memory usage concerns, credit to @denislavski , as of yet unknown eff…

…ects

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Change Log
 
+#### Change log v.1.0.25 (2023-12-19)
+
+**Fix**: possible improve memory usage. Credit to @denislavski (Denislav Naydenov) for opening PR #223 and suggesting this change.
+
 #### Change log v.1.0.24 (2023-10-19)
 
 **Fix**: possible `nil` in loop. Credit to @jkowens for PR #231 and adding a quick fix using a simple guard.

lib/combine_pdf/pdf_public.rb

@@ -206,9 +206,9 @@ def to_pdf(options = {})
       xref_location = loc
       # xref_location = 0
       # out.each { |line| xref_location += line.bytesize + 1}
-      out << "xref\n0 #{indirect_object_count}\n0000000000 65535 f \n"
-      xref.each { |offset| out << (out.pop + ("%010d 00000 n \n" % offset)) }
-      out << out.pop + 'trailer'
+      out << "xref\n0 #{indirect_object_count}\n0000000000 65535 f "
+      xref.each { |offset| out << ("%010d 00000 n " % offset) }
+      out << 'trailer'.freeze
       out << "<<\n/Root #{false || "#{catalog[:indirect_reference_id]} #{catalog[:indirect_generation_number]} R"}"
       out << "/Size #{indirect_object_count}"
       out << "/Info #{@info[:indirect_reference_id]} #{@info[:indirect_generation_number]} R"

test/automated

@@ -16,51 +16,51 @@ require 'combine_pdf'
 # Pry.start
 
 pdf = CombinePDF.load "../../test\ pdfs/filled_form.pdf"
-pdf.save '01_check_radio_buttuns.pdf'
+pdf.save '../tmp/01_check_radio_buttuns.pdf'
 pdf = CombinePDF.load "../../test\ pdfs/filled_form.pdf"
 pdf << CombinePDF.load("../../test\ pdfs/empty_form.pdf")
 pdf << CombinePDF.load("../../test\ pdfs/filled_form.pdf")
-pdf.save '02_check_form_unification_middle_is_empty.pdf'
+pdf.save '../tmp/02_check_form_unification_middle_is_empty.pdf'
 
 pdf = CombinePDF.load "../../test\ pdfs/check_form_data__objstreams_w_versions.pdf"
-pdf.save '02_01_check_form_data_ordering_issue.pdf'
+pdf.save '../tmp/02_01_check_form_data_ordering_issue.pdf'
 
 
 pdf = CombinePDF.load '../../test pdfs/share-font-background.pdf'
 pdf2 = CombinePDF.load '../../test pdfs/share-font-foreground.pdf'
 i = 0
 pdf.pages.each { |pg| pg << pdf2.pages[i] }
-pdf.save '03_check_font_conflict.pdf'
+pdf.save '../tmp/03_check_font_conflict.pdf'
 
 pdf = CombinePDF.load '../../test pdfs/nil_1.pdf'
 pdf2 = CombinePDF.load '../../test pdfs/nil_2.pdf'
 pdf << pdf2
-pdf.save '03_01_nil_value_conflict.pdf'
+pdf.save '../tmp/03_01_nil_value_conflict.pdf'
 
 pdf = CombinePDF.load '../../test pdfs/space_after_streram_keyword.pdf'
-pdf.save '03_02_extra_space_after_stream_keyword.pdf'
+pdf.save '../tmp/03_02_extra_space_after_stream_keyword.pdf'
 
 pdf = CombinePDF.load '../../test pdfs/nested_difference.pdf'
-pdf.save '03_03_nested_difference.pdf'
+pdf.save '../tmp/03_03_nested_difference.pdf'
 
 pdf = CombinePDF.load '../../test pdfs/names_go_haywire_0.pdf'
 pdf << CombinePDF.load('../../test pdfs/names_go_haywire_1.pdf')
-pdf.save '04_check_view_and_names_reference.pdf'
+pdf.save '../tmp/04_check_view_and_names_reference.pdf'
 
 pdf = CombinePDF.load('../../test pdfs/outlines/self_merge_err.pdf')
-pdf.save '05_x1_scribus_test.pdf'
+pdf.save '../tmp/05_x1_scribus_test.pdf'
 pdf = CombinePDF.load('../../test pdfs/outlines/self_merge_err.pdf')
 pdf << CombinePDF.load('../../test pdfs/outlines/self_merge_err.pdf')
-pdf.save '05_x2_scribus_test.pdf'
+pdf.save '../tmp/05_x2_scribus_test.pdf'
 pdf = CombinePDF.load "../../test pdfs/outlines/named_dest.pdf";nil
-pdf.save '05_check_named_dest_links.pdf' # this will take a while
+pdf.save '../tmp/05_check_named_dest_links.pdf' # this will take a while
 pdf = CombinePDF.load "../../test pdfs/outlines/named_dest.pdf";nil
 pdf << CombinePDF.load('../../test pdfs/outlines/named_dest.pdf'); nil
-pdf.save '05_1_timeless_check_named_dest_links.pdf' # never ends... :-(
+pdf.save '../tmp/05_1_timeless_check_named_dest_links.pdf' # never ends... :-(
 
 pdf = CombinePDF.load '../../test pdfs/outline_small.pdf'
 pdf << CombinePDF.load('../../test pdfs/outline_small.pdf')
-pdf.save '06_check_links_to_second_copy.pdf'
+pdf.save '../tmp/06_check_links_to_second_copy.pdf'
 
 lists = %w(../../test\ pdfs/outlines/self_merge_err.pdf ../../test\ pdfs/outlines/big_toc.pdf ../../test\ pdfs/outlines/bigger_toc.pdf ../../test\ pdfs/outlines/named_dest_no_toc.pdf ../../test\ pdfs/outlines/named_dest_no_toc2.pdf ../../test\ pdfs/outlines/named_dest.pdf ../../test\ pdfs/outlines/named_dest2.pdf)
 
@@ -77,7 +77,7 @@ lists.each do |n|
 end
 pdf = CombinePDF.new
 lists.each { |n| pdf << CombinePDF.load(n) }
-pdf.save('07_named destinations.pdf')
+pdf.save('../tmp/07_named destinations.pdf')
 
 pdf = CombinePDF.new
 lists.each { |n| pdf << CombinePDF.load(n) }
@@ -91,15 +91,15 @@ pdf.number_pages(start_at: 1,
                            number_location: [:top, :bottom],
                            opacity: 0.75)
 
-pdf.save('07_named destinations_numbered.pdf')
+pdf.save('../tmp/07_named destinations_numbered.pdf')
 
-CombinePDF.load("../../test\ pdfs/Scribus-unknown_err.pdf").save '08_1-unknown-err-empty-str.pdf'
-CombinePDF.load("../../test\ pdfs/Scribus-unknown_err2.pdf").save '08_2-unknown-err-empty-str.pdf'
-CombinePDF.load("../../test\ pdfs/Scribus-unknown_err3.pdf").save '08_3-unknown-err-empty-str.pdf'
-CombinePDF.load("../../test\ pdfs/xref_in_middle.pdf").save '08_4-xref-in-middle.pdf'
-CombinePDF.load("../../test\ pdfs/xref_split.pdf").save '08_5-xref-fragmented.pdf'
+CombinePDF.load("../../test\ pdfs/Scribus-unknown_err.pdf").save '../tmp/08_1-unknown-err-empty-str.pdf'
+CombinePDF.load("../../test\ pdfs/Scribus-unknown_err2.pdf").save '../tmp/08_2-unknown-err-empty-str.pdf'
+CombinePDF.load("../../test\ pdfs/Scribus-unknown_err3.pdf").save '../tmp/08_3-unknown-err-empty-str.pdf'
+CombinePDF.load("../../test\ pdfs/xref_in_middle.pdf").save '../tmp/08_4-xref-in-middle.pdf'
+CombinePDF.load("../../test\ pdfs/xref_split.pdf").save '../tmp/08_5-xref-fragmented.pdf'
 
-CombinePDF.load("../../test\ pdfs/nil_object.pdf").save('09_nil_in_parsed_array.pdf')
+CombinePDF.load("../../test\ pdfs/nil_object.pdf").save('../tmp/09_nil_in_parsed_array.pdf')
 
 encrypted = [ "../../test\ pdfs/pdf-reader/encrypted_version4_revision4_128bit_aes_user_pass_apples_enc_metadata.pdf",
               "../../test\ pdfs/AESv2\ encrypted.pdf",
@@ -110,7 +110,7 @@ encrypted = [ "../../test\ pdfs/pdf-reader/encrypted_version4_revision4_128bit_a
 encrypted.length.times do |i|
   fname = File.basename encrypted[i]
   begin
-    CombinePDF.load(encrypted[i]).save "10_#{i}_#{fname}"
+    CombinePDF.load(encrypted[i]).save "../tmp/10_#{i}_#{fname}"
   rescue => e
     puts e.class.name, e.message
     if(i == 0)
@@ -126,10 +126,10 @@ IO.binwrite '11_prawn.pdf', (Prawn::Document.new { text 'Hello World!' }).render
 page = CombinePDF.parse((Prawn::Document.new { text 'Hello World!' }).render)
 pdf = CombinePDF.new
 pdf << page
-pdf.save '11_parsed_from_prawn.pdf'
+pdf.save '../tmp/11_parsed_from_prawn.pdf'
 pdf = CombinePDF.new
 pdf << page << page
-pdf.save('11_AcrobatReader_is_unique_page.pdf')
+pdf.save('../tmp/11_AcrobatReader_is_unique_page.pdf')
 
 puts GC.stat.inspect
 # unify = [