def _seek_to_xref_token(
self,
src: Union[io.BufferedIOBase, io.RawIOBase, io.BytesIO],
tok: HighLevelTokenizer,
):
# find "startxref" text
start_of_xref_token_byte_offset = self._find_backwards(
src, tok, "startxref")
assert start_of_xref_token_byte_offset is not None
assert start_of_xref_token_byte_offset != -1
# set tokenizer to "startxref"
src.seek(start_of_xref_token_byte_offset)
token = tok.next_non_comment_token()
assert token is not None
if token.text == "xref":
src.seek(start_of_xref_token_byte_offset)
return
# if we are at startxref, we are reading the XREF table backwards
# and we need to go back to the start of XREF
if token.text == "startxref":
token = tok.next_non_comment_token()
assert token is not None
assert token.token_type == TokenType.NUMBER
start_of_xref_offset = int(token.text)
src.seek(start_of_xref_offset)
def _read_trailer(
self,
src: Union[io.BufferedIOBase, io.RawIOBase, io.BytesIO],
tok: HighLevelTokenizer,
) -> Dictionary:
# return None if there is no trailer
token = tok.next_non_comment_token()
assert token is not None
if token.text != "trailer":
return Dictionary()
# if there is a keyword "trailer" the next token should be TokenType.START_DICT
token = tok.next_non_comment_token()
assert token is not None
assert token.token_type == TokenType.START_DICT
# go back 2 chars "<<"
src.seek(-2, io.SEEK_CUR)
# read dictionary as trailer
trailer_dict = tok.read_dictionary()
# process startxref
token = tok.next_non_comment_token()
assert token is not None
assert token.token_type == TokenType.OTHER
assert token.text == "startxref"
# return
return trailer_dict
def read(
self,
src: Union[io.BufferedIOBase, io.RawIOBase, io.BytesIO],
tok: HighLevelTokenizer,
initial_offset: Optional[int] = None,
) -> "XREF":
"""
This method attempts to read a plaintext XREF from the given io_source.
It will either throw an exception, or return this XREF
"""
if initial_offset is not None:
src.seek(initial_offset)
else:
self._seek_to_xref_token(src, tok)
# now we should be back to the start of XREF
token = tok.next_non_comment_token()
assert token is not None
assert token.text == "xref"
# read xref sections
while True:
xref_section = self._read_section(src, tok)
if len(xref_section) == 0:
break
else:
for r in xref_section:
self.append(r)
# process trailer
self[Name("Trailer")] = self._read_trailer(src, tok)
# return self
return self
def _read_section(
self,
src: Union[io.BufferedIOBase, io.RawIOBase, io.BytesIO],
tok: HighLevelTokenizer,
) -> List[Reference]:
tokens = [tok.next_non_comment_token() for _ in range(0, 2)]
assert tokens[0] is not None
assert tokens[1] is not None
if tokens[0].text in ["trailer", "startxref"]:
src.seek(tokens[0].byte_offset)
return []
assert tokens[0].token_type == TokenType.NUMBER
assert tokens[1].token_type == TokenType.NUMBER
start_object_number = int(tokens[0].text)
number_of_objects = int(tokens[1].text)
indirect_references = []
# read subsection
for i in range(0, number_of_objects):
tokens = [tok.next_non_comment_token() for _ in range(0, 3)]
assert tokens[0] is not None
assert tokens[0].text not in ["trailer", "startxref"]
assert tokens[0].token_type == TokenType.NUMBER
assert tokens[1] is not None
assert tokens[1].token_type == TokenType.NUMBER
assert tokens[2] is not None
assert tokens[2].token_type == TokenType.OTHER
assert tokens[2].text in ["f", "n"]
indirect_references.append(
Reference(
object_number=start_object_number + i,
byte_offset=int(tokens[0].text),
generation_number=int(tokens[1].text),
is_in_use=(tokens[2].text == "n"),
))
# return
return indirect_references
def read(self, cmap_bytes: str) -> "CMap":
N = len(cmap_bytes)
tok = HighLevelTokenizer(io.BytesIO(cmap_bytes.encode("latin-1")))
prev_token: Optional[Token] = None
while tok.tell() < N:
token = tok.next_non_comment_token()
if token is None:
break
# beginbfchar
if token.text == "beginbfchar":
assert prev_token is not None
n = int(prev_token.text)
for j in range(0, n):
obj = tok.read_object()
assert isinstance(obj, HexadecimalString)
c = self._hex_string_to_int_or_tuple(obj)
assert isinstance(c, int)
obj = tok.read_object()
assert isinstance(obj, HexadecimalString)
uc = self._hex_string_to_int_or_tuple(obj)
self._add_symbol(c, uc)
continue
# beginbfrange
if token.text == "beginbfrange":
assert prev_token is not None
n = int(prev_token.text)
for j in range(0, n):
c_start_token = tok.read_object()
assert c_start_token is not None
assert isinstance(c_start_token, HexadecimalString)
c_start = int(str(c_start_token), 16)
c_end_token = tok.read_object()
assert c_end_token is not None
assert isinstance(c_end_token, HexadecimalString)
c_end = int(str(c_end_token), 16)
tmp = tok.read_object()
if isinstance(tmp, HexadecimalString):
uc = self._hex_string_to_int_or_tuple(tmp)
for k in range(0, c_end - c_start + 1):
if isinstance(uc, int):
self._add_symbol(c_start + k, uc + k)
elif isinstance(uc, tuple):
self._add_symbol(c_start + k,
(uc[0], uc[1] + k))
elif isinstance(tmp, list):
for k in range(0, c_end - c_start + 1):
uc = self._hex_string_to_int_or_tuple(tmp[k])
self._add_symbol(c_start + k, uc)
# default
prev_token = token
return self