protected override long ReadNext(BitStreamCtxRL ctx)
{
if (ctx.run_len > 0) {
ctx.run_len--;
return 1L;
}
long d = base.ReadNext (ctx);
if (d == 1L) {
ctx.run_len = (int)(base.ReadNext (ctx) - 1);
}
return d;
}
long BackendAccessRank1(long pos, out long found_pos, BitStreamCtxRL ctx)
{
if (pos < 0) {
found_pos = -1;
return 0;
}
int start_index = -1;
if (this.Samples.Count > 0) {
start_index = GenericSearch.FindFirst<long> (pos, this.Samples);
}
// reset run_len
ctx.run_len = 0;
// int count;
if (start_index < 0) {
//if (this.Offsets.Count > 0 && this.Offsets[0] == 1) {
if (this.Offsets.Count > 0 && this.IsFilled (0)) {
found_pos = pos;
return pos + 1;
} else {
ctx.Seek (0);
int count = Math.Min (this.B, this.M);
return this.SeqAccessRank1 (AccStart, pos, count, out found_pos, ctx);
}
}
int rel_rank = (start_index + 1) * this.B;
//if (this.Offsets.Count > start_index + 1 && this.Offsets[start_index + 1] == 1 + this.Offsets[start_index]) {
if (this.Offsets.Count > start_index + 1 && this.IsFilled(start_index + 1) ) {
found_pos = pos;
long diff_rank = pos - this.Samples[start_index];
return rel_rank + diff_rank;
} else {
ctx.Seek (this.Offsets[start_index]);
int count = Math.Min (this.B, this.M - rel_rank);
return rel_rank + this.SeqAccessRank1 (this.Samples[start_index], pos, count, out found_pos, ctx);
}
}
/// <summary>
/// build methods
/// </summary>
public void Build(IEnumerable<long> orderedList, long n, short b, IIEncoder64 coder = null)
{
this.N = n;
this.B = b;
this.M = 0;
if (coder == null) {
coder = new EliasDelta64 ();
}
this.Coder = coder;
long prev = -1;
var ctx = new BitStreamCtxRL ();
foreach (var current in orderedList) {
if (current == 0) {
prev = AccStart;
}
this.M++;
long diff = current - prev;
//Console.WriteLine ("DIFF {0}, num: {1}, current: {2}", diff, this.M, current);
if (diff == 1) {
++ctx.run_len;
} else {
this.Commit (ctx);
// Console.WriteLine ("%%%%%% diff: {0}, prev: {1}, curr: {2}", diff, prev, current);
Coder.Encode (this.Stream, diff);
}
if ((this.M % this.B) == 0) {
this.Commit (ctx);
this.Samples.Add (current);
this.Offsets.Add (this.Stream.CountBits);
}
if (current >= this.N) {
this.N = current + 1;
}
prev = current;
}
this.Commit (ctx);
/*for (int i = 0; i < this.Samples.Count; i++) {
Console.WriteLine ("-- i: {0}, samples: {1}, offset: {2}", i, Samples[i], Offsets[i]);
}*/
}
protected override void ResetReader(BitStreamCtxRL ctx)
{
ctx.run_len = 0;
}
public override long Select1(long rank, UnraveledSymbolXLB unraveled_ctx)
{
Context ctx = unraveled_ctx.ctx as Context;
if (ctx == null) {
var bctx = new BitStreamCtxRL ();
unraveled_ctx.ctx = ctx = new Context (rank, bctx);
ctx.prev_res = this.BackendSelect1 ((int)rank, ctx.ctx);
} else {
int left = (int)(rank - ctx.prev_arg);
if (left < 0 || left > this.B * 2) {
ctx.prev_res = this.BackendSelect1 ((int)rank, ctx.ctx);
} else {
for (int i = 0; i < left; i++) {
long read = this.ReadNext (ctx.ctx);
ctx.prev_res += read;
}
}
}
ctx.prev_arg = rank;
return ctx.prev_res;
}
int SeqAccessRank1(int curr_pos, int pos, int max, out int found_pos, BitStreamCtxRL ctx)
{
int i = 0;
int u = -1;
while (i < max && curr_pos < pos) {
if (ctx.run_len > 0) {
u = ctx.run_len;
ctx.run_len = 0;
if (curr_pos + u > pos) {
u = pos - curr_pos;
}
curr_pos += u;
i += u;
} else {
u = this.ReadNext (ctx);
if (curr_pos + u > pos) {
break;
}
curr_pos += u;
i++;
}
}
found_pos = curr_pos;
return i;
}
long SeqAccessRank1(long acc, long pos, int max, out long found_pos, BitStreamCtxRL ctx)
{
int i = 0;
while (i < max && acc < pos) {
long u = this.ReadNext (ctx);
if (acc + u > pos) {
found_pos = acc;
return i;
}
acc += u;
i++;
}
found_pos = acc;
return i;
}
long ReadNext(BitStreamCtxRL ctx)
{
if (ctx.run_len > 0) {
ctx.run_len--;
return 1;
}
long d = Coder.Decode (this.Stream, ctx);
if (d == 1) {
ctx.run_len = ((int)Coder.Decode (this.Stream, ctx)) - 1;
}
return d;
}
long BackendAccessRank1(long pos, out long found_pos, BitStreamCtxRL ctx)
{
if (pos < 0) {
found_pos = -1;
return 0;
}
this.ResetReader (ctx);
int start_index = -1;
if (this.Samples.Count > 0) {
start_index = GenericSearch.FindFirst<long> (pos, this.Samples);
}
int count;
if (start_index < 0) {
ctx.Seek (0);
count = Math.Min (this.B, this.M);
return this.SeqAccessRank1 (AccStart, pos, count, out found_pos, ctx);
}
ctx.Seek (this.Offsets[start_index]);
int rel_rank = (start_index + 1) * this.B;
count = Math.Min (this.B, this.M - rel_rank);
return rel_rank + this.SeqAccessRank1 (this.Samples[start_index], pos, count, out found_pos, ctx);
}
/// <summary>
/// Unlocked Select1 useful to some lowlevel operations
/// </summary>
long BackendSelect1(int rank, BitStreamCtxRL ctx)
{
if (rank < 1) {
return -1;
}
this.ResetReader(ctx);
int start_index = (rank - 1) / this.B;
long acc;
int left;
if (start_index == 0) {
acc = AccStart;
ctx.Seek (0);
left = rank;
} else {
acc = this.Samples[start_index - 1];
ctx.Seek (this.Offsets[start_index - 1]);
left = rank - start_index * this.B;
}
// int start_acc = acc;
for (int i = 0; i < left; i++) {
long read = this.ReadNext(ctx);
acc += read;
}
return acc;
}
protected virtual void ResetReader(BitStreamCtxRL ctx)
{
}
protected virtual long ReadNext(BitStreamCtxRL ctx)
{
return Coder.Decode (this.Stream, ctx);
}
/// <summary>
/// Returns the difference between Select1(rank) - Select1(rank-1)
/// </summary>
public long Select1Difference(int rank)
{
if (rank < 1) {
return -1;
}
if (rank == 1) {
return this.Select1 (rank);
}
var ctx = new BitStreamCtxRL ();
this.BackendSelect1 (rank - 1, ctx);
return this.ReadNext (ctx);
}
long BackendSelect1(int rank, BitStreamCtxRL ctx)
{
if (rank < 1) {
return -1;
}
// reset run_len
ctx.run_len = 0;
int start_index = (rank - 1) / this.B;
long acc;
int left;
//Console.WriteLine ("**** BaseSelect1> rank: {0}, start_index: {1}", rank, start_index);
if (start_index == 0) {
//if (this.Offsets.Count > 0 && this.Offsets [0] == 1) {
if (this.Offsets.Count > 0 && this.IsFilled (0)) {
//Console.WriteLine ("**** INSIDE FULL> ");
ctx.run_len = this.B - rank;
return rank - 1;
// this.run_len = this.B;
}
//Console.WriteLine ("**** OUT-SIDE FULL> B: {0}", this.B);
acc = AccStart;
ctx.Seek (0);
left = rank;
} else {
acc = this.Samples [start_index - 1];
left = rank - start_index * this.B;
//if (this.Offsets.Count > start_index && this.Offsets [start_index] == 1 + this.Offsets [start_index - 1]) {
if (this.Offsets.Count > start_index && this.IsFilled(start_index)) {
ctx.run_len = this.B - left;
return acc + left;
}
ctx.Seek (this.Offsets [start_index - 1]);
}
// for (int i = 0; i < left; i++) {
// int read = this.ReadNext (ctx);
// acc += read;
// }
while (left > 0) {
long read;
if (ctx.run_len > 0) {
read = ctx.run_len;
ctx.run_len = 0;
left -= (int)read;
if (left < 0) {
read += left;
ctx.run_len += left;
left = 0;
}
} else {
read = this.ReadNext (ctx);
left--;
}
acc += read;
}
return acc;
}
public Context(long prev_arg, BitStreamCtxRL ctx)
{
this.ctx = ctx;
this.prev_arg = prev_arg;
this.prev_res = long.MinValue;
}
void Commit(BitStreamCtxRL ctx)
{
//Console.WriteLine ("commit run_len: {0}, B: {1}", ctx.run_len, this.B);
if (ctx.run_len > 0) {
if (ctx.run_len == this.B) {
Coder.Encode (this.Stream, 1);
} else {
Coder.Encode (this.Stream, 1);
Coder.Encode (this.Stream, ctx.run_len);
}
ctx.run_len = 0;
}
}
int ReadNext(BitStreamCtxRL ctx)
{
if (ctx.run_len > 0) {
ctx.run_len--;
return 1;
}
int d = Coder.Decode (this.Stream, ctx);
if (d == 1) {
ctx.run_len = Coder.Decode (this.Stream, ctx) - 1;
}
return d;
}
long SeqAccessRank1(long curr_pos, long pos, long max, out long found_pos, BitStreamCtxRL ctx)
{
long i = 0;
long u = -1;
while (i < max && curr_pos < pos) {
if (ctx.run_len > 0) {
u = ctx.run_len;
ctx.run_len = 0;
if (curr_pos + u > pos) {
u = pos - curr_pos;
}
curr_pos += u;
i += u;
} else {
u = this.ReadNext (ctx);
if (curr_pos + u > pos) {
break;
}
curr_pos += u;
i++;
}
}
found_pos = curr_pos;
return i;
}
/// <summary>
/// Extract 'count' differences starting from 'start_index', it saves the output in 'output'.
/// Returns the previous absolute value to start_index (start_index - 1), i.e. the reference
/// </summary>
public long ExtractFrom(int start_index, int count, IList<long> output)
{
long acc;
var ctx = new BitStreamCtxRL ();
if (start_index == 0) {
this.ResetReader (ctx);
acc = -1;
ctx.Seek (0);
} else {
acc = this.BackendSelect1 (start_index, ctx);
}
for (int i = 0; i < count; i++) {
long val = this.ReadNext (ctx);
if (i < output.Count) {
output[i] = val;
} else {
output.Add (val);
}
}
return acc;
}
