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Fixes #1057

The example file contains a huge object with this content:

210891 0 obj
<</Limits [(node00000002) (node00275919)]
/Names [(node00000002) 8591 0 R (node00000006) 190838 0 R (node00000007) 66313 0 R (node00000008) 24685 0 R (node00000009) 208328 0 R (node00000010) 163561 0 R (node00000011) 27134 0 R (node00000012) 126131 0 R (node00000013) 9895 0 R (node00000014) 101713 0 R (node00000015) 64243 0 R (node00000016) 118039 0 R (node00000017)
... continues for more than 5 MBytes ...
(node00275919) 209354 0 R]>>
endobj

This blows up the parsing code in

func DetectKeywords(line string) (endInd int, streamInd int, err error) {

Here the keywords are searched lots of times after the start is advanced for each string literal inside the array (e.g. (node00000002), etc.).

The PR fixes this by searching only once for the keywords and then adjusting the position if strings / comments are found before them. In my tests the example file now parses in about 3 seconds.

@hhrutter
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hhrutter commented Jan 9, 2025

Sounds very cool..
Let me double check your patch of this critical code section.

line := string(buf)

endInd, streamInd, err = model.DetectKeywords(line)
endInd, streamInd, err = model.DetectKeywordsWithContext(c, line)
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Why don't we leave the original method name DetectKeywords and pass in as 2nd parm the context from the caller. does that make any sense?

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There is a(n old) bug in posFloor:

if pos1 < pos2 {
    return pos2
}

should be

if pos1 < pos2 {
    return pos1
}

@hhrutter
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Happy to merge if you can take care of these 2 issues.

@tmm1
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tmm1 commented Feb 11, 2025

@fancycode ping

@hhrutter hhrutter force-pushed the avoid-duplicate-keyword-search branch from 1d7b124 to d94329a Compare February 21, 2025 14:33
@hhrutter hhrutter merged commit eb132fb into pdfcpu:master Feb 21, 2025
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Improve the speed of reading basic PDF information

3 participants