Class Reader

Synopsis

class Reader(object)

Description

No description yet.

Inheritance

Ancestors: object

Decsendents: BaseLoader, FullLoader, SafeLoader, Loader, UnsafeLoader

Methods

__init__
check_printable
determine_encoding
forward
get_mark
peek
prefix
update
update_raw

Source

Lines 45-186 in lib3/yaml/reader.py.

class Reader(object):
    # Reader:
    # - determines the data encoding and converts it to a unicode string,
    # - checks if characters are in allowed range,
    # - adds '\0' to the end.

    # Reader accepts
    #  - a `bytes` object,
    #  - a `str` object,
    #  - a file-like object with its `read` method returning `str`,
    #  - a file-like object with its `read` method returning `unicode`.

    # Yeah, it's ugly and slow.

    def __init__(self, stream):
        self.name = None
        self.stream = None
        self.stream_pointer = 0
        self.eof = True
        self.buffer = ''
        self.pointer = 0
        self.raw_buffer = None
        self.raw_decode = None
        self.encoding = None
        self.index = 0
        self.line = 0
        self.column = 0
        if isinstance(stream, str):
            self.name = "<unicode string>"
            self.check_printable(stream)
            self.buffer = stream+'\0'
        elif isinstance(stream, bytes):
            self.name = "<byte string>"
            self.raw_buffer = stream
            self.determine_encoding()
        else:
            self.stream = stream
            self.name = getattr(stream, 'name', "<file>")
            self.eof = False
            self.raw_buffer = None
            self.determine_encoding()

    def peek(self, index=0):
        try:
            return self.buffer[self.pointer+index]
        except IndexError:
            self.update(index+1)
            return self.buffer[self.pointer+index]

    def prefix(self, length=1):
        if self.pointer+length >= len(self.buffer):
            self.update(length)
        return self.buffer[self.pointer:self.pointer+length]

    def forward(self, length=1):
        if self.pointer+length+1 >= len(self.buffer):
            self.update(length+1)
        while length:
            ch = self.buffer[self.pointer]
            self.pointer += 1
            self.index += 1
            if ch in '\n\x85\u2028\u2029'  \
                    or (ch == '\r' and self.buffer[self.pointer] != '\n'):
                self.line += 1
                self.column = 0
            elif ch != '\uFEFF':
                self.column += 1
            length -= 1

    def get_mark(self):
        if self.stream is None:
            return Mark(self.name, self.index, self.line, self.column,
                    self.buffer, self.pointer)
        else:
            return Mark(self.name, self.index, self.line, self.column,
                    None, None)

    def determine_encoding(self):
        while not self.eof and (self.raw_buffer is None or len(self.raw_buffer) < 2):
            self.update_raw()
        if isinstance(self.raw_buffer, bytes):
            if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
                self.raw_decode = codecs.utf_16_le_decode
                self.encoding = 'utf-16-le'
            elif self.raw_buffer.startswith(codecs.BOM_UTF16_BE):
                self.raw_decode = codecs.utf_16_be_decode
                self.encoding = 'utf-16-be'
            else:
                self.raw_decode = codecs.utf_8_decode
                self.encoding = 'utf-8'
        self.update(1)

    NON_PRINTABLE = re.compile('[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD\U00010000-\U0010ffff]')
    def check_printable(self, data):
        match = self.NON_PRINTABLE.search(data)
        if match:
            character = match.group()
            position = self.index+(len(self.buffer)-self.pointer)+match.start()
            raise ReaderError(self.name, position, ord(character),
                    'unicode', "special characters are not allowed")

    def update(self, length):
        if self.raw_buffer is None:
            return
        self.buffer = self.buffer[self.pointer:]
        self.pointer = 0
        while len(self.buffer) < length:
            if not self.eof:
                self.update_raw()
            if self.raw_decode is not None:
                try:
                    data, converted = self.raw_decode(self.raw_buffer,
                            'strict', self.eof)
                except UnicodeDecodeError as exc:
                    character = self.raw_buffer[exc.start]
                    if self.stream is not None:
                        position = self.stream_pointer-len(self.raw_buffer)+exc.start
                    else:
                        position = exc.start
                    raise ReaderError(self.name, position, character,
                            exc.encoding, exc.reason)
            else:
                data = self.raw_buffer
                converted = len(data)
            self.check_printable(data)
            self.buffer += data
            self.raw_buffer = self.raw_buffer[converted:]
            if self.eof:
                self.buffer += '\0'
                self.raw_buffer = None
                break

    def update_raw(self, size=4096):
        data = self.stream.read(size)
        if self.raw_buffer is None:
            self.raw_buffer = data
        else:
            self.raw_buffer += data
        self.stream_pointer += len(data)
        if not data:
            self.eof = True





Add Discussion as Guest

Log in