186 lines
6.6 KiB
Python
186 lines
6.6 KiB
Python
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# This module contains abstractions for the input stream. You don't have to
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# looks further, there are no pretty code.
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#
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# We define two classes here.
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#
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# Mark(source, line, column)
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# It's just a record and its only use is producing nice error messages.
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# Parser does not use it for any other purposes.
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#
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# Reader(source, data)
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# Reader determines the encoding of `data` and converts it to unicode.
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# Reader provides the following methods and attributes:
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# reader.peek(length=1) - return the next `length` characters
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# reader.forward(length=1) - move the current position to `length` characters.
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# reader.index - the number of the current character.
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# reader.line, stream.column - the line and the column of the current character.
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__all__ = ['Reader', 'ReaderError']
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from .error import YAMLError, Mark
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import codecs, re
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class ReaderError(YAMLError):
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def __init__(self, name, position, character, encoding, reason):
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self.name = name
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self.character = character
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self.position = position
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self.encoding = encoding
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self.reason = reason
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def __str__(self):
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if isinstance(self.character, bytes):
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return "'%s' codec can't decode byte #x%02x: %s\n" \
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" in \"%s\", position %d" \
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% (self.encoding, ord(self.character), self.reason,
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self.name, self.position)
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else:
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return "unacceptable character #x%04x: %s\n" \
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" in \"%s\", position %d" \
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% (self.character, self.reason,
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self.name, self.position)
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class Reader(object):
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# Reader:
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# - determines the data encoding and converts it to a unicode string,
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# - checks if characters are in allowed range,
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# - adds '\0' to the end.
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# Reader accepts
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# - a `bytes` object,
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# - a `str` object,
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# - a file-like object with its `read` method returning `str`,
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# - a file-like object with its `read` method returning `unicode`.
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# Yeah, it's ugly and slow.
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def __init__(self, stream):
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self.name = None
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self.stream = None
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self.stream_pointer = 0
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self.eof = True
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self.buffer = ''
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self.pointer = 0
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self.raw_buffer = None
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self.raw_decode = None
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self.encoding = None
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self.index = 0
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self.line = 0
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self.column = 0
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if isinstance(stream, str):
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self.name = "<unicode string>"
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self.check_printable(stream)
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self.buffer = stream+'\0'
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elif isinstance(stream, bytes):
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self.name = "<byte string>"
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self.raw_buffer = stream
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self.determine_encoding()
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else:
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self.stream = stream
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self.name = getattr(stream, 'name', "<file>")
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self.eof = False
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self.raw_buffer = None
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self.determine_encoding()
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def peek(self, index=0):
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try:
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return self.buffer[self.pointer+index]
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except IndexError:
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self.update(index+1)
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return self.buffer[self.pointer+index]
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def prefix(self, length=1):
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if self.pointer+length >= len(self.buffer):
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self.update(length)
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return self.buffer[self.pointer:self.pointer+length]
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def forward(self, length=1):
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if self.pointer+length+1 >= len(self.buffer):
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self.update(length+1)
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while length:
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ch = self.buffer[self.pointer]
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self.pointer += 1
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self.index += 1
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if ch in '\n\x85\u2028\u2029' \
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or (ch == '\r' and self.buffer[self.pointer] != '\n'):
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self.line += 1
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self.column = 0
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elif ch != '\uFEFF':
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self.column += 1
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length -= 1
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def get_mark(self):
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if self.stream is None:
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return Mark(self.name, self.index, self.line, self.column,
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self.buffer, self.pointer)
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else:
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return Mark(self.name, self.index, self.line, self.column,
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None, None)
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def determine_encoding(self):
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while not self.eof and (self.raw_buffer is None or len(self.raw_buffer) < 2):
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self.update_raw()
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if isinstance(self.raw_buffer, bytes):
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if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
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self.raw_decode = codecs.utf_16_le_decode
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self.encoding = 'utf-16-le'
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elif self.raw_buffer.startswith(codecs.BOM_UTF16_BE):
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self.raw_decode = codecs.utf_16_be_decode
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self.encoding = 'utf-16-be'
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else:
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self.raw_decode = codecs.utf_8_decode
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self.encoding = 'utf-8'
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self.update(1)
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NON_PRINTABLE = re.compile('[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD\U00010000-\U0010ffff]')
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def check_printable(self, data):
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match = self.NON_PRINTABLE.search(data)
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if match:
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character = match.group()
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position = self.index+(len(self.buffer)-self.pointer)+match.start()
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raise ReaderError(self.name, position, ord(character),
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'unicode', "special characters are not allowed")
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def update(self, length):
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if self.raw_buffer is None:
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return
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self.buffer = self.buffer[self.pointer:]
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self.pointer = 0
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while len(self.buffer) < length:
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if not self.eof:
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self.update_raw()
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if self.raw_decode is not None:
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try:
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data, converted = self.raw_decode(self.raw_buffer,
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'strict', self.eof)
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except UnicodeDecodeError as exc:
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character = self.raw_buffer[exc.start]
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if self.stream is not None:
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position = self.stream_pointer-len(self.raw_buffer)+exc.start
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else:
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position = exc.start
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raise ReaderError(self.name, position, character,
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exc.encoding, exc.reason)
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else:
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data = self.raw_buffer
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converted = len(data)
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self.check_printable(data)
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self.buffer += data
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self.raw_buffer = self.raw_buffer[converted:]
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if self.eof:
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self.buffer += '\0'
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self.raw_buffer = None
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break
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def update_raw(self, size=4096):
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data = self.stream.read(size)
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if self.raw_buffer is None:
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self.raw_buffer = data
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else:
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self.raw_buffer += data
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self.stream_pointer += len(data)
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if not data:
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self.eof = True
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