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https://issues.apache.org/jira/browse/PDFBOX-1000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13025339#comment-13025339
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Adam Nichols commented on PDFBOX-1000:
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I updated readWord as described above (ending a "word" on characters like '/',
']', etc.) and was able to remove all the ugly hacks. I confirmed that it
worked on my test PDF.
I'm started work on the lazy evaluation by creating a COSUnread object which is
just a placeholder to let us know that the object hasn't been read yet.
That'll allow reading an indirect reference as a COSObject consisting of: an
objectNumber, generaion, and COSUnread. Later, when we need the data, the
COSUnread will be replaced with the actual object. Or at least that's how I
imagine it working...
I'll post the code again once I'm at least able to read the trailer in a lazy
way, and am able to retrieve the info by automagically reading the data when a
COSUnread is found.
> 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: ConformingPDDocument.java, ConformingPDFParser.java,
> ConformingPDFParserTest.java, XrefEntry.java, 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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