#define initial_bits 10
/**
- * Context that contains an id counter for states and transitions
- * as well as a DLL of automatons used as a stack for NFA construction.
+ * Context that contains an id counter for states and transitions as well as a
+ * DLL of automatons used as a stack for NFA construction.
*/
struct GNUNET_REGEX_Context
{
struct GNUNET_REGEX_Automaton *next;
/**
- * First state of the automaton. This is mainly
- * used for constructing an NFA, where each NFA
- * itself consists of one or more NFAs linked
- * together.
+ * First state of the automaton. This is mainly used for constructing an NFA,
+ * where each NFA itself consists of one or more NFAs linked together.
*/
struct GNUNET_REGEX_State *start;
int accepting;
/**
- * Marking of the state. This is used for marking all visited
- * states when traversing all states of an automaton and for
- * cases where the state id cannot be used (dfa minimization).
+ * Marking of the state. This is used for marking all visited states when
+ * traversing all states of an automaton and for cases where the state id
+ * cannot be used (dfa minimization).
*/
int marked;
/**
- * Marking the state as contained. This is used for checking,
- * if the state is contained in a set in constant time
+ * Marking the state as contained. This is used for checking, if the state is
+ * contained in a set in constant time
*/
int contained;
/**
- * Marking the state as part of an SCC (Strongly Connected Component).
- * All states with the same scc_id are part of the same SCC.
+ * Marking the state as part of an SCC (Strongly Connected Component). All
+ * states with the same scc_id are part of the same SCC. scc_id is 0, if state
+ * is not a part of any SCC.
*/
unsigned int scc_id;
int lowlink;
/**
- * Human readable name of the automaton. Used for debugging
- * and graph creation.
+ * Human readable name of the automaton. Used for debugging and graph
+ * creation.
*/
char *name;
+ /**
+ * Hash of the state.
+ */
GNUNET_HashCode hash;
+ /**
+ * Proof for this state.
+ */
+ char *proof;
+
/**
* Number of transitions from this state to other states.
*/
struct Transition *transitions_tail;
/**
- * Set of states on which this state is based on. Used when
- * creating a DFA out of several NFA states.
+ * Set of states on which this state is based on. Used when creating a DFA out
+ * of several NFA states.
*/
struct GNUNET_REGEX_StateSet *nfa_set;
};
/**
- * Transition between two states. Each state can have 0-n transitions.
- * If label is 0, this is considered to be an epsilon transition.
+ * Transition between two states. Each state can have 0-n transitions. If label
+ * is 0, this is considered to be an epsilon transition.
*/
struct Transition
{
unsigned int id;
/**
- * label for this transition. This is basically the edge label for
- * the graph.
+ * Label for this transition. This is basically the edge label for the graph.
*/
char label;
debug_print_state (struct GNUNET_REGEX_State *s)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "State %i: %s marked: %i accepting: %i scc_id: %i transitions: %i\n", s->id,
- s->name, s->marked, s->accepting, s->scc_id, s->transition_count);
+ "State %i: %s marked: %i accepting: %i scc_id: %i transitions: %i\n",
+ s->id, s->name, s->marked, s->accepting, s->scc_id,
+ s->transition_count);
}
static void
}
/**
- * Recursive function doing DFS with 'v' as a start, detecting all SCCs
- * inside the subgraph reachable from 'v'. Used with scc_tarjan function
- * to detect all SCCs inside an automaton.
+ * Recursive function doing DFS with 'v' as a start, detecting all SCCs inside
+ * the subgraph reachable from 'v'. Used with scc_tarjan function to detect all
+ * SCCs inside an automaton.
*
* @param ctx context
* @param v start vertex
}
}
+/**
+ * Adds a transition from one state to another on 'label'. Does not add
+ * duplicate states.
+ *
+ * @param ctx context
+ * @param from_state starting state for the transition
+ * @param label transition label
+ * @param to_state state to where the transition should point to
+ */
+static void
+state_add_transition (struct GNUNET_REGEX_Context *ctx,
+ struct GNUNET_REGEX_State *from_state, const char label,
+ struct GNUNET_REGEX_State *to_state)
+{
+ int is_dup;
+ struct Transition *t;
+
+ if (NULL == from_state)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n");
+ return;
+ }
+
+ // Do not add duplicate state transitions
+ is_dup = GNUNET_NO;
+ for (t = from_state->transitions_head; NULL != t; t = t->next)
+ {
+ if (t->to_state == to_state && t->label == label &&
+ t->from_state == from_state)
+ {
+ is_dup = GNUNET_YES;
+ break;
+ }
+ }
+
+ if (is_dup)
+ return;
+
+ t = GNUNET_malloc (sizeof (struct Transition));
+ t->id = ctx->transition_id++;
+ t->label = label;
+ t->to_state = to_state;
+ t->from_state = from_state;
+
+ // Add outgoing transition to 'from_state'
+ from_state->transition_count++;
+ GNUNET_CONTAINER_DLL_insert (from_state->transitions_head,
+ from_state->transitions_tail, t);
+}
+
/**
* Compare two states. Used for sorting.
*
}
/**
- * Compare to state sets by comparing the id's of the states that are
- * contained in each set. Both sets are expected to be sorted by id!
+ * Get all edges leaving state 's'.
+ *
+ * @param s state.
+ * @param edges all edges leaving 's'.
+ *
+ * @return number of edges.
+ */
+static unsigned int
+state_get_edges (struct GNUNET_REGEX_State *s, struct GNUNET_REGEX_Edge *edges)
+{
+ struct Transition *t;
+ unsigned int count;
+
+ if (NULL == s)
+ return 0;
+
+ count = 0;
+
+ for (t = s->transitions_head; NULL != t; t = t->next)
+ {
+ if (NULL != t->to_state)
+ {
+ edges[count].label = &t->label;
+ edges[count].destination = t->to_state->hash;
+ count++;
+ }
+ }
+ return count;
+}
+
+/**
+ * Compare to state sets by comparing the id's of the states that are contained
+ * in each set. Both sets are expected to be sorted by id!
*
* @param sset1 first state set
* @param sset2 second state set
}
/**
- * Adds a transition from one state to another on 'label'. Does not add
- * duplicate states.
- *
- * @param ctx context
- * @param from_state starting state for the transition
- * @param label transition label
- * @param to_state state to where the transition should point to
- */
-static void
-state_add_transition (struct GNUNET_REGEX_Context *ctx,
- struct GNUNET_REGEX_State *from_state, const char label,
- struct GNUNET_REGEX_State *to_state)
-{
- int is_dup;
- struct Transition *t;
-
- if (NULL == from_state)
- {
- GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n");
- return;
- }
-
- // Do not add duplicate states
- is_dup = GNUNET_NO;
- for (t = from_state->transitions_head; NULL != t; t = t->next)
- {
- if (t->to_state == to_state
- && t->label == label
- && t->from_state == from_state)
- {
- is_dup = GNUNET_YES;
- break;
- }
- }
-
- if (is_dup)
- return;
-
- t = GNUNET_malloc (sizeof (struct Transition));
-
- t->id = ctx->transition_id++;
- t->label = label;
- t->to_state = to_state;
- t->from_state = from_state;
-
- from_state->transition_count++;
-
- GNUNET_CONTAINER_DLL_insert (from_state->transitions_head,
- from_state->transitions_tail, t);
-}
-
-/**
- * Clears an automaton fragment. Does not destroy the states inside
- * the automaton.
+ * Clears an automaton fragment. Does not destroy the states inside the
+ * automaton.
*
* @param a automaton to be cleared
*/
}
/**
- * Remove a state from the given automaton 'a'. Always use this function
- * when altering the states of an automaton. Will also remove all transitions
- * leading to this state, before destroying it.
+ * Remove a state from the given automaton 'a'. Always use this function when
+ * altering the states of an automaton. Will also remove all transitions leading
+ * to this state, before destroying it.
*
* @param a automaton
* @param s state to remove
}
/**
- * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy 's2'.
+ * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy
+ * 's2'.
*
* @param ctx context
* @param a automaton
for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next)
{
if (t_check->to_state != s1)
- state_add_transition (ctx, s1, t_check->label, t_check->to_state);
+ state_add_transition (ctx, s1, t_check->label, t_check->to_state);
}
// 3. Rename s1 to {s1,s2}
}
/**
- * Add a state to the automaton 'a', always use this function to
- * alter the states DLL of the automaton.
+ * Add a state to the automaton 'a', always use this function to alter the
+ * states DLL of the automaton.
*
* @param a automaton to add the state to
* @param s state that should be added
typedef void (*GNUNET_REGEX_traverse_action) (void *cls,
struct GNUNET_REGEX_State * s);
+static void
+automaton_state_traverse_backward (void *cls, struct GNUNET_REGEX_State *s,
+ GNUNET_REGEX_traverse_action action)
+{
+
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Traversing backwards...\n");
+
+}
+
/**
- * Traverses all states that are reachable from state 's'. Expects
- * the states to be unmarked (s->marked == GNUNET_NO). Performs
- * 'action' on each visited state.
+ * Traverses all states that are reachable from state 's'. Expects the states to
+ * be unmarked (s->marked == GNUNET_NO). Performs 'action' on each visited
+ * state.
*
* @param cls closure.
* @param s start state.
}
/**
- * Traverses the given automaton from it's start state, visiting all
- * reachable states and calling 'action' on each one of them.
+ * Traverses the given automaton from it's start state, visiting all reachable
+ * states and calling 'action' on each one of them.
*
* @param cls closure.
* @param a automaton.
}
/**
- * Creates a new DFA state based on a set of NFA states. Needs to be freed
- * using automaton_destroy_state.
+ * Creates a new DFA state based on a set of NFA states. Needs to be freed using
+ * automaton_destroy_state.
*
* @param ctx context
* @param nfa_states set of NFA states on which the DFA should be based on
}
}
- // If the nfa_states contain an accepting state, the new dfa state is also accepting
+ // If the nfa_states contain an accepting state, the new dfa state is also
+ // accepting
if (cstate->accepting)
s->accepting = 1;
}
}
/**
- * Move from the given state 's' to the next state on
- * transition 'label'
+ * Move from the given state 's' to the next state on transition 'label'
*
* @param s starting state
* @param label edge label to follow
/**
- * Remove all unreachable states from DFA 'a'. Unreachable states
- * are those states that are not reachable from the starting state.
+ * Remove all unreachable states from DFA 'a'. Unreachable states are those
+ * states that are not reachable from the starting state.
*
* @param a DFA automaton
*/
}
/**
- * Remove all dead states from the DFA 'a'. Dead states are those
- * states that do not transition to any other state but themselfes.
+ * Remove all dead states from the DFA 'a'. Dead states are those states that do
+ * not transition to any other state but themselfes.
*
* @param a DFA automaton
*/
int change;
int common_labels;
- for (i = 0, s1 = a->states_head;
- i < a->state_count && NULL != s1;
+ for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1;
i++, s1 = s1->next)
{
s1->marked = i;
}
/**
- * Minimize the given DFA 'a' by removing all unreachable states,
- * removing all dead states and merging all non distinguishable states
+ * Minimize the given DFA 'a' by removing all unreachable states, removing all
+ * dead states and merging all non distinguishable states
*
* @param ctx context
* @param a DFA automaton
}
/**
- * Creates a new NFA fragment. Needs to be cleared using automaton_fragment_clear.
+ * Creates a new NFA fragment. Needs to be cleared using
+ * automaton_fragment_clear.
*
* @param start starting state
* @param end end state
}
/**
- * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment
- * that alternates between a and b (a|b)
+ * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment that
+ * alternates between a and b (a|b)
*
* @param ctx context
*/
return NULL;
}
+/**
+ * Create DFA states based on given 'nfa' and starting with 'dfa_state'.
+ *
+ * @param ctx context.
+ * @param nfa NFA automaton.
+ * @param dfa DFA automaton.
+ * @param dfa_state current dfa state, pass epsilon closure of first nfa state
+ * for starting.
+ */
+static void
+construct_dfa_states (struct GNUNET_REGEX_Context *ctx,
+ struct GNUNET_REGEX_Automaton *nfa,
+ struct GNUNET_REGEX_Automaton *dfa,
+ struct GNUNET_REGEX_State *dfa_state)
+{
+ struct Transition *ctran;
+ struct GNUNET_REGEX_State *state_iter;
+ struct GNUNET_REGEX_State *new_dfa_state;
+ struct GNUNET_REGEX_State *state_contains;
+ struct GNUNET_REGEX_StateSet *tmp;
+ struct GNUNET_REGEX_StateSet *nfa_set;
+
+ for (ctran = dfa_state->transitions_head; NULL != ctran; ctran = ctran->next)
+ {
+ if (0 == ctran->label || NULL != ctran->to_state)
+ continue;
+
+ tmp = nfa_closure_set_create (nfa, dfa_state->nfa_set, ctran->label);
+ nfa_set = nfa_closure_set_create (nfa, tmp, 0);
+ state_set_clear (tmp);
+ new_dfa_state = dfa_state_create (ctx, nfa_set);
+ state_contains = NULL;
+ for (state_iter = dfa->states_head; NULL != state_iter;
+ state_iter = state_iter->next)
+ {
+ if (0 == state_set_compare (state_iter->nfa_set, new_dfa_state->nfa_set))
+ state_contains = state_iter;
+ }
+
+ if (NULL == state_contains)
+ {
+ automaton_add_state (dfa, new_dfa_state);
+ construct_dfa_states (ctx, nfa, dfa, new_dfa_state);
+ ctran->to_state = new_dfa_state;
+ }
+ else
+ {
+ ctran->to_state = state_contains;
+ automaton_destroy_state (new_dfa_state);
+ }
+ }
+}
+
/**
* Construct DFA for the given 'regex' of length 'len'
*
struct GNUNET_REGEX_Context ctx;
struct GNUNET_REGEX_Automaton *dfa;
struct GNUNET_REGEX_Automaton *nfa;
- struct GNUNET_REGEX_StateSet *tmp;
struct GNUNET_REGEX_StateSet *nfa_set;
- struct GNUNET_REGEX_StateSet *dfa_stack;
- struct Transition *ctran;
- struct GNUNET_REGEX_State *dfa_state;
- struct GNUNET_REGEX_State *new_dfa_state;
- struct GNUNET_REGEX_State *state_contains;
- struct GNUNET_REGEX_State *state_iter;
GNUNET_REGEX_context_init (&ctx);
dfa->type = DFA;
// Create DFA start state from epsilon closure
- dfa_stack = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
nfa_set = nfa_closure_create (nfa, nfa->start, 0);
dfa->start = dfa_state_create (&ctx, nfa_set);
automaton_add_state (dfa, dfa->start);
- GNUNET_array_append (dfa_stack->states, dfa_stack->len, dfa->start);
- // Create dfa states by combining nfa states
- while (dfa_stack->len > 0)
- {
- dfa_state = dfa_stack->states[dfa_stack->len - 1];
- GNUNET_array_grow (dfa_stack->states, dfa_stack->len, dfa_stack->len - 1);
+ construct_dfa_states (&ctx, nfa, dfa, dfa->start);
- for (ctran = dfa_state->transitions_head; NULL != ctran;
- ctran = ctran->next)
- {
- if (0 != ctran->label && NULL == ctran->to_state)
- {
- tmp = nfa_closure_set_create (nfa, dfa_state->nfa_set, ctran->label);
- nfa_set = nfa_closure_set_create (nfa, tmp, 0);
- state_set_clear (tmp);
- new_dfa_state = dfa_state_create (&ctx, nfa_set);
- state_contains = NULL;
- for (state_iter = dfa->states_head; NULL != state_iter;
- state_iter = state_iter->next)
- {
- if (0 ==
- state_set_compare (state_iter->nfa_set, new_dfa_state->nfa_set))
- state_contains = state_iter;
- }
-
- if (NULL == state_contains)
- {
- automaton_add_state (dfa, new_dfa_state);
- GNUNET_array_append (dfa_stack->states, dfa_stack->len,
- new_dfa_state);
- ctran->to_state = new_dfa_state;
- }
- else
- {
- ctran->to_state = state_contains;
- automaton_destroy_state (new_dfa_state);
- }
- }
- }
- }
-
- GNUNET_free (dfa_stack);
GNUNET_REGEX_automaton_destroy (nfa);
dfa_minimize (&ctx, dfa);
}
/**
- * Free the memory allocated by constructing the GNUNET_REGEX_Automaton
- * data structure.
+ * Free the memory allocated by constructing the GNUNET_REGEX_Automaton data
+ * structure.
*
* @param a automaton to be destroyed
*/
if (NULL == s_acc)
{
- GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n", s->name);
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n",
+ s->name);
return;
}
fwrite (s_acc, strlen (s_acc), 1, p);
if (NULL == s_tran)
{
- GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n", s->name);
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n",
+ s->name);
return;
}
}
/**
- * Get the first key for the given 'input_string'. This hashes
- * the first x bits of the 'input_strings'.
+ * Get the first key for the given 'input_string'. This hashes the first x bits
+ * of the 'input_strings'.
*
* @param input_string string.
* @param string_len length of the 'input_string'.
return GNUNET_OK;
}
-/**
- * Get all edges leaving state 's'.
- *
- * @param s state.
- * @param edges all edges leaving 's'.
- *
- * @return number of edges.
- */
-static unsigned int
-state_get_edges (struct GNUNET_REGEX_State *s, struct GNUNET_REGEX_Edge *edges)
-{
- struct Transition *t;
- unsigned int count;
-
- if (NULL == s)
- return 0;
-
- count = 0;
-
- for (t = s->transitions_head; NULL != t; t = t->next)
- {
- if (NULL != t->to_state)
- {
- edges[count].label = &t->label;
- edges[count].destination = t->to_state->hash;
- count++;
- }
- }
- return count;
-}
/**
* Iterate over all edges helper function starting from state 's', calling
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