uk_address_parser.rb

class Address
  attr_accessor :address, :flat, :house_number, :house_name, :street, :street2, :street3, :town, :county
  def initialize(address)
  	self.address = address
  end

  def parts
    @parts ||= address.split(/\s?\,\s?/).collect(&:strip)
  end

  def build
    postcode
    build_county
    building_and_street
    build_town
    streets
  end

  def postcode
  	@postcode ||= parts.pop
  end

  def build_county
    @county = parts.pop if counties.include?(parts.last)
  end

  def building_and_street
    case parts.first 
    when number_and_known_street_ending
    	@house_number = $1
    	@street = $2
    	parts.shift
    when known_street_ending_no_number
    	if !house_name && (number_and_any_street_name =~ parts[1] || known_street_ending_no_number =~ parts[1])
    		@house_name = parts.shift
    	  building_and_street
    	else
    	  @street = parts.shift
    	end
    when flat_number
    	@flat = parts.shift
    	building_and_street
    when number_and_any_street_name
    	@house_number = $1
    	@street = $2
    	parts.shift
    else
      unless house_name 
    	  @house_name = parts.shift
    	  building_and_street
    	end
    end
  end

  def number_and_known_street_ending
    /^(\d+\w?)\s([\w\s\-\.]+(#{street_endings.join('|')})$)/i
  end

  def known_street_ending_no_number
  	/^([\w\s\-\.]+(#{street_endings.join('|')})$)/i
  end

  def flat_number
  	/^Flat\s.*\d+.*/
  end

  def number_and_any_street_name
  	/^(\d+\w?)\s([\w\s\-\.]+)$/i
  end

  def build_town
  	@town = parts.pop unless parts.empty?
  end

  def streets
  	return if parts.empty?
  	@street = parts.shift unless street
  	@street2 = parts.shift
  	@street3 = parts.shift
  	raise "unprocessed parts: #{parts}" unless parts.empty?
  end

  def details
    build unless parts.empty?
    {
    	flat: flat,
      house_number: house_number,
      house_name: house_name, 
      street: street, 
      street2: street2, 
      street3: street3,
      town: town,
      county: county,
      postcode: postcode
    }
  end

  def counties
  	[ 
  		'Avon', 'Bedfordshire', 'Berkshire', 'Borders', 'Buckinghamshire', 'Cambridgeshire', 'Central', 
  		'Cheshire', 'Cleveland', 'Clwyd', 'Cornwall', 'County Antrim', 'County Armagh', 'County Down', 
  		'County Fermanagh', 'County Londonderry', 'County Tyrone', 'Cumbria', 'Derbyshire', 'Devon', 
  		'Dorset', 'Dumfries and Galloway', 'Durham', 'Dyfed', 'East Sussex', 'Essex', 'Fife', 
  		'Gloucestershire', 'Grampian', 'Greater Manchester', 'Gwent', 'Gwynedd County', 'Hampshire', 
  		'Herefordshire', 'Hertfordshire', 'Highlands and Islands', 'Humberside', 'Isle of Wight', 
  		'Kent', 'Lancashire', 'Leicestershire', 'Lincolnshire', 'Lothian', 'Merseyside', 'Mid Glamorgan', 
  		'Norfolk', 'North Yorkshire', 'Northamptonshire', 'Northumberland', 'Nottinghamshire', 'Oxfordshire', 
  		'Powys', 'Rutland', 'Shropshire', 'Somerset', 'South Glamorgan', 'South Yorkshire', 'Staffordshire', 
  		'Strathclyde', 'Suffolk', 'Surrey', 'Tayside', 'Tyne and Wear', 'Warwickshire', 'West Glamorgan', 
  		'West Midlands', 'West Sussex', 'West Yorkshire', 'Wiltshire', 'Worcestershire'
  	]
  end

  def street_endings
    [
      'ALLEE', 'ALLEY', 'ALLY', 'ALY', 'ANEX', 'ANNEX', 'ANNX', 'ANX', 'ARC', 'ARCADE', 'AV', 'AVE', 'AVEN', 
      'AVENU', 'AVENUE', 'AVN', 'AVNUE', 'BAYOO', 'BAYOU', 'BCH', 'BEACH', 'BEND', 'BND', 'BLF', 'BLUF', 'BLUFF', 
      'BLUFFS', 'BOT', 'BTM', 'BOTTM', 'BOTTOM', 'BLVD', 'BOUL', 'BOULEVARD', 'BOULV', 'BR', 'BRNCH', 'BRANCH', 
      'BRDGE', 'BRG', 'BRIDGE', 'BRK', 'BROOK', 'BROOKS', 'BURG', 'BURGS', 'BYP', 'BYPA', 'BYPAS', 'BYPASS', 
      'BYPS', 'CAMP', 'CP', 'CMP', 'CANYN', 'CANYON', 'CNYN', 'CAPE', 'CPE', 'CAUSEWAY', 'CAUSWA', 'CSWY', 
      'CEN', 'CENT', 'CENTER', 'CENTR', 'CENTRE', 'CNTER', 'CNTR', 'CTR', 'CENTERS', 'CIR', 'CIRC', 'CIRCL', 
      'CIRCLE', 'CRCL', 'CRCLE', 'CIRCLES', 'CLF', 'CLIFF', 'CLFS', 'CLIFFS', 'CLB', 'CLUB', 'COMMON', 'COMMONS', 
      'COR', 'CORNER', 'CORNERS', 'CORS', 'COURSE', 'CRSE', 'COURT', 'CT', 'COURTS', 'CTS', 'COVE', 'CV', 'COVES', 
      'CREEK', 'CRK', 'CRESCENT', 'CRES', 'CRSENT', 'CRSNT', 'CREST', 'CROSSING', 'CRSSNG', 'XING', 'CROSSROAD', 
      'CROSSROADS', 'CURVE', 'DALE', 'DL', 'DAM', 'DM', 'DIV', 'DIVIDE', 'DV', 'DVD', 'DR', 'DRIV', 'DRIVE', 'DRV', 
      'DRIVES', 'EST', 'ESTATE', 'ESTATES', 'ESTS', 'EXP', 'EXPR', 'EXPRESS', 'EXPRESSWAY', 'EXPW', 'EXPY', 'EXT', 
      'EXTENSION', 'EXTN', 'EXTNSN', 'EXTS', 'FALL', 'FALLS', 'FLS', 'FERRY', 'FRRY', 'FRY', 'FIELD', 'FLD', 'FIELDS', 
      'FLDS', 'FLAT', 'FLT', 'FLATS', 'FLTS', 'FORD', 'FRD', 'FORDS', 'FOREST', 'FORESTS', 'FRST', 'FORG', 'FORGE', 
      'FRG', 'FORGES', 'FORK', 'FRK', 'FORKS', 'FRKS', 'FORT', 'FRT', 'FT', 'FREEWAY', 'FREEWY', 'FRWAY', 'FRWY', 
      'FWY', 'GARDEN', 'GARDN', 'GRDEN', 'GRDN', 'GARDENS', 'GDNS', 'GRDNS', 'GATEWAY', 'GATEWY', 'GATWAY', 'GTWAY', 
      'GTWY', 'GLEN', 'GLN', 'GLENS', 'GREEN', 'GRN', 'GREENS', 'GROV', 'GROVE', 'GRV', 'GROVES', 'HARB', 'HARBOR', 
      'HARBR', 'HBR', 'HRBOR', 'HARBORS', 'HAVEN', 'HVN', 'HT', 'HTS', 'HIGHWAY', 'HIGHWY', 'HIWAY', 'HIWY', 'HWAY', 
      'HWY', 'HILL', 'HL', 'HILLS', 'HLS', 'HLLW', 'HOLLOW', 'HOLLOWS', 'HOLW', 'HOLWS', 'INLT', 'IS', 'ISLAND', 
      'ISLND', 'ISLANDS', 'ISLNDS', 'ISS', 'ISLE', 'ISLES', 'JCT', 'JCTION', 'JCTN', 'JUNCTION', 'JUNCTN', 'JUNCTON', 
      'JCTNS', 'JCTS', 'JUNCTIONS', 'KEY', 'KY', 'KEYS', 'KYS', 'KNL', 'KNOL', 'KNOLL', 'KNLS', 'KNOLLS', 'LK', 
      'LAKE', 'LKS', 'LAKES', 'LAND', 'LANDING', 'LNDG', 'LNDNG', 'LANE', 'LN', 'LGT', 'LIGHT', 'LIGHTS', 'LF', 
      'LOAF', 'LCK', 'LOCK', 'LCKS', 'LOCKS', 'LDG', 'LDGE', 'LODG', 'LODGE', 'LOOP', 'LOOPS', 'MALL', 'MNR', 'MANOR', 
      'MANORS', 'MNRS', 'MEADOW', 'MDW', 'MDWS', 'MEADOWS', 'MEDOWS', 'MEWS', 'MILL', 'MILLS', 'MISSN', 'MSSN', 
      'MOTORWAY', 'MNT', 'MT', 'MOUNT', 'MNTAIN', 'MNTN', 'MOUNTAIN', 'MOUNTIN', 'MTIN', 'MTN', 'MNTNS', 'MOUNTAINS', 
      'NCK', 'NECK', 'ORCH', 'ORCHARD', 'ORCHRD', 'OVAL', 'OVL', 'OVERPASS', 'PARK', 'PRK', 'PARKS', 'PARKWAY', 
      'PARKWY', 'PKWAY', 'PKWY', 'PKY', 'PARKWAYS', 'PKWYS', 'PASS', 'PASSAGE', 'PATH', 'PATHS', 'PIKE', 'PIKES', 
      'PINE', 'PINES', 'PNES', 'PL', 'PLAIN', 'PLN', 'PLAINS', 'PLNS', 'PLAZA', 'PLZ', 'PLZA', 'POINT', 'PT', 'POINTS', 
      'PTS', 'PORT', 'PRT', 'PORTS', 'PRTS', 'PR', 'PRAIRIE', 'PRR', 'RAD', 'RADIAL', 'RADIEL', 'RADL', 'RAMP', 'RANCH', 
      'RANCHES', 'RNCH', 'RNCHS', 'RAPID', 'RPD', 'RAPIDS', 'RPDS', 'REST', 'RST', 'RDG', 'RDGE', 'RIDGE', 'RDGS', 
      'RIDGES', 'RIV', 'RIVER', 'RVR', 'RIVR', 'RD', 'ROAD', 'ROADS', 'RDS', 'ROUTE', 'ROW', 'RUE', 'RUN', 'SHL', 
      'SHOAL', 'SHLS', 'SHOALS', 'SHOAR', 'SHORE', 'SHR', 'SHOARS', 'SHORES', 'SHRS', 'SKYWAY', 'SPG', 'SPNG', 'SPRING', 
      'SPRNG', 'SPGS', 'SPNGS', 'SPRINGS', 'SPRNGS', 'SPUR', 'SPURS', 'SQ', 'SQR', 'SQRE', 'SQU', 'SQUARE', 'SQRS', 
      'SQUARES', 'STA', 'STATION', 'STATN', 'STN', 'STRA', 'STRAV', 'STRAVEN', 'STRAVENUE', 'STRAVN', 'STRVN', 
      'STRVNUE', 'STREAM', 'STREME', 'STRM', 'STREET', 'STRT', 'ST', 'STR', 'STREETS', 'SMT', 'SUMIT', 'SUMITT', 
      'SUMMIT', 'TER', 'TERR', 'TERRACE', 'THROUGHWAY', 'TRACE', 'TRACES', 'TRCE', 'TRACK', 'TRACKS', 'TRAK', 'TRK', 
      'TRKS', 'TRAFFICWAY', 'TRAIL', 'TRAILS', 'TRL', 'TRLS', 'TRAILER', 'TRLR', 'TRLRS', 'TUNEL', 'TUNL', 'TUNLS', 
      'TUNNEL', 'TUNNELS', 'TUNNL', 'TRNPK', 'TURNPIKE', 'TURNPK', 'UNDERPASS', 'UN', 'UNION', 'UNIONS', 'VALLEY', 
      'VALLY', 'VLLY', 'VLY', 'VALLEYS', 'VLYS', 'VDCT', 'VIA', 'VIADCT', 'VIADUCT', 'VIEW', 'VW', 'VIEWS', 'VWS', 
      'VILL', 'VILLAG', 'VILLAGE', 'VILLG', 'VILLIAGE', 'VLG', 'VILLAGES', 'VLGS', 'VILLE', 'VL', 'VIS', 'VIST', 
      'VISTA', 'VST', 'VSTA', 'WALK', 'WALKS', 'WALL', 'WY', 'WAY', 'WAYS', 'WELL', 'WELLS', 'WLS',
      'PLACE'
    ]
  end
end

The following:

Address.new('Flat 1, Bubble House, 12 Long Road, Someton, Worcestershire, WR1 1XX').details

Will generate:

{:flat=>"Flat 1", :house_number=>"12", :house_name=>"Bubble House", :street=>"Long Road", :street2=>nil, :street3=>nil, :town=>"Someton", :county=>"Worcestershire", :postcode=>"WR1 1XX"}