158 lines
4.1 KiB
Ruby
158 lines
4.1 KiB
Ruby
require 'nokogiri'
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require 'avm/node'
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module AVM
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# An XMP document wrapper, providing namespace handling and document reference assistance.
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class XMP
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PREFIXES = {
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'dc' => 'Dublin Core',
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'Iptc4xmpCore' => 'IPTC',
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'photoshop' => 'Photoshop',
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'avm' => 'AVM'
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}
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REQUIRED_NAMESPACES = {
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:x => "adobe:ns:meta/",
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:rdf => "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
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:dc => "http://purl.org/dc/elements/1.1/",
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:photoshop => "http://ns.adobe.com/photoshop/1.0/",
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:avm => "http://www.communicatingastronomy.org/avm/1.0/",
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:Iptc4xmpCore => "http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/"
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}
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attr_reader :doc
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def initialize(doc = nil)
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@doc = doc || empty_xml_doc
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raise StandardError.new('not a Nokogiri node') if !@doc.kind_of?(::Nokogiri::XML::Node)
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ensure_namespaces!
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ensure_descriptions_findable!
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end
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def get_refs
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yield Hash[[ :dublin_core, :iptc, :photoshop, :avm ].collect { |key| [ key, send(key) ] }]
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end
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def self.from_string(string)
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new(Nokogiri::XML(string))
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end
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def ensure_xmlns(string)
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string.gsub(%r{([</@])(\w+):}) { |all, matches| $1 + (prefix_map[$2] || $2) + ':' }
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end
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alias :% :ensure_xmlns
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def ensure_xpath(path)
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[ ensure_xmlns(path), namespaces ]
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end
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def search(path, node = doc)
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node.search(*ensure_xpath(path))
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end
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def at_xpath(path, node = doc)
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node.at_xpath(*ensure_xpath(path))
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end
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def namespaces
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@namespaces ||= doc.document.collect_namespaces
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end
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private
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def current_namespaces
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doc.document.collect_namespaces
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end
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def prefix_map
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@prefix_map ||= Hash[current_namespaces.collect { |prefix, namespace|
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self.class.get_required_namespace(namespace, prefix.gsub('xmlns:', ''))
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}.compact]
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end
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def self.get_required_namespace(namespace, prefix)
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result = nil
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REQUIRED_NAMESPACES.each do |original_prefix, target_namespace|
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result = [ original_prefix.to_s, prefix ] if namespace == target_namespace
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end
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result
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end
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def ensure_namespaces!
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existing = current_namespaces
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REQUIRED_NAMESPACES.each do |namespace, url|
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doc.root.add_namespace_definition(namespace.to_s, url) if !existing.values.include?(url)
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end
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end
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def ensure_descriptions_findable!
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added = []
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search('//rdf:Description').each do |description|
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if first_child = description.first_element_child
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if namespace = first_child.namespace
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prefix = namespace.prefix
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if prefix_description = PREFIXES[prefix_map.index(prefix)]
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description[self % 'rdf:about'] = prefix_description
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added << prefix
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end
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end
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end
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end
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ensure_rdf!
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ensure_missing_descriptions!(added)
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end
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def ensure_rdf!
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doc.first_element_child.add_child(self % '<rdf:RDF />') if !at_xpath('//rdf:RDF')
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end
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def ensure_missing_descriptions!(already_added)
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PREFIXES.each do |prefix, about|
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if !already_added.include?(prefix)
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at_xpath('//rdf:RDF').add_child(self % %{<rdf:Description rdf:about="#{about}" />})
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end
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end
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end
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def dublin_core
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at_rdf_description "Dublin Core"
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end
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def iptc
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at_rdf_description "IPTC"
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end
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def avm
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at_rdf_description "AVM"
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end
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def photoshop
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at_rdf_description "Photoshop"
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end
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def at_rdf_description(about)
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AVM::Node.new(self, at_xpath(%{//rdf:Description[@rdf:about="#{about}"]}))
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end
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def empty_xml_doc
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Nokogiri::XML(<<-XML)
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<x:xmpmeta xmlns:x="adobe:ns:meta/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
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<rdf:RDF>
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<rdf:Description rdf:about="Dublin Core" />
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<rdf:Description rdf:about="IPTC" />
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<rdf:Description rdf:about="Photoshop" />
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<rdf:Description rdf:about="AVM" />
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</rdf:RDF>
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</x:xmpmeta>
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XML
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end
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end
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end
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