Class: RGeo::CoordSys::CS::WKTParser

Inherits:
Object
  • Object
show all
Defined in:
lib/rgeo/coord_sys/cs/wkt_parser.rb

Overview

:nodoc:

Defined Under Namespace

Classes: ArgumentList, AuthorityClause, ExtensionClause, QuotedString, TypeString

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(str) ⇒ WKTParser

Returns a new instance of WKTParser.



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# File 'lib/rgeo/coord_sys/cs/wkt_parser.rb', line 13

def initialize(str)
  @scanner = StringScanner.new(str)
  next_token
end

Instance Attribute Details

#cur_token ⇒ Object (readonly)

Returns the value of attribute cur_token.



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# File 'lib/rgeo/coord_sys/cs/wkt_parser.rb', line 235

def cur_token
  @cur_token
end

Instance Method Details

#consume_tokentype(type) ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/cs/wkt_parser.rb', line 189

def consume_tokentype(type) # :nodoc:
  expect_tokentype(type)
  tok = @cur_token
  next_token
  tok
end

#expect_tokentype(type) ⇒ Object

:nodoc:

Raises:



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# File 'lib/rgeo/coord_sys/cs/wkt_parser.rb', line 196

def expect_tokentype(type) # :nodoc:
  return if type === @cur_token

  raise Error::ParseError, "#{type.inspect} expected but #{@cur_token.inspect} found."
end

#next_token ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/cs/wkt_parser.rb', line 202

def next_token # :nodoc:
  @scanner.skip(/\s+/)
  case @scanner.peek(1)
  when '"'
    @scanner.getch
    @cur_token = QuotedString.new(@scanner.scan(/[^"]*/))
    @scanner.getch
  when ","
    @scanner.getch
    @cur_token = :comma
  when "(", "["
    @scanner.getch
    @cur_token = :begin
  when "]", ")"
    @scanner.getch
    @cur_token = :end
  when /[a-zA-Z]/
    @cur_token = TypeString.new(@scanner.scan(/[a-zA-Z]\w*/))
  when "", nil
    @cur_token = nil
  else
    @scanner.scan_until(/[^\s()\[\],"]+/)
    token = @scanner.matched

    unless token =~ /^[-+]?(\d+(\.\d*)?|\.\d+)(e[-+]?\d+)?$/
      raise Error::ParseError, "Bad token: #{token.inspect}"
    end

    @cur_token = token.to_f
  end
  @cur_token
end

#parse(containing_type = nil) ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/cs/wkt_parser.rb', line 18

def parse(containing_type = nil) # :nodoc:
  if @cur_token.is_a?(QuotedString) ||
    @cur_token.is_a?(Numeric) ||
    (containing_type == "AXIS" && @cur_token.is_a?(TypeString))
    value = @cur_token
    next_token
    return value
  end

  unless @cur_token.is_a?(TypeString)
    raise Error::ParseError, "Found token #{@cur_token} when we expected a value"
  end

  type = @cur_token
  next_token
  consume_tokentype(:begin)
  args = ArgumentList.new
  args << parse(type)
  loop do
    break unless @cur_token == :comma
    next_token
    args << parse(type)
  end
  consume_tokentype(:end)
  obj = nil
  case type
  when "AUTHORITY"
    obj = AuthorityClause.new(args.shift(QuotedString), args.shift(QuotedString))
  when "EXTENSION"
    obj = ExtensionClause.new(args.shift(QuotedString), args.shift(QuotedString))
  when "AXIS"
    obj = AxisInfo.create(args.shift(QuotedString), args.shift(TypeString))
  when "TOWGS84"
    bursa_wolf_params = args.find_all(Numeric)

    unless bursa_wolf_params.size == 7
      raise Error::ParseError, "Expected 7 Bursa Wolf parameters but found #{bursa_wolf_params.size}"
    end

    obj = WGS84ConversionInfo.create(*bursa_wolf_params)
  when "UNIT"
    klass = case containing_type
            when "GEOCCS", "VERT_CS", "PROJCS", "SPHEROID"
              LinearUnit
            when "GEOGCS"
              AngularUnit
            else
              Unit
            end
    obj = klass.create(args.shift(QuotedString), args.shift(Numeric), *args.create_optionals)
  when "PARAMETER"
    obj = ProjectionParameter.create(args.shift(QuotedString), args.shift(Numeric))
  when "PRIMEM"
    obj = PrimeMeridian.create(args.shift(QuotedString), nil, args.shift(Numeric), *args.create_optionals)
  when "SPHEROID"
    obj = Ellipsoid.create_flattened_sphere(
      args.shift(QuotedString),
      args.shift(Numeric),
      args.shift(Numeric),
      args.find_first(LinearUnit),
      *args.create_optionals
    )
  when "PROJECTION"
    name = args.shift(QuotedString)
    obj = Projection.create(name, name, args.find_all(ProjectionParameter), *args.create_optionals)
  when "DATUM"
    name = args.shift(QuotedString)
    ellipsoid = args.find_first(Ellipsoid)
    to_wgs84 = args.find_first(WGS84ConversionInfo)
    obj = HorizontalDatum.create(name, HD_GEOCENTRIC, ellipsoid, to_wgs84, *args.create_optionals)
  when "VERT_DATUM"
    obj = VerticalDatum.create(args.shift(QuotedString), args.shift(Numeric), *args.create_optionals)
  when "LOCAL_DATUM"
    obj = LocalDatum.create(args.shift(QuotedString), args.shift(Numeric), *args.create_optionals)
  when "CS"
    # Not actually valid WKT, but necessary to load and dump factories
    # with placeholder coord_sys objects
    defn = args.shift(QuotedString)
    dim = args.shift(Float).to_i
    optionals = args.create_optionals
    obj = CoordinateSystem.create(defn, dim, *optionals)
  when "COMPD_CS"
    obj = CompoundCoordinateSystem.create(
      args.shift(QuotedString),
      args.shift(CoordinateSystem),
      args.shift(CoordinateSystem),
      *args.create_optionals
    )
  when "LOCAL_CS"
    name = args.shift(QuotedString)
    local_datum = args.find_first(LocalDatum)
    unit = args.find_first(Unit)
    axes = args.find_all(AxisInfo)
    raise Error::ParseError, "Expected at least one AXIS in a LOCAL_CS" unless axes.size > 0
    obj = LocalCoordinateSystem.create(name, local_datum, unit, axes, *args.create_optionals)
  when "GEOCCS"
    name = args.shift(QuotedString)
    horizontal_datum = args.find_first(HorizontalDatum)
    prime_meridian = args.find_first(PrimeMeridian)
    linear_unit = args.find_first(LinearUnit)
    axes = args.find_all(AxisInfo)

    unless axes.size == 0 || axes.size == 3
      raise Error::ParseError, "GEOCCS must contain either 0 or 3 AXIS parameters"
    end

    obj = GeocentricCoordinateSystem.create(
      name,
      horizontal_datum,
      prime_meridian,
      linear_unit,
      axes[0],
      axes[1],
      axes[2],
      *args.create_optionals
    )
  when "VERT_CS"
    name = args.shift(QuotedString)
    vertical_datum = args.find_first(VerticalDatum)
    linear_unit = args.find_first(LinearUnit)
    axis = args.find_first(AxisInfo)
    obj = VerticalCoordinateSystem.create(name, vertical_datum, linear_unit, axis, *args.create_optionals)
  when "GEOGCS"
    name = args.shift(QuotedString)
    horizontal_datum = args.find_first(HorizontalDatum)
    prime_meridian = args.find_first(PrimeMeridian)
    angular_unit = args.find_first(AngularUnit)
    axes = args.find_all(AxisInfo)

    unless axes.size == 0 || axes.size == 2
      raise Error::ParseError, "GEOGCS must contain either 0 or 2 AXIS parameters"
    end

    obj = GeographicCoordinateSystem.create(
      name,
      angular_unit,
      horizontal_datum,
      prime_meridian,
      axes[0],
      axes[1],
      *args.create_optionals
    )
  when "PROJCS"
    name = args.shift(QuotedString)
    geographic_coordinate_system = args.find_first(GeographicCoordinateSystem)
    projection = args.find_first(Projection)
    parameters = args.find_all(ProjectionParameter)
    projection.instance_variable_get(:@parameters).concat(parameters)
    linear_unit = args.find_first(LinearUnit)
    axes = args.find_all(AxisInfo)

    unless axes.size == 0 || axes.size == 2
      raise Error::ParseError, "PROJCS must contain either 0 or 2 AXIS parameters"
    end

    obj = ProjectedCoordinateSystem.create(
      name,
      geographic_coordinate_system,
      projection,
      linear_unit,
      axes[0],
      axes[1],
      *args.create_optionals
    )
  else
    raise Error::ParseError, "Unrecognized type: #{type}"
  end
  args.assert_empty
  obj
end