The Annoyance Filter.pdf - Fourmilab

§125 ANNOYANCE-FILTER PDF TEXT EXTRACTOR 105
125. PDF text extractor.
The pdfTextExtractor decodes Portable Document File .pdf files by opening a pipe to the pdftotext
program. Since this program cannot read a PDF document from standard input, we transcribe the PDF
stream to a temporary file which is passed to pdftotext on the command line; the extracted text is
directed to standard output whence it can be read through the pipe. The temporary file is deleted after
the PDF decoding is complete. Natually, this facility is available only if the system provides pdftotext
and the machinery needed to connect to it.
〈 Class definitions 10 〉 +≡
#ifdef HAVE_PDF_DECODER
class pdfTextExtractor : public applicationStringParser {
protected: bool initialised ;
#ifdef HAVE_FDSTREAM_COMPATIBILITY
fdistream is ;
#else
ifstream is ;
#endif
FILE ∗ip;
#ifdef HAVE_MKSTEMP
char tempfn [256];
#else
char tempfn [L tmpnam + 2];
#endif
public: pdfTextExtractor(mailFolder ∗f = Λ)
: applicationStringParser(f), initialised (false ), ip(Λ) { }
∼pdfTextExtractor( )
{
close ( );
}
virtual string name (void) const
{
return "PDF";
}
bool nextString (string &s);
virtual void close (void)
{
if (ip ≠ Λ) {
#ifndef HAVE_FDSTREAM_COMPATIBILITY
is .close ( );
#endif
pclose (ip);
remove (tempfn );
ip = Λ;
}
applicationStringParser ::close ( );
initialised = false ;
}
};
#endif