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. [:emit_ewkt_srid] If true, embed the SRID of the toplevel geometry. Available only if :type_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 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 85

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

Instance Method Details

#_generate_coords(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 203

def _generate_coords(obj_)  # :nodoc:
  str_ = "#{obj_.x.to_s} #{obj_.y.to_s}"
  str_ << " #{obj_.z.to_s}" if @cur_support_z
  str_ << " #{obj_.m.to_s}" 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 162

def _generate_feature(obj_, toplevel_=false)  # :nodoc:
  type_ = obj_.geometry_type
  tag_ = type_.type_name
  if @tag_format == :ewkt
    if @cur_support_m && !@cur_support_z
      tag_ << 'M'
    end
    if toplevel_ && @emit_ewkt_srid
      tag_ = "SRID=#{obj_.srid};#{tag_}"
    end
  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_.subtype_of?(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 234

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_, contained_ = false) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 216

def _generate_line_string(obj_, contained_=false)  # :nodoc:
  if obj_.is_empty?
    contained_ ? '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 252

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

#_generate_multi_point(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 243

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 261

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

#_generate_point(obj_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 211

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

#_generate_polygon(obj_, contained_ = false) ⇒ Object

:nodoc:



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 225

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

#convert_case ⇒ Object

Returns the case for output. See WKTGenerator for details.



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 127

def convert_case
  @convert_case
end

#convert_case=(value_) ⇒ Object

Sets the case for output. See WKTGenerator for details.



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 132

def convert_case=(value_)
  @convert_case = value_
end

#emit_ewkt_srid=(value_) ⇒ Object

Sets whether SRID is embedded. Available only when the tag_format is :ewkt. See WKTGenerator for details.



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

def emit_ewkt_srid=(value_)
  @emit_ewkt_srid = @type_format == :ewkt && value_
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 104

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 140

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=(value_) ⇒ Object

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



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 122

def square_brackets=(value_)
  @square_brackets = value_ ? true : false
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 116

def square_brackets?
  @square_brackets
end

#tag_format ⇒ Object

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



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 94

def tag_format
  @tag_format
end

#tag_format=(value_) ⇒ Object

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



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# File 'lib/rgeo/wkrep/wkt_generator.rb', line 99

def tag_format=(value_)
  @tag_format = value_
end