (ctx, 1);
1638 state_add_transition (ctx, start, 0, a->start);
1639 state_add_transition (ctx, start, 0, b->start);
1641 state_add_transition (ctx, a->end, 0, end);
1642 state_add_transition (ctx, b->end, 0, end);
1644 a->end->accepting = 0;
1645 b->end->accepting = 0;
1648 new = nfa_fragment_create (start, end);
1649 nfa_add_states (new, a->states_head, a->states_tail);
1650 nfa_add_states (new, b->states_head, b->states_tail);
1651 automaton_fragment_clear (a);
1652 automaton_fragment_clear (b);
1654 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
1658 * Adds a new nfa fragment to the stack
1660 * @param ctx context
1661 * @param lit label for nfa transition
1664 nfa_add_label (struct GNUNET_REGEX_Context *ctx, const char lit)
1666 struct GNUNET_REGEX_Automaton *n;
1667 struct GNUNET_REGEX_State *start;
1668 struct GNUNET_REGEX_State *end;
1670 GNUNET_assert (NULL != ctx);
1672 start = nfa_state_create (ctx, 0);
1673 end = nfa_state_create (ctx, 1);
1674 state_add_transition (ctx, start, lit, end);
1675 n = nfa_fragment_create (start, end);
1676 GNUNET_assert (NULL != n);
1677 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, n);
1681 * Initialize a new context
1683 * @param ctx context
1686 GNUNET_REGEX_context_init (struct GNUNET_REGEX_Context *ctx)
1690 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Context was NULL!");
1694 ctx->transition_id = 0;
1696 ctx->stack_head = NULL;
1697 ctx->stack_tail = NULL;
1701 * Construct an NFA by parsing the regex string of length 'len'.
1703 * @param regex regular expression string
1704 * @param len length of the string
1706 * @return NFA, needs to be freed using GNUNET_REGEX_destroy_automaton
1708 struct GNUNET_REGEX_Automaton *
1709 GNUNET_REGEX_construct_nfa (const char *regex, const size_t len)
1711 struct GNUNET_REGEX_Context ctx;
1712 struct GNUNET_REGEX_Automaton *nfa;
1716 unsigned int altcount;
1717 unsigned int atomcount;
1718 unsigned int pcount;
1725 GNUNET_REGEX_context_init (&ctx);
1734 for (count = 0; count < len && *regexp; count++, regexp++)
1742 nfa_add_concatenation (&ctx);
1744 GNUNET_array_grow (p, pcount, pcount + 1);
1745 p[pcount - 1].altcount = altcount;
1746 p[pcount - 1].atomcount = atomcount;
1753 error_msg = "Cannot append '|' to nothing";
1756 while (--atomcount > 0)
1757 nfa_add_concatenation (&ctx);
1763 error_msg = "Missing opening '('";
1768 // Ignore this: "()"
1770 altcount = p[pcount].altcount;
1771 atomcount = p[pcount].atomcount;
1774 while (--atomcount > 0)
1775 nfa_add_concatenation (&ctx);
1776 for (; altcount > 0; altcount--)
1777 nfa_add_alternation (&ctx);
1779 altcount = p[pcount].altcount;
1780 atomcount = p[pcount].atomcount;
1786 error_msg = "Cannot append '*' to nothing";
1789 nfa_add_star_op (&ctx);
1794 error_msg = "Cannot append '+' to nothing";
1797 nfa_add_plus_op (&ctx);
1802 error_msg = "Cannot append '?' to nothing";
1805 nfa_add_question_op (&ctx);
1807 case 92: /* escape: \ */
1814 nfa_add_concatenation (&ctx);
1816 nfa_add_label (&ctx, *regexp);
1823 error_msg = "Unbalanced parenthesis";
1826 while (--atomcount > 0)
1827 nfa_add_concatenation (&ctx);
1828 for (; altcount > 0; altcount--)
1829 nfa_add_alternation (&ctx);
1831 GNUNET_free_non_null (p);
1833 nfa = ctx.stack_tail;
1834 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa);
1836 if (NULL != ctx.stack_head)
1838 error_msg = "Creating the NFA failed. NFA stack was not empty!";
1845 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex\n");
1846 if (NULL != error_msg)
1847 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "%s\n", error_msg);
1849 GNUNET_free_non_null (p);
1851 while (NULL != ctx.stack_tail)
1853 GNUNET_REGEX_automaton_destroy (ctx.stack_tail);
1854 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail,
1861 * Create DFA states based on given 'nfa' and starting with 'dfa_state'.
1863 * @param ctx context.
1864 * @param nfa NFA automaton.
1865 * @param dfa DFA automaton.
1866 * @param dfa_state current dfa state, pass epsilon closure of first nfa state
1870 construct_dfa_states (struct GNUNET_REGEX_Context *ctx,
1871 struct GNUNET_REGEX_Automaton *nfa,
1872 struct GNUNET_REGEX_Automaton *dfa,
1873 struct GNUNET_REGEX_State *dfa_state)
1875 struct Transition *ctran;
1876 struct GNUNET_REGEX_State *state_iter;
1877 struct GNUNET_REGEX_State *new_dfa_state;
1878 struct GNUNET_REGEX_State *state_contains;
1879 struct GNUNET_REGEX_StateSet *tmp;
1880 struct GNUNET_REGEX_StateSet *nfa_set;
1882 for (ctran = dfa_state->transitions_head; NULL != ctran; ctran = ctran->next)
1884 if (0 == ctran->label || NULL != ctran->to_state)
1887 tmp = nfa_closure_set_create (nfa, dfa_state->nfa_set, ctran->label);
1888 nfa_set = nfa_closure_set_create (nfa, tmp, 0);
1889 state_set_clear (tmp);
1890 new_dfa_state = dfa_state_create (ctx, nfa_set);
1891 state_contains = NULL;
1892 for (state_iter = dfa->states_head; NULL != state_iter;
1893 state_iter = state_iter->next)
1895 if (0 == state_set_compare (state_iter->nfa_set, new_dfa_state->nfa_set))
1896 state_contains = state_iter;
1899 if (NULL == state_contains)
1901 automaton_add_state (dfa, new_dfa_state);
1902 ctran->to_state = new_dfa_state;
1903 construct_dfa_states (ctx, nfa, dfa, new_dfa_state);
1907 ctran->to_state = state_contains;
1908 automaton_destroy_state (new_dfa_state);
1914 * Construct DFA for the given 'regex' of length 'len'
1916 * @param regex regular expression string
1917 * @param len length of the regular expression
1919 * @return DFA, needs to be freed using GNUNET_REGEX_destroy_automaton
1921 struct GNUNET_REGEX_Automaton *
1922 GNUNET_REGEX_construct_dfa (const char *regex, const size_t len)
1924 struct GNUNET_REGEX_Context ctx;
1925 struct GNUNET_REGEX_Automaton *dfa;
1926 struct GNUNET_REGEX_Automaton *nfa;
1927 struct GNUNET_REGEX_StateSet *nfa_set;
1929 GNUNET_REGEX_context_init (&ctx);
1932 nfa = GNUNET_REGEX_construct_nfa (regex, len);
1936 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1937 "Could not create DFA, because NFA creation failed\n");
1941 dfa = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
1944 // Create DFA start state from epsilon closure
1945 nfa_set = nfa_closure_create (nfa, nfa->start, 0);
1946 dfa->start = dfa_state_create (&ctx, nfa_set);
1947 automaton_add_state (dfa, dfa->start);
1949 construct_dfa_states (&ctx, nfa, dfa, dfa->start);
1951 GNUNET_REGEX_automaton_destroy (nfa);
1954 dfa_minimize (&ctx, dfa);
1957 scc_tarjan (&ctx, dfa);
1959 // Create proofs for all states
1960 automaton_create_proofs (dfa);
1966 * Free the memory allocated by constructing the GNUNET_REGEX_Automaton data
1969 * @param a automaton to be destroyed
1972 GNUNET_REGEX_automaton_destroy (struct GNUNET_REGEX_Automaton *a)
1974 struct GNUNET_REGEX_State *s;
1975 struct GNUNET_REGEX_State *next_state;
1980 for (s = a->states_head; NULL != s;)
1982 next_state = s->next;
1983 automaton_destroy_state (s);
1991 * Save the given automaton as a GraphViz dot file
1993 * @param a the automaton to be saved
1994 * @param filename where to save the file
1997 GNUNET_REGEX_automaton_save_graph (struct GNUNET_REGEX_Automaton *a,
1998 const char *filename)
2000 struct GNUNET_REGEX_State *s;
2001 struct Transition *ctran;
2003 char *s_tran = NULL;
2010 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print NFA, was NULL!");
2014 if (NULL == filename || strlen (filename) < 1)
2016 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No Filename given!");
2020 p = fopen (filename, "w");
2024 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not open file for writing: %s",
2029 start = "digraph G {\nrankdir=LR\n";
2030 fwrite (start, strlen (start), 1, p);
2032 for (s = a->states_head; NULL != s; s = s->next)
2036 GNUNET_asprintf (&s_acc,
2037 "\"%s\" [shape=doublecircle, color=\"0.%i 0.8 0.95\"];\n",
2038 s->name, s->scc_id);
2042 GNUNET_asprintf (&s_acc, "\"%s\" [color=\"0.%i 0.8 0.95\"];\n", s->name,
2048 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n",
2052 fwrite (s_acc, strlen (s_acc), 1, p);
2053 GNUNET_free (s_acc);
2056 for (ctran = s->transitions_head; NULL != ctran; ctran = ctran->next)
2058 if (NULL == ctran->to_state)
2060 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2061 "Transition from State %i has has no state for transitioning\n",
2066 if (ctran->label == 0)
2068 GNUNET_asprintf (&s_tran,
2069 "\"%s\" -> \"%s\" [label = \"epsilon\", color=\"0.%i 0.8 0.95\"];\n",
2070 s->name, ctran->to_state->name, s->scc_id);
2074 GNUNET_asprintf (&s_tran,
2075 "\"%s\" -> \"%s\" [label = \"%c\", color=\"0.%i 0.8 0.95\"];\n",
2076 s->name, ctran->to_state->name, ctran->label,
2082 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n",
2087 fwrite (s_tran, strlen (s_tran), 1, p);
2088 GNUNET_free (s_tran);
2094 fwrite (end, strlen (end), 1, p);
2099 * Evaluates the given string using the given DFA automaton
2101 * @param a automaton, type must be DFA
2102 * @param string string that should be evaluated
2104 * @return 0 if string matches, non 0 otherwise
2107 evaluate_dfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2110 struct GNUNET_REGEX_State *s;
2114 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2115 "Tried to evaluate DFA, but NFA automaton given");
2121 for (strp = string; NULL != strp && *strp; strp++)
2123 s = dfa_move (s, *strp);
2128 if (NULL != s && s->accepting)
2135 * Evaluates the given string using the given NFA automaton
2137 * @param a automaton, type must be NFA
2138 * @param string string that should be evaluated
2140 * @return 0 if string matches, non 0 otherwise
2143 evaluate_nfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2146 struct GNUNET_REGEX_State *s;
2147 struct GNUNET_REGEX_StateSet *sset;
2148 struct GNUNET_REGEX_StateSet *new_sset;
2154 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2155 "Tried to evaluate NFA, but DFA automaton given");
2161 sset = nfa_closure_create (a, a->start, 0);
2163 for (strp = string; NULL != strp && *strp; strp++)
2165 new_sset = nfa_closure_set_create (a, sset, *strp);
2166 state_set_clear (sset);
2167 sset = nfa_closure_set_create (a, new_sset, 0);
2168 state_set_clear (new_sset);
2171 for (i = 0; i < sset->len; i++)
2173 s = sset->states[i];
2174 if (NULL != s && s->accepting)
2181 state_set_clear (sset);
2186 * Evaluates the given 'string' against the given compiled regex
2188 * @param a automaton
2189 * @param string string to check
2191 * @return 0 if string matches, non 0 otherwise
2194 GNUNET_REGEX_eval (struct GNUNET_REGEX_Automaton *a, const char *string)
2201 result = evaluate_dfa (a, string);
2204 result = evaluate_nfa (a, string);
2207 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2208 "Evaluating regex failed, automaton has no type!\n");
2209 result = GNUNET_SYSERR;
2217 * Get the first key for the given 'input_string'. This hashes the first x bits
2218 * of the 'input_strings'.
2220 * @param input_string string.
2221 * @param string_len length of the 'input_string'.
2222 * @param key pointer to where to write the hash code.
2224 * @return number of bits of 'input_string' that have been consumed
2225 * to construct the key
2228 GNUNET_REGEX_get_first_key (const char *input_string, unsigned int string_len,
2229 GNUNET_HashCode * key)
2233 size = string_len < initial_bits ? string_len : initial_bits;
2235 if (NULL == input_string)
2237 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Given input string was NULL!\n");
2241 GNUNET_CRYPTO_hash (input_string, size, key);
2247 * Check if the given 'proof' matches the given 'key'.
2249 * @param proof partial regex
2252 * @return GNUNET_OK if the proof is valid for the given key
2255 GNUNET_REGEX_check_proof (const char *proof, const GNUNET_HashCode * key)
2261 * Iterate over all edges helper function starting from state 's', calling
2262 * iterator on for each edge.
2265 * @param iterator iterator function called for each edge.
2266 * @param iterator_cls closure.
2269 iterate_edge (struct GNUNET_REGEX_State *s, GNUNET_REGEX_KeyIterator iterator,
2272 struct Transition *t;
2273 struct GNUNET_REGEX_Edge edges[s->transition_count];
2274 unsigned int num_edges;
2276 if (GNUNET_YES != s->marked)
2278 s->marked = GNUNET_YES;
2280 num_edges = state_get_edges (s, edges);
2282 iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges, edges);
2284 for (t = s->transitions_head; NULL != t; t = t->next)
2285 iterate_edge (t->to_state, iterator, iterator_cls);
2290 * Iterate over all edges starting from start state of automaton 'a'. Calling
2291 * iterator for each edge.
2293 * @param a automaton.
2294 * @param iterator iterator called for each edge.
2295 * @param iterator_cls closure.
2298 GNUNET_REGEX_iterate_all_edges (struct GNUNET_REGEX_Automaton *a,
2299 GNUNET_REGEX_KeyIterator iterator,
2302 struct GNUNET_REGEX_State *s;
2304 for (s = a->states_head; NULL != s; s = s->next)
2305 s->marked = GNUNET_NO;
2307 iterate_edge (a->start, iterator, iterator_cls);