Added --value-expr option

doc/ledger.1

@@ -424,6 +424,7 @@ appeared in the original journal file.
 .It Fl \-unrealized-gains
 .It Fl \-unrealized-losses
 .It Fl \-unround
+.It Fl \-value-expr Ar EXPR
 .It Fl \-verbose
 .It Fl \-verify
 .It Fl \-version

src/session.cc

@@ -112,6 +112,8 @@ std::size_t session_t::read_data(const string& master_account)
     journal->checking_style = journal_t::CHECK_ERROR;
   else if (HANDLED(strict))
     journal->checking_style = journal_t::CHECK_WARNING;
+  else if (HANDLED(value_expr))
+    journal->value_expr     = HANDLER(value_expr).str();
 
 #if defined(HAVE_BOOST_SERIALIZATION)
   optional<archive_t> cache;

src/session.h

@@ -61,6 +61,7 @@ public:
 
   unique_ptr<journal_t> journal;
   parse_context_stack_t parsing_context;
+  optional<expr_t>      value_expr;
 
   explicit session_t();
   virtual ~session_t() {
@@ -107,6 +108,7 @@ public:
     HANDLER(price_db_).report(out);
     HANDLER(price_exp_).report(out);
     HANDLER(strict).report(out);
+    HANDLER(value_expr).report(out);
   }
 
   option_t<session_t> * lookup_option(const char * p);
@@ -154,6 +156,7 @@ public:
   OPTION(session_t, permissive);
   OPTION(session_t, price_db_);
   OPTION(session_t, strict);
+  OPTION(session_t, value_expr);
 };
 
 /**