Added new command: "pricemap [DATE]"

This outputs the pricing relationship of commodities in your data file,
as of DATE (optional), using the DOT language.  If you have graphviz
installed, it can be viewed quite simply using:

  ledger pricemap | dotty -

Each relationship in the graph shows the conversion factor to exchange
one commodity for another, and the date at which this factor was
determined.

src/pool.cc

@@ -364,4 +364,76 @@ commodity_pool_t::parse_price_expression(const std::string&          str,
   return NULL;
 }
 
+void commodity_pool_t::print_pricemap(std::ostream&		  out,
+				      const keep_details_t&       keep,
+				      const optional<datetime_t>& moment)
+{
+  typedef std::map<commodity_t *, commodity_t *> comm_map_t;
+
+  comm_map_t comm_map;
+
+  foreach (const commodities_map::value_type& comm_pair, commodities) {
+    commodity_t * comm(&comm_pair.second->strip_annotations(keep));
+    comm_map.insert(comm_map_t::value_type(comm, NULL));
+  }
+
+  out << "digraph commodities {\n";
+
+  foreach (const comm_map_t::value_type& comm_pair, comm_map) {
+    commodity_t * comm(comm_pair.first);
+    if (comm->has_flags(COMMODITY_BUILTIN))
+      continue;
+
+    out << "    ";
+    if (commodity_t::symbol_needs_quotes(comm->symbol()))
+      out << comm->symbol() << ";\n";
+    else
+      out << "\"" << comm->symbol() << "\";\n";
+
+    if (! comm->has_flags(COMMODITY_NOMARKET) &&
+	(! commodity_pool_t::current_pool->default_commodity ||
+	 comm != commodity_pool_t::current_pool->default_commodity)) {
+      if (optional<commodity_t::varied_history_t&> vhist =
+	  comm->varied_history()) {
+	foreach (const commodity_t::history_by_commodity_map::value_type& pair,
+		 vhist->histories) {
+	  datetime_t most_recent;
+	  amount_t   most_recent_amt;
+	  foreach (const commodity_t::history_map::value_type& inner_pair,
+		   pair.second.prices) {
+	    if ((most_recent.is_not_a_date_time() ||
+		 inner_pair.first > most_recent) &&
+		(! moment || inner_pair.first <= moment)) {
+	      most_recent     = inner_pair.first;
+	      most_recent_amt = inner_pair.second;
+	    }
+	  }
+
+	  if (! most_recent.is_not_a_date_time()) {
+	    out << "    ";
+	    if (commodity_t::symbol_needs_quotes(comm->symbol()))
+	      out << comm->symbol();
+	    else
+	      out << "\"" << comm->symbol() << "\"";
+
+	    out << " -> ";
+
+	    if (commodity_t::symbol_needs_quotes(pair.first->symbol()))
+	      out << pair.first->symbol();
+	    else
+	      out << "\"" << pair.first->symbol() << "\"";
+
+	    out << " [label=\""
+		<< most_recent_amt.number() << "\\n"
+		<< format_date(most_recent.date(), FMT_WRITTEN)
+		<< "\" fontcolor=\"#008e28\"];\n";
+	  }
+	}
+      }
+    }
+  }
+
+  out << "}\n";
+}
+
 } // namespace ledger

src/pool.h

@@ -131,6 +131,12 @@ public:
 			 const bool                  add_prices = true,
 			 const optional<datetime_t>& moment     = none);
 
+  // Output the commodity price map for a given date as a DOT file
+
+  void print_pricemap(std::ostream&		  out,
+		      const keep_details_t&       keep,
+		      const optional<datetime_t>& moment = none);
+
 #if defined(HAVE_BOOST_SERIALIZATION)
 private:
   /** Serialization. */

src/report.cc

@@ -842,6 +842,18 @@ value_t report_t::echo_command(call_scope_t& scope)
   return true;
 }
 
+value_t report_t::pricemap_command(call_scope_t& scope)
+{
+  interactive_t args(scope, "&s");
+  std::ostream& out(output_stream);
+
+  commodity_pool_t::current_pool->print_pricemap
+    (out, what_to_keep(), args.has(0) ?
+     optional<datetime_t>(datetime_t(parse_date(args.get<string>(0)))) : none);
+
+  return true;
+}
+
 option_t<report_t> * report_t::lookup_option(const char * p)
 {
   switch (*p) {
@@ -1415,6 +1427,9 @@ expr_t::ptr_op_t report_t::lookup(const symbol_t::kind_t kind,
 			     HANDLER(prepend_width_).value.to_long()),
 	    *this, "#pricedb"));
       }
+      else if (is_eq(p, "pricemap")) {
+	return MAKE_FUNCTOR(report_t::pricemap_command);
+      }
       else if (is_eq(p, "payees")) {
 	return WRAP_FUNCTOR(reporter<>(new report_payees(*this), *this,
 				       "#payees"));

src/report.h

@@ -198,6 +198,7 @@ public:
 
   value_t reload_command(call_scope_t&);
   value_t echo_command(call_scope_t& scope);
+  value_t pricemap_command(call_scope_t& scope);
 
   keep_details_t what_to_keep() {
     bool lots = HANDLED(lots) || HANDLED(lots_actual);