package YAML::Reader;
use strict;
use warnings;

# This module contains abstractions for the input stream. You don't have to
# looks further, there are no pretty code.
#
# We define two classes here.
#
#   Mark(source, line, column)
# It's just a record and its only use is producing nice error messages.
# Parser does not use it for any other purposes.
#
#   Reader(source, data)
# Reader determines the encoding of `data` and converts it to unicode.
# Reader provides the following methods and attributes:
#   reader.peek(length=1) - return the next `length` characters
#   reader.forward(length=1) - move the current position to `length` characters.
#   reader.index - the number of the current character.
#   reader.line, stream.column - the line and the column of the current character.

#>  __all__ = ['Reader', 'ReaderError']
#>  
#>  from error import YAMLError, Mark

use YAML::Error;

#>  import codecs, re
#>  
#>  # Unfortunately, codec functions in Python 2.3 does not support the `finish`
#>  # arguments, so we have to write our own wrappers.
#>  
#>  try:
#>      codecs.utf_8_decode('', 'strict', False)
#>      from codecs import utf_8_decode, utf_16_le_decode, utf_16_be_decode
#>  
#>  except TypeError:
#>  
#>      def utf_16_le_decode(data, errors, finish=False):
#>          if not finish and len(data) % 2 == 1:
#>              data = data[:-1]
#>          return codecs.utf_16_le_decode(data, errors)
#>  
#>      def utf_16_be_decode(data, errors, finish=False):
#>          if not finish and len(data) % 2 == 1:
#>              data = data[:-1]
#>          return codecs.utf_16_be_decode(data, errors)
#>  
#>      def utf_8_decode(data, errors, finish=False):
#>          if not finish:
#>              # We are trying to remove a possible incomplete multibyte character
#>              # from the suffix of the data.
#>              # The first byte of a multi-byte sequence is in the range 0xc0 to 0xfd.
#>              # All further bytes are in the range 0x80 to 0xbf.
#>              # UTF-8 encoded UCS characters may be up to six bytes long.
#>              count = 0
#>              while count < 5 and count < len(data)   \
#>                      and '\x80' <= data[-count-1] <= '\xBF':
#>                  count -= 1
#>              if count < 5 and count < len(data)  \
#>                      and '\xC0' <= data[-count-1] <= '\xFD':
#>                  data = data[:-count-1]
#>          return codecs.utf_8_decode(data, errors)
#>  
#>  class ReaderError(YAMLError):
#>  
#>      def __init__(self, name, position, character, encoding, reason):
#>          self.name = name
#>          self.character = character
#>          self.position = position
#>          self.encoding = encoding
#>          self.reason = reason
#>  
#>      def __str__(self):
#>          if isinstance(self.character, str):
#>              return "'%s' codec can't decode byte #x%02x: %s\n"  \
#>                      "  in \"%s\", position %d"    \
#>                      % (self.encoding, ord(self.character), self.reason,
#>                              self.name, self.position)
#>          else:
#>              return "unacceptable character #x%04x: %s\n"    \
#>                      "  in \"%s\", position %d"    \
#>                      % (ord(self.character), self.reason,
#>                              self.name, self.position)

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

package YAML::Reader;
use YAML::Processor -base;

field next_layer => '';

sub open {
    my $self = shift;
    $self->SUPER::open(@_);
    my $stream = shift;
    $self->stream($stream);
    # XXX see comment near line 176
    # $self->buffer($stream . "\0");
    $self->buffer($stream);
}

#>  def __init__(self, stream):
#>      self.name = None
#>      self.stream = None
#>      self.stream_pointer = 0
#>      self.eof = True
#>      self.buffer = u''
#>      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, unicode):
#>          self.name = "<unicode string>"
#>          self.check_printable(stream)
#>          self.buffer = stream+u'\0'
#>      elif isinstance(stream, str):
#>          self.name = "<string>"
#>          self.raw_buffer = stream
#>          self.determine_encoding()
#>      else:
#>          self.stream = stream
#>          self.name = getattr(stream, 'name', "<file>")
#>          self.eof = False
#>          self.raw_buffer = ''
#>          self.determine_encoding()

field 'name';
field 'stream';
field 'stream_pointer' => 0;
field 'eof' => 1;
field 'buffer' => '';
field 'pointer' => 0;
field 'raw_buffer';
field 'raw_decode';
field 'encoding';
field 'index' => 0;
field 'line' => 0;
field 'column' => 0;

sub init {
    my $self = shift;
    $self->{buffer} = '';
    $self->{index} = 0;
}

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

sub peek {
    my $self = shift;
    my $index = shift || 0;
    my $buff = $self->{buffer};
    $buff =~ s/\n/\\n/g;
#     WWW "peek -- buffer: [$buff] self.index: [" . $self->{index} . "] index: [$index]\n";
    
    # XXX or maybe the buffer should be initialized with a null char at the end 
    # see comment near line 110
    return "\0" if $self->{index} + $index > length( $self->{buffer} );
    return substr($self->{buffer}, $self->{index} + $index, 1);
}

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

sub prefix {
    my $self = shift;
    my $length = shift || 1;
    return substr($self->{buffer}, 0, $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 u'\n\x85\u2028\u2029'  \
#>                  or (ch == u'\r' and self.buffer[self.pointer] != u'\n'):
#>              self.line += 1
#>              self.column = 0
#>          elif ch != u'\uFEFF':
#>              self.column += 1
#>          length -= 1

sub forward {
    my $self = shift;
    my $length = shift || 1;

# we don't need to check the fullness of the buffer, as we have the
# whole string right now ... someday soon we shall need 

    while ( $length-- ) {
        my $ch = $self->peek();
        if ( 
            $ch =~ /[\n\x85]/
            or ( $ch eq "\r" and $self->peek(2) != "\n" )
        ) {
            $self->{line}++;
            $self->{column} = 0;
        }
        elsif ( $ch ne "\x{FEFF}" ) {
            $self->{column}++
        }
        $self->{index}++;
    }
}
    
#>  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)

sub get_mark {
    my $self = shift;
    if (not defined $self->stream) {
        return YAML::Mark->new(
            name => $self->name,
            index => $self->index,
            line => $self->line,
            column => $self->column,
            buffer => $self->buffer,
            pointer => $self->pointer,
        );
    }
    return YAML::Mark->new(
        name => $self->name,
        index => $self->index,
        line => $self->line,
        column => $self->column,
    );
}

1;

__END__







    def determine_encoding(self):
        while not self.eof and len(self.raw_buffer) < 2:
            self.update_raw()
        if not isinstance(self.raw_buffer, unicode):
            if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
                self.raw_decode = utf_16_le_decode
                self.encoding = 'utf-16-le'
            elif self.raw_buffer.startswith(codecs.BOM_UTF16_BE):
                self.raw_decode = utf_16_be_decode
                self.encoding = 'utf-16-be'
            else:
                self.raw_decode = utf_8_decode
                self.encoding = 'utf-8'
        self.update(1)

    NON_PRINTABLE = re.compile(u'[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD]')
    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, 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, exc:
                    character = exc.object[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 += u'\0'
                self.raw_buffer = None
                break

    def update_raw(self, size=1024):
        data = self.stream.read(size)
        if data:
            self.raw_buffer += data
            self.stream_pointer += len(data)
        else:
            self.eof = True

#try:
#    import psyco
#    psyco.bind(Reader)
#except ImportError:
#    pass