Expression support

- Added Context::getColumns to return a vector of column names.
  This is to help a shift toward using the Column objects to assist
  in the parsing/validation of data entry/modifications.
- Added Column::modifiable to delegate an attributes readable/writeable
  state.  This means the columns will be in charge of their own
  mutability, which will simplify and generalize Command::modify_task.

src/Context.cpp

@@ -411,6 +411,17 @@ void Context::shadow ()
 */
 }
 
+////////////////////////////////////////////////////////////////////////////////
+const std::vector <std::string> Context::getColumns () const
+{
+  std::vector <std::string> output;
+  std::map <std::string, Column*>::const_iterator i;
+  for (i = columns.begin (); i != columns.end (); ++i)
+    output.push_back (i->first);
+
+  return output;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void Context::assumeLocations ()
 {

src/Context.h

@@ -58,6 +58,8 @@ public:
   int getWidth ();                     // determine terminal width
   int getHeight ();                    // determine terminal height
 
+  const std::vector <std::string> getColumns () const;
+
   bool color ();                       // TTY or <other>?
   bool verbose (const std::string&);   // Verbosity control
 

src/columns/ColID.cpp

@@ -42,6 +42,7 @@ ColumnID::ColumnID ()
   _type       = "number";
   _style      = "number";
   _label      = STRING_COLUMN_LABEL_ID;
+  _modifiable = false;
 
   _styles.push_back ("number");
 

src/columns/ColUUID.cpp

@@ -42,6 +42,7 @@ ColumnUUID::ColumnUUID ()
   _type       = "string";
   _style      = "long";
   _label      = STRING_COLUMN_LABEL_UUID;
+  _modifiable = false;
 
   _styles.push_back ("long");
   _styles.push_back ("short");

src/columns/Column.cpp

@@ -132,6 +132,7 @@ Column::Column ()
 , _style ("default")
 , _label ("")
 , _report ("")
+, _modifiable (true)
 {
 }
 
@@ -143,6 +144,7 @@ Column::Column (const Column& other)
   _style      = other._style;
   _label      = other._label;
   _label      = other._report;
+  _modifiable = other._modifiable;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -155,6 +157,7 @@ Column& Column::operator= (const Column& other)
     _style       = other._style;
     _label       = other._label;
     _report      = other._report;
+    _modifiable  = other._modifiable;
   }
 
   return *this;
@@ -166,7 +169,9 @@ bool Column::operator== (const Column& other) const
   return _name       == other._name   &&
          _type       == other._type   &&
          _style      == other._style  &&
-         _label == other._label;
+         _label      == other._label  &&
+         _report     == other._report &&
+         _modifiable == other._modifiable;
 }
 
 ////////////////////////////////////////////////////////////////////////////////

src/columns/Column.h

@@ -48,6 +48,7 @@ public:
   std::string style () const                  { return _style;      }
   std::string label () const                  { return _label;      }
   std::string type () const                   { return _type;       }
+  bool modifiable () const                    { return _modifiable; }
   std::vector <std::string> styles () const   { return _styles;     }
   std::vector <std::string> examples () const { return _examples;   }
 
@@ -68,6 +69,7 @@ protected:
   std::string _style;
   std::string _label;
   std::string _report;
+  bool _modifiable;
   std::vector <std::string> _styles;
   std::vector <std::string> _examples;
 };