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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;
126 * Computed regex (result of RX->NFA->DFA->RX)
128 char *computed_regex;
132 * A state. Can be used in DFA and NFA automatons.
134 struct GNUNET_REGEX_State
137 * This is a linked list.
139 struct GNUNET_REGEX_State *prev;
142 * This is a linked list.
144 struct GNUNET_REGEX_State *next;
152 * If this is an accepting state or not.
157 * Marking of the state. This is used for marking all visited states when
158 * traversing all states of an automaton and for cases where the state id
159 * cannot be used (dfa minimization).
164 * Marking the state as contained. This is used for checking, if the state is
165 * contained in a set in constant time
170 * Marking the state as part of an SCC (Strongly Connected Component). All
171 * states with the same scc_id are part of the same SCC. scc_id is 0, if state
172 * is not a part of any SCC.
177 * Used for SCC detection.
182 * Used for SCC detection.
187 * Human readable name of the automaton. Used for debugging and graph
195 struct GNUNET_HashCode hash;
198 * State ID for proof creation.
200 unsigned int proof_id;
203 * Proof for this state.
208 * Number of transitions from this state to other states.
210 unsigned int transition_count;
213 * DLL of transitions.
215 struct Transition *transitions_head;
218 * DLL of transitions.
220 struct Transition *transitions_tail;
223 * Set of states on which this state is based on. Used when creating a DFA out
224 * of several NFA states.
226 struct GNUNET_REGEX_StateSet *nfa_set;
230 * Transition between two states. Each state can have 0-n transitions. If label
231 * is 0, this is considered to be an epsilon transition.
236 * This is a linked list.
238 struct Transition *prev;
241 * This is a linked list.
243 struct Transition *next;
246 * Unique id of this transition.
251 * Label for this transition. This is basically the edge label for the graph.
256 * State to which this transition leads.
258 struct GNUNET_REGEX_State *to_state;
261 * State from which this transition origins.
263 struct GNUNET_REGEX_State *from_state;
266 * Mark this transition. For example when reversing the automaton.
274 struct GNUNET_REGEX_StateSet
279 struct GNUNET_REGEX_State **states;
282 * Length of the 'states' array.
288 * Debug helper functions
291 debug_print_transitions (struct GNUNET_REGEX_State *);
294 debug_print_state (struct GNUNET_REGEX_State *s)
298 if (NULL == s->proof)
303 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
304 "State %i: %s marked: %i accepting: %i scc_id: %i transitions: %i proof: %s\n",
305 s->id, s->name, s->marked, s->accepting, s->scc_id,
306 s->transition_count, proof);
308 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transitions:\n");
309 debug_print_transitions (s);
313 debug_print_states (struct GNUNET_REGEX_Automaton *a)
315 struct GNUNET_REGEX_State *s;
317 for (s = a->states_head; NULL != s; s = s->next)
318 debug_print_state (s);
322 debug_print_transition (struct Transition *t)
336 if (NULL == t->to_state)
339 to_state = t->to_state->name;
341 if (NULL == t->from_state)
344 from_state = t->from_state->name;
346 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transition %i: From %s on %c to %s\n",
347 t->id, from_state, label, to_state);
351 debug_print_transitions (struct GNUNET_REGEX_State *s)
353 struct Transition *t;
355 for (t = s->transitions_head; NULL != t; t = t->next)
356 debug_print_transition (t);
360 * Recursive function doing DFS with 'v' as a start, detecting all SCCs inside
361 * the subgraph reachable from 'v'. Used with scc_tarjan function to detect all
362 * SCCs inside an automaton.
365 * @param v start vertex
366 * @param index current index
367 * @param stack stack for saving all SCCs
368 * @param stack_size current size of the stack
371 scc_tarjan_strongconnect (struct GNUNET_REGEX_Context *ctx,
372 struct GNUNET_REGEX_State *v, int *index,
373 struct GNUNET_REGEX_State **stack,
374 unsigned int *stack_size)
376 struct GNUNET_REGEX_State *w;
377 struct Transition *t;
382 stack[(*stack_size)++] = v;
385 for (t = v->transitions_head; NULL != t; t = t->next)
388 if (NULL != w && w->index < 0)
390 scc_tarjan_strongconnect (ctx, w, index, stack, stack_size);
391 v->lowlink = (v->lowlink > w->lowlink) ? w->lowlink : v->lowlink;
393 else if (0 != w->contained)
394 v->lowlink = (v->lowlink > w->index) ? w->index : v->lowlink;
397 if (v->lowlink == v->index)
399 w = stack[--(*stack_size)];
407 w->scc_id = ctx->scc_id;
408 w = stack[--(*stack_size)];
411 w->scc_id = ctx->scc_id;
417 * Detect all SCCs (Strongly Connected Components) inside the given automaton.
418 * SCCs will be marked using the scc_id on each state.
424 scc_tarjan (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *a)
427 struct GNUNET_REGEX_State *v;
428 struct GNUNET_REGEX_State *stack[a->state_count];
429 unsigned int stack_size;
431 for (v = a->states_head; NULL != v; v = v->next)
441 for (v = a->states_head; NULL != v; v = v->next)
444 scc_tarjan_strongconnect (ctx, v, &index, stack, &stack_size);
449 * Adds a transition from one state to another on 'label'. Does not add
453 * @param from_state starting state for the transition
454 * @param label transition label
455 * @param to_state state to where the transition should point to
458 state_add_transition (struct GNUNET_REGEX_Context *ctx,
459 struct GNUNET_REGEX_State *from_state, const char label,
460 struct GNUNET_REGEX_State *to_state)
463 struct Transition *t;
464 struct Transition *oth;
466 if (NULL == from_state)
468 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n");
472 // Do not add duplicate state transitions
474 for (t = from_state->transitions_head; NULL != t; t = t->next)
476 if (t->to_state == to_state && t->label == label &&
477 t->from_state == from_state)
487 // sort transitions by label
488 for (oth = from_state->transitions_head; NULL != oth; oth = oth->next)
490 if (oth->label > label)
494 t = GNUNET_malloc (sizeof (struct Transition));
495 t->id = ctx->transition_id++;
497 t->to_state = to_state;
498 t->from_state = from_state;
500 // Add outgoing transition to 'from_state'
501 from_state->transition_count++;
502 GNUNET_CONTAINER_DLL_insert_before (from_state->transitions_head,
503 from_state->transitions_tail, oth, t);
507 * Compare two states. Used for sorting.
509 * @param a first state
510 * @param b second state
512 * @return an integer less than, equal to, or greater than zero
513 * if the first argument is considered to be respectively
514 * less than, equal to, or greater than the second.
517 state_compare (const void *a, const void *b)
519 struct GNUNET_REGEX_State **s1;
520 struct GNUNET_REGEX_State **s2;
522 s1 = (struct GNUNET_REGEX_State **) a;
523 s2 = (struct GNUNET_REGEX_State **) b;
525 return (*s1)->id - (*s2)->id;
529 * Get all edges leaving state 's'.
532 * @param edges all edges leaving 's'.
534 * @return number of edges.
537 state_get_edges (struct GNUNET_REGEX_State *s, struct GNUNET_REGEX_Edge *edges)
539 struct Transition *t;
547 for (t = s->transitions_head; NULL != t; t = t->next)
549 if (NULL != t->to_state)
551 edges[count].label = &t->label;
552 edges[count].destination = t->to_state->hash;
560 * Compare to state sets by comparing the id's of the states that are contained
561 * in each set. Both sets are expected to be sorted by id!
563 * @param sset1 first state set
564 * @param sset2 second state set
566 * @return an integer less than, equal to, or greater than zero
567 * if the first argument is considered to be respectively
568 * less than, equal to, or greater than the second.
571 state_set_compare (struct GNUNET_REGEX_StateSet *sset1,
572 struct GNUNET_REGEX_StateSet *sset2)
577 if (NULL == sset1 || NULL == sset2)
580 result = sset1->len - sset2->len;
582 for (i = 0; i < sset1->len; i++)
587 result = state_compare (&sset1->states[i], &sset2->states[i]);
593 * Clears the given StateSet 'set'
595 * @param set set to be cleared
598 state_set_clear (struct GNUNET_REGEX_StateSet *set)
602 GNUNET_free_non_null (set->states);
608 * Clears an automaton fragment. Does not destroy the states inside the
611 * @param a automaton to be cleared
614 automaton_fragment_clear (struct GNUNET_REGEX_Automaton *a)
621 a->states_head = NULL;
622 a->states_tail = NULL;
628 * Frees the memory used by State 's'
630 * @param s state that should be destroyed
633 automaton_destroy_state (struct GNUNET_REGEX_State *s)
635 struct Transition *t;
636 struct Transition *next_t;
641 GNUNET_free_non_null (s->name);
642 GNUNET_free_non_null (s->proof);
644 for (t = s->transitions_head; NULL != t; t = next_t)
647 GNUNET_CONTAINER_DLL_remove (s->transitions_head, s->transitions_tail, t);
651 state_set_clear (s->nfa_set);
657 * Remove a state from the given automaton 'a'. Always use this function when
658 * altering the states of an automaton. Will also remove all transitions leading
659 * to this state, before destroying it.
662 * @param s state to remove
665 automaton_remove_state (struct GNUNET_REGEX_Automaton *a,
666 struct GNUNET_REGEX_State *s)
668 struct GNUNET_REGEX_State *ss;
669 struct GNUNET_REGEX_State *s_check;
670 struct Transition *t_check;
672 if (NULL == a || NULL == s)
677 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s);
680 // remove all transitions leading to this state
681 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
683 for (t_check = s_check->transitions_head; NULL != t_check;
684 t_check = t_check->next)
686 if (t_check->to_state == ss)
688 GNUNET_CONTAINER_DLL_remove (s_check->transitions_head,
689 s_check->transitions_tail, t_check);
690 s_check->transition_count--;
695 automaton_destroy_state (ss);
699 * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy
704 * @param s1 first state
705 * @param s2 second state, will be destroyed
708 automaton_merge_states (struct GNUNET_REGEX_Context *ctx,
709 struct GNUNET_REGEX_Automaton *a,
710 struct GNUNET_REGEX_State *s1,
711 struct GNUNET_REGEX_State *s2)
713 struct GNUNET_REGEX_State *s_check;
714 struct Transition *t_check;
717 GNUNET_assert (NULL != ctx && NULL != a && NULL != s1 && NULL != s2);
722 // 1. Make all transitions pointing to s2 point to s1
723 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
725 for (t_check = s_check->transitions_head; NULL != t_check;
726 t_check = t_check->next)
728 if (s2 == t_check->to_state)
729 t_check->to_state = s1;
733 // 2. Add all transitions from s2 to sX to s1
734 for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next)
736 if (t_check->to_state != s1)
737 state_add_transition (ctx, s1, t_check->label, t_check->to_state);
740 // 3. Rename s1 to {s1,s2}
741 new_name = GNUNET_strdup (s1->name);
742 GNUNET_free_non_null (s1->name);
743 GNUNET_asprintf (&s1->name, "{%s,%s}", new_name, s2->name);
744 GNUNET_free (new_name);
747 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s2);
749 automaton_destroy_state (s2);
753 * Add a state to the automaton 'a', always use this function to alter the
754 * states DLL of the automaton.
756 * @param a automaton to add the state to
757 * @param s state that should be added
760 automaton_add_state (struct GNUNET_REGEX_Automaton *a,
761 struct GNUNET_REGEX_State *s)
763 GNUNET_CONTAINER_DLL_insert (a->states_head, a->states_tail, s);
768 * Function that is called with each state, when traversing an automaton.
770 * @param cls closure.
771 * @param count current count of the state, from 0 to a->state_count -1.
774 typedef void (*GNUNET_REGEX_traverse_action) (void *cls, unsigned int count,
775 struct GNUNET_REGEX_State * s);
778 * Traverses all states that are reachable from state 's'. Expects the states to
779 * be unmarked (s->marked == GNUNET_NO). Performs 'action' on each visited
782 * @param cls closure.
783 * @param s start state.
784 * @param count current count of the state.
785 * @param action action to be performed on each state.
788 automaton_state_traverse (void *cls, struct GNUNET_REGEX_State *s,
790 GNUNET_REGEX_traverse_action action)
792 struct Transition *t;
794 if (GNUNET_NO == s->marked)
796 s->marked = GNUNET_YES;
799 action (cls, *count, s);
803 for (t = s->transitions_head; NULL != t; t = t->next)
804 automaton_state_traverse (cls, t->to_state, count, action);
809 * Traverses the given automaton from it's start state, visiting all reachable
810 * states and calling 'action' on each one of them.
812 * @param cls closure.
813 * @param a automaton.
814 * @param action action to be performed on each state.
817 automaton_traverse (void *cls, struct GNUNET_REGEX_Automaton *a,
818 GNUNET_REGEX_traverse_action action)
821 struct GNUNET_REGEX_State *s;
823 for (s = a->states_head; NULL != s; s = s->next)
824 s->marked = GNUNET_NO;
828 automaton_state_traverse (cls, a->start, &count, action);
832 * Check if the given string 'str' needs parentheses around it when
833 * using it to generate a regex.
837 * @return GNUNET_YES if parentheses are needed, GNUNET_NO otherwise
840 needs_parentheses (char *str)
847 length = strlen (str);
852 if (str[0] == '(' && str[strlen (str) - 1] == ')')
859 * Remove parentheses surrounding string 'str'.
860 * Example: "(a)" becomes "a".
861 * You need to GNUNET_free the retunred string.
865 * @return string without surrounding parentheses, string 'str' if no preceding
866 * epsilon could be found, NULL if 'str' was NULL
869 remove_parentheses (char *str)
879 length = strlen (str);
881 if (str[0] == '(' && str[length - 1] == ')')
883 new_str = GNUNET_malloc (length - 1);
884 for (j = 0, i = 1; i < length - 1; i++, j++)
889 new_str = GNUNET_strdup (str);
895 * Check if the string 'str' starts with an epsilon (empty string).
896 * Example: "(|a)" is starting with an epsilon.
903 has_epsilon (char *str)
912 return (0 == strncmp (str, "(|", 2) && str[len - 1] == ')');
916 * Remove an epsilon from the string str. Where epsilon is an empty string
917 * Example: str = "(|a|b|c)", result: "a|b|c"
918 * The returned string needs to be freed.
922 * @return string without preceding epsilon, string 'str' if no preceding epsilon
923 * could be found, NULL if 'str' was NULL
926 remove_epsilon (char *str)
938 if (len > 2 && 0 == strncmp (str, "(|", 2) && str[len - 1] == ')')
940 new_str = GNUNET_malloc (len - 1);
943 for (i = 2; i < len - 1; i++)
952 new_str = GNUNET_strdup (str);
959 strkcmp (const char *str1, const char *str2, int k)
961 const char *new_str1;
963 if (NULL == str1 || NULL == str2)
968 return strcmp (new_str1, str2);
972 number_states (void *cls, unsigned int count, struct GNUNET_REGEX_State *s)
974 struct GNUNET_REGEX_State **states;
982 * create proofs for all states in the given automaton. Implementation of the
983 * algorithm descriped in chapter 3.2.1 of "Automata Theory, Languages, and
984 * Computation 3rd Edition" by Hopcroft, Motwani and Ullman.
986 * @param a automaton.
989 automaton_create_proofs (struct GNUNET_REGEX_Automaton *a)
991 struct GNUNET_REGEX_State *states[a->state_count];
992 struct Transition *t;
993 char *R_last[a->state_count][a->state_count];
994 char *R_cur[a->state_count][a->state_count];
1003 char *complete_regex;
1015 int clean_ik_kk_cmp;
1016 int clean_kk_kj_cmp;
1024 // number the states
1025 automaton_traverse (states, a, number_states);
1028 for (i = 0; i < n; i++)
1030 for (j = 0; j < n; j++)
1033 R_last[i][j] = NULL;
1034 for (t = states[i]->transitions_head; NULL != t; t = t->next)
1036 if (t->to_state == states[j])
1038 if (NULL == R_last[i][j])
1039 GNUNET_asprintf (&R_last[i][j], "%c", t->label);
1042 temp_a = R_last[i][j];
1043 GNUNET_asprintf (&R_last[i][j], "%s|%c", R_last[i][j], t->label);
1044 GNUNET_free (temp_a);
1051 if (NULL == R_last[i][j])
1052 GNUNET_asprintf (&R_last[i][j], "");
1055 temp_a = R_last[i][j];
1056 GNUNET_asprintf (&R_last[i][j], "(|%s)", R_last[i][j]);
1057 GNUNET_free (temp_a);
1060 else if (GNUNET_YES == needs_parentheses (R_last[i][j]))
1062 temp_a = R_last[i][j];
1063 GNUNET_asprintf (&R_last[i][j], "(%s)", R_last[i][j]);
1064 GNUNET_free (temp_a);
1071 for (k = 0; k < n; k++)
1073 for (i = 0; i < n; i++)
1075 for (j = 0; j < n; j++)
1077 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, */
1078 /* ">>> R_last[i][j] = %s R_last[i][k] = %s " */
1079 /* "R_last[k][k] = %s R_last[k][j] = %s\n", R_last[i][j], */
1080 /* R_last[i][k], R_last[k][k], R_last[k][j]); */
1086 // Assign R_temp_(ij|ik|kk|kj) to R_last[][] and remove epsilon as well
1087 // as parentheses, so we can better compare the contents
1088 temp_a = remove_epsilon (R_last[i][j]);
1089 R_temp_ij = remove_parentheses (temp_a);
1090 GNUNET_free_non_null (temp_a);
1091 temp_a = remove_epsilon (R_last[i][k]);
1092 R_temp_ik = remove_parentheses (temp_a);
1093 GNUNET_free_non_null (temp_a);
1094 temp_a = remove_epsilon (R_last[k][k]);
1095 R_temp_kk = remove_parentheses (temp_a);
1096 GNUNET_free_non_null (temp_a);
1097 temp_a = remove_epsilon (R_last[k][j]);
1098 R_temp_kj = remove_parentheses (temp_a);
1099 GNUNET_free_non_null (temp_a);
1101 if (NULL != R_last[i][j] && NULL != R_last[k][j])
1102 ij_kj_cmp = strcmp (R_last[i][j], R_last[k][j]);
1106 if (NULL != R_last[i][j] && NULL != R_last[i][k])
1107 ij_ik_cmp = strcmp (R_last[i][j], R_last[i][k]);
1111 if (NULL != R_last[i][k] && NULL != R_last[k][k])
1112 ik_kk_cmp = strcmp (R_last[i][k], R_last[k][k]);
1116 if (NULL != R_last[i][k] && NULL != R_last[k][j])
1117 ik_kj_cmp = strcmp (R_last[i][k], R_last[k][j]);
1121 if (NULL != R_last[k][k] && NULL != R_last[k][j])
1122 kk_kj_cmp = strcmp (R_last[k][k], R_last[k][j]);
1126 if (NULL != R_last[i][k] && NULL != R_temp_kk)
1127 clean_ik_kk_cmp = strcmp (R_last[i][k], R_temp_kk);
1129 clean_ik_kk_cmp = 1;
1131 if (NULL != R_temp_kk && NULL != R_last[k][j])
1132 clean_kk_kj_cmp = strcmp (R_temp_kk, R_last[k][j]);
1134 clean_kk_kj_cmp = -1;
1137 // $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk})^* R^{(k-1)}_{kj}
1138 // With: R_cur[i][j] = R_cur_l | R_cur_r
1139 // Rij(k) = Rij(k-1), because right side (R_cur_r) is empty set (NULL)
1140 if ((NULL == R_last[i][k] || NULL == R_last[k][j] ||
1141 NULL == R_last[k][k]) && NULL != R_last[i][j])
1143 R_cur[i][j] = GNUNET_strdup (R_last[i][j]);
1145 // Everything is NULL, so Rij(k) = NULL
1146 else if ((NULL == R_last[i][k] || NULL == R_last[k][j] ||
1147 NULL == R_last[k][k]) && NULL == R_last[i][j])
1151 // Right side (R_cur_r) not NULL
1154 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, */
1155 /* "R_temp_ij = %s R_temp_ik = %s R_temp_kk = %s R_temp_kj = %s\n", */
1156 /* R_temp_ij, R_temp_ik, R_temp_kk, R_temp_kj); */
1158 GNUNET_assert (NULL != R_last[i][k] && NULL != R_last[k][k] &&
1159 NULL != R_last[k][j]);
1160 GNUNET_assert (NULL != R_temp_ik && NULL != R_temp_kk &&
1163 // construct R_cur_l (and, if necessary R_cur_r)
1164 if (NULL != R_last[i][j])
1166 if (0 == strcmp (R_temp_ij, R_temp_ik) &&
1167 0 == strcmp (R_temp_ik, R_temp_kk) &&
1168 0 == strcmp (R_temp_kk, R_temp_kj))
1170 if (0 == strlen (R_temp_ij))
1172 GNUNET_asprintf (&R_cur_r, "");
1174 // a|(e|a)a*(e|a) = a*
1175 // a|(e|a)(e|a)*(e|a) = a*
1177 // (e|a)|aa*(e|a) = a*
1178 // (e|a)|(e|a)a*a = a*
1179 // (e|a)|(e|a)a*(e|a) = a*
1180 // (e|a)|(e|a)(e|a)*(e|a) = a*
1181 else if ((0 == strncmp (R_last[i][j], "(|", 2)) ||
1182 (0 == strncmp (R_last[i][k], "(|", 2) &&
1183 0 == strncmp (R_last[k][j], "(|", 2)))
1185 if (GNUNET_YES == needs_parentheses (R_temp_ij))
1186 GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_ij);
1188 GNUNET_asprintf (&R_cur_r, "%s*", R_temp_ij);
1193 // a|(e|a)(e|a)*a = a+
1194 // a|a(e|a)*(e|a) = a+
1197 if (GNUNET_YES == needs_parentheses (R_temp_ij))
1198 GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_ij);
1200 GNUNET_asprintf (&R_cur_r, "%s+", R_temp_ij);
1204 else if (0 == ij_ik_cmp && 0 == clean_kk_kj_cmp &&
1205 0 != clean_ik_kk_cmp)
1207 if (strlen (R_last[k][k]) < 1)
1208 R_cur_r = GNUNET_strdup (R_last[i][j]);
1209 else if (GNUNET_YES == needs_parentheses (R_temp_kk))
1210 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][j], R_temp_kk);
1212 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][j], R_last[k][k]);
1217 else if (0 == ij_kj_cmp && 0 == clean_ik_kk_cmp &&
1218 0 != clean_kk_kj_cmp)
1220 if (strlen (R_last[k][k]) < 1)
1221 R_cur_r = GNUNET_strdup (R_last[k][j]);
1222 else if (GNUNET_YES == needs_parentheses (R_temp_kk))
1223 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last[k][j]);
1225 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[k][j]);
1229 // a|a(e|b)*(e|b) = a|ab* = a|a|ab|abb|abbb|... = ab*
1230 else if (0 == ij_ik_cmp && 0 == kk_kj_cmp &&
1231 !has_epsilon (R_last[i][j]) && has_epsilon (R_last[k][k]))
1233 if (needs_parentheses (R_temp_kk))
1234 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][j], R_temp_kk);
1236 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][j], R_temp_kk);
1240 // a|(e|b)(e|b)*a = a|b*a = a|a|ba|bba|bbba|... = b*a
1241 else if (0 == ij_kj_cmp && 0 == ik_kk_cmp &&
1242 !has_epsilon (R_last[i][j]) && has_epsilon (R_last[k][k]))
1244 if (needs_parentheses (R_temp_kk))
1245 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last[i][j]);
1247 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[i][j]);
1253 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "NO SIMPLIFICATION\n"); */
1255 temp_a = remove_parentheses (R_last[i][j]);
1256 R_cur_l = GNUNET_strdup (temp_a);
1257 GNUNET_free (temp_a);
1260 // we have no left side
1266 // construct R_cur_r, if not already constructed
1267 if (NULL == R_cur_r)
1269 length = strlen (R_temp_kk) - strlen (R_last[i][k]);
1271 // a(ba)*bx = (ab)+x
1272 if (length > 0 && NULL != R_last[k][k] && 0 < strlen (R_last[k][k])
1273 && NULL != R_last[k][j] && 0 < strlen (R_last[k][j]) &&
1274 NULL != R_last[i][k] && 0 < strlen (R_last[i][k]) &&
1275 0 == strkcmp (R_temp_kk, R_last[i][k], length) &&
1276 0 == strncmp (R_temp_kk, R_last[k][j], length))
1278 temp_a = GNUNET_malloc (length + 1);
1279 temp_b = GNUNET_malloc ((strlen (R_last[k][j]) - length) + 1);
1284 for (cnt = 0; cnt < strlen (R_last[k][j]); cnt++)
1288 temp_a[length_l] = R_last[k][j][cnt];
1293 temp_b[length_r] = R_last[k][j][cnt];
1297 temp_a[length_l] = '\0';
1298 temp_b[length_r] = '\0';
1301 if (NULL != R_cur_l && 0 == strlen (R_cur_l) &&
1302 0 == strlen (temp_b))
1304 GNUNET_asprintf (&R_cur_r, "(%s%s)*", R_last[i][k], temp_a);
1305 GNUNET_free (R_cur_l);
1310 GNUNET_asprintf (&R_cur_r, "(%s%s)+%s", R_last[i][k], temp_a,
1313 GNUNET_free (temp_a);
1314 GNUNET_free (temp_b);
1316 else if (0 == strcmp (R_temp_ik, R_temp_kk) &&
1317 0 == strcmp (R_temp_kk, R_temp_kj))
1319 // (e|a)a*(e|a) = a*
1320 // (e|a)(e|a)*(e|a) = a*
1321 if (has_epsilon (R_last[i][k]) && has_epsilon (R_last[k][j]))
1323 if (needs_parentheses (R_temp_kk))
1324 GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_kk);
1326 GNUNET_asprintf (&R_cur_r, "%s*", R_temp_kk);
1329 else if (0 == clean_ik_kk_cmp && 0 == clean_kk_kj_cmp &&
1330 !has_epsilon (R_last[i][k]))
1332 if (needs_parentheses (R_temp_kk))
1333 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk);
1335 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk);
1339 // a(e|a)*(e|a) = a+
1344 (has_epsilon (R_last[i][k]) + has_epsilon (R_last[k][k]) +
1345 has_epsilon (R_last[k][j]));
1349 if (needs_parentheses (R_temp_kk))
1350 GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_kk);
1352 GNUNET_asprintf (&R_cur_r, "%s+", R_temp_kk);
1357 // (e|a)(e|a)*b = a*b
1358 else if (0 == strcmp (R_temp_ik, R_temp_kk))
1360 if (has_epsilon (R_last[i][k]))
1362 if (needs_parentheses (R_temp_kk))
1363 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk,
1366 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[k][j]);
1370 if (needs_parentheses (R_temp_kk))
1371 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk,
1374 GNUNET_asprintf (&R_cur_r, "%s+%s", R_temp_kk, R_last[k][j]);
1378 // b(e|a)*(e|a) = ba*
1379 else if (0 == strcmp (R_temp_kk, R_temp_kj))
1381 if (has_epsilon (R_last[k][j]))
1383 if (needs_parentheses (R_temp_kk))
1384 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][k],
1387 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][k], R_temp_kk);
1391 if (needs_parentheses (R_temp_kk))
1392 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_last[i][k],
1395 GNUNET_asprintf (&R_cur_r, "%s+%s", R_last[i][k], R_temp_kk);
1400 if (strlen (R_temp_kk) > 0)
1402 if (needs_parentheses (R_temp_kk))
1404 GNUNET_asprintf (&R_cur_r, "%s(%s)*%s", R_last[i][k],
1405 R_temp_kk, R_last[k][j]);
1409 GNUNET_asprintf (&R_cur_r, "%s%s*%s", R_last[i][k], R_temp_kk,
1415 GNUNET_asprintf (&R_cur_r, "%s%s", R_last[i][k], R_last[k][j]);
1420 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "R_cur_l: %s\n", R_cur_l); */
1421 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "R_cur_r: %s\n", R_cur_r); */
1423 // putting it all together
1424 if (NULL != R_cur_l && NULL != R_cur_r)
1427 if (0 == strcmp (R_cur_l, R_cur_r))
1429 R_cur[i][j] = GNUNET_strdup (R_cur_l);
1431 // R_cur_l | R_cur_r
1434 GNUNET_asprintf (&R_cur[i][j], "(%s|%s)", R_cur_l, R_cur_r);
1437 else if (NULL != R_cur_l)
1439 R_cur[i][j] = GNUNET_strdup (R_cur_l);
1441 else if (NULL != R_cur_r)
1443 R_cur[i][j] = GNUNET_strdup (R_cur_r);
1450 GNUNET_free_non_null (R_cur_l);
1451 GNUNET_free_non_null (R_cur_r);
1454 GNUNET_free_non_null (R_temp_ij);
1455 GNUNET_free_non_null (R_temp_ik);
1456 GNUNET_free_non_null (R_temp_kk);
1457 GNUNET_free_non_null (R_temp_kj);
1461 // set R_last = R_cur
1462 for (i = 0; i < n; i++)
1464 for (j = 0; j < n; j++)
1466 GNUNET_free_non_null (R_last[i][j]);
1468 if (NULL != R_cur[i][j])
1470 R_last[i][j] = GNUNET_strdup (R_cur[i][j]);
1471 GNUNET_free (R_cur[i][j]);
1478 // assign proofs and hashes
1479 for (i = 0; i < n; i++)
1481 if (NULL != R_last[a->start->proof_id][i])
1483 states[i]->proof = GNUNET_strdup (R_last[a->start->proof_id][i]);
1484 GNUNET_CRYPTO_hash (states[i]->proof, strlen (states[i]->proof),
1489 // complete regex for whole DFA: union of all pairs (start state/accepting state(s)).
1490 complete_regex = NULL;
1491 for (i = 0; i < n; i++)
1493 if (states[i]->accepting)
1495 if (NULL == complete_regex && 0 < strlen (R_last[a->start->proof_id][i]))
1496 GNUNET_asprintf (&complete_regex, "%s", R_last[a->start->proof_id][i]);
1497 else if (NULL != R_last[a->start->proof_id][i] &&
1498 0 < strlen (R_last[a->start->proof_id][i]))
1500 temp_a = complete_regex;
1501 GNUNET_asprintf (&complete_regex, "%s|%s", complete_regex,
1502 R_last[a->start->proof_id][i]);
1503 GNUNET_free (temp_a);
1507 a->computed_regex = complete_regex;
1509 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1510 "---------------------------------------------\n");
1511 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Regex: %s\n", a->regex);
1512 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Complete Regex: %s\n", complete_regex);
1513 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1514 "---------------------------------------------\n");
1517 for (i = 0; i < n; i++)
1519 for (j = 0; j < n; j++)
1520 GNUNET_free_non_null (R_last[i][j]);
1525 * Creates a new DFA state based on a set of NFA states. Needs to be freed using
1526 * automaton_destroy_state.
1528 * @param ctx context
1529 * @param nfa_states set of NFA states on which the DFA should be based on
1531 * @return new DFA state
1533 static struct GNUNET_REGEX_State *
1534 dfa_state_create (struct GNUNET_REGEX_Context *ctx,
1535 struct GNUNET_REGEX_StateSet *nfa_states)
1537 struct GNUNET_REGEX_State *s;
1540 struct GNUNET_REGEX_State *cstate;
1541 struct Transition *ctran;
1543 struct Transition *t;
1546 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
1547 s->id = ctx->state_id++;
1557 if (NULL == nfa_states)
1559 GNUNET_asprintf (&s->name, "s%i", s->id);
1563 s->nfa_set = nfa_states;
1565 if (nfa_states->len < 1)
1568 // Create a name based on 'sset'
1569 s->name = GNUNET_malloc (sizeof (char) * 2);
1570 strcat (s->name, "{");
1573 for (i = 0; i < nfa_states->len; i++)
1575 cstate = nfa_states->states[i];
1576 GNUNET_asprintf (&name, "%i,", cstate->id);
1580 len = strlen (s->name) + strlen (name) + 1;
1581 s->name = GNUNET_realloc (s->name, len);
1582 strcat (s->name, name);
1587 // Add a transition for each distinct label to NULL state
1588 for (ctran = cstate->transitions_head; NULL != ctran; ctran = ctran->next)
1590 if (0 != ctran->label)
1594 for (t = s->transitions_head; NULL != t; t = t->next)
1596 if (t->label == ctran->label)
1604 state_add_transition (ctx, s, ctran->label, NULL);
1608 // If the nfa_states contain an accepting state, the new dfa state is also
1610 if (cstate->accepting)
1614 s->name[strlen (s->name) - 1] = '}';
1620 * Move from the given state 's' to the next state on transition 'label'
1622 * @param s starting state
1623 * @param label edge label to follow
1625 * @return new state or NULL, if transition on label not possible
1627 static struct GNUNET_REGEX_State *
1628 dfa_move (struct GNUNET_REGEX_State *s, const char label)
1630 struct Transition *t;
1631 struct GNUNET_REGEX_State *new_s;
1638 for (t = s->transitions_head; NULL != t; t = t->next)
1640 if (label == t->label)
1642 new_s = t->to_state;
1651 * Remove all unreachable states from DFA 'a'. Unreachable states are those
1652 * states that are not reachable from the starting state.
1654 * @param a DFA automaton
1657 dfa_remove_unreachable_states (struct GNUNET_REGEX_Automaton *a)
1659 struct GNUNET_REGEX_State *s;
1660 struct GNUNET_REGEX_State *s_next;
1662 // 1. unmark all states
1663 for (s = a->states_head; NULL != s; s = s->next)
1664 s->marked = GNUNET_NO;
1666 // 2. traverse dfa from start state and mark all visited states
1667 automaton_traverse (NULL, a, NULL);
1669 // 3. delete all states that were not visited
1670 for (s = a->states_head; NULL != s; s = s_next)
1673 if (GNUNET_NO == s->marked)
1674 automaton_remove_state (a, s);
1679 * Remove all dead states from the DFA 'a'. Dead states are those states that do
1680 * not transition to any other state but themselfes.
1682 * @param a DFA automaton
1685 dfa_remove_dead_states (struct GNUNET_REGEX_Automaton *a)
1687 struct GNUNET_REGEX_State *s;
1688 struct Transition *t;
1691 GNUNET_assert (DFA == a->type);
1693 for (s = a->states_head; NULL != s; s = s->next)
1699 for (t = s->transitions_head; NULL != t; t = t->next)
1701 if (NULL != t->to_state && t->to_state != s)
1711 // state s is dead, remove it
1712 automaton_remove_state (a, s);
1717 * Merge all non distinguishable states in the DFA 'a'
1719 * @param ctx context
1720 * @param a DFA automaton
1723 dfa_merge_nondistinguishable_states (struct GNUNET_REGEX_Context *ctx,
1724 struct GNUNET_REGEX_Automaton *a)
1727 int table[a->state_count][a->state_count];
1728 struct GNUNET_REGEX_State *s1;
1729 struct GNUNET_REGEX_State *s2;
1730 struct Transition *t1;
1731 struct Transition *t2;
1732 struct GNUNET_REGEX_State *s1_next;
1733 struct GNUNET_REGEX_State *s2_next;
1735 int num_equal_edges;
1737 for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1;
1743 // Mark all pairs of accepting/!accepting states
1744 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1746 for (s2 = a->states_head; NULL != s2; s2 = s2->next)
1748 table[s1->marked][s2->marked] = 0;
1750 if ((s1->accepting && !s2->accepting) ||
1751 (!s1->accepting && s2->accepting))
1753 table[s1->marked][s2->marked] = 1;
1758 // Find all equal states
1763 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1765 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next)
1767 if (0 != table[s1->marked][s2->marked])
1770 num_equal_edges = 0;
1771 for (t1 = s1->transitions_head; NULL != t1; t1 = t1->next)
1773 for (t2 = s2->transitions_head; NULL != t2; t2 = t2->next)
1775 if (t1->label == t2->label)
1778 if (0 != table[t1->to_state->marked][t2->to_state->marked] ||
1779 0 != table[t2->to_state->marked][t1->to_state->marked])
1781 table[s1->marked][s2->marked] = t1->label != 0 ? t1->label : 1;
1787 if (num_equal_edges != s1->transition_count ||
1788 num_equal_edges != s2->transition_count)
1790 // Make sure ALL edges of possible equal states are the same
1791 table[s1->marked][s2->marked] = -2;
1797 // Merge states that are equal
1798 for (s1 = a->states_head; NULL != s1; s1 = s1_next)
1801 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2_next)
1804 if (table[s1->marked][s2->marked] == 0)
1805 automaton_merge_states (ctx, a, s1, s2);
1811 * Minimize the given DFA 'a' by removing all unreachable states, removing all
1812 * dead states and merging all non distinguishable states
1814 * @param ctx context
1815 * @param a DFA automaton
1818 dfa_minimize (struct GNUNET_REGEX_Context *ctx,
1819 struct GNUNET_REGEX_Automaton *a)
1824 GNUNET_assert (DFA == a->type);
1826 // 1. remove unreachable states
1827 dfa_remove_unreachable_states (a);
1829 // 2. remove dead states
1830 dfa_remove_dead_states (a);
1832 // 3. Merge nondistinguishable states
1833 dfa_merge_nondistinguishable_states (ctx, a);
1837 * Creates a new NFA fragment. Needs to be cleared using
1838 * automaton_fragment_clear.
1840 * @param start starting state
1841 * @param end end state
1843 * @return new NFA fragment
1845 static struct GNUNET_REGEX_Automaton *
1846 nfa_fragment_create (struct GNUNET_REGEX_State *start,
1847 struct GNUNET_REGEX_State *end)
1849 struct GNUNET_REGEX_Automaton *n;
1851 n = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
1857 if (NULL == start && NULL == end)
1860 automaton_add_state (n, end);
1861 automaton_add_state (n, start);
1870 * Adds a list of states to the given automaton 'n'.
1872 * @param n automaton to which the states should be added
1873 * @param states_head head of the DLL of states
1874 * @param states_tail tail of the DLL of states
1877 nfa_add_states (struct GNUNET_REGEX_Automaton *n,
1878 struct GNUNET_REGEX_State *states_head,
1879 struct GNUNET_REGEX_State *states_tail)
1881 struct GNUNET_REGEX_State *s;
1883 if (NULL == n || NULL == states_head)
1885 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n");
1889 if (NULL == n->states_head)
1891 n->states_head = states_head;
1892 n->states_tail = states_tail;
1896 if (NULL != states_head)
1898 n->states_tail->next = states_head;
1899 n->states_tail = states_tail;
1902 for (s = states_head; NULL != s; s = s->next)
1907 * Creates a new NFA state. Needs to be freed using automaton_destroy_state.
1909 * @param ctx context
1910 * @param accepting is it an accepting state or not
1912 * @return new NFA state
1914 static struct GNUNET_REGEX_State *
1915 nfa_state_create (struct GNUNET_REGEX_Context *ctx, int accepting)
1917 struct GNUNET_REGEX_State *s;
1919 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
1920 s->id = ctx->state_id++;
1921 s->accepting = accepting;
1928 GNUNET_asprintf (&s->name, "s%i", s->id);
1934 * Calculates the NFA closure set for the given state.
1936 * @param nfa the NFA containing 's'
1937 * @param s starting point state
1938 * @param label transitioning label on which to base the closure on,
1939 * pass 0 for epsilon transition
1941 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0)
1943 static struct GNUNET_REGEX_StateSet *
1944 nfa_closure_create (struct GNUNET_REGEX_Automaton *nfa,
1945 struct GNUNET_REGEX_State *s, const char label)
1947 struct GNUNET_REGEX_StateSet *cls;
1948 struct GNUNET_REGEX_StateSet *cls_check;
1949 struct GNUNET_REGEX_State *clsstate;
1950 struct GNUNET_REGEX_State *currentstate;
1951 struct Transition *ctran;
1956 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1957 cls_check = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1959 for (clsstate = nfa->states_head; NULL != clsstate; clsstate = clsstate->next)
1960 clsstate->contained = 0;
1962 // Add start state to closure only for epsilon closure
1964 GNUNET_array_append (cls->states, cls->len, s);
1966 GNUNET_array_append (cls_check->states, cls_check->len, s);
1967 while (cls_check->len > 0)
1969 currentstate = cls_check->states[cls_check->len - 1];
1970 GNUNET_array_grow (cls_check->states, cls_check->len, cls_check->len - 1);
1972 for (ctran = currentstate->transitions_head; NULL != ctran;
1973 ctran = ctran->next)
1975 if (NULL != ctran->to_state && label == ctran->label)
1977 clsstate = ctran->to_state;
1979 if (NULL != clsstate && 0 == clsstate->contained)
1981 GNUNET_array_append (cls->states, cls->len, clsstate);
1982 GNUNET_array_append (cls_check->states, cls_check->len, clsstate);
1983 clsstate->contained = 1;
1988 GNUNET_assert (0 == cls_check->len);
1989 GNUNET_free (cls_check);
1993 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
2000 * Calculates the closure set for the given set of states.
2002 * @param nfa the NFA containing 's'
2003 * @param states list of states on which to base the closure on
2004 * @param label transitioning label for which to base the closure on,
2005 * pass 0 for epsilon transition
2007 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0)
2009 static struct GNUNET_REGEX_StateSet *
2010 nfa_closure_set_create (struct GNUNET_REGEX_Automaton *nfa,
2011 struct GNUNET_REGEX_StateSet *states, const char label)
2013 struct GNUNET_REGEX_State *s;
2014 struct GNUNET_REGEX_StateSet *sset;
2015 struct GNUNET_REGEX_StateSet *cls;
2024 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
2026 for (i = 0; i < states->len; i++)
2028 s = states->states[i];
2029 sset = nfa_closure_create (nfa, s, label);
2031 for (j = 0; j < sset->len; j++)
2034 for (k = 0; k < cls->len; k++)
2036 if (sset->states[j]->id == cls->states[k]->id)
2043 GNUNET_array_append (cls->states, cls->len, sset->states[j]);
2045 state_set_clear (sset);
2049 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
2056 * Pops two NFA fragments (a, b) from the stack and concatenates them (ab)
2058 * @param ctx context
2061 nfa_add_concatenation (struct GNUNET_REGEX_Context *ctx)
2063 struct GNUNET_REGEX_Automaton *a;
2064 struct GNUNET_REGEX_Automaton *b;
2065 struct GNUNET_REGEX_Automaton *new;
2067 b = ctx->stack_tail;
2068 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
2069 a = ctx->stack_tail;
2070 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2072 state_add_transition (ctx, a->end, 0, b->start);
2073 a->end->accepting = 0;
2074 b->end->accepting = 1;
2076 new = nfa_fragment_create (NULL, NULL);
2077 nfa_add_states (new, a->states_head, a->states_tail);
2078 nfa_add_states (new, b->states_head, b->states_tail);
2079 new->start = a->start;
2081 automaton_fragment_clear (a);
2082 automaton_fragment_clear (b);
2084 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2088 * Pops a NFA fragment from the stack (a) and adds a new fragment (a*)
2090 * @param ctx context
2093 nfa_add_star_op (struct GNUNET_REGEX_Context *ctx)
2095 struct GNUNET_REGEX_Automaton *a;
2096 struct GNUNET_REGEX_Automaton *new;
2097 struct GNUNET_REGEX_State *start;
2098 struct GNUNET_REGEX_State *end;
2100 a = ctx->stack_tail;
2101 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2105 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2106 "nfa_add_star_op failed, because there was no element on the stack");
2110 start = nfa_state_create (ctx, 0);
2111 end = nfa_state_create (ctx, 1);
2113 state_add_transition (ctx, start, 0, a->start);
2114 state_add_transition (ctx, start, 0, end);
2115 state_add_transition (ctx, a->end, 0, a->start);
2116 state_add_transition (ctx, a->end, 0, end);
2118 a->end->accepting = 0;
2121 new = nfa_fragment_create (start, end);
2122 nfa_add_states (new, a->states_head, a->states_tail);
2123 automaton_fragment_clear (a);
2125 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2129 * Pops an NFA fragment (a) from the stack and adds a new fragment (a+)
2131 * @param ctx context
2134 nfa_add_plus_op (struct GNUNET_REGEX_Context *ctx)
2136 struct GNUNET_REGEX_Automaton *a;
2138 a = ctx->stack_tail;
2139 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2141 state_add_transition (ctx, a->end, 0, a->start);
2143 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a);
2147 * Pops an NFA fragment (a) from the stack and adds a new fragment (a?)
2149 * @param ctx context
2152 nfa_add_question_op (struct GNUNET_REGEX_Context *ctx)
2154 struct GNUNET_REGEX_Automaton *a;
2155 struct GNUNET_REGEX_Automaton *new;
2156 struct GNUNET_REGEX_State *start;
2157 struct GNUNET_REGEX_State *end;
2159 a = ctx->stack_tail;
2160 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2164 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2165 "nfa_add_question_op failed, because there was no element on the stack");
2169 start = nfa_state_create (ctx, 0);
2170 end = nfa_state_create (ctx, 1);
2172 state_add_transition (ctx, start, 0, a->start);
2173 state_add_transition (ctx, start, 0, end);
2174 state_add_transition (ctx, a->end, 0, end);
2176 a->end->accepting = 0;
2178 new = nfa_fragment_create (start, end);
2179 nfa_add_states (new, a->states_head, a->states_tail);
2180 automaton_fragment_clear (a);
2182 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2186 * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment that
2187 * alternates between a and b (a|b)
2189 * @param ctx context
2192 nfa_add_alternation (struct GNUNET_REGEX_Context *ctx)
2194 struct GNUNET_REGEX_Automaton *a;
2195 struct GNUNET_REGEX_Automaton *b;
2196 struct GNUNET_REGEX_Automaton *new;
2197 struct GNUNET_REGEX_State *start;
2198 struct GNUNET_REGEX_State *end;
2200 b = ctx->stack_tail;
2201 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
2202 a = ctx->stack_tail;
2203 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2205 start = nfa_state_create (ctx, 0);
2206 end = nfa_state_create (ctx, 1);
2207 state_add_transition (ctx, start, 0, a->start);
2208 state_add_transition (ctx, start, 0, b->start);
2210 state_add_transition (ctx, a->end, 0, end);
2211 state_add_transition (ctx, b->end, 0, end);
2213 a->end->accepting = 0;
2214 b->end->accepting = 0;
2217 new = nfa_fragment_create (start, end);
2218 nfa_add_states (new, a->states_head, a->states_tail);
2219 nfa_add_states (new, b->states_head, b->states_tail);
2220 automaton_fragment_clear (a);
2221 automaton_fragment_clear (b);
2223 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2227 * Adds a new nfa fragment to the stack
2229 * @param ctx context
2230 * @param lit label for nfa transition
2233 nfa_add_label (struct GNUNET_REGEX_Context *ctx, const char lit)
2235 struct GNUNET_REGEX_Automaton *n;
2236 struct GNUNET_REGEX_State *start;
2237 struct GNUNET_REGEX_State *end;
2239 GNUNET_assert (NULL != ctx);
2241 start = nfa_state_create (ctx, 0);
2242 end = nfa_state_create (ctx, 1);
2243 state_add_transition (ctx, start, lit, end);
2244 n = nfa_fragment_create (start, end);
2245 GNUNET_assert (NULL != n);
2246 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, n);
2250 * Initialize a new context
2252 * @param ctx context
2255 GNUNET_REGEX_context_init (struct GNUNET_REGEX_Context *ctx)
2259 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Context was NULL!");
2263 ctx->transition_id = 0;
2265 ctx->stack_head = NULL;
2266 ctx->stack_tail = NULL;
2270 * Construct an NFA by parsing the regex string of length 'len'.
2272 * @param regex regular expression string
2273 * @param len length of the string
2275 * @return NFA, needs to be freed using GNUNET_REGEX_destroy_automaton
2277 struct GNUNET_REGEX_Automaton *
2278 GNUNET_REGEX_construct_nfa (const char *regex, const size_t len)
2280 struct GNUNET_REGEX_Context ctx;
2281 struct GNUNET_REGEX_Automaton *nfa;
2285 unsigned int altcount;
2286 unsigned int atomcount;
2287 unsigned int pcount;
2294 GNUNET_REGEX_context_init (&ctx);
2303 for (count = 0; count < len && *regexp; count++, regexp++)
2311 nfa_add_concatenation (&ctx);
2313 GNUNET_array_grow (p, pcount, pcount + 1);
2314 p[pcount - 1].altcount = altcount;
2315 p[pcount - 1].atomcount = atomcount;
2322 error_msg = "Cannot append '|' to nothing";
2325 while (--atomcount > 0)
2326 nfa_add_concatenation (&ctx);
2332 error_msg = "Missing opening '('";
2337 // Ignore this: "()"
2339 altcount = p[pcount].altcount;
2340 atomcount = p[pcount].atomcount;
2343 while (--atomcount > 0)
2344 nfa_add_concatenation (&ctx);
2345 for (; altcount > 0; altcount--)
2346 nfa_add_alternation (&ctx);
2348 altcount = p[pcount].altcount;
2349 atomcount = p[pcount].atomcount;
2355 error_msg = "Cannot append '*' to nothing";
2358 nfa_add_star_op (&ctx);
2363 error_msg = "Cannot append '+' to nothing";
2366 nfa_add_plus_op (&ctx);
2371 error_msg = "Cannot append '?' to nothing";
2374 nfa_add_question_op (&ctx);
2376 case 92: /* escape: \ */
2383 nfa_add_concatenation (&ctx);
2385 nfa_add_label (&ctx, *regexp);
2392 error_msg = "Unbalanced parenthesis";
2395 while (--atomcount > 0)
2396 nfa_add_concatenation (&ctx);
2397 for (; altcount > 0; altcount--)
2398 nfa_add_alternation (&ctx);
2400 GNUNET_free_non_null (p);
2402 nfa = ctx.stack_tail;
2403 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa);
2405 if (NULL != ctx.stack_head)
2407 error_msg = "Creating the NFA failed. NFA stack was not empty!";
2411 nfa->regex = GNUNET_strdup (regex);
2416 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex: %s\n", regex);
2417 if (NULL != error_msg)
2418 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "%s\n", error_msg);
2420 GNUNET_free_non_null (p);
2422 while (NULL != (nfa = ctx.stack_head))
2424 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa);
2425 GNUNET_REGEX_automaton_destroy (nfa);
2432 * Create DFA states based on given 'nfa' and starting with 'dfa_state'.
2434 * @param ctx context.
2435 * @param nfa NFA automaton.
2436 * @param dfa DFA automaton.
2437 * @param dfa_state current dfa state, pass epsilon closure of first nfa state
2441 construct_dfa_states (struct GNUNET_REGEX_Context *ctx,
2442 struct GNUNET_REGEX_Automaton *nfa,
2443 struct GNUNET_REGEX_Automaton *dfa,
2444 struct GNUNET_REGEX_State *dfa_state)
2446 struct Transition *ctran;
2447 struct GNUNET_REGEX_State *state_iter;
2448 struct GNUNET_REGEX_State *new_dfa_state;
2449 struct GNUNET_REGEX_State *state_contains;
2450 struct GNUNET_REGEX_StateSet *tmp;
2451 struct GNUNET_REGEX_StateSet *nfa_set;
2453 for (ctran = dfa_state->transitions_head; NULL != ctran; ctran = ctran->next)
2455 if (0 == ctran->label || NULL != ctran->to_state)
2458 tmp = nfa_closure_set_create (nfa, dfa_state->nfa_set, ctran->label);
2459 nfa_set = nfa_closure_set_create (nfa, tmp, 0);
2460 state_set_clear (tmp);
2461 new_dfa_state = dfa_state_create (ctx, nfa_set);
2462 state_contains = NULL;
2463 for (state_iter = dfa->states_head; NULL != state_iter;
2464 state_iter = state_iter->next)
2466 if (0 == state_set_compare (state_iter->nfa_set, new_dfa_state->nfa_set))
2467 state_contains = state_iter;
2470 if (NULL == state_contains)
2472 automaton_add_state (dfa, new_dfa_state);
2473 ctran->to_state = new_dfa_state;
2474 construct_dfa_states (ctx, nfa, dfa, new_dfa_state);
2478 ctran->to_state = state_contains;
2479 automaton_destroy_state (new_dfa_state);
2485 * Construct DFA for the given 'regex' of length 'len'
2487 * @param regex regular expression string
2488 * @param len length of the regular expression
2490 * @return DFA, needs to be freed using GNUNET_REGEX_destroy_automaton
2492 struct GNUNET_REGEX_Automaton *
2493 GNUNET_REGEX_construct_dfa (const char *regex, const size_t len)
2495 struct GNUNET_REGEX_Context ctx;
2496 struct GNUNET_REGEX_Automaton *dfa;
2497 struct GNUNET_REGEX_Automaton *nfa;
2498 struct GNUNET_REGEX_StateSet *nfa_set;
2500 GNUNET_REGEX_context_init (&ctx);
2503 nfa = GNUNET_REGEX_construct_nfa (regex, len);
2507 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2508 "Could not create DFA, because NFA creation failed\n");
2512 dfa = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
2514 dfa->regex = GNUNET_strdup (regex);
2516 // Create DFA start state from epsilon closure
2517 nfa_set = nfa_closure_create (nfa, nfa->start, 0);
2518 dfa->start = dfa_state_create (&ctx, nfa_set);
2519 automaton_add_state (dfa, dfa->start);
2521 construct_dfa_states (&ctx, nfa, dfa, dfa->start);
2523 GNUNET_REGEX_automaton_destroy (nfa);
2526 dfa_minimize (&ctx, dfa);
2529 scc_tarjan (&ctx, dfa);
2531 // Create proofs for all states
2532 automaton_create_proofs (dfa);
2538 * Free the memory allocated by constructing the GNUNET_REGEX_Automaton data
2541 * @param a automaton to be destroyed
2544 GNUNET_REGEX_automaton_destroy (struct GNUNET_REGEX_Automaton *a)
2546 struct GNUNET_REGEX_State *s;
2547 struct GNUNET_REGEX_State *next_state;
2552 GNUNET_free_non_null (a->regex);
2553 GNUNET_free_non_null (a->computed_regex);
2555 for (s = a->states_head; NULL != s;)
2557 next_state = s->next;
2558 automaton_destroy_state (s);
2566 * Save a state to an open file pointer. cls is expected to be a file pointer to
2567 * an open file. Used only in conjunction with
2568 * GNUNET_REGEX_automaton_save_graph.
2570 * @param cls file pointer.
2571 * @param count current count of the state, not used.
2575 GNUNET_REGEX_automaton_save_graph_step (void *cls, unsigned int count,
2576 struct GNUNET_REGEX_State *s)
2579 struct Transition *ctran;
2581 char *s_tran = NULL;
2587 GNUNET_asprintf (&s_acc,
2588 "\"%s(%i)\" [shape=doublecircle, color=\"0.%i 0.8 0.95\"];\n",
2589 s->name, s->proof_id, s->scc_id);
2593 GNUNET_asprintf (&s_acc, "\"%s(%i)\" [color=\"0.%i 0.8 0.95\"];\n", s->name,
2594 s->proof_id, s->scc_id);
2599 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n", s->name);
2602 fwrite (s_acc, strlen (s_acc), 1, p);
2603 GNUNET_free (s_acc);
2606 for (ctran = s->transitions_head; NULL != ctran; ctran = ctran->next)
2608 if (NULL == ctran->to_state)
2610 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2611 "Transition from State %i has no state for transitioning\n",
2616 if (ctran->label == 0)
2618 GNUNET_asprintf (&s_tran,
2619 "\"%s(%i)\" -> \"%s(%i)\" [label = \"epsilon\", color=\"0.%i 0.8 0.95\"];\n",
2620 s->name, s->proof_id, ctran->to_state->name,
2621 ctran->to_state->proof_id, s->scc_id);
2625 GNUNET_asprintf (&s_tran,
2626 "\"%s(%i)\" -> \"%s(%i)\" [label = \"%c\", color=\"0.%i 0.8 0.95\"];\n",
2627 s->name, s->proof_id, ctran->to_state->name,
2628 ctran->to_state->proof_id, ctran->label, s->scc_id);
2633 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n",
2638 fwrite (s_tran, strlen (s_tran), 1, p);
2639 GNUNET_free (s_tran);
2645 * Save the given automaton as a GraphViz dot file
2647 * @param a the automaton to be saved
2648 * @param filename where to save the file
2651 GNUNET_REGEX_automaton_save_graph (struct GNUNET_REGEX_Automaton *a,
2652 const char *filename)
2660 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print NFA, was NULL!");
2664 if (NULL == filename || strlen (filename) < 1)
2666 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No Filename given!");
2670 p = fopen (filename, "w");
2674 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not open file for writing: %s",
2679 start = "digraph G {\nrankdir=LR\n";
2680 fwrite (start, strlen (start), 1, p);
2682 automaton_traverse (p, a, GNUNET_REGEX_automaton_save_graph_step);
2685 fwrite (end, strlen (end), 1, p);
2690 * Evaluates the given string using the given DFA automaton
2692 * @param a automaton, type must be DFA
2693 * @param string string that should be evaluated
2695 * @return 0 if string matches, non 0 otherwise
2698 evaluate_dfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2701 struct GNUNET_REGEX_State *s;
2705 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2706 "Tried to evaluate DFA, but NFA automaton given");
2712 // If the string is empty but the starting state is accepting, we accept.
2713 if ((NULL == string || 0 == strlen (string)) && s->accepting)
2716 for (strp = string; NULL != strp && *strp; strp++)
2718 s = dfa_move (s, *strp);
2723 if (NULL != s && s->accepting)
2730 * Evaluates the given string using the given NFA automaton
2732 * @param a automaton, type must be NFA
2733 * @param string string that should be evaluated
2735 * @return 0 if string matches, non 0 otherwise
2738 evaluate_nfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2741 struct GNUNET_REGEX_State *s;
2742 struct GNUNET_REGEX_StateSet *sset;
2743 struct GNUNET_REGEX_StateSet *new_sset;
2749 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2750 "Tried to evaluate NFA, but DFA automaton given");
2754 // If the string is empty but the starting state is accepting, we accept.
2755 if ((NULL == string || 0 == strlen (string)) && a->start->accepting)
2760 sset = nfa_closure_create (a, a->start, 0);
2762 for (strp = string; NULL != strp && *strp; strp++)
2764 new_sset = nfa_closure_set_create (a, sset, *strp);
2765 state_set_clear (sset);
2766 sset = nfa_closure_set_create (a, new_sset, 0);
2767 state_set_clear (new_sset);
2770 for (i = 0; i < sset->len; i++)
2772 s = sset->states[i];
2773 if (NULL != s && s->accepting)
2780 state_set_clear (sset);
2785 * Evaluates the given 'string' against the given compiled regex
2787 * @param a automaton
2788 * @param string string to check
2790 * @return 0 if string matches, non 0 otherwise
2793 GNUNET_REGEX_eval (struct GNUNET_REGEX_Automaton *a, const char *string)
2800 result = evaluate_dfa (a, string);
2803 result = evaluate_nfa (a, string);
2806 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2807 "Evaluating regex failed, automaton has no type!\n");
2808 result = GNUNET_SYSERR;
2816 * Get the computed regex of the given automaton.
2817 * When constructing the automaton a proof is computed for each state,
2818 * consisting of the regular expression leading to this state. A complete
2819 * regex for the automaton can be computed by combining these proofs.
2820 * As of now this computed regex is only useful for testing.
2823 GNUNET_REGEX_get_computed_regex (struct GNUNET_REGEX_Automaton *a)
2828 return a->computed_regex;
2832 * Get the first key for the given 'input_string'. This hashes the first x bits
2833 * of the 'input_strings'.
2835 * @param input_string string.
2836 * @param string_len length of the 'input_string'.
2837 * @param key pointer to where to write the hash code.
2839 * @return number of bits of 'input_string' that have been consumed
2840 * to construct the key
2843 GNUNET_REGEX_get_first_key (const char *input_string, unsigned int string_len,
2844 struct GNUNET_HashCode *key)
2848 size = string_len < initial_bits ? string_len : initial_bits;
2850 if (NULL == input_string)
2852 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Given input string was NULL!\n");
2856 GNUNET_CRYPTO_hash (input_string, size, key);
2862 * Check if the given 'proof' matches the given 'key'.
2864 * @param proof partial regex
2867 * @return GNUNET_OK if the proof is valid for the given key
2870 GNUNET_REGEX_check_proof (const char *proof, const struct GNUNET_HashCode *key)
2876 * Iterate over all edges helper function starting from state 's', calling
2877 * iterator on for each edge.
2880 * @param iterator iterator function called for each edge.
2881 * @param iterator_cls closure.
2884 iterate_edge (struct GNUNET_REGEX_State *s, GNUNET_REGEX_KeyIterator iterator,
2887 struct Transition *t;
2888 struct GNUNET_REGEX_Edge edges[s->transition_count];
2889 unsigned int num_edges;
2891 if (GNUNET_YES != s->marked)
2893 s->marked = GNUNET_YES;
2895 num_edges = state_get_edges (s, edges);
2897 iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges, edges);
2899 for (t = s->transitions_head; NULL != t; t = t->next)
2900 iterate_edge (t->to_state, iterator, iterator_cls);
2905 * Iterate over all edges starting from start state of automaton 'a'. Calling
2906 * iterator for each edge.
2908 * @param a automaton.
2909 * @param iterator iterator called for each edge.
2910 * @param iterator_cls closure.
2913 GNUNET_REGEX_iterate_all_edges (struct GNUNET_REGEX_Automaton *a,
2914 GNUNET_REGEX_KeyIterator iterator,
2917 struct GNUNET_REGEX_State *s;
2919 for (s = a->states_head; NULL != s; s = s->next)
2920 s->marked = GNUNET_NO;
2922 iterate_edge (a->start, iterator, iterator_cls);