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Parsing X Reference table

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This commit is contained in:
Jakub Melka
2018-11-21 19:30:15 +01:00
parent 58ad59e407
commit 8c93c82228
19 changed files with 625 additions and 58 deletions
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60
PdfForQtLib/sources/pdfparser.cpp
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@ -460,6 +460,19 @@ PDFLexicalAnalyzer::Token PDFLexicalAnalyzer::fetch()
return Token(TokenType::EndOfFile);
}
void PDFLexicalAnalyzer::seek(PDFInteger offset)
{
const PDFInteger limit = std::distance(m_begin, m_end);
if (offset >= 0 && offset < limit)
{
m_current = std::next(m_begin, offset);
}
else
{
error(tr("Trying to seek stream position to %1 bytes from the start, byte offset is invalid.").arg(offset));
}
}
void PDFLexicalAnalyzer::skipWhitespaceAndComments()
{
bool isComment = false;
@ -601,9 +614,19 @@ void PDFParsingContext::endParsingObject(PDFObjectReference reference)
m_activeParsedObjectSet.erase(reference);
}
PDFParser::PDFParser(const char* begin, const char* end, PDFParsingContext* context) :
PDFParser::PDFParser(const QByteArray& data, PDFParsingContext* context, Features features) :
m_context(context),
m_lexicalAnalyzer(begin, end)
m_lexicalAnalyzer(data.constData(), data.constData() + data.size()),
m_features(features)
{
m_lookAhead1 = m_lexicalAnalyzer.fetch();
m_lookAhead2 = m_lexicalAnalyzer.fetch();
}
PDFParser::PDFParser(const char* begin, const char* end, PDFParsingContext* context, Features features) :
m_context(context),
m_lexicalAnalyzer(begin, end),
m_features(features)
{
m_lookAhead1 = m_lexicalAnalyzer.fetch();
m_lookAhead2 = m_lexicalAnalyzer.fetch();
@ -611,13 +634,6 @@ PDFParser::PDFParser(const char* begin, const char* end, PDFParsingContext* cont
PDFObject PDFParser::getObject()
{
/*
*
// Complex PDF objects
,
Dictionary,
Stream,
*/
switch (m_lookAhead1.type)
{
case PDFLexicalAnalyzer::TokenType::Boolean:
@ -744,6 +760,11 @@ PDFObject PDFParser::getObject()
if (m_lookAhead2.type == PDFLexicalAnalyzer::TokenType::Command &&
m_lookAhead2.data.toByteArray() == PDF_STREAM_START_COMMAND)
{
if (!m_features.testFlag(AllowStreams))
{
error(tr("Streams are not allowed in this context."));
}
// Read stream content. According to the PDF Reference 1.7, chapter 3.2.7, stream
// content can be placed in the file. If this is the case, then try to load file
// content in the memory. But even in this case, stream content should be skipped.
@ -852,6 +873,27 @@ void PDFParser::error(const QString& message) const
throw new PDFParserException(message);
}
void PDFParser::seek(PDFInteger offset)
{
m_lexicalAnalyzer.seek(offset);
// We must read lookahead symbols, because we invalidated them
m_lookAhead1 = m_lexicalAnalyzer.fetch();
m_lookAhead2 = m_lexicalAnalyzer.fetch();
}
bool PDFParser::fetchCommand(const char* command)
{
if (m_lookAhead1.type == PDFLexicalAnalyzer::TokenType::Command &&
m_lookAhead1.data.toByteArray() == command)
{
shift();
return true;
}
return false;
}
void PDFParser::shift()
{
m_lookAhead1 = std::move(m_lookAhead2);