Provided by: libebook-tools-perl_0.4.9-1_amd64 bug

NAME

       EBook::Tools - Object class for manipulating and generating E-books

DESCRIPTION

       This module provides an object interface and a number of related procedures intended to create or modify
       documents centered around the International Digital Publishing Forum (IDPF) standards, currently both
       OEBPS v1.2 and OPS/OPF v2.0.

SYNOPSIS

        use EBook::Tools qw(split_metadata system_tidy_xml);
        $EBook::Tools::tidysafety = 2;

        my $opffile = split_metadata('ebook.html');
        my $otheropffile = 'alternate.opf';
        my $retval = system_tidy_xml($opffile,'tidy-backup.xml');
        my $ebook = EBook::Tools->new($opffile);
        $ebook->fix_opf20;
        $ebook->fix_misc;
        $ebook->print;
        $ebook->save;

        $ebook->init($otheropffile);
        $ebook->fix_oeb12;
        $ebook->gen_epub;

DEPENDENCIES

   Perl Modules
       Archive::Zip
       Data::UUID (or OSSP::UUID)
       Date::Manip
           Note  that  Date::Manip  will die on MS Windows system unless the TZ environment variable is set in a
           specific manner. See:

           http://search.cpan.org/perldoc?Date::Manip#TIME_ZONES

       File::MimeInfo
       HTML::Parser
       Tie::IxHash
       Time::Local
       XML::Twig

   Other Programs
       Tidy
           The command "tidy" needs to be available, and ideally on the path.  If it isn't on the path,  package
           variable  "$tidycmd"  can  be set to its absolute path.  If tidy cannot be found, "system_tidy_xml()"
           and "system_tidy_xhtml()" will be nonfunctional.

CONFIGURABLE PACKAGE VARIABLES

       %dcelements12
           A tied  IxHash  mapping  an  all-lowercase  list  of  Dublin  Core  metadata  element  names  to  the
           capitalization  dictated by the OEB 1.2 specification, used by the fix_oeb12() and fix_oeb12_dcmeta()
           methods.  Changing the tags in this list will change  the  tags  recognized  and  placed  inside  the
           <dc-metadata> element.

           Order is preserved and significant -- fix_oeb12 will output DC metadata elements in the same order as
           in this hash, though order for tags of the same name is preserved from the input file.

       %dcelements20
           A  tied  IxHash  mapping  an  all-lowercase  list  of  Dublin Core metadata element names to the all-
           lowercase form dictated by the OPF 2.0 specification (which means it maps the all-lowercase  tags  to
           themselves).   It  is  used  by the fix_opf20() and fix_opf20_dcmeta() methods.  Changing the tags in
           this list will change the tags recognized and placed directly under the <metadata> element.

           Order is preserved and significant -- fix_opf20 will output DC metadata elements in the same order as
           in this hash, though order for tags of the same name is preserved from the input file.

       %nonxmlentity2char
           This is the %entity2char conversion map from HTML::Entities with the 5 pre-defined XML entities (amp,
           gt, lt, quot, apos) removed.  This is used during by "init()" to sanitize the OPF  file  data  before
           parsing.   This  hash  can  be  modified  to allow and convert other non-standard entities to unicode
           characters.  See HTML::Entities for details.

       %publishermap
           A hash mapping known variants of publisher names to a canonical form, used by "fix_publisher()",  and
           thus also indirectly by "fix_misc()".

           Keys  should be entered in lowercase.  The hash can also be set empty to prevent fix_publisher() from
           taking any action at all.

       %relatorcodes
           A hash mapping the MARC Relator Codes (see: http://www.loc.gov/marc/relators/relacode.html) to  their
           descriptive names.

       $tidycmd
           The  tidy  executable  name.   This  has  to be a fully qualified pathname if tidy isn't on the path.
           Defaults to 'tidy'.

       $tidyxhtmlerrors
           The name of the error output file from system_tidy_xhtml().  Defaults to 'tidyxhtml-errors.txt'

       $tidyxmlerrors
           The name of the error output file from system_tidy_xml().  Defaults to 'tidyxml-errors.txt'

       $tidysafety
           The safety level to use when running tidy (default is 1).  Potential values are:

           "$tidysafety < 1":
               No checks performed, no error files kept, works like a clean tidy -m

               This setting is DANGEROUS!

           "$tidysafety == 1":
               Overwrites original file if there were no errors, but even if there were warnings.  Keeps  a  log
               of errors, but not warnings.

           "$tidysafety == 2":
               Overwrites  original  file if there were no errors, but even if there were warnings.  Keeps a log
               of both errors and warnings.

           "$tidysafety == 3":
               Overwrites original file only if there were no errors or warnings.  Keeps a log  of  both  errors
               and warnings.

           $tidysafety = 4>:
               Never overwrites original file.  Keeps a log of both errors and warnings.

       %validspecs
           A  hash  mapping  valid  specification strings to themselves, primarily used to undefine unrecognized
           values.  Default valid values are 'OEB12' and 'OPF20'.

CONSTRUCTORS AND INITIALIZATION

   "new($filename)"
       Instantiates a new EBook::Tools object.  If $filename is specified, it will also  immediately  initialize
       itself via the "init" method.

   "init($filename)"
       Initializes  the  object from an existing OPF file.  If $filename is specified and exists, the OEB object
       will be set to read and write to that file before attempting to initialize.   Otherwise,  if  the  object
       currently  points  to an OPF file it will use that name.  If there is no OPF filename data, and $filename
       was not specified, it will  make  a  last-ditch  attempt  to  find  an  OPF  file  first  by  looking  in
       META-INF/container.xml,  and  if nothing is found there, by looking in the current directory for a single
       OPF file.

       If no such files or found (or more than one is found), the initialization croaks.

   "init_blank(%args)"
       Initializes an object containing nothing more than the basic  OPF  framework,  suitable  for  adding  new
       documents when creating an e-book from scratch.

       Arguments

       "init_blank" takes up to three optional named arguments:

       "opffile"
           This  specifies  the  OPF  filename  to  use.   If not specified, defaults to the name of the current
           working directory with ".opf" appended

       "author"
           This specifies the content of the initial dc:creator element.  If not specified, defaults to "Unknown
           Author".

       "title"
           This specifies the content of the initial dc:title element. If not specified,  defaults  to  "Unknown
           Title".

       Example

        init_blank('opffile' => 'newfile.opf',
                   'title' => 'The Great Unknown');

ACCESSOR METHODS

       The  following  methods  return  data  deeper  in the structure than the auto-accessors, but still do not
       modify any object data or files.

   "adult()"
       Returns the text of the Mobipocket-specific <Adult> element, if it exists.  Expected values are 'yes' and
       undef.

   "contributor_list()"
       Returns a list containing the text of all dc:contributor elements (case-insensitive) or undef if none are
       found.

       In scalar context, returns the first contributor, not the last.

   "date_list(%args)"
       Returns the text of all dc:date elements (case-insensitive) matching the specified attributes.

       In scalar context, returns the first match, not the last.

       Returns undef if no matches are found.

       Arguments

       •   "id" - 'id' attribute that must be matched exactly for the result to be added to the list

       •   "event" 'opf:event' or 'event' attribute that must be matched exactly for the result to be  added  to
           the list

       If  both arguments are specified a value is added to the list if it matches either one (i.e. the logic is
       OR).

   "description()"
       Returns the description of the e-book, if set, or undef otherwise.

   "element_list(%args)"
       Returns a list containing the text values of all elements matching the specified criteria.

       Arguments

       •   "cond"

           The XML::Twig search condition used to find the elements.  Typically this is just the GI (tag) of the
           element you wish to find, but it can also be a "qr//" expression,  coderef,  or  anything  else  that
           XML::Twig can work with.  See the XML::Twig documentation for details.

           If this is not specified, an error is added and the method returns undef.

       •   "id" (optional)

           'id' attribute that must be matched exactly for the result to be added to the list

       •   "scheme" (optional)

           'opf:scheme'  or  'scheme'  attribute  that must be matched exactly for the result to be added to the
           list

       •   "event" (optional)

           'opf:event' or 'event' attribute that must be matched exactly for the result to be added to the list

       If more than one of the arguments "id", "scheme", or "event" are specified a value is added to  the  list
       if it matches any one (i.e. the logic is OR).

   "errors()"
       Returns an arrayref containing any generated error messages.

   "identifier()"
       Returns the text of the dc:identifier element pointed to by the 'unique-identifier' attribute of the root
       'package' element, or undef if it could not be located.

   "isbn_list(%args)"
       Returns  a  list  of all ISBNs matching the specified attributes.  See "twigelt_is_isbn()" for a detailed
       description of how the ISBN elements are found.

       Returns undef if no matches are found.

       In scalar context returns the first match, not the last.

       See also "isbns(%args)".

       Arguments

       •   "id" (optional)

           'id' attribute that must be matched exactly for the result to be added to the list

       •   "scheme" (optional)

           'opf:scheme' or 'scheme' attribute that must be matched exactly for the result to  be  added  to  the
           list

       If  both arguments are specified a value is added to the list if it matches either one (i.e. the logic is
       OR).

   "isbns(%args)"
       Returns all of the ISBN identifiers matching the specificied attributes as a list of hashrefs,  with  one
       hash  per  ISBN identifier presented in the order that the identifiers are found.  The hash keys are 'id'
       (containing the value of the 'id' attribute), 'scheme' (containing the value of either  the  'opf:scheme'
       or 'scheme' attribute, whichever is found first), and 'isbn' (containing the text of the element).

       If no entries are found, returns undef.

       In scalar context returns the first match, not the last.

       See also "isbn_list(%args)".

       Arguments

       "isbns()" takes two optional named arguments:

       •   "id" - 'id' attribute that must be matched exactly for the result to be added to the list

       •   "scheme" - 'opf:scheme' or 'scheme' attribute that must be matched exactly for the result to be added
           to the list

       If  both arguments are specified a value is added to the list if it matches either one (i.e. the logic is
       OR).

   "languages()"
       Returns a list containing the text of all dc:language (case-insensitive) entries, or undef  if  none  are
       found.

       In scalar context returns the first match, not the last.

   "manifest(%args)"
       Returns  all  of  the items in the manifest as a list of hashrefs, with one hash per manifest item in the
       order that they appear, where the hash keys are  'id',  'href',  and  'media-type',  each  returning  the
       appropriate attribute, if any.

       In scalar context, returns the first match, not the last.

       Arguments

       "manifest()" takes four optional named arguments:

       •   "id" - 'id' attribute to match

       •   "href" - 'href' attribute to match

       •   "mtype" - 'media-type' attribute to match

       •   "logic" - logic to use (valid values are 'and' or 'or', default: 'and')

       If  any  of the named arguments are specified, "manifest()" will return only items matching the specified
       criteria.  This is an exact case-sensitive match, but it can (especially in  the  case  of  mtype)  still
       return multiple elements.

       Return values

       Returns  undef if there is no <manifest> element directly underneath <package>, or if <manifest> contains
       no items.

       See also

       "manifest_hrefs()", "spine()"

       Example

        @manifest = $ebook->manifest(id => 'ncx',
                                     mtype => 'text/xml',
                                     logic => 'or');

   "manifest_hrefs()"
       Returns a list of all of the hrefs in the current OPF manifest, or the empty list if none are found.

       In scalar context returns the first href, not the last.

       See also: "manifest()", "spine_idrefs()"

   "opffile()"
       Returns the name of the file where the OPF metadata will be stored or undef if no value is found..

   "primary_author()"
       Finds the primary author of the book, defined as the first 'dc:creator'  entry  (case-insensitive)  where
       either  the  attribute  opf:role="aut"  or role="aut", or the first 'dc:creator' entry if no entries with
       either attribute can be found.  Entries must actually have text to be considered.

       In list context, returns a two-item list, the first of which is the text of the entry (the author  name),
       and  the  second  element  of  which  is  the  value  of  the 'opf:file-as' or 'file-as' attribute (where
       'opf:file-as' is given precedence if both are present).

       In scalar context, returns the text of the entry (the author name).

       If no entries are found, returns undef.

       Uses "twigelt_is_author()" in the first half of the search.

       Example

        my ($fileas, $author) = $ebook->primary_author;
        my $author = $ebook->primary_author;

   "print_errors()"
       Prints the current list of errors to STDERR.

   "print_warnings()"
       Prints the current list of warnings to STDERR.

   "print_opf()"
       Prints the OPF file to the default filehandle

   "publishers()"
       Returns a list containing the text of all dc:publisher (case-insensitive) entries, or undef if  none  are
       found.

       In scalar context returns the first match, not the last.

   "retailprice()"
       Returns  a  two-scalar list, the first scalar being the text of the Mobipocket-specific <SRP> element, if
       it exists, and the second being the 'Currency' attribute of that element, if it exists.

       In scalar context, returns just the text (price).

       Returns undef if the SRP element is not found.

   "review()"
       Returns the text of the Mobipocket-specific <Review> element, if it exists.  Returns undef if one is  not
       found.

   "rights('id' =" 'identifier')>
       Returns a list containing the text of all of dc:rights or dc:copyrights (case-insensitive) entries in the
       e-book, or undef if none are found.

       In scalar context returns the first match, not the last.

       If  the  optional  named  argument  'id' is specified, it will only return entries where the id attribute
       matches the specified identifier.  Although this still returns a list, if more than one entry is found, a
       warning is logged.

       Note that dc:copyrights is not a valid Dublin Core element -- it is included  only  because  some  broken
       Mobipocket books use it.

   "search_knownuids()"
       Searches  the  OPF  twig for the first dc:identifier (case-insensitive) element with an ID matching known
       UID IDs.

       Returns the ID if a match is found, undef otherwise

   "search_knownuidschemes()"
       Searches descendants of the OPF twig element for the first <dc:identifier> or <dc:Identifier>  subelement
       with the attribute 'scheme' or 'opf:scheme' matching a known list of schemes for unique IDs

       NOTE:  this  is  NOT a case-insensitive search!  If you have to deal with really bizarre input, make sure
       that you run "fix_oeb12()" or "fix_opf20()" before calling "fix_packageid()" or "fix_misc()".

       Returns the ID if a match is found, undef otherwise.

   "spec()"
       Returns the version of the OEB specification currently in use.  Valid values  are  "OEB12"  and  "OPF20".
       This  value  will default to undef until "fix_oeb12" or "fix_opf20" is called, as there is no way for the
       object to know what specification is being conformed to (if any) until it attempts to enforce it.

   "spine()"
       Returns all of the manifest items referenced in the spine as a  list  of  hashrefs,  with  one  hash  per
       manifest item in the order that they appear, where the hash keys are 'id', 'href', and 'media-type', each
       returning the appropriate attribute, if any.

       In scalar context, returns the first item, not the last.

       Returns  undef  if  there  is no <spine> element directly underneath <package>, or if <spine> contains no
       itemrefs.  If <spine> exists, but <manifest> does not, or a spine itemref exists but  points  an  ID  not
       found in the manifest, spine() logs an error and returns undef.

       See also: "spine_idrefs()", "manifest()"

   "spine_idrefs()"
       Returns a list of all of the idrefs in the current OPF spine, or the empty list if none are found.

       In scalar context, returns the first idref, not the last.

       See also: "spine()", "manifest_hrefs()"

   "subject_list()"
       Returns a list containing the text of all dc:subject elements or undef if none are found.

       In scalar context, returns the first subject, not the last.

   "title()"
       Returns  the  title  of  the  e-book,  or  undef  if no dc:title element (case-insensitive) exists.  If a
       dc:title element exists, but contains no text, returns an empty string.

   "twig()"
       Returns the raw XML::Twig object used to store the OPF metadata.

       Although this twig can be manipulated via the standard XML::Twig methods, doing so requires  caution  and
       is  not  recommended.   In  particular,  changing  the root element from here will cause the EBook::Tools
       internal twig and twigroot attributes to become unlinked and the result of any subsequent action  is  not
       defined.

   "twigcheck()"
       Croaks  showing  the  calling  location  unless $self has both a twig and a twigroot, and the twigroot is
       <package>.  Used as a sanity check for methods that use twig or twigroot.

   "twigroot()"
       Returns the raw XML::Twig root element used to store the OPF metadata.

       This twig element can be manipulated via the standard XML::Twig::Elt methods, but care  should  be  taken
       not  to  attempt  to cut this element from its twig as doing so will cause the EBook::Tools internal twig
       and twigroot attributes to become unlinked and the result of any subsequent action is not defined.

   "warnings()"
       Returns an arrayref containing any generated warning messages.

MODIFIER METHODS

       Unless otherwise specified, all modifier methods return undef if an error was added to  the  error  list,
       and true otherwise (even if a warning was added to the warning list).

   "add_document($href,$id,$mediatype)"
       Adds  a  document to the OPF manifest and spine, creating <manifest> and <spine> if necessary.  To add an
       item only to the OPF manifest, see add_item().

       Arguments

       $href
           The href to the document in question.  Usually, this  is  just  a  filename  (or  relative  path  and
           filename)  of  a file in the current working directory.  If you are planning to eventually generate a
           .epub book, all hrefs MUST be in or below the current working directory.

           The method returns undef if $href is not defined or empty.

       $id The XML ID to use.  If not specified, defaults to the href with invalid characters removed.

           This must be unique not only to the manifest list, but to every  element  in  the  OPF  file.   If  a
           duplicate ID exists, the method sets an error and returns undef.

       $mediatype (optional)
           The  mime  type  of the document.  If not specified, will attempt to autodetect the mime type, and if
           that fails, will default to 'application/xhtml+xml'.

   "add_error(@errors)"
       Adds @errors to the list of object errors.  Each member of @errors should  be  a  string  containing  the
       entire text of the error, with no ending newline.

       SEE ALSO: "add_warning()", "clear_errors()", "clear_warnerr()"

   "add_identifier(%args)"
       Creates a new dc:identifier element containing the specified text, id, and scheme.

       If  a  <dc-metadata>  element  exists  underneath  <metadata>,  the  identifier  element  will be created
       underneath the <dc-metadata> in OEB 1.2  format,  otherwise  the  title  element  is  created  underneath
       <metadata> in OPF 2.0 format.

       Returns the twig element containing the new identifier.

       Arguments

       "add_identifier()" takes three named arguments, one mandatory, two optional.

       •   "text" - the text of the identifier.  This is mandatory, and the method croaks if it is not present.

       •   "scheme" - 'opf:scheme' or 'scheme' attribute to be added (optional)

       •   "id"  -  'id'  attribute  to be added.  If this is specified, and the id is already in use, a warning
           will be added but the method  will  continue,  removing  the  id  attribute  from  the  element  that
           previously contained it.

   "add_item($href,$id,$mediatype)"
       Adds  a  document  to the OPF manifest (but not spine), creating <manifest> if necessary.  To add an item
       only to both the OPF manifest and spine, see add_document().

       Arguments

       $href
           The href to the document in question.  Usually, this  is  just  a  filename  (or  relative  path  and
           filename)  of  a file in the current working directory.  If you are planning to eventually generate a
           .epub book, all hrefs MUST be in or below the current working directory.

       $id The XML ID to use.  If not specified, defaults to the href with all nonword characters removed.

           This must be unique not only to the manifest list, but to every  element  in  the  OPF  file.   If  a
           duplicate ID exists, the method sets an error and returns undef.

       $mediatype (optional)
           The  mime  type  of the document.  If not specified, will attempt to autodetect the mime type, and if
           that fails, will set an error and return undef.

   add_metadata(%args)
       Creates a metadata element with the specified text, attributes, and parent.

       If a <dc-metadata> element exists underneath <metadata>, the language element will be created  underneath
       the <dc-metadata> and any standard attributes will be created in OEB 1.2 format, otherwise the element is
       created underneath <metadata> in OPF 2.0 format.

       Returns 1 on success, returns undef if no gi or if no text was specified.

       Arguments

       "gi"
           The  generic  identifier  (tag)  of  the  metadata element to alter or create.  If not specified, the
           method sets an error and returns undef.

       "parent"
           The generic identifier (tag) of the parent to use for any newly created element.  If  not  specified,
           defaults to 'dc-metadata' if 'dc-metadata' exists underneath 'metadata', and 'metadata' otherwise.

           A  newly  created  element  will  be  created under the first element found with this gi.  A modified
           element will be moved under the first element found with this gi.

           Newly created elements will use OPF 2.0 attribute names if the  parent  is  'metadata'  and  OEB  1.2
           attribute names otherwise.

       "text"
           This  specifies  the  element  text  to  set.  If not specified, the method sets an error and returns
           undef.

       "id" (optional)
           This specifies the ID to set on the element.  If set and the ID is  already  in  use,  a  warning  is
           logged and the ID is removed from the other location and assigned to the element.

       "fileas" (optional)
           This specifies the file-as attribute to set on the element.

       "role" (optional)
           This specifies the role attribute to set on the element.

       "scheme" (optional)
           This specifies the scheme attribute to set on the element.

       Example

        $retval = $ebook->add_metadata(gi => 'AuthorNonstandard',
                                       text => 'Element Text',
                                       id => 'customid',
                                       fileas => 'Text, Element',
                                       role => 'xxx',
                                       scheme => 'code');

   "add_subject(%args)"
       Creates a new dc:subject element containing the specified text, code, and id.

       If  a  <dc-metadata> element exists underneath <metadata>, the subject element will be created underneath
       the <dc-metadata> in OEB 1.2 format, otherwise the title element is created underneath <metadata> in  OPF
       2.0 format.

       Returns the twig element containing the new subject.

       Arguments

       "add_subject()" takes four named arguments, one mandatory, three optional.

       •   "text" - the text of the subject.  This is mandatory, and the method croaks if it is not present.

       •   "scheme" (optional) - 'opf:scheme' or 'scheme' attribute to be added.  Be warned that neither the OEB
           1.2  nor  the  OPF  2.0  specifications  allow  a  scheme  to be added to this element, so if this is
           specified, the resulting OPF file will fail to validate against either standard.

       •   "basiccode" (optional) - 'BASICCode' attribute to be added.  Be warned that  this  is  a  Mobipocket-
           specific  attribute  that  does not exist in either the OEB 1.2 nor the OPF 2.0 specifications, so if
           this is specified, the resulting OPF file will fail to validate against either standard.

       •   "id" (optional) - 'id' attribute to be added.  If this is specified, and the id is already in use,  a
           warning  will  be added but the method will continue, removing the id attribute from the element that
           previously contained it.

   "add_warning(@newwarning)"
       Joins @newwarning to a single string and adds it to the list of object warnings.  The warning should  not
       end with a newline newline.

       SEE ALSO: "add_error()", "clear_warnings()", "clear_warnerr()"

   "clear_errors()"
       Clear the current list of errors

   "clear_warnerr()"
       Clear both the error and warning lists

   "clear_warnings()"
       Clear the current list of warnings

   "delete_meta_filepos()"
       Deletes metadata elements with the attribute 'filepos' underneath the given parent element

       These are secondary metadata elements included in the output from mobi2html may that are not used.

   "fix_dates()"
       Standardizes  all  <dc:date>  elements  via fix_datestring().  Adds a warning to the object for each date
       that could not be fixed.

       Called from "fix_misc()".

   "fix_guide()"
       Fixes problems related to the OPF guide elements, specifically:

       •   Deletes empty guide elements

       •   Moves all reference elements directly underneath the guide element

       •   Finds reference elements with a href with only an anchor portion and assigns them to the first  spine
           href.   This  only works if the spine is in working condition, so it may be wise to run "fix_spine()"
           before "fix_guide()" if the input is expected to be very badly broken.

       Logs a warning if a reference href is found that does not appear in the manifest.

   "fix_languages(%args)"
       Checks through  the  <dc:language>  elements  (case-insensitive)  and  removes  any  duplicates.   If  no
       <dc:language> elements are found, one is created.

       TODO: Also convert language names to IANA language and region codes.

       Arguments

       •   "default"

           The  default language string to use when creating a new language element.  If not specified, defaults
           to 'en'.

   "fix_links()"
       Checks through the links in the manifest and checks them for anything they might link to, adding anything
       missing to the manifest.

       A warning is added for every manifest item missing a href.

       If no <manifest> element exists directly underneath the <package> root, or <manifest> contains no  items,
       the method logs a warning and returns undef.  Otherwise, it returns 1.

   "fix_manifest()"
       Finds all <item> elements and moves them underneath <manifest>, creating <manifest> if necessary.

       Logs  a  warning but continues if it finds an <item> with a missing id or href attribute.  If both id and
       href attributes are missing, logs a warning, skips moving  the  item  entirely  (unless  it  was  already
       underneath  <manifest>,  in which case it is moved to preserve its sort order along all other items under
       <manifest>), but otherwise continues.

   "fix_metastructure_basic()"
       Verifies that <metadata> exists (creating it if necessary), and  moves  it  to  be  the  first  child  of
       <package>.

       Used in "fix_metastructure_oeb12()", "fix_packageid()", and "set_primary_author(%args)".

   "fix_metastructure_oeb12()"
       Verifies  the  existence  of  <metadata>,  <dc-metadata>,  and <x-metadata>, creating them as needed, and
       making sure that <metadata> is a child of <package>, while <dc-metadata> and <x-metadata> are children of
       <metadata>.

       Used in "fix_oeb12()" and "fix_mobi()".

   "fix_misc()"
       Fixes miscellaneous potential problems in  OPF  data.   Specifically,  this  is  a  shortcut  to  calling
       "delete_meta_filepos()",    "fix_packageid()",   "fix_dates()",   "fix_languages()",   "fix_publisher()",
       "fix_manifest()", "fix_spine()", "fix_guide()", and "fix_links()".

       The objective here is that you can run either "fix_misc()" and either "fix_oeb12()" or "fix_opf20()"  and
       a perfectly valid OPF file will result from only two calls.

   "fix_mobi()"
       Manipulates the twig to fix Mobipocket-specific issues

       •   Force  the  OEB  1.2  structure  (although  not  the  namespace,  DTD,  or  capitalization),  so that
           <dc-metadata> and <x-metadata> are guaranteed to exist.

       •   Find and move all Mobi-specific elements to <x-metadata>

       •   If no <output> element exists, creates one for a utf-8 ebook

       Note that the forced creation of <output> will cause the  OPF  file  to  become  noncompliant  with  IDPF
       specifications.

   "fix_oeb12()"
       Modifies the OPF data to conform to the OEB 1.2 standard

       Specifically, this involves:

       •   adding the OEB 1.2 doctype

       •   removing OPF 2.0 version and namespace attributes

       •   setting the OEB 1.2 namespace on <package>

       •   moving  all of the dc-metadata elements underneath an element with tag <dc-metadata>, which itself is
           forced to be underneath <metadata>, which is created if it doesn't exist.

       •   moving any remaining tags underneath <x-metadata>, again forced to be under <metadata>

       •   making the dc-metadata tags conform to the OEB v1.2 capitalization

   "fix_oeb12_dcmetatags()"
       Makes a case-insensitive search for tags matching a known list of DC metadata elements and  corrects  the
       capitalization  to  the  OEB  1.2  standard.   Also  corrects 'dc:Copyrights' to 'dc:Rights'.  See global
       variable $dcelements12.

       The "fix_oeb12()" method does this also, but fix_oeb12_dcmetatags() is usable  separately  for  the  case
       where  you  want  DC metadata elements with consistent tag names, but don't want them moved from wherever
       they are.

   "fix_opf20()"
       Modifies the OPF data to conform to the OPF 2.0 standard

       Specifically, this involves:

       •   moving all of the dc-metadata and x-metadata elements directly underneath <metadata>

       •   removing the <dc-metadata> and <x-metadata> elements themselves

       •   lowercasing the dc-metadata tags (and fixing dc:copyrights to dc:rights)

       •   setting namespaces on dc-metata OPF attributes

       •   setting version and xmlns attributes on <package>

       •   setting xmlns:dc and xmlns:opf on <metadata>

   "fix_opf20_dcmetatags()"
       Makes a case-insensitive search for tags matching a known list of DC metadata elements and  corrects  the
       capitalization  to  the  OPF  2.0  standard.   Also corrects 'dc:copyrights' to 'dc:rights'.  See package
       variable %dcelements20.

       The "fix_opf20()" method does this also, but "fix_opf20_dcmetatags()" is usable separately for  the  case
       where  you  want  DC metadata elements with consistent tag names, but don't want them moved from wherever
       they are.

   "fix_packageid()"
       Checks the <package> element for the attribute 'unique-identifier', makes sure that it  is  mapped  to  a
       valid  dc:identifier  subelement,  and if not, searches those subelements for an identifier to assign, or
       creates one if nothing can be found.

       Requires that <metadata> exist.  Croaks if it doesn't.  Run "fix_oeb12()" or "fix_opf20()" before calling
       this if the input might be very broken.

   "fix_publisher()"
       Standardizes publisher names in all dc:publisher entities, mapping known variants of a  publisher's  name
       to a canonical form via package variable %publishermap.

       Publisher entries with no text are deleted.

   "fix_spine()"
       Fixes problems with the OPF spine, specifically:

       Moves all <itemref> elements underneath <spine>, creating <spine> if necessary.

   "gen_epub(%args)"
       Creates   a   .epub   format   e-book.   This  will  create  (or  overwrite)  the  files  'mimetype'  and
       'META-INF/container.xml' in the current directory, creating the subdirectory META-INF as needed.

       Arguments

       This method can take two optional named arguments.

       "filename"
           The filename of the .epub output file.  If not specified, takes the base name of  the  opf  file  and
           adds a .epub extension.

       "dir"
           The  directory to output the .epub file.  If not specified, uses the current working directory.  If a
           specified directory does not exist, it will be created, or the method will croak.

       Example

        gen_epub(filename => 'mybook.epub',
                 dir => '../epub_books');

   "gen_epub_files()"
       Generates the "mimetype" and "META-INF/container.xml" files expected by a .epub container, but  does  not
       actually generate the .epub file itself.  This will be called automatically by "gen_epub".

   "gen_ncx($filename)"
       Creates  a NCX-format table of contents from the package unique-identifier, the dc:title, dc:creator, and
       spine elements, and then add the NCX entry to the manifest if it is not already referenced.

       Adds an error and fails if any of those cannot be found.  The first available dc:title is taken, but will
       prioritize  dc:creator  elements  with  opf:role="aut"  over  those   with   no   role   attribute   (see
       twigelt_is_author() for details).

       WARNING:  This  method  REQUIRES  that  the  e-book  be  in  OPF  2.0 format to function correctly.  Call
       fix_opf20() before calling gen_ncx().  gen_ncx() will log an error and fail if $self{spec} is not set  to
       OPF20.

       Arguments

       $filename : The filename to save to.  If not specified, will use 'toc.ncx'.

       This method will overwrite any existing file.

       Returns a twig containing the NCX XML, or undef on failure.

   "save()"
       Saves the OPF file to disk.  Existing files are backed up to filename.backup.

   "set_adult($bool)"
       Sets  the  Mobipocket-specific  <Adult> element, creating or deleting it as necessary.  If $bool is true,
       the text is set to 'yes'.  If it is defined but false, any existing  elements  are  deleted.   If  it  is
       undefined, the method immediately returns.

       If  a  new  element  has  to  be created, "fix_metastructure_oeb12" is called to ensure that <x-metadata>
       exists and the element is created under <x-metadata>,  as  Mobipocket  elements  are  not  recognized  by
       Mobipocket's software when placed directly under <metadata>

   "set_date(%args)"
       Sets  the  date  metadata for a given event.  If more than one dc:date or dc:Date element is present with
       the specified event attribute, sets the first.  If no dc:date element is present with the specified event
       attribute, a new element is created.

       If a <dc-metadata> element exists underneath <metadata>, the date element will be created underneath  the
       <dc-metadata>  in OEB 1.2 format, otherwise the title element is created underneath <metadata> in OPF 2.0
       format.

       Returns 1 on success, logs an error and returns undef if no text or event was specified.

       Arguments

       "text"
           This specifies the description to use as the text of the element.  If not specified, the method  sets
           an error and returns undef.

       "event"
           This  specifies  the  event  attribute  for the date.  If not specified, the method sets an error and
           returns undef.

       "id" (optional)
           This specifies the ID to set on the element.  If set and the ID is  already  in  use,  a  warning  is
           logged and the ID is removed from the other location and assigned to the element.

   set_description(%args)
       Sets  the  text  and optionally ID of the first dc:description element found (case-insensitive).  Creates
       the element if one did  not  exist.   If  a  <dc-metadata>  element  exists  underneath  <metadata>,  the
       description  element  will be created underneath the <dc-metadata> in OEB 1.2 format, otherwise the title
       element is created underneath <metadata> in OPF 2.0 format.

       Returns 1 on success, returns undef if no publisher was specified.

       Arguments

       "set_description()" takes one required and one optional named argument

       "text"
           This specifies the description to use as the text of the  element.   If  not  specified,  the  method
           returns undef.

       "id" (optional)
           This  specifies  the  ID  to  set  on the element.  If set and the ID is already in use, a warning is
           logged and the ID is removed from the other location and assigned to the element.

       Example

        $retval = $ebook->set_description('text' => 'A really good book',
                                          'id' => 'mydescid');

   "set_language(%args)"
       Sets the text and optionally the ID of the first dc:language element found  (case-insensitive).   Creates
       the  element if one did not exist.  If a <dc-metadata> element exists underneath <metadata>, the language
       element will be created underneath the <dc-metadata> in OEB 1.2 format, otherwise the  title  element  is
       created underneath <metadata> in OPF 2.0 format.

       Returns 1 on success, returns undef if no text was specified.

       Arguments

       "text"
           This  specifies  the  language  set as the text of the element.  If not specified, the method sets an
           error and returns undef.  This should be an IANA language code, and it will be lowercased  before  it
           is set.

       "id" (optional)
           This  specifies  the  ID  to  set  on the element.  If set and the ID is already in use, a warning is
           logged and the ID is removed from the other location and assigned to the element.

       Example

        $retval = $ebook->set_language('text' => 'en-us',
                                       'id' => 'langid');

   set_metadata(%args)
       Sets the text and optionally the ID  of  the  first  specified  element  type  found  (case-insensitive).
       Creates the element if one did not exist (with the exact capitalization specified).

       If  a <dc-metadata> element exists underneath <metadata>, the language element will be created underneath
       the <dc-metadata> and any standard attributes will be created in OEB 1.2 format, otherwise the element is
       created underneath <metadata> in OPF 2.0 format.

       Returns 1 on success, returns undef if no gi or if no text was specified.

       Arguments

       "gi"
           The generic identifier (tag) of the metadata element to alter  or  create.   If  not  specified,  the
           method sets an error and returns undef.

       "parent"
           The  generic  identifier (tag) of the parent to use for any newly created element.  If not specified,
           defaults to 'dc-metadata' if 'dc-metadata' exists underneath 'metadata', and 'metadata' otherwise.

           A newly created element will be created under the first element  found  with  this  gi.   A  modified
           element will be moved under the first element found with this gi.

           Newly  created  elements  will  use  OPF  2.0 attribute names if the parent is 'metadata' and OEB 1.2
           attribute names otherwise.

       "text"
           This specifies the element text to set.  If not specified, the  method  sets  an  error  and  returns
           undef.

       "id" (optional)
           This  specifies  the  ID  to  set  on the element.  If set and the ID is already in use, a warning is
           logged and the ID is removed from the other location and assigned to the element.

       "fileas" (optional)
           This specifies the file-as attribute to set on the element.

       "role" (optional)
           This specifies the role attribute to set on the element.

       "scheme" (optional)
           This specifies the scheme attribute to set on the element.

       Example

        $retval = $ebook->set_metadata(gi => 'AuthorNonstandard',
                                       text => 'Element Text',
                                       id => 'customid',
                                       fileas => 'Text, Element',
                                       role => 'xxx',
                                       scheme => 'code');

   set_opffile($filename)
       Sets the filename used to store the OPF metadata.

       Returns 1 on success; sets an error message and returns undef if no filename was specified.

   set_retailprice(%args)
       Sets the Mobipocket-specific  <SRP>  element  (Suggested  Retail  Price),  creating  or  deleting  it  as
       necessary.

       If  a  new  element  has  to  be created, "fix_metastructure_oeb12" is called to ensure that <x-metadata>
       exists and the element is created under <x-metadata>,  as  Mobipocket  elements  are  not  recognized  by
       Mobipocket's software when placed directly under <metadata>

       Arguments

       •   "text"

           The  price  to  set  as  the text of the element.  If this is undefined, the method sets an error and
           returns undef.  If it is set but false, any existing <SRP> element is deleted.

       •   "currency" (optional)

           The value to set on the 'Currency' attribute.  If not provided, defaults to 'USD' (US Dollars)

   set_primary_author(%args)
       Sets the text, id, file-as, and role attributes of the primary author element (see "primary_author()" for
       details on how this is found), or if no primary author exists,  creates  a  new  element  containing  the
       information.

       This  method  calls  "fix_metastructure_basic()" to enforce the presence of the <metadata> element.  When
       creating a new element, the method will use the OEB 1.2 element name and create  the  element  underneath
       <dc-metadata>  if  an  existing  <dc-metadata>  element  is  found underneath <metadata>.  If no existing
       <dc-metadata> element is found, the new element will be created with the OPF 2.0  element  name  directly
       underneath  <metadata>.   Regardless,  it  is probably a good idea to call "fix_oeb12()" or "fix_opf20()"
       after calling this method to ensure a consistent scheme.

       Arguments

       Three optional named arguments can be passed:

       •   "text"

           Specifies the author text to set.  If omitted and a primary author element exists, the text  will  be
           left  as  is;  if  omitted  and  a  primary  author element cannot be found, an error message will be
           generated and the method will return undef.

       •   "fileas"

           Specifies the 'file-as' attribute to set.  If omitted  and  a  primary  author  element  exists,  any
           existing  attribute  will be left untouched; if omitted and a primary author element cannot be found,
           the newly created element will not have this attribute.

       •   "id"

           Specifies the 'id' attribute to set.  If this is specified, and the id is already in use,  a  warning
           will  be  added  but  the  method  will  continue,  removing  the  id attribute from the element that
           previously contained it.

           If this is omitted and a primary author element exists, any existing id will be  left  untouched;  if
           omitted  and  a primary author element cannot be found, the newly created element will not have an id
           set.

       If called with no arguments, the only effect this method has is to enforce that either an  'opf:role'  or
       'role' attribute is set to 'aut' on the primary author element.

       Return values

       Returns 1 if successful, returns undef and sets an error message if the author argument is missing and no
       primary author element was found.

   "set_publisher(%args)"
       Sets  the text and optionally the ID of the first dc:publisher element found (case-insensitive).  Creates
       the element if one did not exist.  If a <dc-metadata> element exists underneath <metadata>, the publisher
       element will be created underneath the <dc-metadata> in OEB 1.2 format, otherwise the  title  element  is
       created underneath <metadata> in OPF 2.0 format.

       Returns 1 on success, returns undef if no publisher was specified.

       Arguments

       "set_publisher()" takes one required and one optional named argument

       "text"
           This  specifies  the  publisher name to set as the text of the element.  If not specified, the method
           returns undef.

       "id" (optional)
           This specifies the ID to set on the element.  If set and the ID is  already  in  use,  a  warning  is
           logged and the ID is removed from the other location and assigned to the element.

       Example

        $retval = $ebook->set_publisher('text' => 'My Publishing House',
                                        'id' => 'mypubid');

   set_review(%args)
       Sets  the  text  and  optionally  ID of the first <Review> element found (case-insensitive), creating the
       element if one did not exist.

       This is a Mobipocket-specific element and if it needs to be created  it  will  always  be  created  under
       <x-metadata> with "fix_metastructure_oeb12()" called to ensure that <x-metadata> exists.

       Returns 1 on success, returns undef if no review text was specified

       Arguments

       "text"
           This  specifies  the  description  to  use  as the text of the element.  If not specified, the method
           returns undef.

       "id" (optional)
           This specifies the ID to set on the element.  If set and the ID is  already  in  use,  a  warning  is
           logged and the ID is removed from the other location and assigned to the element.

       Example

        $retval = $ebook->set_review('text' => 'This book is perfect!',
                                     'id' => 'revid');

   "set_rights(%args)"
       Sets  the  text of the first dc:rights or dc:copyrights element found (case-insensitive).  If the element
       found has the gi of dc:copyrights, it  will  be  changed  to  dc:rights.   This  is  to  correct  certain
       noncompliant Mobipocket files.

       Creates  the  element if one did not exist.  If a <dc-metadata> element exists underneath <metadata>, the
       title element will be created underneath the <dc-metadata> in OEB 1.2 format, otherwise the title element
       is created underneath <metadata> in OPF 2.0 format.

       Returns 1 on success, returns undef if no rights string was specified.

       Arguments

       •   "text"

           This specifies the text of the element.  If not specified, the method returns undef.

       •   "id" (optional)

           This specifies the ID to set on the element.  If set and the ID is  already  in  use,  a  warning  is
           logged but the method continues anyway.

   "set_spec($spec)"
       Sets  the OEB specification to match when modifying OPF data.  Allowable values are 'OEB12', 'OPF20', and
       'MOBI12'.

       Returns 1 if successful; returns undef and sets an error message if an unknown specification was set.

   "set_title(%args)"
       Sets the text or id of the first dc:title element found (case-insensitive).  Creates the element  if  one
       did  not  exist.   If  a  <dc-metadata>  element  exists underneath <metadata>, the title element will be
       created underneath the <dc-metadata> in OEB 1.2 format, otherwise the title element is created underneath
       <metadata> in OPF 2.0 format.

       Arguments

       set_title() takes two optional named arguments.  If neither is specified, the method will do nothing.

       •   "text"

           This specifies the text of the element.  If not specified, and no title element is  found,  an  error
           will  be set and the method will return undef -- set_title() will refuse to create a dc:title element
           with no text.

       •   "id"

           This specifies the ID to set on the element.  If set and the ID is  already  in  use,  a  warning  is
           logged but the method continues anyway.

   "set_type(%args)"
       Sets  the  text and optionally the ID of the first dc:type element found (case-insensitive).  Creates the
       element if one did not exist.  If a <dc-metadata> element exists  underneath  <metadata>,  the  publisher
       element  will  be  created underneath the <dc-metadata> in OEB 1.2 format, otherwise the title element is
       created underneath <metadata> in OPF 2.0 format.

       Returns 1 on success, returns undef if no publisher was specified.

       Arguments

       "set_type()" takes one required and one optional named argument

       "text"
           This specifies the publisher name to set as the text of the element.  If not  specified,  the  method
           returns undef.

       "id" (optional)
           This  specifies  the  ID  to  set  on the element.  If set and the ID is already in use, a warning is
           logged and the ID is removed from the other location and assigned to the element.

       Example

        $retval = $ebook->set_type('text' => 'Short Story',
                                   'id' => 'mytypeid');

PROCEDURES

       All procedures are exportable, but none are exported by default.  All procedures can be exported by using
       the ":all" tag.

   "create_epub_container($opffile)"
       Creates the XML file META-INF/container.xml pointing to the specified OPF file.

       Creates the META-INF directory if necessary.  Will destroy any non-directory file named 'META-INF' in the
       current  directory.   If  META-INF/container.xml  already  exists,  it   will   rename   that   file   to
       META-INF/container.xml.backup.

       Arguments

       $opffile
           The  OPF  filename  (and  path, if necessary) to use in the container.  If not specified, looks for a
           sole OPF file in the current working directory.  Fails if more than one is found.

       Return values

       Returns a twig representing the container data if successful, undef otherwise

   "create_epub_mimetype()"
       Creates a file named 'mimetype' in the current working directory  containing  'application/epub+zip'  (no
       trailing newline)

       Destroys and overwrites that file if it exists.

       Returns the mimetype string if successful, undef otherwise.

   "debug($level,@message)"
       Prints  a debugging message to "STDERR" if package variable $debug is greater than or equal to $level.  A
       trailing newline is appended, and should not be part of @message.

       Returns true or dies.

   "excerpt_line($text)"
       Takes as an argument a list of text pieces that will be joined.  If the joined length is  less  than  70,
       all of the joined text is returned.

       If the joined length is greater than 70, the return string is the first 30 characters followed by ' [...]
       ' followed by the last 30 characters.

   "find_in_path($pattern,@extradirs)"
       Searches  through  $ENV{PATH} (and optionally any additional directories specified in @extradirs) for the
       first regular file matching $pattern.  $pattern itself can take two forms: if  passed  a  "qr//"  regular
       expression, that expression is used directly.  If passed any other string, that string will be used for a
       case-insensitive  exact  match  where the extension '.bat', '.com', or '.exe' is optional (i.e. the final
       pattern will be "qr/^ $pattern (\.bat|\.com|\.exe)? $/ix").

       Returns the first match found, or undef if there were no matches or if no pattern was specified.

   "find_links($filename)"
       Searches through a file for href and src attributes, and returns a list of unique links  with  any  named
       anchors  removed (e.g. 'myfile.html#part7' returns as just 'myfile.html').  If no links are found, or the
       file does not exist, returns undef.

       Does not check to see if the links are local.  Requires that links be surrounded by  double  quotes,  not
       single  or  left  bare.   Assumes that any link will not be broken across multiple lines, so it will (for
       example) fail to find:

        <img src=
        "myfile.jpg">

       though it can find:

        <img
         src="myfile.jpg">

       This also does not distinguish between local files and remote links.

   "find_opffile()"
       Attempts to locate an OPF file, first by calling "get_container_rootfile()"  to  check  the  contents  of
       "META-INF/container.xml",  and then by looking for a single file with the extension ".opf" in the current
       working directory.

       Returns the filename of the OPF file, or undef if nothing was found.

   "fix_datestring($datestring)"
       Takes a date string and attempts to convert it to the limited  subset  of  ISO8601  allowed  by  the  OPF
       standard (YYYY, YYYY-MM, or YYYY-MM-DD).

       In the special case of finding MM/DD/YYYY, it assumes that it was a Mobipocket-mangled date, and not only
       converts  it,  but  will  strip  the  day  information  if  the  day  is '01', and both the month and day
       information if both month and day are '01'.  This is  because  Mobipocket  Creator  enforces  a  complete
       MM/DD/YYYY  even  if  the  month and day aren't known, and it is common practice to use 01 for an unknown
       value.

       Arguments

       $datestring
           A date string in a format recognizable by Date::Manip

       Returns $fixeddate

       $fixeddate : the corrected string, or undef on failure

   "get_container_rootfile($container)"
       Opens and parses an OPS/epub container, extracting the 'full-path' attribute of element 'rootfile'

       Arguments

       $container
           The OPS container to parse.  Defaults to 'META-INF/container.xml'

       Return values

       Returns a string containing the rootfile on success, undef on failure.

   "hexstring($bindata)"
       Takes as an argument a scalar containing a sequence of binary bytes.  Returns a  string  converting  each
       octet of the data to its two-digit hexadecimal equivalent.  There is no leading "0x" on the string.

   "print_memory($label)"
       Checks  /proc/$PID/statm  and  prints  out  a line to STDERR showing the current memory usage.  This is a
       debugging tool that will likely fail to do anything useful on a system without a /proc system  compatible
       with Linux.

       Arguments

       $label
           If defined, will be output along with the memory usage.

       Returns 1 on success, undef otherwise.

   "split_metadata($metahtmlfile, $metafile)"
       Takes  a  psuedo-HTML  containing one or more <metadata>...</metadata> blocks and splits out the metadata
       blocks into an XML file ready to be used as an OPF document.  The input HTML file  is  rewritten  without
       the metadata.

       If  $metafile (or the temporary HTML-only file created during the split) already exists, it will be moved
       to filename.backup.

       Arguments

       $metahtmlfile
           The filename of the pseudo-HTML file

       $metafile (optional)
           The filename to write out any extracted metadata.  If not specified, will default to the basename  of
           $metahtmlfile with '.opf' appended.

       Returns the filename the metadata was written to, or undef if no metadata was found.

   "split_pre($htmlfile,$outfilebase)"
       Splits  <pre>...</pre>  blocks  out  of  a  source HTML file into their own separate HTML files including
       required  headers.   Each  block  will  be  written  to  its  own  file  following  the   naming   format
       "$outfilebase-###.html",  where  ###  is  a three-digit number beginning at 001 and incrementing for each
       block found.  If  $outfilebase  is  not  specified,  it  defaults  to  the  basename  of  $htmlfile  with
       "-pre-###.html" appended.  The

       Returns a list containing all filenames created.

   "strip_script(%args)"
       Strips any <script>...</script> blocks out of a HTML file.

       Arguments

       "infile"
           Specifies the input file.  If not specified, the sub croaks.

       "outfile"
           Specifies  the  output  file.   If  not  specified,  it  defaults to "infile" (i.e. the input file is
           overwritten).

       "noscript"
           If set to true, the sub will strip <noscript>...</noscript> blocks as well.

   "system_tidy_xhtml($infile,$outfile)"
       Runs tidy on a XHTML file semi-safely (using a secondary file)

       Converts HTML to XHTML if necessary

       Arguments

       $infile
           The filename to tidy

       $outfile
           The filename to use for tidy output if the safety condition to overwrite the input file isn't met.

           Defaults to "infile-tidy.ext" if not specified.

       Global variables used

       $tidycmd
           the location of the tidy executable

       $tidyxhtmlerrors
           the filename to use to output errors

       $tidysafety
           the safety factor to use (see CONFIGURABLE GLOBAL VARIABLES, above)

       Return Values

       Returns the return value from tidy

       0 - no errors
       1 - warnings only
       2 - errors
       Dies horribly if the return value is unexpected

   "system_tidy_xml($infile,$outfile)"
       Runs tidy on an XML file semi-safely (using a secondary file)

       Arguments

       $infile
           The filename to tidy

       $outfile (optional)
           The filename to use for tidy output if the safety condition to overwrite the input file isn't met.

           Defaults to "infile-tidy.ext" if not specified.

       Global variables used

       $tidycmd
           the name of the tidy executable

       $tidyxmlerrors
           the filename to use to output errors

       $tidysafety
           the safety factor to use (see CONFIGURABLE GLOBAL VARIABLES, above)

       Return values

       Returns the return value from tidy

       0 - no errors
       1 - warnings only
       2 - errors
       Dies horribly if the return value is unexpected

   "trim"
       Removes any whitespace characters from the beginning or end of every  string  in  @list  (also  works  on
       scalars).

        trim;               # trims $_ inplace
        $new = trim;        # trims (and returns) a copy of $_
        trim $str;          # trims $str inplace
        $new = trim $str;   # trims (and returns) a copy of $str
        trim @list;         # trims @list inplace
        @new = trim @list;  # trims (and returns) a copy of @list

       This was shamelessly copied from japhy's example at perlmonks.org:

       http://www.perlmonks.org/?node_id=36684

       If needed for large lists, it would probably be better to use String::Strip.

   "twigelt_create_uuid($gi)"
       Creates an unlinked element with the specified gi (tag), and then assigns it the id and scheme attributes
       'UUID'.

       Arguments

       $gi : The gi (tag) to use for the element
           Default: 'dc:identifier'

       Returns the element.

   "twigelt_detect_duplicate($element1, $element2)"
       Takes  two  twig elements and returns 1 if they have the same GI (tag), text, and attributes, but are not
       actually the same element.  The GI comparison is case-insensitive.  The others are case-sensitive.

       Returns 0 otherwise.

       Croaks if passed anything but twig elements.

   "twigelt_fix_oeb12_atts($element)"
       Checks the attributes in a twig element to see if they match OPF names with an opf: namespace, and if so,
       removes the namespace.  Used by the fix_oeb12() method.

       Takes as a sole argument a twig element.

       Returns that element with the modified attributes, or undef if the  element  didn't  exist.   Returns  an
       unmodified element if both att and opf:att exist.

   "twigelt_fix_opf20_atts($element)"
       Checks  the  attributes  in  a  twig  element to see if they match OPF names, and if so, prepends the OPF
       namespace.  Used by the fix_opf20() method.

       Takes as a sole argument a twig element.

       Returns that element with the modified attributes, or undef if the element didn't exist.

   "twigelt_is_author($element)"
       Takes as an argument a twig element.  Returns true if the element is a dc:creator (case-insensitive) with
       either a opf:role="aut" or role="aut" attribute defined.   Returns  undef  otherwise,  and  also  if  the
       element has no text.

       Croaks if fed no argument, or fed an argument that isn't a twig element.

       Intended to be used as a twig search condition.

       Example

        my @elements = $ebook->twigroot->descendants(\&twigelt_is_author);

   "twigelt_is_isbn($element)"
       Takes  as  an argument a twig element.  Returns true if the element is a dc:identifier (case-insensitive)
       where any of the id, opf:scheme, or scheme attributes start with 'isbn', '-isbn',  'eisbn',  or  'e-isbn'
       (again case-insensitive).

       Returns undef otherwise, and also if the element has no text.

       Croaks if fed no argument, or fed an argument that isn't a twig element.

       Intended to be used as a twig search condition.

       Example

        my @elements = $ebook->twigroot->descendants(\&twigelt_is_isbn);

   "twigelt_is_knownuid($element)"
       Takes  as  an argument a twig element.  Returns true if the element is a dc:identifier (case-insensitive)
       element with an "id" attribute matching the known  IDs  of  proper  unique  identifiers  suitable  for  a
       package-id (also case-insensitive).  Returns undef otherwise.

       Croaks if fed no argument, or fed an argument that isn't a twig element.

       Intended to be used as a twig search condition.

       Example

        my @elements = $ebook->twigroot->descendants(\&twigelt_is_knownuid);

   "usedir($dir)"
       Changes the current working directory to the one specified, creating it if necessary.

       Returns  the  current  working  directory  before  the change.  If no directory is specified, returns the
       current working directory without changing anything.

       Croaks on any failure.

   "userconfigdir()"
       Returns the directory in which user configuration files and helper programs are  expected  to  be  found,
       creating that directory if it does not exist.  Typically, this directory is "$ENV{HOME}/.ebooktools", but
       on      MSWin32      systems      if      that      directory      does      not      already      exist,
       "$ENV{USERPROFILE}/ApplicationData/EBook-Tools" is returned (and potentially created) instead.

       If $ENV{HOME} (and $ENV{USERPROFILE} on MSWin32) are not set, the sub returns undef.

   "ymd_validate($year,$month,$day)"
       Make sure month and day have valid values.  Return the passed values if they are, return 3 undefs if not.
       Testing of month or day can be skipped by passing undef in that spot.

BUGS AND LIMITATIONS

       •   need to implement fix_primary_author() to convert names to standard 'last, first' naming format

       •   fix_links() could be improved to download remote URIs instead of ignoring them.

       •   fix_links() needs to check the <reference> links under <guide>

       •   fix_links() needs to be redone with HTML::TreeBuilder to avoid the  weakness  with  newlines  between
           attribute names and values

       •   Need  to implement fix_tours() that should collect the related elements and delete the parent if none
           are found.  Empty <tours> elements aren't allowed.

       •   fix_languages() needs to convert language names into IANA language codes.

       •   set_language() should add a warning if the text isn't a valid IANA language code.

       •   NCX generation only generates from the spine.  It should be possible to  use  a  TOC  html  file  for
           generation  instead.   In  the  long term, it should be possible to generate one from the headers and
           anchors in arbitrary HTML files.

       •   It might be better to use sysread / index / substr / syswrite in &split_metadata to handle the  split
           in 10k chunks, to avoid massive memory usage on large files.

           This  may  not  be worth the effort, since the average size for most books is less than 500k, and the
           largest books are rarely over 10M.

       •   The only generator is currently for .epub books.  PDF, PalmDoc, Mobipocket, Plucker, and  iSiloX  are
           eventually planned.

       •   Although  I  like  keeping  warnings  associated  with  the  ebook  object, it may be better to throw
           exceptions on errors and catch them later.  This probably won't be implemented until it bites someone
           who complains, though.

       •   Unit tests are incomplete

AUTHOR

       Zed Pobre <zed@debian.org>

LICENSE AND COPYRIGHT

       Copyright 2008 Zed Pobre

       Licensed to the public under the terms of the GNU GPL, version 2

perl v5.14.2                                       2012-01-22                                  EBook::Tools(3pm)