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This file is part of Sambamba.
Copyright (C) 2012 Artem Tarasov <>
Sambamba is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
Sambamba is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
module alignmentrange;
import virtualoffset;
import chunkinputstream;
import alignment;
import std.algorithm;
import std.system;
import utils.switchendianness;
/// Tuple of virtual offset of the alignment, and the alignment itself.
struct AlignmentBlock {
VirtualOffset start_virtual_offset;
VirtualOffset end_virtual_offset;
Alignment alignment;
alias alignment this;
/// Policies for alignmentRange
mixin template withOffsets() {
Returns: virtual offsets of beginning and end of the current alignment
plus the current alignment itself.
AlignmentBlock front() @property {
return AlignmentBlock(_start_voffset,
private VirtualOffset _start_voffset;
private void beforeNextAlignmentLoad() {
_start_voffset = _stream.virtualTell();
/// ditto
mixin template withoutOffsets() {
Returns: current alignment
Alignment front() @property {
return _current_record;
private void beforeNextAlignmentLoad() {}
class AlignmentRange(alias IteratePolicy)
/// Create new range from IChunkInputStream.
this(ref IChunkInputStream stream) {
_stream = stream;
_endian_stream = new EndianStream(_stream, Endian.littleEndian);
bool empty() @property const {
return _empty;
mixin IteratePolicy;
void popFront() {
IChunkInputStream _stream;
EndianStream _endian_stream;
Alignment _current_record;
bool _empty = false;
Reads next alignment block from stream.
void readNext() {
// In fact, on BAM files containing a special EOF BGZF block
// this condition will be always false!
// The reason is that we don't want to unpack next block just
// in order to see if it's an EOF one or not.
if (_stream.eof()) {
_empty = true;
// In order to get the right virtual offset, we need to do it here.
// Here's where _empty is really set!
int block_size = void;
ubyte* ptr = cast(ubyte*)(&block_size);
auto _read = 0;
while (_read < int.sizeof) {
auto _actually_read = _endian_stream.readBlock(ptr, int.sizeof - _read);
if (_actually_read == 0) {
version(development) {
import std.stdio;
stderr.writeln("[info][alignment range] empty, read ", _read, " bytes, expected ", int.sizeof);
_empty = true;
_read += _actually_read;
ptr += _actually_read;
if (std.system.endian != Endian.littleEndian) {
switchEndianness(&block_size, int.sizeof);
_current_record = Alignment(_stream.readSlice(block_size));
/// Returns: lazy range of Alignment structs constructed from a given stream.
auto alignmentRange(alias IteratePolicy=withoutOffsets)(ref IChunkInputStream stream) {
return new AlignmentRange!IteratePolicy(stream);
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