diff options
Diffstat (limited to 'vendor/github.com/willf/bitset/bitset.go')
| -rw-r--r-- | vendor/github.com/willf/bitset/bitset.go | 72 |
1 files changed, 62 insertions, 10 deletions
diff --git a/vendor/github.com/willf/bitset/bitset.go b/vendor/github.com/willf/bitset/bitset.go index 22e5d42e5..21e889da2 100644 --- a/vendor/github.com/willf/bitset/bitset.go +++ b/vendor/github.com/willf/bitset/bitset.go @@ -138,6 +138,9 @@ func (b *BitSet) Len() uint { // extendSetMaybe adds additional words to incorporate new bits if needed func (b *BitSet) extendSetMaybe(i uint) { if i >= b.length { // if we need more bits, make 'em + if i >= Cap() { + panic("You are exceeding the capacity") + } nsize := wordsNeeded(i + 1) if b.set == nil { b.set = make([]uint64, nsize) @@ -160,7 +163,12 @@ func (b *BitSet) Test(i uint) bool { return b.set[i>>log2WordSize]&(1<<(i&(wordSize-1))) != 0 } -// Set bit i to 1 +// Set bit i to 1, the capacity of the bitset is automatically +// increased accordingly. +// If i>= Cap(), this function will panic. +// Warning: using a very large value for 'i' +// may lead to a memory shortage and a panic: the caller is responsible +// for providing sensible parameters in line with their memory capacity. func (b *BitSet) Set(i uint) *BitSet { b.extendSetMaybe(i) b.set[i>>log2WordSize] |= 1 << (i & (wordSize - 1)) @@ -176,7 +184,11 @@ func (b *BitSet) Clear(i uint) *BitSet { return b } -// SetTo sets bit i to value +// SetTo sets bit i to value. +// If i>= Cap(), this function will panic. +// Warning: using a very large value for 'i' +// may lead to a memory shortage and a panic: the caller is responsible +// for providing sensible parameters in line with their memory capacity. func (b *BitSet) SetTo(i uint, value bool) *BitSet { if value { return b.Set(i) @@ -184,7 +196,11 @@ func (b *BitSet) SetTo(i uint, value bool) *BitSet { return b.Clear(i) } -// Flip bit at i +// Flip bit at i. +// If i>= Cap(), this function will panic. +// Warning: using a very large value for 'i' +// may lead to a memory shortage and a panic: the caller is responsible +// for providing sensible parameters in line with their memory capacity. func (b *BitSet) Flip(i uint) *BitSet { if i >= b.length { return b.Set(i) @@ -193,26 +209,51 @@ func (b *BitSet) Flip(i uint) *BitSet { return b } -// Shrink shrinks BitSet to desired length in bits. It clears all bits > length -// and reduces the size and length of the set. +// Shrink shrinks BitSet so that the provided value is the last possible +// set value. It clears all bits > the provided index and reduces the size +// and length of the set. +// +// Note that the parameter value is not the new length in bits: it is the +// maximal value that can be stored in the bitset after the function call. +// The new length in bits is the parameter value + 1. Thus it is not possible +// to use this function to set the length to 0, the minimal value of the length +// after this function call is 1. // // A new slice is allocated to store the new bits, so you may see an increase in // memory usage until the GC runs. Normally this should not be a problem, but if you // have an extremely large BitSet its important to understand that the old BitSet will // remain in memory until the GC frees it. -func (b *BitSet) Shrink(length uint) *BitSet { - idx := wordsNeeded(length + 1) +func (b *BitSet) Shrink(lastbitindex uint) *BitSet { + length := lastbitindex + 1 + idx := wordsNeeded(length) if idx > len(b.set) { return b } shrunk := make([]uint64, idx) copy(shrunk, b.set[:idx]) b.set = shrunk - b.length = length + 1 - b.set[idx-1] &= (allBits >> (uint64(64) - uint64(length&(wordSize-1)) - 1)) + b.length = length + b.set[idx-1] &= (allBits >> (uint64(64) - uint64(length&(wordSize-1)))) return b } +// Compact shrinks BitSet to so that we preserve all set bits, while minimizing +// memory usage. Compact calls Shrink. +func (b *BitSet) Compact() *BitSet { + idx := len(b.set) - 1 + for ; idx >= 0 && b.set[idx] == 0; idx-- { + } + newlength := uint((idx + 1) << log2WordSize) + if newlength >= b.length { + return b // nothing to do + } + if newlength > 0 { + return b.Shrink(newlength - 1) + } + // We preserve one word + return b.Shrink(63) +} + // InsertAt takes an index which indicates where a bit should be // inserted. Then it shifts all the bits in the set to the left by 1, starting // from the given index position, and sets the index position to 0. @@ -323,6 +364,9 @@ func (b *BitSet) DeleteAt(i uint) *BitSet { // including possibly the current index // along with an error code (true = valid, false = no set bit found) // for i,e := v.NextSet(0); e; i,e = v.NextSet(i + 1) {...} +// +// Users concerned with performance may want to use NextSetMany to +// retrieve several values at once. func (b *BitSet) NextSet(i uint) (uint, bool) { x := int(i >> log2WordSize) if x >= len(b.set) { @@ -358,6 +402,14 @@ func (b *BitSet) NextSet(i uint) (uint, bool) { // j += 1 // } // +// +// It is possible to retrieve all set bits as follow: +// +// indices := make([]uint, bitmap.Count()) +// bitmap.NextSetMany(0, indices) +// +// However if bitmap.Count() is large, it might be preferable to +// use several calls to NextSetMany, for performance reasons. func (b *BitSet) NextSetMany(i uint, buffer []uint) (uint, []uint) { myanswer := buffer capacity := cap(buffer) @@ -809,7 +861,7 @@ func (b *BitSet) ReadFrom(stream io.Reader) (int64, error) { newset := New(uint(length)) if uint64(newset.length) != length { - return 0, errors.New("Unmarshalling error: type mismatch") + return 0, errors.New("unmarshalling error: type mismatch") } // Read remaining bytes as set |