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[librarian.git] / librarian / dcparser.py
diff --git a/librarian/dcparser.py b/librarian/dcparser.py
index 830b089..b5b1c22 100644 (file)
--- a/librarian/dcparser.py
+++ b/librarian/dcparser.py
@@ -1,14 +1,29 @@
 # -*- coding: utf-8 -*-
 # -*- coding: utf-8 -*-
+#
+# This file is part of Librarian, licensed under GNU Affero GPLv3 or later.
+# Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
+#
 from xml.parsers.expat import ExpatError
 from datetime import date
 import time
 from xml.parsers.expat import ExpatError
 from datetime import date
 import time
+import re
+from librarian.util import roman_to_int
 
 
-from librarian import ValidationError, NoDublinCore
+from librarian import (ValidationError, NoDublinCore, ParseError, DCNS, RDFNS,
+                       XMLNS, WLURI, WLNS, PLMETNS)
 
 
-import lxml.etree as etree # ElementTree API using libxml2
+import lxml.etree as etree  # ElementTree API using libxml2
 from lxml.etree import XMLSyntaxError
 
 
 from lxml.etree import XMLSyntaxError
 
 
+class TextPlus(unicode):
+    pass
+
+
+class DatePlus(date):
+    pass
+
+
 # ==============
 # = Converters =
 # ==============
 # ==============
 # = Converters =
 # ==============
@@ -17,156 +32,240 @@ class Person(object):
     def __init__(self, last_name, *first_names):
         self.last_name = last_name
         self.first_names = first_names
     def __init__(self, last_name, *first_names):
         self.last_name = last_name
         self.first_names = first_names
-        
+
     @classmethod
     def from_text(cls, text):
     @classmethod
     def from_text(cls, text):
-        parts = [ token.strip() for token in text.split(',') ]
+        parts = [token.strip() for token in text.split(',')]
         if len(parts) == 1:
             surname = parts[0]
             names = []
         elif len(parts) != 2:
         if len(parts) == 1:
             surname = parts[0]
             names = []
         elif len(parts) != 2:
-            raise ValueError("Invalid person name. There should be at most one comma: \"%s\"." % text)
+            raise ValueError("Invalid person name. There should be at most one comma: \"%s\"." % text.encode('utf-8'))
         else:
             surname = parts[0]
             if len(parts[1]) == 0:
                 # there is no non-whitespace data after the comma
                 raise ValueError("Found a comma, but no names given: \"%s\" -> %r." % (text, parts))
         else:
             surname = parts[0]
             if len(parts[1]) == 0:
                 # there is no non-whitespace data after the comma
                 raise ValueError("Found a comma, but no names given: \"%s\" -> %r." % (text, parts))
-            names = [ name for name in parts[1].split() if len(name) ] # all non-whitespace tokens
+            names = parts[1].split()
         return cls(surname, *names)
         return cls(surname, *names)
-    
+
+    def readable(self):
+        return u" ".join(self.first_names + (self.last_name,))
+
     def __eq__(self, right):
         return self.last_name == right.last_name and self.first_names == right.first_names
     def __eq__(self, right):
         return self.last_name == right.last_name and self.first_names == right.first_names
-    
-    
+
+    def __cmp__(self, other):
+        return cmp((self.last_name, self.first_names), (other.last_name, other.first_names))
+
+    def __hash__(self):
+        return hash((self.last_name, self.first_names))
+
     def __unicode__(self):
         if len(self.first_names) > 0:
             return '%s, %s' % (self.last_name, ' '.join(self.first_names))
         else:
             return self.last_name
     def __unicode__(self):
         if len(self.first_names) > 0:
             return '%s, %s' % (self.last_name, ' '.join(self.first_names))
         else:
             return self.last_name
-        
+
     def __repr__(self):
         return 'Person(last_name=%r, first_names=*%r)' % (self.last_name, self.first_names)
 
     def __repr__(self):
         return 'Person(last_name=%r, first_names=*%r)' % (self.last_name, self.first_names)
 
+
 def as_date(text):
 def as_date(text):
+    """Dates for digitization of pictures. It seems we need the following:
+ranges:                '1350-1450',
+centuries:     "XVIII w.'
+half centuries/decades: '2 poł. XVIII w.', 'XVII w., l. 20'
+later-then: 'po 1450'
+circa 'ok. 1813-1814', 'ok.1876-ok.1886
+turn: 1893/1894
+for now we will translate this to some single date losing information of course.
+    """
     try:
     try:
-        try:
-            t = time.strptime(text, '%Y-%m-%d')
-        except ValueError:
-            t = time.strptime(text, '%Y')
-        return date(t[0], t[1], t[2])
+        # check out the "N. poł X w." syntax
+        if isinstance(text, str):
+            text = text.decode("utf-8")
+
+        century_format = u"(?:([12]) *poł[.]? +)?([MCDXVI]+) *w[.,]*(?: *l[.]? *([0-9]+))?"
+        vague_format = u"(?:po *|ok. *)?([0-9]{4})(-[0-9]{2}-[0-9]{2})?"
+
+        m = re.match(century_format, text)
+        m2 = re.match(vague_format, text)
+        if m:
+            half = m.group(1)
+            decade = m.group(3)
+            century = roman_to_int(str(m.group(2)))
+            if half is not None:
+                if decade is not None:
+                    raise ValueError("Bad date format. Cannot specify both half and decade of century")
+                half = int(half)
+                t = ((century*100 + (half-1)*50), 1, 1)
+            else:
+                decade = int(decade or 0)
+                t = ((century*100 + decade), 1, 1)
+        elif m2:
+            year = m2.group(1)
+            mon_day = m2.group(2)
+            if mon_day:
+                t = time.strptime(year + mon_day, "%Y-%m-%d")
+            else:
+                t = time.strptime(year, '%Y')
+        else:
+            raise ValueError
+
+        return DatePlus(t[0], t[1], t[2])
     except ValueError, e:
         raise ValueError("Unrecognized date format. Try YYYY-MM-DD or YYYY.")
 
     except ValueError, e:
         raise ValueError("Unrecognized date format. Try YYYY-MM-DD or YYYY.")
 
+
 def as_person(text):
     return Person.from_text(text)
 
 def as_person(text):
     return Person.from_text(text)
 
+
 def as_unicode(text):
     if isinstance(text, unicode):
         return text
     else:
 def as_unicode(text):
     if isinstance(text, unicode):
         return text
     else:
-        return text.decode('utf-8')
+        return TextPlus(text.decode('utf-8'))
+
+
+def as_wluri_strict(text):
+    return WLURI.strict(text)
+
 
 class Field(object):
 
 class Field(object):
-    def __init__(self, uri, attr_name, type=as_unicode, multiple=False, salias=None, **kwargs):
+    def __init__(self, uri, attr_name, validator=as_unicode, strict=None, multiple=False, salias=None, **kwargs):
         self.uri = uri
         self.name = attr_name
         self.uri = uri
         self.name = attr_name
-        self.validator = type
+        self.validator = validator
+        self.strict = strict
         self.multiple = multiple
         self.salias = salias
 
         self.multiple = multiple
         self.salias = salias
 
-        self.required = kwargs.get('required', True) and not kwargs.has_key('default')
+        self.required = kwargs.get('required', True) and 'default' not in kwargs
         self.default = kwargs.get('default', [] if multiple else [None])
 
         self.default = kwargs.get('default', [] if multiple else [None])
 
-    def validate_value(self, val):
+    def validate_value(self, val, strict=False):
+        if strict and self.strict is not None:
+            validator = self.strict
+        else:
+            validator = self.validator
         try:
             if self.multiple:
         try:
             if self.multiple:
-                if self.validator is None:
+                if validator is None:
                     return val
                     return val
-                return [ self.validator(v) if v is not None else v for v in val ]
+                new_values = []
+                for v in val:
+                    nv = v
+                    if v is not None:
+                        nv = validator(v)
+                        if hasattr(v, 'lang'):
+                            setattr(nv, 'lang', v.lang)
+                    new_values.append(nv)
+                return new_values
             elif len(val) > 1:
             elif len(val) > 1:
-                raise ValidationError("Mulitply values not allowed for field '%s'" % self.uri)
+                raise ValidationError("Multiple values not allowed for field '%s'" % self.uri)
             elif len(val) == 0:
                 raise ValidationError("Field %s has no value to assign. Check your defaults." % self.uri)
             else:
             elif len(val) == 0:
                 raise ValidationError("Field %s has no value to assign. Check your defaults." % self.uri)
             else:
-                if self.validator is None or val[0] is None:
+                if validator is None or val[0] is None:
                     return val[0]
                     return val[0]
-                return self.validator(val[0])
+                nv = validator(val[0])
+                if hasattr(val[0], 'lang'):
+                    setattr(nv, 'lang', val[0].lang)
+                return nv
         except ValueError, e:
             raise ValidationError("Field '%s' - invald value: %s" % (self.uri, e.message))
 
         except ValueError, e:
             raise ValidationError("Field '%s' - invald value: %s" % (self.uri, e.message))
 
-    def validate(self, fdict):
-        if not fdict.has_key(self.uri):
+    def validate(self, fdict, fallbacks=None, strict=False):
+        if fallbacks is None:
+            fallbacks = {}
+        if self.uri not in fdict:
             if not self.required:
             if not self.required:
-                f = self.default
+                # Accept single value for single fields and saliases.
+                if self.name in fallbacks:
+                    if self.multiple:
+                        f = fallbacks[self.name]
+                    else:
+                        f = [fallbacks[self.name]]
+                elif self.salias and self.salias in fallbacks:
+                    f = [fallbacks[self.salias]]
+                else:
+                    f = self.default
             else:
                 raise ValidationError("Required field %s not found" % self.uri)
         else:
             f = fdict[self.uri]
 
             else:
                 raise ValidationError("Required field %s not found" % self.uri)
         else:
             f = fdict[self.uri]
 
-        return self.validate_value(f)
+        return self.validate_value(f, strict=strict)
 
 
-# ==========
-# = Parser =
-# ==========
+    def __eq__(self, other):
+        if isinstance(other, Field) and other.name == self.name:
+            return True
+        return False
 
 
-class XMLNamespace(object):
-    '''Represents XML namespace.'''
-    
-    def __init__(self, uri):
-        self.uri = uri
 
 
-    def __call__(self, tag):
-        return '{%s}%s' % (self.uri, tag)
+class DCInfo(type):
+    def __new__(mcs, classname, bases, class_dict):
+        fields = list(class_dict['FIELDS'])
 
 
-    def __contains__(self, tag):
-        return tag.startswith(str(self))
+        for base in bases[::-1]:
+            if hasattr(base, 'FIELDS'):
+                for field in base.FIELDS[::-1]:
+                    try:
+                        fields.index(field)
+                    except ValueError:
+                        fields.insert(0, field)
 
 
-    def __repr__(self):
-        return 'XMLNamespace(%r)' % self.uri
-    
-    def __str__(self):
-        return '%s' % self.uri
+        class_dict['FIELDS'] = tuple(fields)
+        return super(DCInfo, mcs).__new__(mcs, classname, bases, class_dict)
 
 
 
 
-class BookInfo(object):
-    RDF = XMLNamespace('http://www.w3.org/1999/02/22-rdf-syntax-ns#')
-    DC = XMLNamespace('http://purl.org/dc/elements/1.1/')
-    
+class WorkInfo(object):
+    __metaclass__ = DCInfo
+
     FIELDS = (
     FIELDS = (
-        Field( DC('creator'), 'author', as_person),
-        Field( DC('title'), 'title'),
-        Field( DC('subject.period'), 'epoches', salias='epoch', multiple=True),
-        Field( DC('subject.type'), 'kinds', salias='kind', multiple=True),
-        Field( DC('subject.genre'), 'genres', salias='genre', multiple=True),
-        Field( DC('date'), 'created_at', as_date),
-        Field( DC('date.pd'), 'released_to_public_domain_at', as_date, required=False),
-        Field( DC('contributor.editor'), 'editors', \
-            as_person, salias='editor', multiple=True, default=[]),
-        Field( DC('contributor.translator'), 'translators', \
-            as_person,  salias='translator', multiple=True, default=[]),
-        Field( DC('contributor.technical_editor'), 'technical_editors',
-            as_person, salias='technical_editor', multiple=True, default=[]),
-        Field( DC('publisher'), 'publisher'),
-        Field( DC('source'), 'source_name', required=False),
-        Field( DC('source.URL'), 'source_url', required=False),
-        Field( DC('identifier.url'), 'url'),
-        Field( DC('relation.hasPart'), 'parts', multiple=True, required=False),
-        Field( DC('rights.license'), 'license', required=False),
-        Field( DC('rights'), 'license_description'), 
+        Field(DCNS('creator'), 'authors', as_person, salias='author', multiple=True),
+        Field(DCNS('title'), 'title'),
+        Field(DCNS('type'), 'type', required=False, multiple=True),
+
+        Field(DCNS('contributor.editor'), 'editors',
+              as_person, salias='editor', multiple=True, required=False),
+        Field(DCNS('contributor.technical_editor'), 'technical_editors',
+              as_person, salias='technical_editor', multiple=True, required=False),
+        Field(DCNS('contributor.funding'), 'funders', salias='funder', multiple=True, required=False),
+        Field(DCNS('contributor.thanks'), 'thanks', required=False),
+
+        Field(DCNS('date'), 'created_at'),
+        Field(DCNS('date.pd'), 'released_to_public_domain_at', as_date, required=False),
+        Field(DCNS('publisher'), 'publisher', multiple=True),
+
+        Field(DCNS('language'), 'language'),
+        Field(DCNS('description'), 'description', required=False),
+
+        Field(DCNS('source'), 'source_name', required=False),
+        Field(DCNS('source.URL'), 'source_url', required=False),
+        Field(DCNS('identifier.url'), 'url', WLURI, strict=as_wluri_strict),
+        Field(DCNS('rights.license'), 'license', required=False),
+        Field(DCNS('rights'), 'license_description'),
+
+        Field(PLMETNS('digitisationSponsor'), 'sponsors', multiple=True, required=False),
+        Field(WLNS('digitisationSponsorNote'), 'sponsor_note', required=False),
+        Field(WLNS('developmentStage'), 'stage', required=False),
     )
 
     @classmethod
     )
 
     @classmethod
-    def from_string(cls, xml):
+    def from_string(cls, xml, *args, **kwargs):
         from StringIO import StringIO
         from StringIO import StringIO
-        return cls.from_file(StringIO(xml))
-   
+        return cls.from_file(StringIO(xml), *args, **kwargs)
+
     @classmethod
     @classmethod
-    def from_file(cls, xmlfile):
-        desc_tag = None        
+    def from_file(cls, xmlfile, *args, **kwargs):
+        desc_tag = None
         try:
         try:
-            iter = etree.iterparse(xmlfile, ['start', 'end'])            
+            iter = etree.iterparse(xmlfile, ['start', 'end'])
             for (event, element) in iter:
             for (event, element) in iter:
-                if element.tag == cls.RDF('RDF') and event == 'start':
+                if element.tag == RDFNS('RDF') and event == 'start':
                     desc_tag = element
                     break
 
                     desc_tag = element
                     break
 
@@ -176,47 +275,66 @@ class BookInfo(object):
 
             # continue 'till the end of RDF section
             for (event, element) in iter:
 
             # continue 'till the end of RDF section
             for (event, element) in iter:
-                if element.tag == cls.RDF('RDF') and event == 'end':
+                if element.tag == RDFNS('RDF') and event == 'end':
                     break
 
             # if there is no end, Expat should yell at us with an ExpatError
                     break
 
             # if there is no end, Expat should yell at us with an ExpatError
-            
+
             # extract data from the element and make the info
             # extract data from the element and make the info
-            return cls.from_element(desc_tag)
+            return cls.from_element(desc_tag, *args, **kwargs)
         except XMLSyntaxError, e:
             raise ParseError(e)
         except ExpatError, e:
             raise ParseError(e)
 
     @classmethod
         except XMLSyntaxError, e:
             raise ParseError(e)
         except ExpatError, e:
             raise ParseError(e)
 
     @classmethod
-    def from_element(cls, rdf_tag):
+    def from_element(cls, rdf_tag, *args, **kwargs):
         # the tree is already parsed, so we don't need to worry about Expat errors
         field_dict = {}
         # the tree is already parsed, so we don't need to worry about Expat errors
         field_dict = {}
-        desc = rdf_tag.find(".//" + cls.RDF('Description') )        
-        
+        desc = rdf_tag.find(".//" + RDFNS('Description'))
+
         if desc is None:
             raise NoDublinCore("No DublinCore section found.")
 
         if desc is None:
             raise NoDublinCore("No DublinCore section found.")
 
+        lang = None
+        p = desc
+        while p is not None and lang is None:
+            lang = p.attrib.get(XMLNS('lang'))
+            p = p.getparent()
+
         for e in desc.getchildren():
             fv = field_dict.get(e.tag, [])
         for e in desc.getchildren():
             fv = field_dict.get(e.tag, [])
-            fv.append(e.text)
+            if e.text is not None:
+                text = e.text
+                if not isinstance(text, unicode):
+                    text = text.decode('utf-8')
+                val = TextPlus(text)
+                val.lang = e.attrib.get(XMLNS('lang'), lang)
+                if e.tag == 'meta':
+                    meta_id = e.attrib.get('id')
+                    if meta_id and meta_id.endswith('-id'):
+                        field_dict[meta_id] = [val.replace('ISBN-', 'ISBN ')]
+            else:
+                val = e.text
+            fv.append(val)
             field_dict[e.tag] = fv
             field_dict[e.tag] = fv
-                
-        return cls( desc.attrib, field_dict )        
 
 
-    def __init__(self, rdf_attrs, dc_fields):
+        return cls(desc.attrib, field_dict, *args, **kwargs)
+
+    def __init__(self, rdf_attrs, dc_fields, fallbacks=None, strict=False):
         """rdf_attrs should be a dictionary-like object with any attributes of the RDF:Description.
         """rdf_attrs should be a dictionary-like object with any attributes of the RDF:Description.
-        dc_fields - dictionary mapping DC fields (with namespace) to list of text values for the 
+        dc_fields - dictionary mapping DC fields (with namespace) to list of text values for the
         given field. """
 
         given field. """
 
-        self.about = rdf_attrs.get(self.RDF('about'))
+        self.about = rdf_attrs.get(RDFNS('about'))
         self.fmap = {}
 
         for field in self.FIELDS:
         self.fmap = {}
 
         for field in self.FIELDS:
-            value = field.validate( dc_fields )
+            value = field.validate(dc_fields, fallbacks=fallbacks, strict=strict)
             setattr(self, 'prop_' + field.name, value)
             self.fmap[field.name] = field
             setattr(self, 'prop_' + field.name, value)
             self.fmap[field.name] = field
-            if field.salias: self.fmap[field.salias] = field
+            if field.salias:
+                self.fmap[field.salias] = field
 
     def __getattribute__(self, name):
         try:
 
     def __getattribute__(self, name):
         try:
@@ -224,11 +342,11 @@ class BookInfo(object):
             value = object.__getattribute__(self, 'prop_'+field.name)
             if field.name == name:
                 return value
             value = object.__getattribute__(self, 'prop_'+field.name)
             if field.name == name:
                 return value
-            else: # singular alias
+            else:  # singular alias
                 if not field.multiple:
                     raise "OUCH!! for field %s" % name
                 if not field.multiple:
                     raise "OUCH!! for field %s" % name
-                
-                return value[0]
+
+                return value[0] if value else None
         except (KeyError, AttributeError):
             return object.__getattribute__(self, name)
 
         except (KeyError, AttributeError):
             return object.__getattribute__(self, name)
 
@@ -237,7 +355,7 @@ class BookInfo(object):
             field = object.__getattribute__(self, 'fmap')[name]
             if field.name == name:
                 object.__setattr__(self, 'prop_'+field.name, newvalue)
             field = object.__getattribute__(self, 'fmap')[name]
             if field.name == name:
                 object.__setattr__(self, 'prop_'+field.name, newvalue)
-            else: # singular alias
+            else:  # singular alias
                 if not field.multiple:
                     raise "OUCH! while setting field %s" % name
 
                 if not field.multiple:
                     raise "OUCH! while setting field %s" % name
 
@@ -246,43 +364,63 @@ class BookInfo(object):
             return object.__setattr__(self, name, newvalue)
 
     def update(self, field_dict):
             return object.__setattr__(self, name, newvalue)
 
     def update(self, field_dict):
-        """Update using field_dict. Verify correctness, but don't check if all 
+        """Update using field_dict. Verify correctness, but don't check if all
         required fields are present."""
         for field in self.FIELDS:
         required fields are present."""
         for field in self.FIELDS:
-            if field_dict.has_key(field.name):
+            if field.name in field_dict:
                 setattr(self, field.name, field_dict[field.name])
 
                 setattr(self, field.name, field_dict[field.name])
 
-    def to_etree(self, parent = None):
+    def to_etree(self, parent=None):
         """XML representation of this object."""
         """XML representation of this object."""
-        #etree._namespace_map[str(self.RDF)] = 'rdf'
-        #etree._namespace_map[str(self.DC)] = 'dc'
-        
+        # etree._namespace_map[str(self.RDF)] = 'rdf'
+        # etree._namespace_map[str(self.DC)] = 'dc'
+
         if parent is None:
         if parent is None:
-            root = etree.Element(self.RDF('RDF'))
+            root = etree.Element(RDFNS('RDF'))
         else:
         else:
-            root = parent.makeelement(self.RDF('RDF'))
+            root = parent.makeelement(RDFNS('RDF'))
+
+        description = etree.SubElement(root, RDFNS('Description'))
 
 
-        description = etree.SubElement(root, self.RDF('Description'))
-        
         if self.about:
         if self.about:
-            description.set(self.RDF('about'), self.about)
-        
+            description.set(RDFNS('about'), self.about)
+
         for field in self.FIELDS:
             v = getattr(self, field.name, None)
             if v is not None:
                 if field.multiple:
         for field in self.FIELDS:
             v = getattr(self, field.name, None)
             if v is not None:
                 if field.multiple:
-                    if len(v) == 0: continue
+                    if len(v) == 0:
+                        continue
                     for x in v:
                         e = etree.Element(field.uri)
                     for x in v:
                         e = etree.Element(field.uri)
-                        e.text = unicode(x)
+                        if x is not None:
+                            e.text = unicode(x)
                         description.append(e)
                 else:
                     e = etree.Element(field.uri)
                     e.text = unicode(v)
                     description.append(e)
                         description.append(e)
                 else:
                     e = etree.Element(field.uri)
                     e.text = unicode(v)
                     description.append(e)
-        
+
         return root
 
         return root
 
+    def serialize(self):
+        rdf = {'about': {'uri': RDFNS('about'), 'value': self.about}}
+
+        dc = {}
+        for field in self.FIELDS:
+            v = getattr(self, field.name, None)
+            if v is not None:
+                if field.multiple:
+                    if len(v) == 0:
+                        continue
+                    v = [unicode(x) for x in v if x is not None]
+                else:
+                    v = unicode(v)
+
+                dc[field.name] = {'uri': field.uri, 'value': v}
+        rdf['fields'] = dc
+        return rdf
+
     def to_dict(self):
         result = {'about': self.about}
         for field in self.FIELDS:
     def to_dict(self):
         result = {'about': self.about}
         for field in self.FIELDS:
@@ -290,17 +428,48 @@ class BookInfo(object):
 
             if v is not None:
                 if field.multiple:
 
             if v is not None:
                 if field.multiple:
-                    if len(v) == 0: continue
-                    v = [ unicode(x) for x in v ]
+                    if len(v) == 0:
+                        continue
+                    v = [unicode(x) for x in v if x is not None]
                 else:
                     v = unicode(v)
                 result[field.name] = v
 
             if field.salias:
                 v = getattr(self, field.salias)
                 else:
                     v = unicode(v)
                 result[field.name] = v
 
             if field.salias:
                 v = getattr(self, field.salias)
-                if v is not None: result[field.salias] = v
-        
+                if v is not None:
+                    result[field.salias] = unicode(v)
+
         return result
 
         return result
 
-def parse(file_name):
-    return BookInfo.from_file(file_name)
+
+class BookInfo(WorkInfo):
+    FIELDS = (
+        Field(DCNS('audience'), 'audiences', salias='audience', multiple=True, required=False),
+
+        Field(DCNS('subject.period'), 'epochs', salias='epoch', multiple=True, required=False),
+        Field(DCNS('subject.type'), 'kinds', salias='kind', multiple=True, required=False),
+        Field(DCNS('subject.genre'), 'genres', salias='genre', multiple=True, required=False),
+                
+        Field(DCNS('contributor.translator'), 'translators',
+              as_person,  salias='translator', multiple=True, required=False),
+        Field(DCNS('relation.hasPart'), 'parts', WLURI, strict=as_wluri_strict, multiple=True, required=False),
+        Field(DCNS('relation.isVariantOf'), 'variant_of', WLURI, strict=as_wluri_strict, required=False),
+
+        Field(DCNS('relation.coverImage.url'), 'cover_url', required=False),
+        Field(DCNS('relation.coverImage.attribution'), 'cover_by', required=False),
+        Field(DCNS('relation.coverImage.source'), 'cover_source', required=False),
+        # WLCover-specific.
+        Field(WLNS('coverBarColor'), 'cover_bar_color', required=False),
+        Field(WLNS('coverBoxPosition'), 'cover_box_position', required=False),
+        Field(WLNS('coverClass'), 'cover_class', default=['default']),
+        Field('pdf-id',  'isbn_pdf',  required=False),
+        Field('epub-id', 'isbn_epub', required=False),
+        Field('mobi-id', 'isbn_mobi', required=False),
+        Field('txt-id',  'isbn_txt',  required=False),
+        Field('html-id', 'isbn_html', required=False),
+    )
+
+
+def parse(file_name, cls=BookInfo):
+    return cls.from_file(file_name)