Class: Dse::Geometry::Point

Inherits:
Object
  • Object
show all
Includes:
Cassandra::CustomData
Defined in:
lib/dse/geometry/point.rb

Overview

Encapsulates a 2D point with x,y coordinates. It corresponds to the org.apache.cassandra.db.marshal.PointType column type in DSE.

See Also:

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Point

Returns a new instance of Point.

Examples:

Construct a Point with numeric arguments.

point = Point.new(3, 4)

Construct a Point with a wkt string.

point = Point.new('POINT (3.0 4.0)')

Parameters:

  • args (Array<Numeric>, Array<String>) —

    varargs-style arguments in two forms:

    • two-element numeric array representing x,y coordinates.
    • one-element string array with the wkt representation.


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# File 'lib/dse/geometry/point.rb', line 39

def initialize(*args)
  # The constructor has two forms:
  # 1. two numeric args (x,y)
  # 2. one String arg as the wkt representation.

  case args.size
  when 2
    x, y = args
    Cassandra::Util.assert_instance_of(::Numeric, x)
    Cassandra::Util.assert_instance_of(::Numeric, y)
    Cassandra::Util.assert(!x.nan?, 'x cannot be Float::NAN') if x.is_a?(Float)
    Cassandra::Util.assert(!y.nan?, 'y cannot be Float::NAN') if y.is_a?(Float)
    @x = x.to_f
    @y = y.to_f
  when 1
    wkt = args.first
    Cassandra::Util.assert_instance_of(String, wkt)
    # subsitute eol chars in the string with a space.
    wkt.gsub!(EOL_RE, ' ')
    match = wkt.match(WKT_RE)
    raise ArgumentError, "#{wkt.inspect} is not a valid WKT representation of a point" unless match
    @x, @y = self.class.parse_wkt_internal(match[1])
  else
    raise ArgumentError,
          'wrong number of arguments: use one string argument (wkt) or two numeric arguments (x,y)'
  end
end

Instance Attribute Details

#x ⇒ Float (readonly)

Returns the x coordinate of the point.

Returns:

  • (Float) —

    the x coordinate of the point.



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# File 'lib/dse/geometry/point.rb', line 20

def x
  @x
end

#y ⇒ Float (readonly)

Returns the y coordinate of the point.

Returns:

  • (Float) —

    the y coordinate of the point.



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# File 'lib/dse/geometry/point.rb', line 22

def y
  @y
end

Class Method Details

.deserialize(data) ⇒ Point

Deserialize the given data into an instance of this domain object class.

Parameters:

  • data (String) —

    byte-array representation of a column value of this custom type.

Returns:

Raises:

  • (Cassandra::Errors::DecodingError) —

    upon failure.



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# File 'lib/dse/geometry/point.rb', line 130

def self.deserialize(data)
  buffer = Cassandra::Protocol::CqlByteBuffer.new(data)
  little_endian = buffer.read(1) != "\x00"

  # Depending on the endian-ness of the data, we want to read it differently. Wrap the buffer
  # with an "endian-aware" reader that reads the desired way.
  buffer = Dse::Util::EndianBuffer.new(buffer, little_endian)

  type = buffer.read_unsigned
  raise Cassandra::Errors::DecodingError, "Point data-type value should be 1, but was #{type}" if type != 1
  deserialize_raw(buffer)
end

.type ⇒ Cassandra::Types::Custom

Returns type of column that is processed by this domain object class.

Returns:

  • (Cassandra::Types::Custom) —

    type of column that is processed by this domain object class.



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# File 'lib/dse/geometry/point.rb', line 122

def self.type
  TYPE
end

Instance Method Details

#serialize ⇒ String

Serialize this domain object into a byte array to send to DSE.

Returns:

  • (String) —

    byte-array representation of this domain object.



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# File 'lib/dse/geometry/point.rb', line 154

def serialize
  buffer = Cassandra::Protocol::CqlByteBuffer.new

  # Serialize little-endian.

  buffer << "\x01"

  # This is a point.
  buffer.append([1].pack(Cassandra::Protocol::Formats::INT_FORMAT_LE))

  # Write out x and y.
  serialize_raw(buffer)

  buffer
end

#to_s ⇒ String

Returns a human-readable English string describing this Dse::Geometry::Point.

Returns:



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# File 'lib/dse/geometry/point.rb', line 73

def to_s
  "#{@x},#{@y}"
end

#wkt ⇒ String

Returns well-known-text representation of this point.

Returns:

  • (String) —

    well-known-text representation of this point.



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# File 'lib/dse/geometry/point.rb', line 68

def wkt
  "POINT (#{wkt_internal})"
end