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Common: Optimize BitSet iterator

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This commit is contained in:
Yuri Kunde Schlesner 2016-12-18 21:48:12 -08:00
parent 92bf5c88e6
commit d36ec905b1
1 changed files with 19 additions and 14 deletions
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33
src/common/bit_set.h
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@ -121,22 +121,19 @@ public:
class Iterator { class Iterator {
public: public:
Iterator(const Iterator& other) : m_val(other.m_val), m_bit(other.m_bit) {} Iterator(const Iterator& other) : m_val(other.m_val), m_bit(other.m_bit) {}
Iterator(IntTy val, int bit) : m_val(val), m_bit(bit) {} Iterator(IntTy val) : m_val(val), m_bit(0) {}
Iterator& operator=(Iterator other) { Iterator& operator=(Iterator other) {
new (this) Iterator(other); new (this) Iterator(other);
return *this; return *this;
} }
int operator*() { int operator*() {
return m_bit; return m_bit + ComputeLsb();
} }
Iterator& operator++() { Iterator& operator++() {
if (m_val == 0) { int lsb = ComputeLsb();
m_bit = -1; m_val >>= lsb + 1;
} else { m_bit += lsb + 1;
int bit = LeastSignificantSetBit(m_val); m_has_lsb = false;
m_val &= ~(1 << bit);
m_bit = bit;
}
return *this; return *this;
} }
Iterator operator++(int _) { Iterator operator++(int _) {
@ -145,15 +142,24 @@ public:
return other; return other;
} }
bool operator==(Iterator other) const { bool operator==(Iterator other) const {
return m_bit == other.m_bit; return m_val == other.m_val;
} }
bool operator!=(Iterator other) const { bool operator!=(Iterator other) const {
return m_bit != other.m_bit; return m_val != other.m_val;
} }
private: private:
int ComputeLsb() {
if (!m_has_lsb) {
m_lsb = LeastSignificantSetBit(m_val);
m_has_lsb = true;
}
return m_lsb;
}
IntTy m_val; IntTy m_val;
int m_bit; int m_bit;
int m_lsb = -1;
bool m_has_lsb = false;
}; };
BitSet() : m_val(0) {} BitSet() : m_val(0) {}
@ -221,11 +227,10 @@ public:
} }
Iterator begin() const { Iterator begin() const {
Iterator it(m_val, 0); return Iterator(m_val);
return ++it;
} }
Iterator end() const { Iterator end() const {
return Iterator(m_val, -1); return Iterator(0);
} }
IntTy m_val; IntTy m_val;