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Contents
# Author:: Eyal Oren
# Copyright:: (c) 2005-2006 Eyal Oren
# License:: LGPL
require 'active_rdf'
require 'uuidtools'
require 'strscan'
# ntriples parser
class NTriplesParser
# parses an input string of ntriples and returns a nested array of [s, p, o]
# (which are in turn ActiveRDF objects)
def self.parse(input)
# need unique identifier for this batch of triples (to detect occurence of
# same bnodes _:#1
uuid = UUID.random_create.to_s
input.collect do |triple|
nodes = []
scanner = StringScanner.new(triple)
scanner.skip(/\s+/)
while not scanner.eos?
nodes << scanner.scan(Node)
scanner.skip(/\s+/)
scanner.terminate if nodes.size == 3
end
# handle bnodes if necessary (bnodes need to have uri generated)
subject = case nodes[0]
when BNode
RDFS::Resource.new("http://www.activerdf.org/bnode/#{uuid}/#$1")
when Resource
RDFS::Resource.new($1)
end
predicate = case nodes[1]
when Resource
RDFS::Resource.new($1)
end
# handle bnodes and literals if necessary (literals need unicode fixing)
object = case nodes[2]
when BNode
RDFS::Resource.new("http://www.activerdf.org/bnode/#{uuid}/#$1")
when Literal
fix_unicode($1)
when Resource
RDFS::Resource.new($1)
end
# collect s, p, o into array to be returned
[subject, predicate, object]
end
end
private
# constants for extracting resources/literals from sql results
Node = Regexp.union(/"(?:\\"|[^"])*"/,/_:\S*/,/<[^>]*>/)
BNode = /_:(\S*)/
Resource = /<([^>]*)>/
Literal = /"((?:\\"|[^"])*)"/
# fixes unicode characters in literals (because we parse them wrongly somehow)
def self.fix_unicode(str)
tmp = str.gsub(/\\\u([0-9a-fA-F]{4,4})/u){ "U+#$1" }
tmp.gsub(/U\+([0-9a-fA-F]{4,4})/u){["#$1".hex ].pack('U*')}
end
end
Version data entries
10 entries across 10 versions & 1 rubygems