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https://issues.apache.org/jira/browse/PDFBOX-1000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13145344#comment-13145344
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Maruan Sahyoun commented on PDFBOX-1000:
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Hi Adam,

I'm looking into putting some work into the conforming parser. But first let me 
ask some questions:
# what are the main areas you were trying to address? To me the most pressing 
need was the correct Xref resolution but that has been solved 
# is there some further work you put into this you would like to post before 
there are any changes?

Kind regards

Maruan


                
> Conforming parser
> -----------------
>
>                 Key: PDFBOX-1000
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-1000
>             Project: PDFBox
>          Issue Type: New Feature
>          Components: Parsing
>            Reporter: Adam Nichols
>            Assignee: Adam Nichols
>         Attachments: COSUnread.java, ConformingPDDocument.java, 
> ConformingPDFParser.java, ConformingPDFParserTest.java, XrefEntry.java, 
> conforming-parser.patch, gdb-refcard.pdf
>
>
> A conforming parser will start at the end of the file and read backward until 
> it has read the EOF marker, the xref location, and trailer[1].  Once this is 
> read, it will read in the xref table so it can locate other objects and 
> revisions.  This also allows skipping objects which have been rendered 
> obsolete (per the xref table)[2].  It also allows the minimum amount of 
> information to be read when the file is loaded, and then subsequent 
> information will be loaded if and when it is requested.  This is all laid out 
> in the official PDF specification, ISO 32000-1:2008.
> Existing code will be re-used where possible, but this will require new 
> classes in order to accommodate the lazy reading which is a very different 
> paradigm from the existing parser.  Using separate classes will also 
> eliminate the possibility of regression bugs from making their way into the 
> PDDocument or BaseParser classes.  Changes to existing classes will be kept 
> to a minimum in order to prevent regression bugs.
> [1] Section 7.5.5 "Conforming readers should read a PDF file from its end"
> [2] Section 7.5.4 "the entire file need not be read to locate any particular 
> object"

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