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https://issues.apache.org/jira/browse/PDFBOX-1000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13186816#comment-13186816
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Timo Boehme commented on PDFBOX-1000:
-------------------------------------
PDFLexer:
- I also do like the rich comments
- buffering of to be read chars: for my NonSequentialPDFParser (PDFBOX-1199) I
already implemented a random file access with LRU buffering of pages
(RandomAccessBufferedFileInputStream.java) ; maybe with some modifications we
should use this for file access
- stream processing: reading stream with looking for 'endstream' should only be
done if length attribute is broken (does not exist or no 'endstream' at
specified position); there are 2 reasons: 1) 'endstream' can simply appear as
normal content, 2) performance: you can simply read 'length' bytes; or even
better: use an object referencing the original file stream with offsets, thus
no byte copying is needed
- isNumeric() optimization:
return ( c >= '0' && c <= '9' )
|| c == '.' || c == '+' || c == '-';
}
> 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, PDFLexer.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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