agenda for fsa

git-svn-id: https://ws10smt.googlecode.com/svn/trunk@612 ec762483-ff6d-05da-a07a-a48fb63a330f

8 files changed, 329 insertions, 45 deletions

diff --git a/decoder/apply_fsa_models.cc b/decoder/apply_fsa_models.cc
index 7cd5fc6d..f9c94ec3 100755
--- a/decoder/apply_fsa_models.cc
+++ b/decoder/apply_fsa_models.cc
@@ -13,6 +13,8 @@
 #include "utoa.h"
 #include "hash.h"
 #include "value_array.h"
+#include "d_ary_heap.h"
+#include "agenda.h"
 
 #define DFSA(x) x
 #define DPFSA(x) x
@@ -72,12 +74,15 @@ struct get_second {
 
 struct PrefixTrieNode;
 struct PrefixTrieEdge {
+//  PrefixTrieEdge() {  }
+//  explicit PrefixTrieEdge(prob_t p) : p(p),dest(0) {  }
   prob_t p;// viterbi additional prob, i.e. product over path incl. p_final = total rule prob
   //DPFSA()
   // we can probably just store deltas, but for debugging remember the full p
   //    prob_t delta; //
   PrefixTrieNode *dest;
-  WordID w; // for lhs, this will be positive NTHandle instead
+  bool is_final() const { return dest==0; }
+  WordID w; // for lhs, this will be nonneg NTHandle instead.  //  not set if is_final() // actually, set to lhs nt index
 
   // for sorting most probable first in adj; actually >(p)
   inline bool operator <(PrefixTrieEdge const& o) const {
@@ -88,33 +93,55 @@ struct PrefixTrieEdge {
 struct PrefixTrieNode {
   prob_t p; // viterbi (max prob) of rule this node leads to - when building.  telescope later onto edges for best-first.
 #if TRIE_START_LHS
-  bool final; // may also have successors, of course
-  prob_t p_final; // additional prob beyond what we already paid. while building, this is the total prob
+//  bool final; // may also have successors, of course.  we don't really need to track this; a null dest edge in the adj list lets us encounter the fact in best first order.
+//  prob_t p_final; // additional prob beyond what we already paid. while building, this is the total prob
+// instead of storing final, we'll say that an edge with a NULL dest is a final edge.  this way it gets sorted into the list of adj.
+
   // instead of completed map, we have trie start w/ lhs.
-  NTHandle lhs; // instead of storing this in Item.
+  NTHandle lhs; // nonneg. - instead of storing this in Item.
 #else
   typedef FSA_MAP(LHS,RuleHandle) Completed; // can only have one rule w/ a given signature (duplicates should be collapsed when making CFG).  but there may be multiple rules, with different LHS
   Completed completed;
 #endif
-  explicit PrefixTrieNode(prob_t p=1) : p(p),final(false) {  }
+  enum { ROOT=-1 };
+  explicit PrefixTrieNode(NTHandle lhs=ROOT,prob_t p=1) : p(p),lhs(lhs) {
+    //final=false;
+  }
+  bool is_root() const { return lhs==ROOT; } // means adj are the nonneg lhs indices, and we have the index edge_for still available
 
   // outgoing edges will be ordered highest p to worst p
 
   typedef FSA_MAP(WordID,PrefixTrieEdge) PrefixTrieEdgeFor;
 public:
   PrefixTrieEdgeFor edge_for; //TODO: move builder elsewhere?  then need 2nd hash or edge include pointer to builder.  just clear this later
+  bool have_adj() const {
+    return adj.size()>=edge_for.size();
+  }
+  bool no_adj() const {
+    return adj.empty();
+  }
+
   void index_adj() {
     index_adj(edge_for);
   }
-
   template <class M>
   void index_adj(M &m) {
+    assert(have_adj());
     m.clear();
     for (int i=0;i<adj.size();++i) {
       PrefixTrieEdge const& e=adj[i];
       m[e.w]=e;
     }
   }
+  template <class PV>
+  void index_root(PV &v) {
+    v.resize(adj.size());
+    for (int i=0,e=adj.size();i!=e;++i) {
+      PrefixTrieEdge const& e=adj[i];
+      // assert(e.p.is_1());  // actually, after done_building, e will have telescoped dest->p/p.
+      v[e.w]=e.dest;
+    }
+  }
 
   // call only once.
   void done_building_r() {
@@ -124,18 +151,18 @@ public:
   }
 
   // for done_building; compute incremental (telescoped) edge p
-  PrefixTrieEdge const& operator()(PrefixTrieEdgeFor::value_type &pair) const {
-    PrefixTrieEdge &e=pair.second;
+  PrefixTrieEdge const& operator()(PrefixTrieEdgeFor::value_type const& pair) const {
+    PrefixTrieEdge &e=const_cast<PrefixTrieEdge&>(pair.second);
     e.p=(e.dest->p)/p;
     return e;
   }
 
   // call only once.
   void done_building() {
-    adj.reinit_map(edge_for.begin(),edge_for.end(),*this);
-    if (final)
-      p_final/=p;
+    adj.reinit_map(edge_for,*this);
+//    if (final) p_final/=p;
     std::sort(adj.begin(),adj.end());
+    //TODO: store adjacent differences on edges (compared to
   }
 
   typedef ValueArray<PrefixTrieEdge>  Adj;
@@ -143,8 +170,6 @@ public:
   Adj adj;
 
   typedef WordID W;
-  typedef NTHandle N; // not negative
-  typedef W const* RI;
 
   // let's compute p_min so that every rule reachable from the created node has p at least this low.
   PrefixTrieNode *improve_edge(PrefixTrieEdge const& e,prob_t rulep) {
@@ -153,28 +178,46 @@ public:
     return d;
   }
 
-  PrefixTrieNode *build(W w,prob_t rulep) {
+  inline PrefixTrieNode *build(W w,prob_t rulep) {
+    return build(lhs,w,rulep);
+  }
+  inline PrefixTrieNode *build_lhs(NTHandle w,prob_t rulep) {
+    return build(w,w,rulep);
+  }
+
+  PrefixTrieNode *build(NTHandle lhs_,W w,prob_t rulep) {
     PrefixTrieEdgeFor::iterator i=edge_for.find(w);
     if (i!=edge_for.end())
       return improve_edge(i->second,rulep);
     PrefixTrieEdge &e=edge_for[w];
-    return e.dest=new PrefixTrieNode(rulep);
+    return e.dest=new PrefixTrieNode(lhs_,rulep);
   }
 
-  void set_final(prob_t pf) {
-    final=true;p_final=pf;
+  void set_final(NTHandle lhs_,prob_t pf) {
+    assert(no_adj());
+//    final=true; // don't really need to track this.
+    PrefixTrieEdge &e=edge_for[-1];
+    e.p=pf;
+    e.dest=0;
+    e.w=lhs_;
+    if (pf>p)
+      p=pf;
   }
 
-#ifdef HAVE_TAIL_RECURSE
-  // add string i...end
-  void build(RI i,RI end, prob_t rulep) {
-    if (i==end) {
-      set_final(rulep);
-    } else
-    // tail recursion:
-      build(*i)->build(i+1,end,rulep);
+private:
+  void destroy_children() {
+    assert(adj.size()>=edge_for.size());
+    for (int i=0,e=adj.size();i<e;++i) {
+      PrefixTrieNode *c=adj[i].dest;
+      if (c) { // final state has no end
+        delete c;
+      }
+    }
+  }
+public:
+  ~PrefixTrieNode() {
+    destroy_children();
   }
-#endif
 };
 
 #if TRIE_START_LHS
@@ -200,34 +243,77 @@ struct PrefixTrie {
   }
   void operator()(int ri) const {
     Rule const& r=rules()[ri];
+    NTHandle lhs=r.lhs;
     prob_t p=r.p;
-    PrefixTrieNode *n=const_cast<PrefixTrieNode&>(root).build(r.lhs,p);
+    PrefixTrieNode *n=const_cast<PrefixTrieNode&>(root).build_lhs(lhs,p);
     for (RHS::const_iterator i=r.rhs.begin(),e=r.rhs.end();;++i) {
       if (i==e) {
-        n->set_final(p);
+        n->set_final(lhs,p);
         break;
       }
       n=n->build(*i,p);
     }
-#ifdef HAVE_TAIL_RECURSE
-    root.build(r.lhs,r.p)->build(r.rhs,r.p);
-#endif
+//    root.build(lhs,r.p)->build(r.rhs,r.p);
   }
+
+
 };
 
-// these should go in a global best-first queue
+typedef std::size_t ItemHash;
+
 struct Item {
-  prob_t forward;
+  explicit Item(PrefixTrieNode *dot,int next=0) : dot(dot),next(next) {  }
+  PrefixTrieNode *dot; // dot is a function of the stuff already recognized, and gives a set of suffixes y to complete to finish a rhs for lhs() -> dot y.  for a lhs A -> . *, this will point to lh2[A]
+  int next; // index of dot->adj to complete (if dest==0), or predict (if NT), or scan (if word)
+  NTHandle lhs() const { return dot->lhs; }
+  inline ItemHash hash() const {
+    return GOLDEN_MEAN_FRACTION*next^((ItemHash)dot>>4); // / sizeof(PrefixTrieNode), approx., i.e. lower order bits of ptr are nonrandom
+  }
+};
+
+inline ItemHash hash_value(Item const& x) {
+  return x.hash();
+}
+
+Item null_item((PrefixTrieNode*)0);
+
+// these should go in a global best-first queue
+struct ItemP {
+  ItemP() : forward(init_0()),inner(init_0()) {  }
+  prob_t forward; // includes inner prob.
   // NOTE: sum = viterbi (max)
   /* The forward probability alpha_i(X[k]->x.y) is the sum of the probabilities of all
      constrained paths of length that end in state X[k]->x.y*/
   prob_t inner;
   /* The inner probability beta_i(X[k]->x.y) is the sum of the probabilities of all
      paths of length i-k that start in state X[k,k]->.xy and end in X[k,i]->x.y, and generate the input symbols x[k,...,i-1] */
-  PrefixTrieNode *dot; // dot is a function of the stuff already recognized, and gives a set of suffixes y to complete to finish a rhs for lhs() -> dot y
-  NTHandle lhs() const { return dot->lhs; }
 };
 
+struct Chart {
+  //Agenda<Item> a;
+  //typedef HASH_MAP(Item,ItemP,boost::hash<Item>) Items;
+  //typedef Items::iterator FindItem;
+  //typedef std::pair<FindItem,bool> InsertItem;
+//  Items items;
+  CFG &cfg; // TODO: remove this from Chart
+  NTHandle goal_nt;
+  PrefixTrie trie;
+  typedef std::vector<PrefixTrieNode *> LhsToTrie; // will have to check lhs2[lhs].p for best cost of some rule with that lhs, then use edge deltas after?  they're just caching a very cheap computation, really
+  LhsToTrie lhs2; // no reason to use a map or hash table; every NT in the CFG will have some rule rhses.  lhs_to_trie[i]=root.edge_for[i], i.e. we still have a root trie node conceptually, we just access through this since it's faster.
+
+  void enqueue(Item const& item,ItemP const& p) {
+//    FindItem f=items.find(item);
+//    if (f==items.end()) ;
+
+  }
+
+  Chart(CFG &cfg) :cfg(cfg),trie(cfg) {
+    goal_nt=cfg.goal_nt;
+    trie.root.index_root(lhs2);
+  }
+};
+
+
 }//anon ns
 
 
@@ -279,7 +365,7 @@ void ApplyFsa::ApplyBottomUp()
 void ApplyFsa::ApplyEarley()
 {
   hgcfg.GiveCFG(cfg);
-  PrefixTrie rt(cfg);
+  Chart chart(cfg);
   // don't need to uniq - option to do that already exists in cfg_options
   //TODO:
 }
diff --git a/decoder/cfg.cc b/decoder/cfg.cc
index b2219193..651978d2 100755
--- a/decoder/cfg.cc
+++ b/decoder/cfg.cc
@@ -8,6 +8,7 @@
 #include "fast_lexical_cast.hpp"
 //#include "indices_after.h"
 #include "show.h"
+#include "null_traits.h"
 
 #define DUNIQ(x) x
 #define DBIN(x)
@@ -31,6 +32,7 @@ using namespace std;
 typedef CFG::Rule Rule;
 typedef CFG::NTOrder NTOrder;
 typedef CFG::RHS RHS;
+typedef CFG::BinRhs BinRhs;
 
 /////index ruleids:
 void CFG::UnindexRules() {
@@ -166,11 +168,11 @@ void CFG::SortLocalBestFirst(NTHandle ni) {
 /////binarization:
 namespace {
 
-CFG::BinRhs null_bin_rhs(std::numeric_limits<int>::min(),std::numeric_limits<int>::min());
+BinRhs null_bin_rhs(std::numeric_limits<int>::min(),std::numeric_limits<int>::min());
 
 // index i >= N.size()?  then it's in M[i-N.size()]
 //WordID first,WordID second,
-string BinStr(CFG::BinRhs const& b,CFG::NTs const& N,CFG::NTs const& M)
+string BinStr(BinRhs const& b,CFG::NTs const& N,CFG::NTs const& M)
 {
   int nn=N.size();
   ostringstream o;
@@ -203,7 +205,7 @@ string BinStr(RHS const& r,CFG::NTs const& N,CFG::NTs const& M)
 }
 
 
-WordID BinName(CFG::BinRhs const& b,CFG::NTs const& N,CFG::NTs const& M)
+WordID BinName(BinRhs const& b,CFG::NTs const& N,CFG::NTs const& M)
 {
   return TD::Convert(BinStr(b,N,M));
 }
@@ -213,22 +215,27 @@ WordID BinName(RHS const& b,CFG::NTs const& N,CFG::NTs const& M)
   return TD::Convert(BinStr(b,N,M));
 }
 
+/*
 template <class Rhs>
 struct null_for;
 
-typedef CFG::BinRhs BinRhs;
 
 template <>
 struct null_for<BinRhs> {
   static BinRhs null;
 };
-BinRhs null_for<BinRhs>::null(std::numeric_limits<int>::min(),std::numeric_limits<int>::min());
 
 template <>
 struct null_for<RHS> {
   static RHS null;
 };
-RHS null_for<RHS>::null(1,std::numeric_limits<int>::min());
+*/
+
+template <>
+BinRhs null_traits<BinRhs>::null(std::numeric_limits<int>::min(),std::numeric_limits<int>::min());
+
+template <>
+RHS null_traits<RHS>::null(1,std::numeric_limits<int>::min());
 
 template <class Rhs>
 struct add_virtual_rules {
@@ -243,7 +250,7 @@ struct add_virtual_rules {
   R2L rhs2lhs; // an rhs maps to this -virtntid, or original id if length 1
   bool name_nts;
   add_virtual_rules(CFG &cfg,bool name_nts=false) : nts(cfg.nts),rules(cfg.rules),newnt(-nts.size()),newruleid(rules.size()),name_nts(name_nts) {
-    HASH_MAP_EMPTY(rhs2lhs,null_for<Rhs>::null);
+    HASH_MAP_EMPTY(rhs2lhs,null_traits<Rhs>::null);
   }
   NTHandle get_virt(Rhs const& r) {
     NTHandle nt=get_default(rhs2lhs,r,newnt);
diff --git a/utils/agenda.h b/utils/agenda.h
new file mode 100755
index 00000000..8198f077
--- /dev/null
+++ b/utils/agenda.h
@@ -0,0 +1,95 @@
+#ifndef AGENDA_H
+#define AGENDA_H
+
+/*
+  a priority queue where you expect to queue the same item at different
+  priorities several times before finally popping it.  higher priority = better.
+  so in best first you'd be using negative cost or e^-cost (probabilities, in
+  other words).
+
+  this means you have a way to look up a key and see its location in the queue,
+  so its priority can be adjusted (or, simpler implementation: so when you pop,
+  you see if you've already popped before at a lower cost, and skip the
+  subsequent pops).
+
+  it's assumed that you'll never queue an item @ a better priority after it has
+  already been popped.  that is, the agenda will track already completed items.
+  maybe in the future i will let you recompute a cheaper way to reach things
+  after first-pop also, it's assumed that we're always improving prios of
+  existing items, never making them worse (even though technically this is
+  possible and sensible if it hasn't been popped yet).
+
+  simple binary max heap for now.  there are better practical options w/
+  superior cache locaility.  movements in the heap need to update a record for
+  that key of where the key went.  i do this by creating canonical key pointers
+  out of boost object pools (if the key were lightweight e.g. an int, then it
+  would make sense to use the hash lookup too
+
+  since i'm doing key hashing to start with, i also allow you to attach some
+  arbitrary data (value) payload beyond key+priority.
+
+  hash map from key to done (has been popped) -> set where doneness is marked in key item?
+
+  a slightly different way to make an adjustable heap would be to use
+  tree-structured parent/children links intrusively (or mapped by key) in the
+  key, rather than indices in a compact binary-tree heap
+
+ */
+
+#include "best.h"
+#include "hash.h"
+#include "d_ary_heap.h"
+#include "lvalue_pmap.h"
+#include <vector>
+#include <functional>
+
+/*
+template <class P>
+struct priority_traits {
+  typedef typename P::priority_type priority_type;
+};
+
+// P p has priority_traits<P>::type &p->agenda_priority() and unsigned &p->agenda_location(), and bool & p->agenda_done()
+// this is really 4 functors in 1 (or lvalue property maps); you can supply your own as the Prio type in Agenda<...> below ; state is allowed.
+template <class P>
+struct AdjustablePriority {
+  typedef AdjustablePriority<P> Self;
+  typedef typename priority_traits<P>::priority_type Priority;
+  Priority & priority(P const &x) {
+    return x->agenda_priority();
+  }
+  unsigned & location(P const &x) { // this gets updated by push, pop, and adjust
+    return x->agenda_location();
+  }
+  void is_done(P const& x) const {
+    return x->agenda_done();
+  }
+  void set_done(P const& x) const {
+    x->agenda_done()=true;
+  }
+};
+*/
+
+typedef best_t agenda_best_t;
+
+PMAP_MEMBER_INDIRECT(LocationMap,unsigned,location)
+PMAP_MEMBER_INDIRECT(PriorityMap,best_t,priority)
+
+// LocMap and PrioMap are boost property maps put(locmap,key,size_t), Better(get(priomap,k1),get(priomap,k2)) means k1 should be above k2 (be popped first).  Locmap and PrioMap may have state; the rest are assumed stateless functors
+template <class Item,class Hash=boost::hash<Item>,class Equal=std::equal_to<Item>,class Better=std::less<Item> >
+struct Agenda {
+  /* this is less generic than it could be, because I want to use a single hash mapping to intern to canonical mutable object pointers, where the property maps are just lvalue accessors */
+/*
+  typedef Item *CanonItem;
+  static const std::size_t heap_arity=4; // might be fastest possible (depends on key size probably - cache locality is bad w/ arity=2)
+  typedef std::vector<CanonItem> HeapStorage;
+  typedef boost::detail::d_ary_heap_indirect<Key,heap_arity,LocMap,PrioMap,Better,HeapStorage> Heap;
+  HASH_SET<Key,Hash,Equal> queued;
+  typedef LocationMap<ItemP>
+  LocMap locmap;
+  PrioMap priomap;
+  Agenda(LocMap const& lm=LocMap(),PrioMap const& pm=PrioMap()) : locmap(lm), priomap(pm) {  }
+*/
+};
+
+#endif
diff --git a/utils/best.h b/utils/best.h
new file mode 100755
index 00000000..8ff896bb
--- /dev/null
+++ b/utils/best.h
@@ -0,0 +1,13 @@
+#ifndef UTILS__BEST_H
+#define UTILS__BEST_H
+
+#include "max_plus.h"
+
+typedef MaxPlus<double> best_t;
+
+inline bool operator <(best_t const& a,best_t const& b) {
+  return a.v_>b.v_; // intentionally reversed, so default min-heap, sort, etc. put best first.
+}
+
+
+#endif
diff --git a/utils/hash.h b/utils/hash.h
index 7e38bb2c..e9584dd5 100755
--- a/utils/hash.h
+++ b/utils/hash.h
@@ -9,17 +9,23 @@
 #ifdef HAVE_SPARSEHASH
 # include <google/dense_hash_map>
 # define HASH_MAP google::dense_hash_map
+# define HASH_SET google::dense_hash_set
 # define HASH_MAP_RESERVED(h,empty,deleted) do { h.set_empty_key(empty); h.set_deleted_key(deleted); } while(0)
 # define HASH_MAP_EMPTY(h,empty) do { h.set_empty_key(empty); } while(0)
 #else
 # include <tr1/unordered_map>
 # define HASH_MAP std::tr1::unordered_map
+# define HASH_SET std::tr1::unordered_set
 # define HASH_MAP_RESERVED(h,empty,deleted)
 # define HASH_MAP_EMPTY(h,empty)
 #endif
 
 #define BOOST_HASHED_MAP(k,v) HASH_MAP<k,v,boost::hash<k> >
 
+namespace {
+const unsigned GOLDEN_MEAN_FRACTION=2654435769U;
+}
+
 // assumes C is POD
 template <class C>
 struct murmur_hash
diff --git a/utils/lvalue_pmap.h b/utils/lvalue_pmap.h
new file mode 100755
index 00000000..03ddf5e7
--- /dev/null
+++ b/utils/lvalue_pmap.h
@@ -0,0 +1,25 @@
+#ifndef LVALUE_PMAP_H
+#define LVALUE_PMAP_H
+
+#include <boost/property_map/property_map.hpp>
+
+// i checked: boost provides get and put given []
+
+// lvalue property map pmapname<P> that is: P p; valtype &v=p->name;
+#define PMAP_MEMBER_INDIRECT(pmapname,valtype,name) template <class P> struct pmapname {  \
+  typedef P key_type; \
+  typedef valtype value_type; \
+  typedef value_type & reference; \
+  typedef boost::lvalue_property_map_tag category;          \
+  reference operator[](key_type p) const { return p->name; } \
+};
+
+#define PMAP_MEMBER_INDIRECT_2(pmapname,name) template <class P,class R> struct pmapname {    \
+  typedef P key_type; \
+  typedef R value_type; \
+  typedef value_type & reference; \
+  typedef boost::lvalue_property_map_tag category; \
+  reference operator[](key_type p) const { return p->name; } \
+};
+
+#endif
diff --git a/utils/null_traits.h b/utils/null_traits.h
new file mode 100755
index 00000000..fac857d9
--- /dev/null
+++ b/utils/null_traits.h
@@ -0,0 +1,26 @@
+#ifndef NULL_TRAITS_H
+#define NULL_TRAITS_H
+
+template <class V>
+struct null_traits {
+  static V null; //TODO: maybe take out default null and make ppl explicitly define?  they may be surprised that they need to when they include a header lib that uses null_traits
+};
+// global bool is_null(V const& v)
+
+// definitely override this, and possibly set_null and is_null.  that's the point.
+template <class V>
+V null_traits<V>::null;
+//TODO: are we getting single init of the static null object?
+
+template <class V>
+void set_null(V &v) {
+  v=null_traits<V>::null;
+}
+
+template <class V>
+void is_null(V const& v) {
+  return v==null_traits<V>::null;
+}
+
+
+#endif
diff --git a/utils/value_array.h b/utils/value_array.h
index 82e66e8d..a10f754f 100755
--- a/utils/value_array.h
+++ b/utils/value_array.h
@@ -103,6 +103,12 @@ protected:
     }
   }
 
+  template <class C,class F>
+  inline void init_map(C const& c,F const& f) {
+    alloc(c.size());
+    copy_construct_map(c.begin(),c.end(),array,f);
+  }
+  // warning: std::distance is likely slow on maps (anything other than random access containers.  so container version using size will be better
   template <class I,class F>
   inline void init_range_map(I itr, I end,F const& f) {
     alloc(std::distance(itr,end));
@@ -123,11 +129,25 @@ public:
   {
     init(s,t);
   }
-  void resize(size_type s, const_reference t = T()) {
+  void reinit(size_type s, const_reference t = T()) {
     clear();
     init(s,t);
   }
 
+  //copy any existing data like std::vector.  not A::construct exception safe.  try blah blah?
+  void resize(size_type s, const_reference t = T()) {
+    pointer na=A::allocate(s);
+    size_type nc=s<sz ? s : sz;
+    size_type i=0;
+    for (;i<nc;++i)
+      A::construct(na+i,array[i]);
+    for (;i<s;++i)
+      A::construct(na+i,t);
+    clear();
+    array=na;
+    sz=s;
+  }
+
   template <class I>
   void reinit(I itr, I end) {
     clear();
@@ -135,10 +155,16 @@ public:
   }
 
   template <class I,class F>
-  void reinit_map(I itr, I end,F const& map) {
+  void reinit_map(I itr,I end,F const& map) {
     clear();
     init_range_map(itr,end,map);
   }
+  // warning: std::distance is likely slow on maps,lists (anything other than random access containers.  so container version below using size() will be better
+  template <class C,class F>
+  void reinit_map(C const& c,F const& map) {
+    clear();
+    init_map(c,map);
+  }
 
   template <class I>
   ValueArray(I itr, I end)