# -----------------------------------------------------------------------------
# 
# Feature factory interface
# 
# -----------------------------------------------------------------------------
# Copyright 2010 Daniel Azuma
# 
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
# * Redistributions of source code must retain the above copyright notice,
#   this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
#   this list of conditions and the following disclaimer in the documentation
#   and/or other materials provided with the distribution.
# * Neither the name of the copyright holder, nor the names of any other
#   contributors to this software, may be used to endorse or promote products
#   derived from this software without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
# -----------------------------------------------------------------------------
;


module RGeo
  
  module Feature
    
    
    # A FactoryGenerator is a callable object (usually a Proc) that
    # takes a configuration as a hash and returns a factory. These are
    # often used, e.g., by parsers to determine what factory the parsed
    # geometry should have.
    # 
    # See the call method for a list of common configuration parameters.
    # Different generators will support different parameters. There is
    # no mechanism defined to reflect on the capabilities of a factory
    # generator.
    # 
    # Many of the implementations provide a factory method for creating
    # factories. For example, RGeo::Cartesian::preferred_factory can be
    # called to create a factory using the preferred Cartesian
    # implementation. Thus, to get a corresponding factory generator,
    # you can use the <tt>method</tt> method. e.g.
    # 
    #  factory_generator = ::RGeo::Cartesian.method(:preferred_factory)
    # 
    # FactoryGenerator is defined as a module and is provided
    # primarily for the sake of documentation. Implementations need not
    # necessarily include this module itself. Therefore, you should not
    # depend on the kind_of? method to determine if an object is a
    # factory generator.
    
    module FactoryGenerator
      
      
      # Generate a factory given a configuration as a hash.
      # 
      # If the generator does not recognize or does not support a given
      # configuration value, the behavior is usually determined by the
      # <tt>:strict</tt> configuration element. If <tt>strict</tt> is
      # set to true, the generator should fail fast and return nil or
      # raise an exception. If it is set to false, the generator should
      # attempt to do the best it can, even if it means returning a
      # factory that does not match the requested configuration.
      # 
      # Common parameters are as follows. These are intended as a
      # recommendation only. There is no hard requirement for any
      # particular factory generator to support them.
      # 
      # <tt>:strict</tt>::
      #   If true, return nil or raise an exception if any configuration
      #   was not recognized or not supportable. Otherwise, if false,
      #   the generator should attempt to do its best to return some
      #   viable factory, even if it does not strictly match the
      #   requested configuration. Default is usually false.
      # <tt>:srid</tt>::
      #   The SRID for the factory and objects it creates.
      #   Default is usually 0.
      # <tt>:support_z_coordinate</tt>::
      #   Support the <tt>z_coordinate</tt> capability.
      #   Default is usually false.
      # <tt>:support_m_coordinate</tt>::
      #   Support the <tt>m_coordinate</tt> capability.
      #   Default is usually false.
      
      def call(config_={})
        nil
      end
      
      
      # Return a new FactoryGenerator that calls the given delegate, but
      # modifies the configuration passed to it. You can provide defaults
      # for configuration values not explicitly specified, and you can
      # force certain values to override the given configuration.
      
      def self.decorate(delegate_, default_config_={}, force_config_={})
        ::Proc.new{ |c_| delegate_.call(default_config_.merge(c_).merge(force_config_)) }
      end
      
      
    end
    
    
  end
  
end