The Parser class is now a generic PDF object parser, of which the new
DocumentParser class derives. DocumentParser now takes over all
functions relating to linearization, pages, xref and trailer handling.
This allows the use of multiple parsers in the same document's
context, which will be needed in order to handle PDF object streams.
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
These are mostly minor mistakes I've encountered while working on the
removal of StringView(char const*). The usage of builder.put_string over
Format<FormatString>::format is preferrable as it will avoid the
indirection altogether when there's no formatting to be done. Similarly,
there is no need to do format(builder, "{}", number) when
builder.put_u64(number) works equally well.
Additionally a few Strings where only constant strings were used are
replaced with StringViews.
Security handlers manage encryption and decription of PDF files. The
standard security handler uses RC4/MD5 to perform its crypto (AES as
well, but that is not yet implemented).
This isn't a complete conversion to ErrorOr<void>, but a good chunk.
The end goal here is to propagate buffer allocation failures to the
caller, and allow the use of TRY() with formatting functions.
Old situation:
Object.h defines Object
Object.h defines ArrayObject
ArrayObject requires the definition of Object
ArrayObject requires the definition of Value
Value.h defines Value
Value requires the definition of Object
Therefore, a file with the single line "#include <Value.h>" used to
raise compilation errors; certainly not something that one might expect
from a library.
This patch splits up the definitions in Object.h to break the cycle.
Now, Object.h only defines Object, Value.h still only defines Value (and
includes Object.h), and the new header ObjectDerivatives.h defines
ArrayObject (and includes both Object.h and Value.h).
This is a big step, as most PDFs which are downloaded online will be
linearized. Pretty much the only difference is that the xref structure
is slightly different.
The Parser should hold information relevant for parsing, whereas the
Document should hold information relevant for displaying pages.
With this in mind, there is no reason for the Document to hold the
xref table and trailer. These objects have been moved to the Parser,
which allows the Parser to expose less public methods (which will be
even more evident once linearized PDFs are supported).
We now follow nested page tree nodes to find all of the actual
page dicts, whereas previously we just assumed the root level
page tree node contained all of the page children directly.
This commit introduces the ability to parse the document catalog dict,
as well as the page tree and individual pages. Pages obviously aren't
fully parsed, as we won't care about most of the fields until we
start actually rendering PDFs.
One of the primary benefits of the PDF format is laziness. PDFs are
not meant to be parsed all at once, and the same is true for pages.
When a Document is constructed, it builds a map of page number to
object index, but it does not fetch and parse any of the pages. A page
is only parsed when a caller requests that particular page (and is
cached going forwards).
Additionally, this commit also adds an object_cast function which
logs bad casts if DEBUG_PDF is set. Additionally, utility functions
were added to ArrayObject and DictObject to get all types of objects
from the collections to avoid having to manually cast.
This commit adds a parser as well as the Reader class, which serves
as a utility to aid in reading the PDF both forwards and in reverse.
The parser currently is capable of reading xref tables, as well as
all values. We don't really do anything with any of this information,
however.
