118 lines
2.8 KiB
Go
118 lines
2.8 KiB
Go
// +build 386 amd64,!appengine
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package roaring
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import (
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"errors"
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"io"
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"reflect"
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"unsafe"
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)
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func (ac *arrayContainer) writeTo(stream io.Writer) (int, error) {
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buf := uint16SliceAsByteSlice(ac.content)
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return stream.Write(buf)
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}
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func (bc *bitmapContainer) writeTo(stream io.Writer) (int, error) {
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if bc.cardinality <= arrayDefaultMaxSize {
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return 0, errors.New("refusing to write bitmap container with cardinality of array container")
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}
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buf := uint64SliceAsByteSlice(bc.bitmap)
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return stream.Write(buf)
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}
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// readFrom reads an arrayContainer from stream.
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// PRE-REQUISITE: you must size the arrayContainer correctly (allocate b.content)
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// *before* you call readFrom. We can't guess the size in the stream
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// by this point.
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func (ac *arrayContainer) readFrom(stream io.Reader) (int, error) {
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buf := uint16SliceAsByteSlice(ac.content)
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return io.ReadFull(stream, buf)
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}
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func (bc *bitmapContainer) readFrom(stream io.Reader) (int, error) {
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buf := uint64SliceAsByteSlice(bc.bitmap)
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n, err := io.ReadFull(stream, buf)
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bc.computeCardinality()
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return n, err
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}
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func uint64SliceAsByteSlice(slice []uint64) []byte {
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// make a new slice header
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header := *(*reflect.SliceHeader)(unsafe.Pointer(&slice))
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// update its capacity and length
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header.Len *= 8
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header.Cap *= 8
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// return it
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return *(*[]byte)(unsafe.Pointer(&header))
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}
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func uint16SliceAsByteSlice(slice []uint16) []byte {
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// make a new slice header
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header := *(*reflect.SliceHeader)(unsafe.Pointer(&slice))
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// update its capacity and length
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header.Len *= 2
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header.Cap *= 2
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// return it
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return *(*[]byte)(unsafe.Pointer(&header))
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}
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func (bc *bitmapContainer) asLittleEndianByteSlice() []byte {
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return uint64SliceAsByteSlice(bc.bitmap)
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}
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// Deserialization code follows
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func byteSliceAsUint16Slice(slice []byte) []uint16 {
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if len(slice)%2 != 0 {
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panic("Slice size should be divisible by 2")
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}
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// make a new slice header
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header := *(*reflect.SliceHeader)(unsafe.Pointer(&slice))
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// update its capacity and length
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header.Len /= 2
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header.Cap /= 2
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// return it
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return *(*[]uint16)(unsafe.Pointer(&header))
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}
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func byteSliceAsUint64Slice(slice []byte) []uint64 {
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if len(slice)%8 != 0 {
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panic("Slice size should be divisible by 8")
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}
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// make a new slice header
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header := *(*reflect.SliceHeader)(unsafe.Pointer(&slice))
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// update its capacity and length
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header.Len /= 8
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header.Cap /= 8
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// return it
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return *(*[]uint64)(unsafe.Pointer(&header))
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}
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func byteSliceAsInterval16Slice(slice []byte) []interval16 {
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if len(slice)%4 != 0 {
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panic("Slice size should be divisible by 4")
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}
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// make a new slice header
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header := *(*reflect.SliceHeader)(unsafe.Pointer(&slice))
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// update its capacity and length
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header.Len /= 4
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header.Cap /= 4
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// return it
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return *(*[]interval16)(unsafe.Pointer(&header))
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}
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