1 # This module contains abstractions for the input stream. You don't have to
2 # looks further, there are no pretty code.
4 # We define two classes here.
6 # Mark(source, line, column)
7 # It's just a record and its only use is producing nice error messages.
8 # Parser does not use it for any other purposes.
10 # Reader(source, data)
11 # Reader determines the encoding of `data` and converts it to unicode.
12 # Reader provides the following methods and attributes:
13 # reader.peek(length=1) - return the next `length` characters
14 # reader.forward(length=1) - move the current position to `length` characters.
15 # reader.index - the number of the current character.
16 # reader.line, stream.column - the line and the column of the current character.
18 __all__ = ['Reader', 'ReaderError']
20 from .error import YAMLError, Mark
24 class ReaderError(YAMLError):
26 def __init__(self, name, position, character, encoding, reason):
28 self.character = character
29 self.position = position
30 self.encoding = encoding
34 if isinstance(self.character, bytes):
35 return "'%s' codec can't decode byte #x%02x: %s\n" \
36 " in \"%s\", position %d" \
37 % (self.encoding, ord(self.character), self.reason,
38 self.name, self.position)
40 return "unacceptable character #x%04x: %s\n" \
41 " in \"%s\", position %d" \
42 % (self.character, self.reason,
43 self.name, self.position)
47 # - determines the data encoding and converts it to a unicode string,
48 # - checks if characters are in allowed range,
49 # - adds '\0' to the end.
54 # - a file-like object with its `read` method returning `str`,
55 # - a file-like object with its `read` method returning `unicode`.
57 # Yeah, it's ugly and slow.
59 def __init__(self, stream):
62 self.stream_pointer = 0
66 self.raw_buffer = None
67 self.raw_decode = None
72 if isinstance(stream, str):
73 self.name = "<unicode string>"
74 self.check_printable(stream)
75 self.buffer = stream+'\0'
76 elif isinstance(stream, bytes):
77 self.name = "<byte string>"
78 self.raw_buffer = stream
79 self.determine_encoding()
82 self.name = getattr(stream, 'name', "<file>")
84 self.raw_buffer = None
85 self.determine_encoding()
87 def peek(self, index=0):
89 return self.buffer[self.pointer+index]
92 return self.buffer[self.pointer+index]
94 def prefix(self, length=1):
95 if self.pointer+length >= len(self.buffer):
97 return self.buffer[self.pointer:self.pointer+length]
99 def forward(self, length=1):
100 if self.pointer+length+1 >= len(self.buffer):
101 self.update(length+1)
103 ch = self.buffer[self.pointer]
106 if ch in '\n\x85\u2028\u2029' \
107 or (ch == '\r' and self.buffer[self.pointer] != '\n'):
115 if self.stream is None:
116 return Mark(self.name, self.index, self.line, self.column,
117 self.buffer, self.pointer)
119 return Mark(self.name, self.index, self.line, self.column,
122 def determine_encoding(self):
123 while not self.eof and (self.raw_buffer is None or len(self.raw_buffer) < 2):
125 if isinstance(self.raw_buffer, bytes):
126 if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
127 self.raw_decode = codecs.utf_16_le_decode
128 self.encoding = 'utf-16-le'
129 elif self.raw_buffer.startswith(codecs.BOM_UTF16_BE):
130 self.raw_decode = codecs.utf_16_be_decode
131 self.encoding = 'utf-16-be'
133 self.raw_decode = codecs.utf_8_decode
134 self.encoding = 'utf-8'
137 NON_PRINTABLE = re.compile('[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD]')
138 def check_printable(self, data):
139 match = self.NON_PRINTABLE.search(data)
141 character = match.group()
142 position = self.index+(len(self.buffer)-self.pointer)+match.start()
143 raise ReaderError(self.name, position, ord(character),
144 'unicode', "special characters are not allowed")
146 def update(self, length):
147 if self.raw_buffer is None:
149 self.buffer = self.buffer[self.pointer:]
151 while len(self.buffer) < length:
154 if self.raw_decode is not None:
156 data, converted = self.raw_decode(self.raw_buffer,
158 except UnicodeDecodeError as exc:
159 character = self.raw_buffer[exc.start]
160 if self.stream is not None:
161 position = self.stream_pointer-len(self.raw_buffer)+exc.start
164 raise ReaderError(self.name, position, character,
165 exc.encoding, exc.reason)
167 data = self.raw_buffer
168 converted = len(data)
169 self.check_printable(data)
171 self.raw_buffer = self.raw_buffer[converted:]
174 self.raw_buffer = None
177 def update_raw(self, size=4096):
178 data = self.stream.read(size)
179 if self.raw_buffer is None:
180 self.raw_buffer = data
182 self.raw_buffer += data
183 self.stream_pointer += len(data)