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Diffstat (limited to 'vendor/github.com/bits-and-blooms/bitset/bitset.go')
| -rw-r--r-- | vendor/github.com/bits-and-blooms/bitset/bitset.go | 952 |
1 files changed, 952 insertions, 0 deletions
diff --git a/vendor/github.com/bits-and-blooms/bitset/bitset.go b/vendor/github.com/bits-and-blooms/bitset/bitset.go new file mode 100644 index 000000000..d688806a5 --- /dev/null +++ b/vendor/github.com/bits-and-blooms/bitset/bitset.go @@ -0,0 +1,952 @@ +/* +Package bitset implements bitsets, a mapping +between non-negative integers and boolean values. It should be more +efficient than map[uint] bool. + +It provides methods for setting, clearing, flipping, and testing +individual integers. + +But it also provides set intersection, union, difference, +complement, and symmetric operations, as well as tests to +check whether any, all, or no bits are set, and querying a +bitset's current length and number of positive bits. + +BitSets are expanded to the size of the largest set bit; the +memory allocation is approximately Max bits, where Max is +the largest set bit. BitSets are never shrunk. On creation, +a hint can be given for the number of bits that will be used. + +Many of the methods, including Set,Clear, and Flip, return +a BitSet pointer, which allows for chaining. + +Example use: + + import "bitset" + var b BitSet + b.Set(10).Set(11) + if b.Test(1000) { + b.Clear(1000) + } + if B.Intersection(bitset.New(100).Set(10)).Count() > 1 { + fmt.Println("Intersection works.") + } + +As an alternative to BitSets, one should check out the 'big' package, +which provides a (less set-theoretical) view of bitsets. + +*/ +package bitset + +import ( + "bufio" + "bytes" + "encoding/base64" + "encoding/binary" + "encoding/json" + "errors" + "fmt" + "io" + "strconv" +) + +// the wordSize of a bit set +const wordSize = uint(64) + +// log2WordSize is lg(wordSize) +const log2WordSize = uint(6) + +// allBits has every bit set +const allBits uint64 = 0xffffffffffffffff + +// default binary BigEndian +var binaryOrder binary.ByteOrder = binary.BigEndian + +// default json encoding base64.URLEncoding +var base64Encoding = base64.URLEncoding + +// Base64StdEncoding Marshal/Unmarshal BitSet with base64.StdEncoding(Default: base64.URLEncoding) +func Base64StdEncoding() { base64Encoding = base64.StdEncoding } + +// LittleEndian Marshal/Unmarshal Binary as Little Endian(Default: binary.BigEndian) +func LittleEndian() { binaryOrder = binary.LittleEndian } + +// A BitSet is a set of bits. The zero value of a BitSet is an empty set of length 0. +type BitSet struct { + length uint + set []uint64 +} + +// Error is used to distinguish errors (panics) generated in this package. +type Error string + +// safeSet will fixup b.set to be non-nil and return the field value +func (b *BitSet) safeSet() []uint64 { + if b.set == nil { + b.set = make([]uint64, wordsNeeded(0)) + } + return b.set +} + +// From is a constructor used to create a BitSet from an array of integers +func From(buf []uint64) *BitSet { + return &BitSet{uint(len(buf)) * 64, buf} +} + +// Bytes returns the bitset as array of integers +func (b *BitSet) Bytes() []uint64 { + return b.set +} + +// wordsNeeded calculates the number of words needed for i bits +func wordsNeeded(i uint) int { + if i > (Cap() - wordSize + 1) { + return int(Cap() >> log2WordSize) + } + return int((i + (wordSize - 1)) >> log2WordSize) +} + +// New creates a new BitSet with a hint that length bits will be required +func New(length uint) (bset *BitSet) { + defer func() { + if r := recover(); r != nil { + bset = &BitSet{ + 0, + make([]uint64, 0), + } + } + }() + + bset = &BitSet{ + length, + make([]uint64, wordsNeeded(length)), + } + + return bset +} + +// Cap returns the total possible capacity, or number of bits +func Cap() uint { + return ^uint(0) +} + +// Len returns the number of bits in the BitSet. +// Note the difference to method Count, see example. +func (b *BitSet) Len() uint { + return b.length +} + +// 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) + } else if cap(b.set) >= nsize { + b.set = b.set[:nsize] // fast resize + } else if len(b.set) < nsize { + newset := make([]uint64, nsize, 2*nsize) // increase capacity 2x + copy(newset, b.set) + b.set = newset + } + b.length = i + 1 + } +} + +// Test whether bit i is set. +func (b *BitSet) Test(i uint) bool { + if i >= b.length { + return false + } + return b.set[i>>log2WordSize]&(1<<(i&(wordSize-1))) != 0 +} + +// 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)) + return b +} + +// Clear bit i to 0 +func (b *BitSet) Clear(i uint) *BitSet { + if i >= b.length { + return b + } + b.set[i>>log2WordSize] &^= 1 << (i & (wordSize - 1)) + return b +} + +// 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) + } + return b.Clear(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) + } + b.set[i>>log2WordSize] ^= 1 << (i & (wordSize - 1)) + return b +} + +// FlipRange bit in [start, end). +// If end>= Cap(), this function will panic. +// Warning: using a very large value for 'end' +// 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) FlipRange(start, end uint) *BitSet { + if start >= end { + return b + } + + b.extendSetMaybe(end - 1) + var startWord uint = start >> log2WordSize + var endWord uint = end >> log2WordSize + b.set[startWord] ^= ^(^uint64(0) << (start & (wordSize - 1))) + for i := startWord; i < endWord; i++ { + b.set[i] = ^b.set[i] + } + b.set[endWord] ^= ^uint64(0) >> (-end & (wordSize - 1)) + return b +} + +// 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(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 + 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. +// +// Depending on the size of your BitSet, and where you are inserting the new entry, +// this method could be extremely slow and in some cases might cause the entire BitSet +// to be recopied. +func (b *BitSet) InsertAt(idx uint) *BitSet { + insertAtElement := (idx >> log2WordSize) + + // if length of set is a multiple of wordSize we need to allocate more space first + if b.isLenExactMultiple() { + b.set = append(b.set, uint64(0)) + } + + var i uint + for i = uint(len(b.set) - 1); i > insertAtElement; i-- { + // all elements above the position where we want to insert can simply by shifted + b.set[i] <<= 1 + + // we take the most significant bit of the previous element and set it as + // the least significant bit of the current element + b.set[i] |= (b.set[i-1] & 0x8000000000000000) >> 63 + } + + // generate a mask to extract the data that we need to shift left + // within the element where we insert a bit + dataMask := ^(uint64(1)<<uint64(idx&(wordSize-1)) - 1) + + // extract that data that we'll shift + data := b.set[i] & dataMask + + // set the positions of the data mask to 0 in the element where we insert + b.set[i] &= ^dataMask + + // shift data mask to the left and insert its data to the slice element + b.set[i] |= data << 1 + + // add 1 to length of BitSet + b.length++ + + return b +} + +// String creates a string representation of the Bitmap +func (b *BitSet) String() string { + // follows code from https://github.com/RoaringBitmap/roaring + var buffer bytes.Buffer + start := []byte("{") + buffer.Write(start) + counter := 0 + i, e := b.NextSet(0) + for e { + counter = counter + 1 + // to avoid exhausting the memory + if counter > 0x40000 { + buffer.WriteString("...") + break + } + buffer.WriteString(strconv.FormatInt(int64(i), 10)) + i, e = b.NextSet(i + 1) + if e { + buffer.WriteString(",") + } + } + buffer.WriteString("}") + return buffer.String() +} + +// DeleteAt deletes the bit at the given index position from +// within the bitset +// All the bits residing on the left of the deleted bit get +// shifted right by 1 +// The running time of this operation may potentially be +// relatively slow, O(length) +func (b *BitSet) DeleteAt(i uint) *BitSet { + // the index of the slice element where we'll delete a bit + deleteAtElement := i >> log2WordSize + + // generate a mask for the data that needs to be shifted right + // within that slice element that gets modified + dataMask := ^((uint64(1) << (i & (wordSize - 1))) - 1) + + // extract the data that we'll shift right from the slice element + data := b.set[deleteAtElement] & dataMask + + // set the masked area to 0 while leaving the rest as it is + b.set[deleteAtElement] &= ^dataMask + + // shift the previously extracted data to the right and then + // set it in the previously masked area + b.set[deleteAtElement] |= (data >> 1) & dataMask + + // loop over all the consecutive slice elements to copy each + // lowest bit into the highest position of the previous element, + // then shift the entire content to the right by 1 + for i := int(deleteAtElement) + 1; i < len(b.set); i++ { + b.set[i-1] |= (b.set[i] & 1) << 63 + b.set[i] >>= 1 + } + + b.length = b.length - 1 + + return b +} + +// NextSet returns the next bit set from the specified index, +// 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) { + return 0, false + } + w := b.set[x] + w = w >> (i & (wordSize - 1)) + if w != 0 { + return i + trailingZeroes64(w), true + } + x = x + 1 + for x < len(b.set) { + if b.set[x] != 0 { + return uint(x)*wordSize + trailingZeroes64(b.set[x]), true + } + x = x + 1 + + } + return 0, false +} + +// NextSetMany returns many next bit sets from the specified index, +// including possibly the current index and up to cap(buffer). +// If the returned slice has len zero, then no more set bits were found +// +// buffer := make([]uint, 256) // this should be reused +// j := uint(0) +// j, buffer = bitmap.NextSetMany(j, buffer) +// for ; len(buffer) > 0; j, buffer = bitmap.NextSetMany(j,buffer) { +// for k := range buffer { +// do something with buffer[k] +// } +// 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) + x := int(i >> log2WordSize) + if x >= len(b.set) || capacity == 0 { + return 0, myanswer[:0] + } + skip := i & (wordSize - 1) + word := b.set[x] >> skip + myanswer = myanswer[:capacity] + size := int(0) + for word != 0 { + r := trailingZeroes64(word) + t := word & ((^word) + 1) + myanswer[size] = r + i + size++ + if size == capacity { + goto End + } + word = word ^ t + } + x++ + for idx, word := range b.set[x:] { + for word != 0 { + r := trailingZeroes64(word) + t := word & ((^word) + 1) + myanswer[size] = r + (uint(x+idx) << 6) + size++ + if size == capacity { + goto End + } + word = word ^ t + } + } +End: + if size > 0 { + return myanswer[size-1], myanswer[:size] + } + return 0, myanswer[:0] +} + +// NextClear returns the next clear bit from the specified index, +// including possibly the current index +// along with an error code (true = valid, false = no bit found i.e. all bits are set) +func (b *BitSet) NextClear(i uint) (uint, bool) { + x := int(i >> log2WordSize) + if x >= len(b.set) { + return 0, false + } + w := b.set[x] + w = w >> (i & (wordSize - 1)) + wA := allBits >> (i & (wordSize - 1)) + index := i + trailingZeroes64(^w) + if w != wA && index < b.length { + return index, true + } + x++ + for x < len(b.set) { + index = uint(x)*wordSize + trailingZeroes64(^b.set[x]) + if b.set[x] != allBits && index < b.length { + return index, true + } + x++ + } + return 0, false +} + +// ClearAll clears the entire BitSet +func (b *BitSet) ClearAll() *BitSet { + if b != nil && b.set != nil { + for i := range b.set { + b.set[i] = 0 + } + } + return b +} + +// wordCount returns the number of words used in a bit set +func (b *BitSet) wordCount() int { + return len(b.set) +} + +// Clone this BitSet +func (b *BitSet) Clone() *BitSet { + c := New(b.length) + if b.set != nil { // Clone should not modify current object + copy(c.set, b.set) + } + return c +} + +// Copy into a destination BitSet +// Returning the size of the destination BitSet +// like array copy +func (b *BitSet) Copy(c *BitSet) (count uint) { + if c == nil { + return + } + if b.set != nil { // Copy should not modify current object + copy(c.set, b.set) + } + count = c.length + if b.length < c.length { + count = b.length + } + return +} + +// Count (number of set bits). +// Also known as "popcount" or "population count". +func (b *BitSet) Count() uint { + if b != nil && b.set != nil { + return uint(popcntSlice(b.set)) + } + return 0 +} + +// Equal tests the equivalence of two BitSets. +// False if they are of different sizes, otherwise true +// only if all the same bits are set +func (b *BitSet) Equal(c *BitSet) bool { + if c == nil || b == nil { + return c == b + } + if b.length != c.length { + return false + } + if b.length == 0 { // if they have both length == 0, then could have nil set + return true + } + // testing for equality shoud not transform the bitset (no call to safeSet) + + for p, v := range b.set { + if c.set[p] != v { + return false + } + } + return true +} + +func panicIfNull(b *BitSet) { + if b == nil { + panic(Error("BitSet must not be null")) + } +} + +// Difference of base set and other set +// This is the BitSet equivalent of &^ (and not) +func (b *BitSet) Difference(compare *BitSet) (result *BitSet) { + panicIfNull(b) + panicIfNull(compare) + result = b.Clone() // clone b (in case b is bigger than compare) + l := int(compare.wordCount()) + if l > int(b.wordCount()) { + l = int(b.wordCount()) + } + for i := 0; i < l; i++ { + result.set[i] = b.set[i] &^ compare.set[i] + } + return +} + +// DifferenceCardinality computes the cardinality of the differnce +func (b *BitSet) DifferenceCardinality(compare *BitSet) uint { + panicIfNull(b) + panicIfNull(compare) + l := int(compare.wordCount()) + if l > int(b.wordCount()) { + l = int(b.wordCount()) + } + cnt := uint64(0) + cnt += popcntMaskSlice(b.set[:l], compare.set[:l]) + cnt += popcntSlice(b.set[l:]) + return uint(cnt) +} + +// InPlaceDifference computes the difference of base set and other set +// This is the BitSet equivalent of &^ (and not) +func (b *BitSet) InPlaceDifference(compare *BitSet) { + panicIfNull(b) + panicIfNull(compare) + l := int(compare.wordCount()) + if l > int(b.wordCount()) { + l = int(b.wordCount()) + } + for i := 0; i < l; i++ { + b.set[i] &^= compare.set[i] + } +} + +// Convenience function: return two bitsets ordered by +// increasing length. Note: neither can be nil +func sortByLength(a *BitSet, b *BitSet) (ap *BitSet, bp *BitSet) { + if a.length <= b.length { + ap, bp = a, b + } else { + ap, bp = b, a + } + return +} + +// Intersection of base set and other set +// This is the BitSet equivalent of & (and) +func (b *BitSet) Intersection(compare *BitSet) (result *BitSet) { + panicIfNull(b) + panicIfNull(compare) + b, compare = sortByLength(b, compare) + result = New(b.length) + for i, word := range b.set { + result.set[i] = word & compare.set[i] + } + return +} + +// IntersectionCardinality computes the cardinality of the union +func (b *BitSet) IntersectionCardinality(compare *BitSet) uint { + panicIfNull(b) + panicIfNull(compare) + b, compare = sortByLength(b, compare) + cnt := popcntAndSlice(b.set, compare.set) + return uint(cnt) +} + +// InPlaceIntersection destructively computes the intersection of +// base set and the compare set. +// This is the BitSet equivalent of & (and) +func (b *BitSet) InPlaceIntersection(compare *BitSet) { + panicIfNull(b) + panicIfNull(compare) + l := int(compare.wordCount()) + if l > int(b.wordCount()) { + l = int(b.wordCount()) + } + for i := 0; i < l; i++ { + b.set[i] &= compare.set[i] + } + for i := l; i < len(b.set); i++ { + b.set[i] = 0 + } + if compare.length > 0 { + b.extendSetMaybe(compare.length - 1) + } +} + +// Union of base set and other set +// This is the BitSet equivalent of | (or) +func (b *BitSet) Union(compare *BitSet) (result *BitSet) { + panicIfNull(b) + panicIfNull(compare) + b, compare = sortByLength(b, compare) + result = compare.Clone() + for i, word := range b.set { + result.set[i] = word | compare.set[i] + } + return +} + +// UnionCardinality computes the cardinality of the uniton of the base set +// and the compare set. +func (b *BitSet) UnionCardinality(compare *BitSet) uint { + panicIfNull(b) + panicIfNull(compare) + b, compare = sortByLength(b, compare) + cnt := popcntOrSlice(b.set, compare.set) + if len(compare.set) > len(b.set) { + cnt += popcntSlice(compare.set[len(b.set):]) + } + return uint(cnt) +} + +// InPlaceUnion creates the destructive union of base set and compare set. +// This is the BitSet equivalent of | (or). +func (b *BitSet) InPlaceUnion(compare *BitSet) { + panicIfNull(b) + panicIfNull(compare) + l := int(compare.wordCount()) + if l > int(b.wordCount()) { + l = int(b.wordCount()) + } + if compare.length > 0 { + b.extendSetMaybe(compare.length - 1) + } + for i := 0; i < l; i++ { + b.set[i] |= compare.set[i] + } + if len(compare.set) > l { + for i := l; i < len(compare.set); i++ { + b.set[i] = compare.set[i] + } + } +} + +// SymmetricDifference of base set and other set +// This is the BitSet equivalent of ^ (xor) +func (b *BitSet) SymmetricDifference(compare *BitSet) (result *BitSet) { + panicIfNull(b) + panicIfNull(compare) + b, compare = sortByLength(b, compare) + // compare is bigger, so clone it + result = compare.Clone() + for i, word := range b.set { + result.set[i] = word ^ compare.set[i] + } + return +} + +// SymmetricDifferenceCardinality computes the cardinality of the symmetric difference +func (b *BitSet) SymmetricDifferenceCardinality(compare *BitSet) uint { + panicIfNull(b) + panicIfNull(compare) + b, compare = sortByLength(b, compare) + cnt := popcntXorSlice(b.set, compare.set) + if len(compare.set) > len(b.set) { + cnt += popcntSlice(compare.set[len(b.set):]) + } + return uint(cnt) +} + +// InPlaceSymmetricDifference creates the destructive SymmetricDifference of base set and other set +// This is the BitSet equivalent of ^ (xor) +func (b *BitSet) InPlaceSymmetricDifference(compare *BitSet) { + panicIfNull(b) + panicIfNull(compare) + l := int(compare.wordCount()) + if l > int(b.wordCount()) { + l = int(b.wordCount()) + } + if compare.length > 0 { + b.extendSetMaybe(compare.length - 1) + } + for i := 0; i < l; i++ { + b.set[i] ^= compare.set[i] + } + if len(compare.set) > l { + for i := l; i < len(compare.set); i++ { + b.set[i] = compare.set[i] + } + } +} + +// Is the length an exact multiple of word sizes? +func (b *BitSet) isLenExactMultiple() bool { + return b.length%wordSize == 0 +} + +// Clean last word by setting unused bits to 0 +func (b *BitSet) cleanLastWord() { + if !b.isLenExactMultiple() { + b.set[len(b.set)-1] &= allBits >> (wordSize - b.length%wordSize) + } +} + +// Complement computes the (local) complement of a biset (up to length bits) +func (b *BitSet) Complement() (result *BitSet) { + panicIfNull(b) + result = New(b.length) + for i, word := range b.set { + result.set[i] = ^word + } + result.cleanLastWord() + return +} + +// All returns true if all bits are set, false otherwise. Returns true for +// empty sets. +func (b *BitSet) All() bool { + panicIfNull(b) + return b.Count() == b.length +} + +// None returns true if no bit is set, false otherwise. Returns true for +// empty sets. +func (b *BitSet) None() bool { + panicIfNull(b) + if b != nil && b.set != nil { + for _, word := range b.set { + if word > 0 { + return false + } + } + return true + } + return true +} + +// Any returns true if any bit is set, false otherwise +func (b *BitSet) Any() bool { + panicIfNull(b) + return !b.None() +} + +// IsSuperSet returns true if this is a superset of the other set +func (b *BitSet) IsSuperSet(other *BitSet) bool { + for i, e := other.NextSet(0); e; i, e = other.NextSet(i + 1) { + if !b.Test(i) { + return false + } + } + return true +} + +// IsStrictSuperSet returns true if this is a strict superset of the other set +func (b *BitSet) IsStrictSuperSet(other *BitSet) bool { + return b.Count() > other.Count() && b.IsSuperSet(other) +} + +// DumpAsBits dumps a bit set as a string of bits +func (b *BitSet) DumpAsBits() string { + if b.set == nil { + return "." + } + buffer := bytes.NewBufferString("") + i := len(b.set) - 1 + for ; i >= 0; i-- { + fmt.Fprintf(buffer, "%064b.", b.set[i]) + } + return buffer.String() +} + +// BinaryStorageSize returns the binary storage requirements +func (b *BitSet) BinaryStorageSize() int { + return binary.Size(uint64(0)) + binary.Size(b.set) +} + +// WriteTo writes a BitSet to a stream +func (b *BitSet) WriteTo(stream io.Writer) (int64, error) { + length := uint64(b.length) + + // Write length + err := binary.Write(stream, binaryOrder, length) + if err != nil { + return 0, err + } + + // Write set + err = binary.Write(stream, binaryOrder, b.set) + return int64(b.BinaryStorageSize()), err +} + +// ReadFrom reads a BitSet from a stream written using WriteTo +func (b *BitSet) ReadFrom(stream io.Reader) (int64, error) { + var length uint64 + + // Read length first + err := binary.Read(stream, binaryOrder, &length) + if err != nil { + return 0, err + } + newset := New(uint(length)) + + if uint64(newset.length) != length { + return 0, errors.New("unmarshalling error: type mismatch") + } + + // Read remaining bytes as set + err = binary.Read(stream, binaryOrder, newset.set) + if err != nil { + return 0, err + } + + *b = *newset + return int64(b.BinaryStorageSize()), nil +} + +// MarshalBinary encodes a BitSet into a binary form and returns the result. +func (b *BitSet) MarshalBinary() ([]byte, error) { + var buf bytes.Buffer + writer := bufio.NewWriter(&buf) + + _, err := b.WriteTo(writer) + if err != nil { + return []byte{}, err + } + + err = writer.Flush() + + return buf.Bytes(), err +} + +// UnmarshalBinary decodes the binary form generated by MarshalBinary. +func (b *BitSet) UnmarshalBinary(data []byte) error { + buf := bytes.NewReader(data) + reader := bufio.NewReader(buf) + + _, err := b.ReadFrom(reader) + + return err +} + +// MarshalJSON marshals a BitSet as a JSON structure +func (b *BitSet) MarshalJSON() ([]byte, error) { + buffer := bytes.NewBuffer(make([]byte, 0, b.BinaryStorageSize())) + _, err := b.WriteTo(buffer) + if err != nil { + return nil, err + } + + // URLEncode all bytes + return json.Marshal(base64Encoding.EncodeToString(buffer.Bytes())) +} + +// UnmarshalJSON unmarshals a BitSet from JSON created using MarshalJSON +func (b *BitSet) UnmarshalJSON(data []byte) error { + // Unmarshal as string + var s string + err := json.Unmarshal(data, &s) + if err != nil { + return err + } + + // URLDecode string + buf, err := base64Encoding.DecodeString(s) + if err != nil { + return err + } + + _, err = b.ReadFrom(bytes.NewReader(buf)) + return err +} |