*/
struct GNUNET_REGEX_Context
{
+ /**
+ * Unique state id.
+ */
unsigned int state_id;
+
+ /**
+ * Unique transition id.
+ */
unsigned int transition_id;
/**
- * DLL of GNUNET_REGEX_Automaton's used as a stack
+ * DLL of GNUNET_REGEX_Automaton's used as a stack.
*/
struct GNUNET_REGEX_Automaton *stack_head;
+
+ /**
+ * DLL of GNUNET_REGEX_Automaton's used as a stack.
+ */
struct GNUNET_REGEX_Automaton *stack_tail;
};
+/**
+ * Type of an automaton.
+ */
enum GNUNET_REGEX_automaton_type
{
NFA,
};
/**
- * Automaton representation
+ * Automaton representation.
*/
struct GNUNET_REGEX_Automaton
{
+ /**
+ * This is a linked list.
+ */
struct GNUNET_REGEX_Automaton *prev;
+
+ /**
+ * This is a linked list.
+ */
struct GNUNET_REGEX_Automaton *next;
+ /**
+ * First state of the automaton. This is mainly
+ * used for constructing an NFA, where each NFA
+ * itself consists of one or more NFAs linked
+ * together.
+ */
struct State *start;
+
+ /**
+ * End state of the automaton.
+ */
struct State *end;
+ /**
+ * Number of states in the automaton.
+ */
unsigned int state_count;
+
+ /**
+ * DLL of states.
+ */
struct State *states_head;
+
+ /**
+ * DLL of states
+ */
struct State *states_tail;
+ /**
+ * Type of the automaton.
+ */
enum GNUNET_REGEX_automaton_type type;
};
*/
struct State
{
+ /**
+ * This is a linked list.
+ */
struct State *prev;
+
+ /**
+ * This is a linked list.
+ */
struct State *next;
+ /**
+ * Unique state id.
+ */
unsigned int id;
+
+ /**
+ * If this is an accepting state or not.
+ */
int accepting;
+
+ /**
+ * Marking of the state. This is used for marking all visited
+ * states when traversing all states of an automaton and for
+ * cases where the state id cannot be used (dfa minimization).
+ */
int marked;
+
+ /**
+ * Human readable name of the automaton. Used for debugging
+ * and graph creation.
+ */
char *name;
+ /**
+ * Number of transitions from this state to other states.
+ */
unsigned int transition_count;
+
+ /**
+ * DLL of transitions.
+ */
struct Transition *transitions_head;
+
+ /**
+ * DLL of transitions.
+ */
struct Transition *transitions_tail;
+ /**
+ * Set of states on which this state is based on. Used when
+ * creating a DFA out of several NFA states.
+ */
struct StateSet *nfa_set;
};
*/
struct Transition
{
+ /**
+ * This is a linked list.
+ */
struct Transition *prev;
+
+ /**
+ * This is a linked list.
+ */
struct Transition *next;
+ /**
+ * Unique id of this transition.
+ */
unsigned int id;
+
+ /**
+ * Literal for this transition. This is basically the edge label for
+ * the graph.
+ */
char literal;
+
+ /**
+ * State to which this transition leads.
+ */
struct State *state;
};
/**
- * Set of states
+ * Set of states.
*/
struct StateSet
{
/**
- * Array of states
+ * Array of states.
*/
struct State **states;
+
+ /**
+ * Length of the 'states' array.
+ */
unsigned int len;
};
* @param sset1 first state set
* @param sset2 second state set
*
- * @return 0 if they are equal, non 0 otherwise
+ * @return an integer less than, equal to, or greater than zero
+ * if the first argument is considered to be respectively
+ * less than, equal to, or greater than the second.
*/
static int
state_set_compare (struct StateSet *sset1, struct StateSet *sset2)
{
+ int result;
int i;
- if (sset1->len != sset2->len)
+ if (NULL == sset1 || NULL == sset2)
return 1;
+ result = sset1->len - sset2->len;
+
for (i = 0; i < sset1->len; i++)
{
- if (sset1->states[i]->id != sset2->states[i]->id)
- {
- return 1;
- }
+ if (0 != result)
+ break;
+
+ result = state_compare (&sset1->states[i], &sset2->states[i]);
}
- return 0;
+ return result;
}
/**
static void
automaton_fragment_clear (struct GNUNET_REGEX_Automaton *a)
{
+ if (NULL == a)
+ return;
+
a->start = NULL;
a->end = NULL;
a->states_head = NULL;
struct Transition *t;
struct Transition *next_t;
+ if (NULL == s)
+ return;
+
if (NULL != s->name)
GNUNET_free (s->name);
struct State *s_check;
struct Transition *t_check;
+ if (NULL == a || NULL == s)
+ return;
+
// remove state
ss = s;
GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s);
s->marked = 1; // mark s as visited
for (t = s->transitions_head; NULL != t; t = t->next)
{
+ // add next states to stack
if (NULL != t->state && 0 == t->state->marked)
- {
- // add next states to stack
- stack[stack_len] = t->state;
- stack_len++;
- }
+ stack[++stack_len] = t->state;
}
}
/**
* Merge all non distinguishable states in the DFA 'a'
*
+ * @param ctx context
* @param a DFA automaton
*/
static void
* Minimize the given DFA 'a' by removing all unreachable states,
* removing all dead states and merging all non distinguishable states
*
+ * @param ctx context
* @param a DFA automaton
*/
static void
}
/**
- * Calculates the NFA closure set for the given state
+ * Calculates the NFA closure set for the given state.
*
* @param s starting point state
* @param literal transitioning literal on which to base the closure on,
* pass 0 for epsilon transition
*
- * @return nfa closure on 'literal' (epsilon closure if 'literal' is 0)
+ * @return sorted nfa closure on 'literal' (epsilon closure if 'literal' is 0)
*/
static struct StateSet *
nfa_closure_create (struct State *s, const char literal)
* @param literal transitioning literal for which to base the closure on,
* pass 0 for epsilon transition
*
- * @return nfa closure on 'literal' (epsilon closure if 'literal' is 0)
+ * @return sorted nfa closure on 'literal' (epsilon closure if 'literal' is 0)
*/
static struct StateSet *
nfa_closure_set_create (struct StateSet *states, const char literal)
GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a);
}
+/**
+ * Pops an NFA fragment (a) from the stack and adds a new fragment (a?)
+ *
+ * @param ctx context
+ */
+static void
+nfa_add_question_op (struct GNUNET_REGEX_Context *ctx)
+{
+ struct GNUNET_REGEX_Automaton *a;
+ struct GNUNET_REGEX_Automaton *new;
+ struct State *start;
+ struct State *end;
+
+ a = ctx->stack_tail;
+ GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
+
+ if (NULL == a)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "nfa_add_question_op failed, because there was no element on the stack");
+ return;
+ }
+
+ start = nfa_state_create (ctx, 0);
+ end = nfa_state_create (ctx, 1);
+
+ add_transition (ctx, start, 0, a->start);
+ add_transition (ctx, start, 0, end);
+ add_transition (ctx, a->end, 0, end);
+
+ a->end->accepting = 0;
+
+ new = nfa_fragment_create (start, end);
+ nfa_add_states (new, a->states_head, a->states_tail);
+ automaton_fragment_clear (a);
+
+ GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
+}
+
/**
* Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment
* that alternates between a and b (a|b)
}
nfa_add_plus_op (&ctx);
break;
+ case '?':
+ if (atomcount == 0)
+ {
+ error_msg = "Cannot append '?' to nothing";
+ goto error;
+ }
+ nfa_add_question_op (&ctx);
+ break;
case 92: /* escape: \ */
regexp++;
count++;
projects / oweals / gnunet.git / blobdiff