Class: RGeo::WKRep::WKTGenerator

Inherits:
Object
  • Object
show all
Defined in:
lib/rgeo/wkrep/wkt_generator.rb

Overview

This class provides the functionality of serializing a geometry as WKT (well-known text) format. You may also customize the serializer to generate PostGIS EWKT extensions to the output, or to follow the Simple Features Specification 1.2 extensions for Z and M.

To use this class, create an instance with the desired settings and customizations, and call the generate method.

Configuration options

The following options are recognized. These can be passed to the constructor, or set on the object afterwards.

:tag_format

The format for tags. Possible values are :wkt11, indicating SFS 1.1 WKT (i.e. no Z or M markers in the tags) but with Z and/or M values added in if they are present; :wkt11_strict, indicating SFS 1.1 WKT with Z and M dropped from the output (since WKT strictly does not support the Z or M dimensions); :ewkt, indicating the PostGIS EWKT extensions (i.e. “M” appended to tag names if M but not Z is present); or :wkt12, indicating SFS 1.2 WKT tags that indicate the presence of Z and M in a separate token. Default is :wkt11. This option can also be specified as :type_format.

:emit_ewkt_srid

If true, embed the SRID of the toplevel geometry. Available only if :tag_format is :ewkt. Default is false.

:square_brackets

If true, uses square brackets rather than parentheses. Default is false.

:convert_case

Possible values are :upper, which changes all letters in the output to ALL CAPS; :lower, which changes all letters to lower case; or nil, indicating no case changes from the default (which is not specified exactly, but is chosen by the generator to emphasize readability.) Default is nil.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts_ = {}) ⇒ WKTGenerator

Create and configure a WKT generator. See the WKTGenerator documentation for the options that can be passed.



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 51

def initialize(opts_ = {})
  @tag_format = opts_[:tag_format] || opts_[:type_format] || :wkt11
  @emit_ewkt_srid = @tag_format == :ewkt ?
    (opts_[:emit_ewkt_srid] ? true : false) : nil
  @square_brackets = opts_[:square_brackets] ? true : false
  @convert_case = opts_[:convert_case]
end

Instance Attribute Details

#convert_case ⇒ Object (readonly)

Returns the case for output. See WKTGenerator for details.



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 75

def convert_case
  @convert_case
end

#tag_format ⇒ Object (readonly) Also known as: type_format

Returns the format for type tags. See WKTGenerator for details.



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 60

def tag_format
  @tag_format
end

Instance Method Details

#_generate_coords(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 147

def _generate_coords(obj_) # :nodoc:
  str_ = "#{obj_.x} #{obj_.y}"
  str_ << " #{obj_.z}" if @cur_support_z
  str_ << " #{obj_.m}" if @cur_support_m
  str_
end

#_generate_feature(obj_, toplevel_ = false) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 110

def _generate_feature(obj_, toplevel_ = false) # :nodoc:
  type_ = obj_.geometry_type
  type_ = Feature::LineString if type_.subtype_of?(Feature::LineString)
  tag_ = type_.type_name
  if @tag_format == :ewkt
    tag_ << "M" if @cur_support_m && !@cur_support_z
    tag_ = "SRID=#{obj_.srid};#{tag_}" if toplevel_ && @emit_ewkt_srid
  elsif @tag_format == :wkt12
    if @cur_support_z
      if @cur_support_m
        tag_ << " ZM"
      else
        tag_ << " Z"
      end
    elsif @cur_support_m
      tag_ << " M"
    end
  end
  if type_ == Feature::Point
    "#{tag_} #{_generate_point(obj_)}"
  elsif type_ == Feature::LineString
    "#{tag_} #{_generate_line_string(obj_)}"
  elsif type_ == Feature::Polygon
    "#{tag_} #{_generate_polygon(obj_)}"
  elsif type_ == Feature::GeometryCollection
    "#{tag_} #{_generate_geometry_collection(obj_)}"
  elsif type_ == Feature::MultiPoint
    "#{tag_} #{_generate_multi_point(obj_)}"
  elsif type_ == Feature::MultiLineString
    "#{tag_} #{_generate_multi_line_string(obj_)}"
  elsif type_ == Feature::MultiPolygon
    "#{tag_} #{_generate_multi_polygon(obj_)}"
  else
    raise Error::ParseError, "Unrecognized geometry type: #{type_}"
  end
end

#_generate_geometry_collection(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 174

def _generate_geometry_collection(obj_) # :nodoc:
  if obj_.is_empty?
    "EMPTY"
  else
    "#{@begin_bracket}#{obj_.map { |f_| _generate_feature(f_) }.join(', ')}#{@end_bracket}"
  end
end

#_generate_line_string(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 158

def _generate_line_string(obj_) # :nodoc:
  if obj_.is_empty?
    "EMPTY"
  else
    "#{@begin_bracket}#{obj_.points.map { |p_| _generate_coords(p_) }.join(', ')}#{@end_bracket}"
  end
end

#_generate_multi_line_string(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 190

def _generate_multi_line_string(obj_) # :nodoc:
  if obj_.is_empty?
    "EMPTY"
  else
    "#{@begin_bracket}#{obj_.map { |f_| _generate_line_string(f_) }.join(', ')}#{@end_bracket}"
  end
end

#_generate_multi_point(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 182

def _generate_multi_point(obj_) # :nodoc:
  if obj_.is_empty?
    "EMPTY"
  else
    "#{@begin_bracket}#{obj_.map { |f_| _generate_point(f_) }.join(', ')}#{@end_bracket}"
  end
end

#_generate_multi_polygon(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 198

def _generate_multi_polygon(obj_) # :nodoc:
  if obj_.is_empty?
    "EMPTY"
  else
    "#{@begin_bracket}#{obj_.map { |f_| _generate_polygon(f_) }.join(', ')}#{@end_bracket}"
  end
end

#_generate_point(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 154

def _generate_point(obj_) # :nodoc:
  "#{@begin_bracket}#{_generate_coords(obj_)}#{@end_bracket}"
end

#_generate_polygon(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 166

def _generate_polygon(obj_) # :nodoc:
  if obj_.is_empty?
    "EMPTY"
  else
    "#{@begin_bracket}#{([_generate_line_string(obj_.exterior_ring)] + obj_.interior_rings.map { |r_| _generate_line_string(r_) }).join(', ')}#{@end_bracket}"
  end
end

#_properties ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 77

def _properties # :nodoc:
  {
    "tag_format" => @tag_format.to_s,
    "emit_ewkt_srid" => @emit_ewkt_srid,
    "square_brackets" => @square_brackets,
    "convert_case" => @convert_case ? @convert_case.to_s : nil
  }
end

#emit_ewkt_srid? ⇒ Boolean

Returns whether SRID is embedded. See WKTGenerator for details.

Returns:

  • (Boolean) 


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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 64

def emit_ewkt_srid?
  @emit_ewkt_srid
end

#generate(obj_) ⇒ Object

Generate and return the WKT format for the given geometry object, according to the current settings.



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 89

def generate(obj_)
  @begin_bracket = @square_brackets ? "[" : "("
  @end_bracket = @square_brackets ? "]" : ")"
  factory_ = obj_.factory
  if @tag_format == :wkt11_strict
    @cur_support_z = nil
    @cur_support_m = nil
  else
    @cur_support_z = factory_.property(:has_z_coordinate)
    @cur_support_m = factory_.property(:has_m_coordinate)
  end
  str_ = _generate_feature(obj_, true)
  if @convert_case == :upper
    str_.upcase
  elsif @convert_case == :lower
    str_.downcase
  else
    str_
  end
end

#square_brackets? ⇒ Boolean

Returns whether square brackets rather than parens are output. See WKTGenerator for details.

Returns:

  • (Boolean) 


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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 70

def square_brackets?
  @square_brackets
end