Class: RGeo::WKRep::WKBParser

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

Overview

This class provides the functionality of parsing a geometry from WKB (well-known binary) format. You may also customize the parser to recognize PostGIS EWKB extensions to the input, or Simple Features Specification 1.2 extensions for Z and M coordinates.

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

Configuration options

You must provide each parser with an RGeo::Feature::FactoryGenerator. It should understand the configuration options :srid, :has_z_coordinate, and :has_m_coordinate. You may also pass a specific RGeo::Feature::Factory, or nil to specify the default Cartesian FactoryGenerator.

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

:support_ewkb

Activate support for PostGIS EWKB type codes, which use high order bits in the type code to signal the presence of Z, M, and SRID values in the data. Default is false.

:support_wkb12

Activate support for SFS 1.2 extensions to the type codes, which use values greater than 1000 to signal the presence of Z and M values in the data. SFS 1.2 types such as triangle, tin, and polyhedralsurface are NOT yet supported. Default is false.

:ignore_extra_bytes

If true, extra bytes at the end of the data are ignored. If false (the default), extra bytes will trigger a parse error.

:default_srid

A SRID to pass to the factory generator if no SRID is present in the input. Defaults to nil (i.e. don't specify a SRID).

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(factory_generator = nil, opts = {}) ⇒ WKBParser

Create and configure a WKB parser. See the WKBParser documentation for the options that can be passed.


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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 50

def initialize(factory_generator = nil, opts = {})
  if factory_generator.is_a?(Feature::Factory::Instance)
    @factory_generator = Feature::FactoryGenerator.single(factory_generator)
    @exact_factory = factory_generator
  elsif factory_generator.respond_to?(:call)
    @factory_generator = factory_generator
    @exact_factory = nil
  else
    @factory_generator = Cartesian.method(:preferred_factory)
    @exact_factory = nil
  end
  @support_ewkb = opts[:support_ewkb] ? true : false
  @support_wkb12 = opts[:support_wkb12] ? true : false
  @ignore_extra_bytes = opts[:ignore_extra_bytes] ? true : false
  @default_srid = opts[:default_srid]
end

Instance Attribute Details

#exact_factoryObject (readonly)

If this parser was given an exact factory, returns it; otherwise returns nil.


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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 72

def exact_factory
  @exact_factory
end

#factory_generatorObject (readonly)

Returns the factory generator. See WKBParser for details.


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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 68

def factory_generator
  @factory_generator
end

Instance Method Details

#ignore_extra_bytes?Boolean

Returns true if this parser ignores extra bytes. See WKBParser for details.

Returns:

  • (Boolean)

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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 88

def ignore_extra_bytes?
  @ignore_extra_bytes
end

#parse(data) ⇒ Object Also known as: parse_hex

Parse the given binary data or hexadecimal string, and return a geometry object.

The #parse_hex method is a synonym, present for historical reasons but deprecated. Use #parse instead.


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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 107

def parse(data)
  data = [data].pack("H*") if data[0, 1] =~ /[0-9a-fA-F]/
  @cur_has_z = nil
  @cur_has_m = nil
  @cur_srid = nil
  @cur_dims = 2
  @cur_factory = nil
  begin
    start_scanner(data)
    obj = parse_object(false)
    unless @ignore_extra_bytes
      bytes = bytes_remaining
      if bytes > 0
        raise Error::ParseError, "Found #{bytes} extra bytes at the end of the stream."
      end
    end
  ensure
    @data = nil
  end
  obj
end

#propertiesObject


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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 92

def properties
  {
    "support_ewkb" => @support_ewkb,
    "support_wkb12" => @support_wkb12,
    "ignore_extra_bytes" => @ignore_extra_bytes,
    "default_srid" => @default_srid
  }
end

#support_ewkb?Boolean

Returns true if this parser supports EWKB. See WKBParser for details.

Returns:

  • (Boolean)

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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 76

def support_ewkb?
  @support_ewkb
end

#support_wkb12?Boolean

Returns true if this parser supports SFS 1.2 extensions. See WKBParser for details.

Returns:

  • (Boolean)

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# File 'lib/rgeo/wkrep/wkb_parser.rb', line 82

def support_wkb12?
  @support_wkb12
end