text: ////////////////////////////////////////////////////////////////////////////////
  //
  // Copyright 2006 - 2021, Paul Beckingham, Federico Hernandez.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  //
  // https://www.opensource.org/licenses/mit-license.php
  //
  ////////////////////////////////////////////////////////////////////////////////
  
  #include <cmake.h>
  #include <ColTypeDuration.h>
  #include <Context.h>
  #include <Eval.h>
  #include <Variant.h>
  #include <Filter.h>
  #include <format.h>
  
  extern Task& contextTask;
  
  ////////////////////////////////////////////////////////////////////////////////
  ColumnTypeDuration::ColumnTypeDuration ()
  {
    _type = "duration";
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  bool ColumnTypeDuration::validate (const std::string& input) const
  {
    return input.length () ? true : false;
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  void ColumnTypeDuration::modify (Task& task, const std::string& value)
  {
    // Try to evaluate 'value'.  It might work.
    Variant evaluatedValue;
    try
    {
      Eval e;
      e.addSource (domSource);
      contextTask = task;
      e.evaluateInfixExpression (value, evaluatedValue);
    }
  
    catch (...)
    {
      evaluatedValue = Variant (value);
    }
  
    // The duration is stored in raw form, but it must still be valid,
    // and therefore is parsed first.
    std::string label = "  [1;37;43mMODIFICATION[0m ";
    if (evaluatedValue.type () == Variant::type_duration)
    {
      // Store the raw value, for 'recur'.
      Context::getContext ().debug (label + _name + " <-- " + (std::string) evaluatedValue + " <-- '" + value + '\'');
      task.set (_name, evaluatedValue);
    }
    else
      throw format ("The duration value '{1}' is not supported.", value);
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  