Summary: regex cleanup and bugfixes

Author: szengel

1 files changed, 248 insertions, 0 deletions

diff --git a/src/regex/regex_graph.c b/src/regex/regex_graph.c
new file mode 100644
index 000000000..3230ea702
--- /dev/null
+++ b/src/regex/regex_graph.c
@@ -0,0 +1,248 @@
+/*
+     This file is part of GNUnet
+     (C) 2012 Christian Grothoff (and other contributing authors)
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+/**
+ * @file src/regex/regex_graph.c
+ * @brief functions for creating .dot graphs from regexes
+ * @author Maximilian Szengel
+ */
+#include "platform.h"
+#include "gnunet_regex_lib.h"
+#include "regex_internal.h"
+
+/**
+ * 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 scc_counter counter for numbering the sccs
+ * @param v start vertex
+ * @param index current index
+ * @param stack stack for saving all SCCs
+ * @param stack_size current size of the stack
+ */
+static void
+scc_tarjan_strongconnect (unsigned int *scc_counter,
+                          struct GNUNET_REGEX_State *v, unsigned int *index,
+                          struct GNUNET_REGEX_State **stack,
+                          unsigned int *stack_size)
+{
+  struct GNUNET_REGEX_State *w;
+  struct GNUNET_REGEX_Transition *t;
+
+  v->index = *index;
+  v->lowlink = *index;
+  (*index)++;
+  stack[(*stack_size)++] = v;
+  v->contained = 1;
+
+  for (t = v->transitions_head; NULL != t; t = t->next)
+  {
+    w = t->to_state;
+    if (NULL != w && w->index < 0)
+    {
+      scc_tarjan_strongconnect (scc_counter, w, index, stack, stack_size);
+      v->lowlink = (v->lowlink > w->lowlink) ? w->lowlink : v->lowlink;
+    }
+    else if (0 != w->contained)
+      v->lowlink = (v->lowlink > w->index) ? w->index : v->lowlink;
+  }
+
+  if (v->lowlink == v->index)
+  {
+    w = stack[--(*stack_size)];
+    w->contained = 0;
+
+    if (v != w)
+    {
+      (*scc_counter)++;
+      while (v != w)
+      {
+        w->scc_id = *scc_counter;
+        w = stack[--(*stack_size)];
+        w->contained = 0;
+      }
+      w->scc_id = *scc_counter;
+    }
+  }
+}
+
+
+/**
+ * Detect all SCCs (Strongly Connected Components) inside the given automaton.
+ * SCCs will be marked using the scc_id on each state.
+ *
+ * @param a the automaton for which SCCs should be computed and assigned.
+ */
+static void
+scc_tarjan (struct GNUNET_REGEX_Automaton *a)
+{
+  unsigned int index;
+  unsigned int scc_counter;
+  struct GNUNET_REGEX_State *v;
+  struct GNUNET_REGEX_State *stack[a->state_count];
+  unsigned int stack_size;
+
+  for (v = a->states_head; NULL != v; v = v->next)
+  {
+    v->contained = 0;
+    v->index = -1;
+    v->lowlink = -1;
+  }
+
+  stack_size = 0;
+  index = 0;
+  scc_counter = 0;
+
+  for (v = a->states_head; NULL != v; v = v->next)
+  {
+    if (v->index < 0)
+      scc_tarjan_strongconnect (&scc_counter, v, &index, stack, &stack_size);
+  }
+}
+
+
+/**
+ * Save a state to an open file pointer. cls is expected to be a file pointer to
+ * an open file. Used only in conjunction with
+ * GNUNET_REGEX_automaton_save_graph.
+ *
+ * @param cls file pointer.
+ * @param count current count of the state, not used.
+ * @param s state.
+ */
+void
+GNUNET_REGEX_automaton_save_graph_step (void *cls, unsigned int count,
+                                        struct GNUNET_REGEX_State *s)
+{
+  FILE *p;
+  struct GNUNET_REGEX_Transition *ctran;
+  char *s_acc = NULL;
+  char *s_tran = NULL;
+
+  p = cls;
+
+  if (s->accepting)
+  {
+    GNUNET_asprintf (&s_acc,
+                     "\"%s(%i)\" [shape=doublecircle, color=\"0.%i 0.8 0.95\"];\n",
+                     s->name, s->proof_id, s->scc_id);
+  }
+  else
+  {
+    GNUNET_asprintf (&s_acc, "\"%s(%i)\" [color=\"0.%i 0.8 0.95\"];\n", s->name,
+                     s->proof_id, s->scc_id);
+  }
+
+  if (NULL == s_acc)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n", s->name);
+    return;
+  }
+  fwrite (s_acc, strlen (s_acc), 1, p);
+  GNUNET_free (s_acc);
+  s_acc = NULL;
+
+  for (ctran = s->transitions_head; NULL != ctran; ctran = ctran->next)
+  {
+    if (NULL == ctran->to_state)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Transition from State %i has no state for transitioning\n",
+                  s->id);
+      continue;
+    }
+
+    if (ctran->label == 0)
+    {
+      GNUNET_asprintf (&s_tran,
+                       "\"%s(%i)\" -> \"%s(%i)\" [label = \"epsilon\", color=\"0.%i 0.8 0.95\"];\n",
+                       s->name, s->proof_id, ctran->to_state->name,
+                       ctran->to_state->proof_id, s->scc_id);
+    }
+    else
+    {
+      GNUNET_asprintf (&s_tran,
+                       "\"%s(%i)\" -> \"%s(%i)\" [label = \"%c\", color=\"0.%i 0.8 0.95\"];\n",
+                       s->name, s->proof_id, ctran->to_state->name,
+                       ctran->to_state->proof_id, ctran->label, s->scc_id);
+    }
+
+    if (NULL == s_tran)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n",
+                  s->name);
+      return;
+    }
+
+    fwrite (s_tran, strlen (s_tran), 1, p);
+    GNUNET_free (s_tran);
+    s_tran = NULL;
+  }
+}
+
+
+/**
+ * Save the given automaton as a GraphViz dot file
+ *
+ * @param a the automaton to be saved
+ * @param filename where to save the file
+ */
+void
+GNUNET_REGEX_automaton_save_graph (struct GNUNET_REGEX_Automaton *a,
+                                   const char *filename)
+{
+  char *start;
+  char *end;
+  FILE *p;
+
+  if (NULL == a)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print NFA, was NULL!");
+    return;
+  }
+
+  if (NULL == filename || strlen (filename) < 1)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No Filename given!");
+    return;
+  }
+
+  p = fopen (filename, "w");
+
+  if (NULL == p)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not open file for writing: %s",
+                filename);
+    return;
+  }
+
+  /* First add the SCCs to the automaton, so we can color them nicely */
+  scc_tarjan (a);
+
+  start = "digraph G {\nrankdir=LR\n";
+  fwrite (start, strlen (start), 1, p);
+
+  GNUNET_REGEX_automaton_traverse (a, &GNUNET_REGEX_automaton_save_graph_step,
+                                   p);
+
+  end = "\n}\n";
+  fwrite (end, strlen (end), 1, p);
+  fclose (p);
+}