Class: Traject::HorizonBibAuthMerge

Inherits:
Object
  • Object
show all
Defined in:
lib/traject/horizon_bib_auth_merge.rb

Overview

Merges ‘bib text’ and ‘auth text’ lines from Horizon, using bib text as template when neccesary.

merged_str = HorizonBibAuthMerge.new(tag, bib_text_str, auth_text_str).merge!

Strings passed in may be mutated for efficiency. So you can only call merge! once, it’s just utility.

Constant Summary collapse

@@up_to_subfield_t_re = 
/\A(.*)\x1Ft/

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tag, bibtext, authtext) ⇒ HorizonBibAuthMerge

Pass in bibtext and authtext as String – you probably need to get column values from JDBC as bytes and then use String.from_java_bytes to avoid messing up possible Marc8 encoding.

bibtext is either text or longtext column from fullbib, preferring longtext. authtext is either xref_text or xref_longtext from fullbib, preferring xref_longtext.



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# File 'lib/traject/horizon_bib_auth_merge.rb', line 22

def initialize(tag, bibtext, authtext)
  @merged = false

  @tag      = tag
  @bibtext  = bibtext
  @authtext = authtext

  # remove terminal MARC Field Terminator if present.
  @bibtext.chomp!("\x1E") if @bibtext
  @authtext.chomp!("\x1E") if @authtext
end

Instance Attribute Details

#authtext ⇒ Object (readonly)

Returns the value of attribute authtext.



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# File 'lib/traject/horizon_bib_auth_merge.rb', line 11

def authtext
  @authtext
end

#bibtext ⇒ Object (readonly)

Returns the value of attribute bibtext.



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# File 'lib/traject/horizon_bib_auth_merge.rb', line 11

def bibtext
  @bibtext
end

#tag ⇒ Object (readonly)

Returns the value of attribute tag.



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# File 'lib/traject/horizon_bib_auth_merge.rb', line 11

def tag
  @tag
end

Instance Method Details

#merge! ⇒ Object

Returns merged string, composed of a marc ‘field’, with subfields seperated by seperator control chars. Does not include terminal MARC Field Seperator.

Will mutate bibtext and authtext for efficiency.

Raises:

  • (Exception) 


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# File 'lib/traject/horizon_bib_auth_merge.rb', line 39

def merge!
  raise Exception.new("Can only call `merge!` once, already called.") if @merged
  @merged = true

  # just one? (Or neither?) Just return it.
  return authtext if bibtext.nil?
  return bibtext  if authtext.nil?


  # For 240 and 243, it seems that anything before the first $t should
  # be ignored in authtext template -- we need to actually remove it, 
  # so later when we append any leftover fields, we don't get those. 
  if tag == '240' || tag == '243'
    authtext.sub!(@@up_to_subfield_t_re, "\x1Ft")
  end


  # We need to do a crazy combination of template in text with values in authtext.
  # horizon, you so crazy. text template is like:
  #"\x1Fa.\x1Fp ;\x1Fv81."
  # which means each subfield after the \x1F, merge in
  # the subfield value from the auth record if it's present,
  # otherwise don't.
  #
  # plus some weird as hell stuff with punctuation and spaces, I can't
  # even explain it, just trial and error'd it comparing to marcout.
  bibtext.gsub!(/\x1F([^\x1F\x1E])( ?)([[:punct:] ]*)/) do

    subfield       = $1
    space          = $2
    maybe_punct    = $3


    # okay this is crazy hacky reverse engineering, I don't really
    # know what's going on but for 240 and 243, 'a' in template
    # is filled by 't' in auth tag.
    auth_subfield = if subfield == "a" && (tag == "240" || tag == "243")
      "t"
    else
      subfield
    end

    # Find substitute fill-in value from authtext, if it can
    # be found -- first subfield indicated. Then we REMOVE
    # it from authtext, so next time this subfield is asked for,
    # subsequent subfield with that code will be used.
    substitute = nil
    authtext.sub!(/\x1F#{Regexp.escape auth_subfield}([^\x1F\x1E]*)/) do
      substitute = $1
      ''
    end

    if substitute


      # Dealing with punctuation is REALLY CONFUSING -- reverse engineering
      # HIP/Horizon, which does WEIRD THINGS.
      # But we seem to have arrived at something that appears to match all cases
      # we can find of what HIP/Horizon does.
      #
      # If the auth value already ends up with the same punctuation from the template,
      # _leave it alone_ -- including preserving all spaces near the punct in the auth
      # value.
      #
      # Otherwise, remove all punct from the auth value, then add in the punct from the template,
      # along with any spaces before the punct in the template.
      if maybe_punct && maybe_punct.length > 0
        # remove all punctuation from end of auth value? to use punct from template instead?
        # But preserve initial spaces from template? Unless it already ends
        # with the punctuation, in which case don't touch it, to avoid
        # messing up spaces? WEIRD, yeah.
        unless substitute.end_with? maybe_punct
          substitute.gsub!(/[[:punct:]]+\Z/, "")
          # This adding the #{space} back in, is consistent with what HIP does.
          # I have no idea if it's right or a bug in HIP, but being consistent.
          # neither leaving it in nor taking it out is exactly consistent with HznExportMarc,
          # which seems to have bugs.
          substitute << "#{space}#{maybe_punct}"
        end
      end

      "\x1F#{subfield}#{substitute}"
    else # just keep original, which has no maybe_punct
      "\x1F#{subfield}"
    end
  end

  # Sometimes there's leftover text at the end of authtext that wasn't 
  # included in the bibtext template. Horizon's marc reconstruction
  # seems to just include this on the end, we will too. 
  # Relies on 'prior to $t' fields being removed from 240 and 243 earlier,
  # to avoid including them when we shouldn't. 
  if authtext.length > 0
    bibtext << authtext
  end



  # We mutated bibtext to fill in template, now just return it.
  return bibtext
end