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

180 lines
3.6 KiB
Ruby

# --
# Copyright (C) 2008-2009 10gen Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ++
# A byte buffer.
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
# Appends a second ByteBuffer object, +buffer+, to the current buffer.
def append!(buffer)
@buf = @buf + buffer.to_a
self
end
# Prepends a second ByteBuffer object, +buffer+, to the current buffer.
def prepend!(buffer)
@buf = buffer.to_a + @buf
self
end
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
def put_int(i, offset=nil)
a = []
[i].pack(@int_pack_order).each_byte { |b| a << b }
put_array(a, offset)
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
def put_double(d, offset=nil)
a = []
[d].pack(@double_pack_order).each_byte { |b| a << b }
put_array(a, offset)
end
# If +size+ == nil, returns one byte. Else returns array of bytes of length
# # +size+.
def get(len=nil)
one_byte = len.nil?
len ||= 1
check_read_length(len)
start = @cursor
@cursor += len
if one_byte
@buf[start]
else
if @buf.respond_to? "unpack"
@buf[start, len].unpack("C*")
else
@buf[start, len]
end
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
if @buf.respond_to? "unpack"
@buf.unpack("C*")
else
@buf
end
end
def to_s
if @buf.respond_to? "pack"
@buf.pack("C*")
else
@buf
end
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