Move the handling of ALLCHARS (-k'*') into the Positions class.

14 files changed, 396 insertions, 239 deletions

diff --git a/ChangeLog b/ChangeLog
index e4f2495..ffed0de 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,55 @@
+2002-12-12  Bruno Haible  <bruno@clisp.org>
+
+	* src/positions.h (Positions::is_useall, Positions::set_useall,
+	Positions::iterator, Positions::reviterator): New method declarations.
+	(Positions::_useall): New field.
+	(PositionIterator): Make constructor private. Add a constructor and a
+	copy constructor.
+	(PositionIterator::remaining): New declaration.
+	(PositionReverseIterator): Make constructor private. Add a constructor
+	and a copy constructor.
+	(PositionReverseIterator::remaining): New declaration.
+	(PositionReverseIterator::_minindex): New field.
+	* src/positions.icc (Positions::Positions): Initialize _useall.
+	(Positions::operator=): Likewise.
+	(Positions::is_useall, Positions::set_useall): New methods.
+	(Positions::sort): Do nothing if _useall is set.
+	(Positions::iterator, Positions::reviterator): New methods.
+	(PositionIterator::PositionIterator): New constructor.
+	(PositionIterator::remaining): New method.
+	(PositionReverseIterator::PositionReverseIterator): New constructor.
+	(PositionReverseIterator::next): Use _minindex as bound.
+	(PositionReverseIterator::remaining): New method.
+	* src/positions.cc (Positions::add, Positions::remove): Reset the
+	useall flag.
+	(Positions::print): Handle the useall case.
+	* src/options.h (ALLCHARS): Remove.
+	* src/options.cc (Options::~Options): Update.
+	(Options::parse_options): Use Positions::set_useall().
+	* src/keyword.h (KeywordExt::init_selchars_tuple,
+	KeywordExt::init_selchars_multiset, KeywordExt::init_selchars_low):
+	Remove use_all_chars argument.
+	* src/keyword.cc (KeywordExt::init_selchars_low): Remove use_all_chars
+	argument. Tell the position iterator to stop at _allchars_length.
+	Remove special case code for -k'*'.
+	(KeywordExt::init_selchars_tuple, KeywordExt::init_selchars_multiset):
+	Remove use_all_chars argument.
+	* src/search.h (Search::init_selchars_tuple): Remove use_all_chars
+	argument.
+	(Search::init_selchars_multiset): Likewise.
+	* src/search.cc (Search::init_selchars_tuple): Remove use_all_chars
+	argument.
+	(Search::count_duplicates_tuple, Search::find_positions): Update.
+	(Search::compute_alpha_unify): Remove special case code for -k'*'.
+	(Search::init_selchars_multiset): Remove use_all_chars argument.
+	(Search::count_duplicates_multiset): Update.
+	(Search::find_alpha_inc): Remove special case code for -k'*'.
+	(Search::prepare): Update.
+	(Search::get_max_keysig_size): Update.
+	* src/output.cc (Output::output_hash_function): Remove special case
+	code for -k'*'.
+	* tests/chill.exp: Regenerated.
+
 2002-12-11  Bruno Haible  <bruno@clisp.org>
 
 	Change the positions to be 0-based, instead of 1-based.
diff --git a/src/keyword.cc b/src/keyword.cc
index fc819b6..fbf1a0a 100644
--- a/src/keyword.cc
+++ b/src/keyword.cc
@@ -48,64 +48,62 @@ static inline void sort_char_set (unsigned int *base, int len)
 }
 
 /* Initializes selchars and selchars_length.
-   The hash function will be computed as
-   asso_values[allchars[key_pos[0]]] + asso_values[allchars[key_pos[1]]] + ...
-   We compute selchars as the multiset
-     { allchars[key_pos[0]], allchars[key_pos[1]], ... }
-   so that the hash function becomes
-     asso_values[selchars[0]] + asso_values[selchars[1]] + ...
+
+   General idea:
+     The hash function will be computed as
+         asso_values[allchars[key_pos[0]]] +
+         asso_values[allchars[key_pos[1]]] + ...
+     We compute selchars as the multiset
+         { allchars[key_pos[0]], allchars[key_pos[1]], ... }
+     so that the hash function becomes
+         asso_values[selchars[0]] + asso_values[selchars[1]] + ...
    Furthermore we sort the selchars array, to ease detection of duplicates
    later.
+
+   More in detail: The arguments alpha_unify (used for case-insensitive
+   hash functions) and alpha_inc (used to disambiguate permutations)
+   apply slight modifications. The hash function will be computed as
+       sum (j=0,1,...: k = key_pos[j]:
+            asso_values[alpha_unify[allchars[k]+alpha_inc[k]]])
+       + (allchars_length if !option[NOLENGTH], 0 otherwise).
+   We compute selchars as the multiset
+       { alpha_unify[allchars[k]+alpha_inc[k]] : j=0,1,..., k = key_pos[j] }
+   so that the hash function becomes
+       asso_values[selchars[0]] + asso_values[selchars[1]] + ...
+       + (allchars_length if !option[NOLENGTH], 0 otherwise).
  */
 
 unsigned int *
-KeywordExt::init_selchars_low (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc)
+KeywordExt::init_selchars_low (const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc)
 {
-  const char *k = _allchars;
-  unsigned int *key_set =
-    new unsigned int[(use_all_chars ? _allchars_length : positions.get_size ())];
+  /* Iterate through the list of positions, initializing selchars
+     (via ptr).  */
+  PositionIterator iter = positions.iterator(_allchars_length);
+
+  unsigned int *key_set = new unsigned int[iter.remaining()];
   unsigned int *ptr = key_set;
 
-  if (use_all_chars)
-    /* Use all the character positions in the KEY.  */
-    for (int i = _allchars_length; i > 0; k++, i--)
-      {
-        unsigned int c = static_cast<unsigned char>(*k);
-        if (alpha_inc)
-          c += alpha_inc[k-_allchars];
-        if (alpha_unify)
-          c = alpha_unify[c];
-        *ptr = c;
-        ptr++;
-      }
-  else
-    /* Only use those character positions specified by the user.  */
+  for (int i; (i = iter.next ()) != PositionIterator::EOS; )
     {
-      /* Iterate through the list of key_positions, initializing selchars
-         (via ptr).  */
-      PositionIterator iter (positions);
-
-      for (int i; (i = iter.next ()) != PositionIterator::EOS; )
+      unsigned int c;
+      if (i == Positions::LASTCHAR)
+        /* Special notation for last KEY position, i.e. '$'.  */
+        c = static_cast<unsigned char>(_allchars[_allchars_length - 1]);
+      else if (i < _allchars_length)
         {
-          unsigned int c;
-          if (i == Positions::LASTCHAR)
-            /* Special notation for last KEY position, i.e. '$'.  */
-            c = static_cast<unsigned char>(_allchars[_allchars_length - 1]);
-          else if (i < _allchars_length)
-            {
-              /* Within range of KEY length, so we'll keep it.  */
-              c = static_cast<unsigned char>(_allchars[i]);
-              if (alpha_inc)
-                c += alpha_inc[i];
-            }
-          else
-            /* Out of range of KEY length, so we'll just skip it.  */
-            continue;
-          if (alpha_unify)
-            c = alpha_unify[c];
-          *ptr = c;
-          ptr++;
+          /* Within range of KEY length, so we'll keep it.  */
+          c = static_cast<unsigned char>(_allchars[i]);
+          if (alpha_inc)
+            c += alpha_inc[i];
         }
+      else
+        /* Out of range of KEY length, the iterator should not have
+           produced this.  */
+        abort ();
+      if (alpha_unify)
+        c = alpha_unify[c];
+      *ptr = c;
+      ptr++;
     }
 
   _selchars = key_set;
@@ -115,16 +113,16 @@ KeywordExt::init_selchars_low (bool use_all_chars, const Positions& positions, c
 }
 
 void
-KeywordExt::init_selchars_tuple (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify)
+KeywordExt::init_selchars_tuple (const Positions& positions, const unsigned int *alpha_unify)
 {
-  init_selchars_low (use_all_chars, positions, alpha_unify, NULL);
+  init_selchars_low (positions, alpha_unify, NULL);
 }
 
 void
-KeywordExt::init_selchars_multiset (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc)
+KeywordExt::init_selchars_multiset (const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc)
 {
   unsigned int *selchars =
-    init_selchars_low (use_all_chars, positions, alpha_unify, alpha_inc);
+    init_selchars_low (positions, alpha_unify, alpha_inc);
 
   /* Sort the selchars elements alphabetically.  */
   sort_char_set (selchars, _selchars_length);
diff --git a/src/keyword.h b/src/keyword.h
index 9f09186..c0e2156 100644
--- a/src/keyword.h
+++ b/src/keyword.h
@@ -68,9 +68,9 @@ struct KeywordExt : public Keyword
 
   /* Methods depending on the keyposition list.  */
   /* Initializes selchars and selchars_length, without reordering.  */
-  void                  init_selchars_tuple (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify);
+  void                  init_selchars_tuple (const Positions& positions, const unsigned int *alpha_unify);
   /* Initializes selchars and selchars_length, with reordering.  */
-  void                  init_selchars_multiset (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc);
+  void                  init_selchars_multiset (const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc);
   /* Deletes selchars.  */
   void                  delete_selchars ();
 
@@ -81,7 +81,7 @@ struct KeywordExt : public Keyword
   int                   _final_index;
 
 private:
-  unsigned int *        init_selchars_low (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc);
+  unsigned int *        init_selchars_low (const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc);
 };
 
 /* An abstract factory for creating Keyword instances.
diff --git a/src/options.cc b/src/options.cc
index 6e8793e..8880858 100644
--- a/src/options.cc
+++ b/src/options.cc
@@ -514,14 +514,14 @@ Options::~Options ()
                _function_name, _hash_name, _wordlist_name, _slot_name,
                _initializer_suffix, _asso_iterations, _jump, _size_multiple,
                _initial_asso_value, _delimiters, _total_switches);
-      if (_option_word & ALLCHARS)
+      if (_key_positions.is_useall())
         fprintf (stderr, "all characters are used in the hash function\n");
       else
         {
           fprintf (stderr, "maximum keysig size = %d\nkey positions are: \n",
                    _key_positions.get_size());
 
-          PositionIterator iter (_key_positions);
+          PositionIterator iter = _key_positions.iterator();
           for (int pos; (pos = iter.next()) != PositionIterator::EOS; )
             if (pos == Positions::LASTCHAR)
               fprintf (stderr, "$\n");
@@ -773,9 +773,10 @@ Options::parse_options (int argc, char *argv[])
             PositionStringParser sparser (/*getopt*/optarg, 1, Positions::MAX_KEY_POS, Positions::LASTCHAR, BAD_VALUE, EOS);
 
             if (/*getopt*/optarg [0] == '*') /* Use all the characters for hashing!!!! */
-              _option_word |= ALLCHARS;
+              _key_positions.set_useall(true);
             else
               {
+                _key_positions.set_useall(false);
                 int *key_positions = _key_positions.pointer();
                 int *key_pos;
 
diff --git a/src/options.h b/src/options.h
index 7eb7fe1..0bde55c 100644
--- a/src/options.h
+++ b/src/options.h
@@ -96,22 +96,19 @@ enum Option_Type
   /* Use the given key positions.  */
   POSITIONS    = 1 << 16,
 
-  /* Use all characters in hash function.  */
-  ALLCHARS     = 1 << 17,
-
   /* Handle duplicate hash values for keywords.  */
-  DUP          = 1 << 18,
+  DUP          = 1 << 17,
 
   /* Don't include keyword length in hash computations.  */
-  NOLENGTH     = 1 << 19,
+  NOLENGTH     = 1 << 18,
 
   /* Randomly initialize the associated values table.  */
-  RANDOM       = 1 << 20,
+  RANDOM       = 1 << 19,
 
   /* --- Informative output --- */
 
   /* Enable debugging (prints diagnostics to stderr).  */
-  DEBUG        = 1 << 21
+  DEBUG        = 1 << 20
 };
 
 /* Class manager for gperf program Options.  */
@@ -197,8 +194,7 @@ public:
   /* Sets the delimiters string, if not already set.  */
   void                  set_delimiters (const char *delimiters);
 
-  /* Returns key positions.
-     Only to be used if !options[ALLCHARS].  */
+  /* Returns key positions.  */
   const Positions&      get_key_positions () const;
 
 private:
diff --git a/src/options.icc b/src/options.icc
index a9295a0..f519133 100644
--- a/src/options.icc
+++ b/src/options.icc
@@ -135,8 +135,7 @@ Options::get_delimiters () const
   return _delimiters;
 }
 
-/* Returns key positions.
-   Only to be used if !options[ALLCHARS].  */
+/* Returns key positions.  */
 INLINE const Positions&
 Options::get_key_positions () const
 {
diff --git a/src/output.cc b/src/output.cc
index 05ac35a..94e5952 100644
--- a/src/output.cc
+++ b/src/output.cc
@@ -606,7 +606,7 @@ Output::output_hash_function () const
   printf ("{\n");
 
   /* First the asso_values array.  */
-  if (option[ALLCHARS] || _key_positions.get_size() > 0)
+  if (_key_positions.get_size() > 0)
     {
       printf ("  static %s%s asso_values[] =\n"
               "    {",
@@ -633,31 +633,7 @@ Output::output_hash_function () const
               "    };\n");
     }
 
-  if (option[ALLCHARS])
-    {
-      /* User wants *all* characters considered in hash.  */
-      printf ("  register int hval = %s;\n\n"
-              "  switch (%s)\n"
-              "    {\n"
-              "      default:\n",
-              option[NOLENGTH] ? "0" : "len",
-              option[NOLENGTH] ? "len" : "hval");
-
-      for (int i = _max_key_len; i > 0; i--)
-        {
-          printf ("      case %d:\n"
-                  "        hval += asso_values[%sstr[%d]",
-                  i, char_to_index, i - 1);
-          if (_alpha_inc[i - 1])
-            printf ("+%u", _alpha_inc[i - 1]);
-          printf ("];\n");
-        }
-
-      printf ("        break;\n"
-              "    }\n"
-              "  return hval;\n");
-    }
-  else if (_key_positions.get_size() == 0)
+  if (_key_positions.get_size() == 0)
     {
       /* Trivial case: No key positions at all.  */
       printf ("  return %s;\n",
@@ -668,7 +644,7 @@ Output::output_hash_function () const
       /* Iterate through the key positions.  Remember that Positions::sort()
          has sorted them in decreasing order, with Positions::LASTCHAR coming
          last.  */
-      PositionIterator iter (_key_positions);
+      PositionIterator iter = _key_positions.iterator(_max_key_len);
       int key_pos;
 
       /* Get the highest key position.  */
diff --git a/src/output.h b/src/output.h
index 843fdad..780b4f1 100644
--- a/src/output.h
+++ b/src/output.h
@@ -119,7 +119,7 @@ private:
   int const             _max_key_len;
   /* Minimum length of the shortest keyword. */
   int const             _min_key_len;
-  /* Key positions.  Only to be used if !options[ALLCHARS].  */
+  /* Key positions.  */
   Positions const       _key_positions;
   /* Adjustments to add to bytes add specific key positions.  */
   const unsigned int * const _alpha_inc;
diff --git a/src/positions.cc b/src/positions.cc
index 2a096c1..f6439e3 100644
--- a/src/positions.cc
+++ b/src/positions.cc
@@ -50,6 +50,8 @@ Positions::contains (int pos) const
 void
 Positions::add (int pos)
 {
+  set_useall (false);
+
   unsigned int count = _size;
 
   if (count == MAX_SIZE)
@@ -78,6 +80,8 @@ Positions::add (int pos)
 void
 Positions::remove (int pos)
 {
+  set_useall (false);
+
   unsigned int count = _size;
   if (count > 0)
     {
@@ -120,40 +124,45 @@ Positions::remove (int pos)
 void
 Positions::print () const
 {
-  bool first = true;
-  bool seen_LASTCHAR = false;
-  unsigned int count = _size;
-  const int *p = _positions + _size - 1;
-
-  for (; count > 0; p--)
+  if (_useall)
+    printf ("*");
+  else
     {
-      count--;
-      if (*p == LASTCHAR)
-        seen_LASTCHAR = true;
-      else
+      bool first = true;
+      bool seen_LASTCHAR = false;
+      unsigned int count = _size;
+      const int *p = _positions + _size - 1;
+
+      for (; count > 0; p--)
         {
-          if (!first)
-            printf (",");
-          printf ("%d", *p + 1);
-          if (count > 0 && p[-1] == *p + 1)
+          count--;
+          if (*p == LASTCHAR)
+            seen_LASTCHAR = true;
+          else
             {
-              printf ("-");
-              do
+              if (!first)
+                printf (",");
+              printf ("%d", *p + 1);
+              if (count > 0 && p[-1] == *p + 1)
                 {
-                  p--;
-                  count--;
+                  printf ("-");
+                  do
+                    {
+                      p--;
+                      count--;
+                    }
+                  while (count > 0 && p[-1] == *p + 1);
+                  printf ("%d", *p + 1);
                 }
-              while (count > 0 && p[-1] == *p + 1);
-              printf ("%d", *p + 1);
+              first = false;
             }
-          first = false;
         }
-    }
-  if (seen_LASTCHAR)
-    {
-      if (!first)
-        printf (",");
-      printf ("$");
+      if (seen_LASTCHAR)
+        {
+          if (!first)
+            printf (",");
+          printf ("$");
+        }
     }
 }
 
diff --git a/src/positions.h b/src/positions.h
index 984195a..d16c214 100644
--- a/src/positions.h
+++ b/src/positions.h
@@ -57,10 +57,12 @@ public:
   Positions&            operator= (const Positions& src);
 
   /* Accessors.  */
+  bool                  is_useall () const;
   int                   operator[] (unsigned int index) const;
   unsigned int          get_size () const;
 
   /* Write access.  */
+  void                  set_useall (bool useall);
   int *                 pointer ();
   void                  set_size (unsigned int size);
 
@@ -68,6 +70,17 @@ public:
      Returns true if there are no duplicates, false otherwise.  */
   bool                  sort ();
 
+  /* Creates an iterator, returning the positions in descending order.  */
+  PositionIterator      iterator () const;
+  /* Creates an iterator, returning the positions in descending order,
+     that apply to strings of length <= maxlen.  */
+  PositionIterator      iterator (int maxlen) const;
+  /* Creates an iterator, returning the positions in ascending order.  */
+  PositionReverseIterator reviterator () const;
+  /* Creates an iterator, returning the positions in ascending order,
+     that apply to strings of length <= maxlen.  */
+  PositionReverseIterator reviterator (int maxlen) const;
+
   /* Set operations.  Assumes the array is in reverse order.  */
   bool                  contains (int pos) const;
   void                  add (int pos);
@@ -77,6 +90,8 @@ public:
   void                  print () const;
 
 private:
+  /* The special case denoted by '*'.  */
+  bool                  _useall;
   /* Number of positions.  */
   unsigned int          _size;
   /* Array of positions.  0 for the first char, 1 for the second char etc.,
@@ -88,9 +103,10 @@ private:
 
 class PositionIterator
 {
+  friend class Positions;
 public:
-  /* Initializes an iterator through POSITIONS.  */
-                        PositionIterator (Positions const& positions);
+  /* Copy constructor.  */
+                        PositionIterator (const PositionIterator& src);
 
   /* End of iteration marker.  */
   enum {                EOS = -2 };
@@ -98,7 +114,16 @@ public:
   /* Retrieves the next position, or EOS past the end.  */
   int                   next ();
 
+  /* Returns the number of remaining positions, i.e. how often next() will
+     return a value != EOS.  */
+  unsigned int          remaining () const;
+
 private:
+  /* Initializes an iterator through POSITIONS.  */
+                        PositionIterator (Positions const& positions);
+  /* Initializes an iterator through POSITIONS, ignoring positions >= maxlen.  */
+                        PositionIterator (Positions const& positions, int maxlen);
+
   const Positions&      _set;
   unsigned int          _index;
 };
@@ -108,9 +133,10 @@ private:
 
 class PositionReverseIterator
 {
+  friend class Positions;
 public:
-  /* Initializes an iterator through POSITIONS.  */
-                        PositionReverseIterator (Positions const& positions);
+  /* Copy constructor.  */
+                        PositionReverseIterator (const PositionReverseIterator& src);
 
   /* End of iteration marker.  */
   enum {                EOS = -2 };
@@ -118,9 +144,19 @@ public:
   /* Retrieves the next position, or EOS past the end.  */
   int                   next ();
 
+  /* Returns the number of remaining positions, i.e. how often next() will
+     return a value != EOS.  */
+  unsigned int          remaining () const;
+
 private:
+  /* Initializes an iterator through POSITIONS.  */
+                        PositionReverseIterator (Positions const& positions);
+  /* Initializes an iterator through POSITIONS, ignoring positions >= maxlen.  */
+                        PositionReverseIterator (Positions const& positions, int maxlen);
+
   const Positions&      _set;
   unsigned int          _index;
+  unsigned int          _minindex;
 };
 
 #ifdef __OPTIMIZE__
diff --git a/src/positions.icc b/src/positions.icc
index 32af6b1..ca9347d 100644
--- a/src/positions.icc
+++ b/src/positions.icc
@@ -30,20 +30,23 @@
 
 INLINE
 Positions::Positions ()
-  : _size (0)
+  : _useall (false),
+    _size (0)
 {
 }
 
 INLINE
 Positions::Positions (int pos1)
-  : _size (1)
+  : _useall (false),
+    _size (1)
 {
   _positions[0] = pos1;
 }
 
 INLINE
 Positions::Positions (int pos1, int pos2)
-  : _size (2)
+  : _useall (false),
+    _size (2)
 {
   _positions[0] = pos1;
   _positions[1] = pos2;
@@ -53,7 +56,8 @@ Positions::Positions (int pos1, int pos2)
 
 INLINE
 Positions::Positions (const Positions& src)
-  : _size (src._size)
+  : _useall (src._useall),
+    _size (src._size)
 {
   memcpy (_positions, src._positions, _size * sizeof (_positions[0]));
 }
@@ -63,6 +67,7 @@ Positions::Positions (const Positions& src)
 INLINE Positions&
 Positions::operator= (const Positions& src)
 {
+  _useall = src._useall;
   _size = src._size;
   memcpy (_positions, src._positions, _size * sizeof (_positions[0]));
   return *this;
@@ -70,6 +75,12 @@ Positions::operator= (const Positions& src)
 
 /* Accessors.  */
 
+INLINE bool
+Positions::is_useall () const
+{
+  return _useall;
+}
+
 INLINE int
 Positions::operator[] (unsigned int index) const
 {
@@ -84,6 +95,20 @@ Positions::get_size () const
 
 /* Write access.  */
 
+INLINE void
+Positions::set_useall (bool useall)
+{
+  _useall = useall;
+  if (useall)
+    {
+      /* The positions are 0, 1, ..., MAX_KEY_POS-1, in descending order.  */
+      _size = MAX_KEY_POS;
+      int *ptr = _positions;
+      for (int i = MAX_KEY_POS - 1; i >= 0; i--)
+        *ptr++ = i;
+    }
+}
+
 INLINE int *
 Positions::pointer ()
 {
@@ -101,6 +126,9 @@ Positions::set_size (unsigned int size)
 INLINE bool
 Positions::sort ()
 {
+  if (_useall)
+    return true;
+
   /* Bubble sort.  */
   bool duplicate_free = true;
   int *base = _positions;
@@ -121,6 +149,36 @@ Positions::sort ()
   return duplicate_free;
 }
 
+/* Creates an iterator, returning the positions in descending order.  */
+INLINE PositionIterator
+Positions::iterator () const
+{
+  return PositionIterator (*this);
+}
+
+/* Creates an iterator, returning the positions in descending order,
+   that apply to strings of length <= maxlen.  */
+INLINE PositionIterator
+Positions::iterator (int maxlen) const
+{
+  return PositionIterator (*this, maxlen);
+}
+
+/* Creates an iterator, returning the positions in ascending order.  */
+INLINE PositionReverseIterator
+Positions::reviterator () const
+{
+  return PositionReverseIterator (*this);
+}
+
+/* Creates an iterator, returning the positions in ascending order,
+   that apply to strings of length <= maxlen.  */
+INLINE PositionReverseIterator
+Positions::reviterator (int maxlen) const
+{
+  return PositionReverseIterator (*this, maxlen);
+}
+
 /* ------------------------- Class PositionIterator ------------------------ */
 
 /* Initializes an iterator through POSITIONS.  */
@@ -131,6 +189,24 @@ PositionIterator::PositionIterator (Positions const& positions)
 {
 }
 
+/* Initializes an iterator through POSITIONS, ignoring positions >= maxlen.  */
+INLINE
+PositionIterator::PositionIterator (Positions const& positions, int maxlen)
+  : _set (positions)
+{
+  if (positions._useall)
+    _index = (maxlen <= Positions::MAX_KEY_POS ? Positions::MAX_KEY_POS - maxlen : 0);
+  else
+    {
+      unsigned int index;
+      for (index = 0;
+           index < positions._size && positions._positions[index] >= maxlen;
+           index++)
+        ;
+      _index = index;
+    }
+}
+
 /* Retrieves the next position, or EOS past the end.  */
 INLINE int
 PositionIterator::next ()
@@ -138,19 +214,72 @@ PositionIterator::next ()
   return (_index < _set._size ? _set._positions[_index++] : EOS);
 }
 
+/* Returns the number of remaining positions, i.e. how often next() will
+   return a value != EOS.  */
+INLINE unsigned int
+PositionIterator::remaining () const
+{
+  return _set._size - _index;
+}
+
+/* Copy constructor.  */
+INLINE
+PositionIterator::PositionIterator (const PositionIterator& src)
+  : _set (src._set),
+    _index (src._index)
+{
+}
+
 /* --------------------- Class PositionReverseIterator --------------------- */
 
 /* Initializes an iterator through POSITIONS.  */
 INLINE
 PositionReverseIterator::PositionReverseIterator (Positions const& positions)
   : _set (positions),
+    _index (_set._size),
+    _minindex (0)
+{
+}
+
+/* Initializes an iterator through POSITIONS, ignoring positions >= maxlen.  */
+INLINE
+PositionReverseIterator::PositionReverseIterator (Positions const& positions, int maxlen)
+  : _set (positions),
     _index (_set._size)
 {
+  if (positions._useall)
+    _minindex = (maxlen <= Positions::MAX_KEY_POS ? Positions::MAX_KEY_POS - maxlen : 0);
+  else
+    {
+      unsigned int index;
+      for (index = 0;
+           index < positions._size && positions._positions[index] >= maxlen;
+           index++)
+        ;
+      _minindex = index;
+    }
 }
 
 /* Retrieves the next position, or EOS past the end.  */
 INLINE int
 PositionReverseIterator::next ()
 {
-  return (_index > 0 ? _set._positions[--_index] : EOS);
+  return (_index > _minindex ? _set._positions[--_index] : EOS);
+}
+
+/* Returns the number of remaining positions, i.e. how often next() will
+   return a value != EOS.  */
+INLINE unsigned int
+PositionReverseIterator::remaining () const
+{
+  return _index - _minindex;
+}
+
+/* Copy constructor.  */
+INLINE
+PositionReverseIterator::PositionReverseIterator (const PositionReverseIterator& src)
+  : _set (src._set),
+    _index (src._index),
+    _minindex (src._minindex)
+{
 }
diff --git a/src/search.cc b/src/search.cc
index a1b71a8..61fb5ef 100644
--- a/src/search.cc
+++ b/src/search.cc
@@ -175,10 +175,10 @@ Search::compute_alpha_unify () const
 
 /* Initializes each keyword's _selchars array.  */
 void
-Search::init_selchars_tuple (bool use_all_chars, const Positions& positions) const
+Search::init_selchars_tuple (const Positions& positions) const
 {
   for (KeywordExt_List *temp = _head; temp; temp = temp->rest())
-    temp->first()->init_selchars_tuple(use_all_chars, positions, _alpha_unify);
+    temp->first()->init_selchars_tuple(positions, _alpha_unify);
 }
 
 /* Deletes each keyword's _selchars array.  */
@@ -199,7 +199,7 @@ Search::count_duplicates_tuple (const Positions& positions) const
   /* Run through the keyword list and count the duplicates incrementally.
      The result does not depend on the order of the keyword list, thanks to
      the formula above.  */
-  init_selchars_tuple (option[ALLCHARS], positions);
+  init_selchars_tuple (positions);
 
   unsigned int count = 0;
   {
@@ -411,7 +411,7 @@ Search::find_positions ()
     {
       /* Print the result.  */
       fprintf (stderr, "\nComputed positions: ");
-      PositionReverseIterator iter (_key_positions);
+      PositionReverseIterator iter = _key_positions.reviterator();
       bool seen_lastchar = false;
       bool first = true;
       for (int i; (i = iter.next ()) != PositionReverseIterator::EOS; )
@@ -482,49 +482,29 @@ Search::compute_alpha_unify (const Positions& positions, const unsigned int *alp
         {
           KeywordExt *keyword = temp->first();
 
-          if (option[ALLCHARS])
-            /* Iterate through all character positions.  */
-            for (int i = 0; i < keyword->_allchars_length; i++)
-              {
-                unsigned int c = static_cast<unsigned char>(keyword->_allchars[i]);
-                if (c >= 'A' && c <= 'Z')
-                  c += 'a' - 'A';
-                if (c >= 'a' && c <= 'z')
-                  {
-                    c += alpha_inc[i];
-                    /* Unify c with c - ('a'-'A').  */
-                    unsigned int d = alpha_unify[c];
-                    unsigned int b = c - ('a'-'A');
-                    for (int a = b; a >= 0 && alpha_unify[a] == b; a -= ('a'-'A'))
-                      alpha_unify[a] = d;
-                  }
-              }
-          else
-            {
-              /* Iterate through the selected character positions.  */
-              PositionIterator iter (positions);
+          /* Iterate through the selected character positions.  */
+          PositionIterator iter = positions.iterator(keyword->_allchars_length);
 
-              for (int i; (i = iter.next ()) != PositionIterator::EOS; )
+          for (int i; (i = iter.next ()) != PositionIterator::EOS; )
+            {
+              unsigned int c;
+              if (i == Positions::LASTCHAR)
+                c = static_cast<unsigned char>(keyword->_allchars[keyword->_allchars_length - 1]);
+              else if (i < keyword->_allchars_length)
+                c = static_cast<unsigned char>(keyword->_allchars[i]);
+              else
+                abort ();
+              if (c >= 'A' && c <= 'Z')
+                c += 'a' - 'A';
+              if (c >= 'a' && c <= 'z')
                 {
-                  unsigned int c;
-                  if (i == Positions::LASTCHAR)
-                    c = static_cast<unsigned char>(keyword->_allchars[keyword->_allchars_length - 1]);
-                  else if (i < keyword->_allchars_length)
-                    c = static_cast<unsigned char>(keyword->_allchars[i]);
-                  else
-                    continue;
-                  if (c >= 'A' && c <= 'Z')
-                    c += 'a' - 'A';
-                  if (c >= 'a' && c <= 'z')
-                    {
-                      if (i != Positions::LASTCHAR)
-                        c += alpha_inc[i];
-                      /* Unify c with c - ('a'-'A').  */
-                      unsigned int d = alpha_unify[c];
-                      unsigned int b = c - ('a'-'A');
-                      for (int a = b; a >= 0 && alpha_unify[a] == b; a -= ('a'-'A'))
-                        alpha_unify[a] = d;
-                    }
+                  if (i != Positions::LASTCHAR)
+                    c += alpha_inc[i];
+                  /* Unify c with c - ('a'-'A').  */
+                  unsigned int d = alpha_unify[c];
+                  unsigned int b = c - ('a'-'A');
+                  for (int a = b; a >= 0 && alpha_unify[a] == b; a -= ('a'-'A'))
+                    alpha_unify[a] = d;
                 }
             }
         }
@@ -537,10 +517,10 @@ Search::compute_alpha_unify (const Positions& positions, const unsigned int *alp
 
 /* Initializes each keyword's _selchars array.  */
 void
-Search::init_selchars_multiset (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc) const
+Search::init_selchars_multiset (const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc) const
 {
   for (KeywordExt_List *temp = _head; temp; temp = temp->rest())
-    temp->first()->init_selchars_multiset(use_all_chars, positions, alpha_unify, alpha_inc);
+    temp->first()->init_selchars_multiset(positions, alpha_unify, alpha_inc);
 }
 
 /* Count the duplicate keywords that occur with the given set of positions
@@ -554,7 +534,7 @@ Search::count_duplicates_multiset (const unsigned int *alpha_inc) const
   /* Run through the keyword list and count the duplicates incrementally.
      The result does not depend on the order of the keyword list, thanks to
      the formula above.  */
-  init_selchars_multiset (option[ALLCHARS], _key_positions,
+  init_selchars_multiset (_key_positions,
                           compute_alpha_unify (_key_positions, alpha_inc),
                           alpha_inc);
 
@@ -596,35 +576,34 @@ Search::find_alpha_inc ()
     {
       /* Look which _alpha_inc[i] we are free to increment.  */
       unsigned int nindices;
-      if (option[ALLCHARS])
-        nindices = _max_key_len;
-      else
-        {
-          /* Ignore Positions::LASTCHAR.  Remember that since Positions are
-             sorted in decreasing order, Positions::LASTCHAR comes last.  */
-          nindices = (_key_positions.get_size() == 0
-                      || _key_positions[_key_positions.get_size() - 1]
-                         != Positions::LASTCHAR
-                      ? _key_positions.get_size()
-                      : _key_positions.get_size() - 1);
-        }
+      {
+        nindices = 0;
+        PositionIterator iter = _key_positions.iterator(_max_key_len);
+        for (;;)
+          {
+            int key_pos = iter.next ();
+            if (key_pos == PositionIterator::EOS)
+              break;
+            if (key_pos != Positions::LASTCHAR)
+              nindices++;
+          }
+      }
 
       unsigned int indices[nindices];
-      if (option[ALLCHARS])
-        for (unsigned int j = 0; j < nindices; j++)
-          indices[j] = j;
-      else
-        {
-          PositionIterator iter (_key_positions);
-          for (unsigned int j = 0; j < nindices; j++)
-            {
-              int key_pos = iter.next ();
-              if (key_pos == PositionIterator::EOS
-                  || key_pos == Positions::LASTCHAR)
-                abort ();
-              indices[j] = key_pos;
-            }
-        }
+      {
+        unsigned int j = 0;
+        PositionIterator iter = _key_positions.iterator(_max_key_len);
+        for (;;)
+          {
+            int key_pos = iter.next ();
+            if (key_pos == PositionIterator::EOS)
+              break;
+            if (key_pos != Positions::LASTCHAR)
+              indices[j++] = key_pos;
+          }
+        if (!(j == nindices))
+          abort ();
+      }
 
       /* Perform several rounds of searching for a good alpha increment.
          Each round reduces the number of artificial collisions by adding
@@ -670,32 +649,16 @@ Search::find_alpha_inc ()
         {
           /* Print the result.  */
           fprintf (stderr, "\nComputed alpha increments: ");
-          if (option[ALLCHARS])
-            {
-              bool first = true;
-              for (unsigned int j = 0; j < nindices; j++)
-                if (current[indices[j]] != 0)
-                  {
-                    if (!first)
-                      fprintf (stderr, ", ");
-                    fprintf (stderr, "%u:+%u",
-                             indices[j] + 1, current[indices[j]]);
-                    first = false;
-                  }
-            }
-          else
-            {
-              bool first = true;
-              for (unsigned int j = nindices; j-- > 0; )
-                if (current[indices[j]] != 0)
-                  {
-                    if (!first)
-                      fprintf (stderr, ", ");
-                    fprintf (stderr, "%u:+%u",
-                             indices[j] + 1, current[indices[j]]);
-                    first = false;
-                  }
-            }
+          bool first = true;
+          for (unsigned int j = nindices; j-- > 0; )
+            if (current[indices[j]] != 0)
+              {
+                if (!first)
+                  fprintf (stderr, ", ");
+                fprintf (stderr, "%u:+%u",
+                         indices[j] + 1, current[indices[j]]);
+                first = false;
+              }
           fprintf (stderr, "\n");
         }
     }
@@ -713,8 +676,7 @@ Search::prepare ()
   KeywordExt_List *temp;
 
   /* Initialize each keyword's _selchars array.  */
-  init_selchars_multiset(option[ALLCHARS], _key_positions,
-                         _alpha_unify, _alpha_inc);
+  init_selchars_multiset(_key_positions, _alpha_unify, _alpha_inc);
 
   /* Check for duplicates, i.e. keywords with the same _selchars array
      (and - if !option[NOLENGTH] - also the same length).
@@ -831,7 +793,7 @@ Search::max_key_length () const
 int
 Search::get_max_keysig_size () const
 {
-  return option[ALLCHARS] ? _max_key_len : _key_positions.get_size();
+  return _key_positions.is_useall() ? _max_key_len : _key_positions.get_size();
 }
 
 /* ---------------------- Finding good asso_values[] ----------------------- */
diff --git a/src/search.h b/src/search.h
index 0cd2829..9d14aec 100644
--- a/src/search.h
+++ b/src/search.h
@@ -50,7 +50,7 @@ private:
   unsigned int *        compute_alpha_unify () const;
 
   /* Initializes each keyword's _selchars array.  */
-  void                  init_selchars_tuple (bool use_all_chars, const Positions& positions) const;
+  void                  init_selchars_tuple (const Positions& positions) const;
   /* Deletes each keyword's _selchars array.  */
   void                  delete_selchars () const;
 
@@ -67,7 +67,7 @@ private:
   unsigned int *        compute_alpha_unify (const Positions& positions, const unsigned int *alpha_inc) const;
 
   /* Initializes each keyword's _selchars array.  */
-  void                  init_selchars_multiset (bool use_all_chars, const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc) const;
+  void                  init_selchars_multiset (const Positions& positions, const unsigned int *alpha_unify, const unsigned int *alpha_inc) const;
 
   /* Count the duplicate keywords that occur with the given set of positions
      and a given alpha_inc[] array.  */
diff --git a/tests/chill.exp b/tests/chill.exp
index 089843f..4d90f67 100644
--- a/tests/chill.exp
+++ b/tests/chill.exp
@@ -55,7 +55,6 @@ hash (str, len)
   switch (hval)
     {
       default:
-      case 30:
         hval += asso_values[(unsigned char)str[29]];
       case 29:
         hval += asso_values[(unsigned char)str[28]];