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#include "opaque_trie_iterator.h"
#include "comptrie_impl.h"
#include "node.h"
namespace NCompactTrie {
TOpaqueTrieIterator::TOpaqueTrieIterator(const TOpaqueTrie& trie, const char* emptyValue, bool atend,
size_t maxKeyLength)
: Trie(trie)
, EmptyValue(emptyValue)
, AtEmptyValue(emptyValue && !atend)
, MaxKeyLength(maxKeyLength)
{
if (!AtEmptyValue && !atend)
Forward();
}
bool TOpaqueTrieIterator::operator==(const TOpaqueTrieIterator& rhs) const {
return (Trie == rhs.Trie &&
Forks == rhs.Forks &&
EmptyValue == rhs.EmptyValue &&
AtEmptyValue == rhs.AtEmptyValue &&
MaxKeyLength == rhs.MaxKeyLength);
}
bool TOpaqueTrieIterator::HasMaxKeyLength() const {
return MaxKeyLength != size_t(-1) && MeasureNarrowKey() == MaxKeyLength;
}
bool TOpaqueTrieIterator::Forward() {
if (AtEmptyValue) {
AtEmptyValue = false;
bool res = Forward(); // TODO delete this after format change
if (res && MeasureNarrowKey() != 0) {
return res; // there was not "\0" key
}
// otherwise we are skipping "\0" key
}
if (!Trie.Length)
return false;
if (Forks.Empty()) {
TFork fork(Trie.Data, 0, Trie.Length, Trie.SkipFunction);
Forks.Push(fork);
} else {
TFork* topFork = &Forks.Top();
while (!topFork->NextDirection()) {
if (topFork->Node.GetOffset() >= Trie.Length)
return false;
Forks.Pop();
if (Forks.Empty())
return false;
topFork = &Forks.Top();
}
}
Y_ASSERT(!Forks.Empty());
while (Forks.Top().CurrentDirection != D_FINAL && !HasMaxKeyLength()) {
TFork nextFork = Forks.Top().NextFork(Trie.SkipFunction);
Forks.Push(nextFork);
}
TFork& top = Forks.Top();
static_assert(D_FINAL < D_NEXT, "relative order of NEXT and FINAL directions has changed");
if (HasMaxKeyLength() && top.CurrentDirection == D_FINAL && top.HasDirection(D_NEXT)) {
top.NextDirection();
}
return true;
}
bool TOpaqueTrieIterator::Backward() {
if (AtEmptyValue)
return false;
if (!Trie.Length) {
if (EmptyValue) {
// A trie that has only the empty value;
// we are not at the empty value, so move to it.
AtEmptyValue = true;
return true;
} else {
// Empty trie.
return false;
}
}
if (Forks.Empty()) {
TFork fork(Trie.Data, 0, Trie.Length, Trie.SkipFunction);
fork.LastDirection();
Forks.Push(fork);
} else {
TFork* topFork = &Forks.Top();
while (!topFork->PrevDirection()) {
if (topFork->Node.GetOffset() >= Trie.Length)
return false;
Forks.Pop();
if (!Forks.Empty()) {
topFork = &Forks.Top();
} else {
// When there are no more forks,
// we have to iterate over the empty value.
if (!EmptyValue)
return false;
AtEmptyValue = true;
return true;
}
}
}
Y_ASSERT(!Forks.Empty());
while (Forks.Top().CurrentDirection != D_FINAL && !HasMaxKeyLength()) {
TFork nextFork = Forks.Top().NextFork(Trie.SkipFunction);
nextFork.LastDirection();
Forks.Push(nextFork);
}
TFork& top = Forks.Top();
static_assert(D_FINAL < D_NEXT, "relative order of NEXT and FINAL directions has changed");
if (HasMaxKeyLength() && top.CurrentDirection == D_NEXT && top.HasDirection(D_FINAL)) {
top.PrevDirection();
}
if (MeasureNarrowKey() == 0) {
// This is the '\0' key, skip it and get to the EmptyValue.
AtEmptyValue = true;
Forks.Clear();
}
return true;
}
const char* TOpaqueTrieIterator::GetValuePtr() const {
if (!Forks.Empty()) {
const TFork& lastFork = Forks.Top();
Y_ASSERT(lastFork.Node.IsFinal() && lastFork.CurrentDirection == D_FINAL);
return Trie.Data + lastFork.GetValueOffset();
}
Y_ASSERT(AtEmptyValue);
return EmptyValue;
}
//-------------------------------------------------------------------------
TString TForkStack::GetKey() const {
if (HasEmptyKey()) {
return TString();
}
TString result(Key);
if (TopHasLabelInKey()) {
result.append(Top().GetLabel());
}
return result;
}
bool TForkStack::HasEmptyKey() const {
// Special case: if we get a single zero label, treat it as an empty key
// TODO delete this after format change
if (TopHasLabelInKey()) {
return Key.size() == 0 && Top().GetLabel() == '\0';
} else {
return Key.size() == 1 && Key[0] == '\0';
}
}
size_t TForkStack::MeasureKey() const {
size_t result = Key.size() + (TopHasLabelInKey() ? 1 : 0);
if (result == 1 && HasEmptyKey()) {
return 0;
}
return result;
}
//-------------------------------------------------------------------------
TFork::TFork(const char* data, size_t offset, size_t limit, const ILeafSkipper& skipper)
: Node(data, offset, skipper)
, Data(data)
, Limit(limit)
, CurrentDirection(TDirection(0))
{
#if COMPTRIE_DATA_CHECK
if (Node.GetOffset() >= Limit - 1)
ythrow yexception() << "gone beyond the limit, data is corrupted";
#endif
while (CurrentDirection < D_MAX && !HasDirection(CurrentDirection)) {
++CurrentDirection;
}
}
bool TFork::operator==(const TFork& rhs) const {
return (Data == rhs.Data &&
Node.GetOffset() == rhs.Node.GetOffset() &&
CurrentDirection == rhs.CurrentDirection);
}
inline bool TFork::NextDirection() {
do {
++CurrentDirection;
} while (CurrentDirection < D_MAX && !HasDirection(CurrentDirection));
return CurrentDirection < D_MAX;
}
inline bool TFork::PrevDirection() {
if (CurrentDirection == TDirection(0)) {
return false;
}
do {
--CurrentDirection;
} while (CurrentDirection > 0 && !HasDirection(CurrentDirection));
return HasDirection(CurrentDirection);
}
void TFork::LastDirection() {
CurrentDirection = D_MAX;
PrevDirection();
}
bool TFork::SetDirection(TDirection direction) {
if (!HasDirection(direction)) {
return false;
}
CurrentDirection = direction;
return true;
}
char TFork::GetLabel() const {
return Node.GetLabel();
}
size_t TFork::GetValueOffset() const {
return Node.GetLeafOffset();
}
}
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