mongo-ruby-driver/lib/mongo/util/byte_buffer.rb

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# --
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# Copyright (C) 2008 10gen Inc.
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License, version 3, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
# for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# ++
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# A byte buffer.
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class ByteBuffer
attr_reader :order
def initialize(initial_data=[])
@buf = initial_data
@cursor = 0
self.order = :little_endian
end
# +endianness+ should be :little_endian or :big_endian. Default is :little_endian
def order=(endianness)
@order = endianness
@int_pack_order = endianness == :little_endian ? 'V' : 'N'
@double_pack_order = endianness == :little_endian ? 'E' : 'G'
end
def rewind
@cursor = 0
end
def position
@cursor
end
def position=(val)
@cursor = val
end
def clear
@buf = []
rewind
end
def size
@buf.size
end
alias_method :length, :size
def put(byte, offset=nil)
@cursor = offset if offset
@buf[@cursor] = byte
@cursor += 1
end
def put_array(array, offset=nil)
@cursor = offset if offset
@buf[@cursor, array.length] = array
@cursor += array.length
end
if RUBY_VERSION >= '1.9'
def put_int(i, offset=nil)
put_array([i].pack(@int_pack_order).split(//).collect{|c| c.bytes.first}, offset)
end
else
def put_int(i, offset=nil)
put_array([i].pack(@int_pack_order).split(//).collect{|c| c[0]}, offset)
end
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end
def put_long(i, offset=nil)
offset = @cursor unless offset
if @int_pack_order == 'N'
put_int(i >> 32, offset)
put_int(i & 0xffffffff, offset + 4)
else
put_int(i & 0xffffffff, offset)
put_int(i >> 32, offset + 4)
end
end
if RUBY_VERSION >= '1.9'
def put_double(d, offset=nil)
put_array([d].pack(@double_pack_order).split(//).collect{|c| c.bytes.first}, offset)
end
else
def put_double(d, offset=nil)
put_array([d].pack(@double_pack_order).split(//).collect{|c| c[0]}, offset)
end
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end
# If +size+ == 1, returns one byte. Else returns array of bytes of length
# +size+.
def get(len=1)
check_read_length(len)
start = @cursor
@cursor += len
if len == 1
@buf[start]
else
@buf[start, len]
end
end
def get_int
check_read_length(4)
vals = ""
(@cursor..@cursor+3).each { |i| vals << @buf[i].chr }
@cursor += 4
vals.unpack(@int_pack_order)[0]
end
def get_long
i1 = get_int
i2 = get_int
if @int_pack_order == 'N'
(i1 << 32) + i2
else
(i2 << 32) + i1
end
end
def get_double
check_read_length(8)
vals = ""
(@cursor..@cursor+7).each { |i| vals << @buf[i].chr }
@cursor += 8
vals.unpack(@double_pack_order)[0]
end
def more?
@cursor < @buf.size
end
def to_a
@buf
end
def to_s
@buf.pack("C*")
end
def dump
@buf.each_with_index { |c, i| $stderr.puts "#{'%04d' % i}: #{'%02x' % c} #{'%03o' % c} #{'%s' % c.chr} #{'%3d' % c}" }
end
private
def check_read_length(len)
raise "attempt to read past end of buffer" if @cursor + len > @buf.length
end
end