Scopes can now provide a description of themselves

This isn't being used yet, but it likely will to improve the information
presented to users if their value expressions fail to compile or
evaluate.

src/account.h

@@ -89,6 +89,10 @@ public:
   }
   ~account_t();
 
+  virtual string description() {
+    return string(_("account ")) + fullname();
+  }
+
   operator string() const {
     return fullname();
   }

src/global.h

@@ -55,6 +55,10 @@ public:
   global_scope_t(char ** envp);
   ~global_scope_t();
 
+  virtual string description() {
+    return _("global scope");
+  }
+
   void           read_init();
   void           read_environment_settings(char * envp[]);
   strings_list   read_command_arguments(scope_t& scope, strings_list args);

src/post.h

@@ -99,6 +99,16 @@ public:
     TRACE_DTOR(post_t);
   }
 
+  virtual string description() {
+    if (pos) {
+      std::ostringstream buf;
+      buf << _("posting at line %1") << pos->beg_line;
+      return buf.str();
+    } else {
+      return string(_("generated posting"));
+    }
+  }
+
   virtual bool has_tag(const string& tag,
                        bool          inherit = true) const;
   virtual bool has_tag(const mask_t&           tag_mask,

src/report.h

@@ -125,6 +125,10 @@ public:
     output_stream.close();
   }
 
+  virtual string description() {
+    return _("current report");
+  }
+
   void normalize_options(const string& verb);
   void normalize_period();
   void parse_query_args(const value_t& args, const string& whence);

src/scope.h

@@ -109,6 +109,8 @@ public:
     TRACE_DTOR(scope_t);
   }
 
+  virtual string description() = 0;
+
   virtual void define(const symbol_t::kind_t, const string&,
                       expr_t::ptr_op_t) {}
   virtual expr_t::ptr_op_t lookup(const symbol_t::kind_t kind,
@@ -191,6 +193,10 @@ public:
     TRACE_DTOR(bind_scope_t);
   }
 
+  virtual string description() {
+    return grandchild.description();
+  }
+
   virtual void define(const symbol_t::kind_t kind, const string& name,
                       expr_t::ptr_op_t def) {
     parent->define(kind, name, def);
@@ -262,6 +268,16 @@ public:
     TRACE_DTOR(symbol_scope_t);
   }
 
+  virtual string description() {
+    if (parent)
+      return parent->description();
+#if !defined(NO_ASSERTS)
+    else
+      assert(false);
+#endif
+    return empty_string;
+  }
+
   virtual void define(const symbol_t::kind_t kind, const string& name,
                       expr_t::ptr_op_t def);
 
@@ -299,6 +315,10 @@ public:
     TRACE_DTOR(context_scope_t);
   }
 
+  virtual string description() {
+    return parent->description();
+  }
+
   virtual value_t::type_t type_context() const {
     return value_type_context;
   }
@@ -351,6 +371,10 @@ public:
     TRACE_DTOR(call_scope_t);
   }
 
+  virtual string description() {
+    return context_scope_t::description();
+  }
+
   void set_args(const value_t& _args) {
     args = _args;
   }
@@ -617,6 +641,10 @@ public:
   value_scope_t(scope_t& _parent, const value_t& _value)
     : child_scope_t(_parent), value(_value) {}
   
+  virtual string description() {
+    return parent->description();
+  }
+
   virtual expr_t::ptr_op_t lookup(const symbol_t::kind_t kind,
                                   const string& name)
   {

src/session.h

@@ -64,6 +64,10 @@ public:
     TRACE_DTOR(session_t);
   }
 
+  virtual string description() {
+    return _("current session");
+  }
+
   void set_flush_on_next_data_file(const bool truth) {
     flush_on_next_data_file = truth;
   }

src/textual.cc

@@ -112,6 +112,10 @@ namespace {
 
     ~instance_t();
 
+    virtual string description() {
+      return _("textual parser");
+    }
+
     void parse();
     std::streamsize read_line(char *& line);
     bool peek_whitespace_line() {

src/xact.h

@@ -117,6 +117,16 @@ public:
     TRACE_DTOR(xact_t);
   }
 
+  virtual string description() {
+    if (pos) {
+      std::ostringstream buf;
+      buf << _("transaction at line %1") << pos->beg_line;
+      return buf.str();
+    } else {
+      return string(_("generated transaction"));
+    }
+  }
+
   virtual void add_post(post_t * post);
 
   string idstring() const;
@@ -194,6 +204,16 @@ public:
     TRACE_DTOR(auto_xact_t);
   }
 
+  virtual string description() {
+    if (pos) {
+      std::ostringstream buf;
+      buf << _("automated transaction at line %1") << pos->beg_line;
+      return buf.str();
+    } else {
+      return string(_("generated automated transaction"));
+    }
+  }
+
   virtual void parse_tags(const char * p,
                           scope_t&,
                           bool         overwrite_existing = true) {
@@ -242,6 +262,16 @@ class period_xact_t : public xact_base_t
     TRACE_DTOR(period_xact_t);
   }
 
+  virtual string description() {
+    if (pos) {
+      std::ostringstream buf;
+      buf << _("periodic transaction at line %1") << pos->beg_line;
+      return buf.str();
+    } else {
+      return string(_("generated periodic transaction"));
+    }
+  }
+
 #if defined(HAVE_BOOST_SERIALIZATION)
 private:
   /** Serialization. */