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Fix paragraph viewing bugs+indexing helpers for ring buffer

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bloeys
2022-07-24 20:56:20 +04:00
parent 75c33325f7
commit 10372dd743
3 changed files with 141 additions and 91 deletions
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51
ring/ring.go
View File

@ -1,6 +1,7 @@
package ring
import (
"github.com/bloeys/nterm/assert"
"golang.org/x/exp/constraints"
)
@ -73,10 +74,46 @@ func (b *Buffer[T]) Get(index uint64) (val T) {
return b.Data[(b.Start+int64(index))%b.Cap]
}
func (b *Buffer[T]) AbsIndex(relIndex uint64) uint64 {
// AbsIndexFromRel takes an index relative to Buffer.Start and returns an absolute index into Buffer.Data
func (b *Buffer[T]) AbsIndexFromRel(relIndex uint64) uint64 {
return uint64((b.Start + int64(relIndex)) % b.Cap)
}
// RelIndexFromAbs takes an index into Buffer.Data and returns an index relative to Buffer.Start
func (b *Buffer[T]) RelIndexFromAbs(absIndex uint64) uint64 {
assert.T(absIndex < uint64(b.Cap), "absIndex must be between 0 and Buffer.Cap-1")
return uint64((int64(absIndex) - b.Start + b.Cap) % b.Cap)
}
// AbsIndexFromWriteCount takes the total number of elements written and returns the index of the
// last written element after 'writeCount' writes.
//
// For example, if writeCount=1 then the index of last written element (the returned value) is zero.
// For a buffer of cap=4, after 5 writes the last updated index is absIndex=0
//
// writeCount=0 is undefined because no elements have been written to yet. In this case zero is returned.
func (b *Buffer[T]) AbsIndexFromWriteCount(writeCount uint64) uint64 {
if writeCount == 0 {
return 0
}
return (writeCount - 1) % uint64(b.Cap)
}
// RelIndexFromWriteCount takes the total number of elements written and returns the index of the
// last written element after 'writeCount' writes relative to the current Buffer.Start value.
//
// For example, if writeCount=1 then the index of last written element (the returned value) is zero.
// For a buffer of cap=4, after 5 writes the last updated index is absIndex=0
//
// writeCount=0 is undefined because no elements have been written to yet. In this case zero is returned.
func (b *Buffer[T]) RelIndexFromWriteCount(writeCount uint64) uint64 {
if writeCount == 0 {
return 0
}
return b.RelIndexFromAbs(b.AbsIndexFromWriteCount(writeCount))
}
// Views returns two slices that have 'Len' elements in total between them.
// The first slice is from Start till min(Start+Len, Cap). If Start+Len<=Cap then the first slice contains all the data and the second is empty.
// If Start+Len>Cap then the first slice contains the data from Start till Cap, and the second slice contains data from 0 till Start+Len-Cap (basically the remaining elements to reach Len in total)
@ -91,11 +128,19 @@ func (b *Buffer[T]) Views() (v1, v2 []T) {
}
v1 = b.Data[b.Start:]
v2 = b.Data[:b.Start+b.Len-b.Cap]
v2 = b.Data[:(b.Start+b.Len)%b.Cap]
return
}
func (b *Buffer[T]) ViewsFromTo(fromIndex, toIndex uint64) (v1, v2 []T) {
func (b *Buffer[T]) ViewsFromToWriteCount(fromIndex, toIndex uint64) (v1, v2 []T) {
fromIndex = b.RelIndexFromWriteCount(fromIndex)
toIndex = b.RelIndexFromWriteCount(toIndex)
return b.ViewsFromToRelIndex(fromIndex, toIndex)
}
// ViewsFromToRelIndex takes indices relative to Buffer.Start and returns views adjusted to contain
// elements between these two indices (inclusive)
func (b *Buffer[T]) ViewsFromToRelIndex(fromIndex, toIndex uint64) (v1, v2 []T) {
toIndex++ // We convert the index into a length (e.g. from=0, to=0 is from=0, len=1)
if toIndex <= fromIndex || fromIndex >= uint64(b.Len) {

28
ring/ring_test.go
View File

@ -71,77 +71,77 @@ func TestRing(t *testing.T) {
// ViewsFromTo
b2 = ring.NewBuffer[int](4)
v11, v22 := b2.ViewsFromTo(0, 0)
v11, v22 := b2.ViewsFromToRelIndex(0, 0)
Check(t, 0, len(v11))
Check(t, 0, len(v22))
b2.Write(1, 2, 3, 4)
v11, v22 = b2.ViewsFromTo(5, 0)
v11, v22 = b2.ViewsFromToRelIndex(5, 0)
Check(t, 0, len(v11))
Check(t, 0, len(v22))
v11, v22 = b2.ViewsFromTo(0, 0)
v11, v22 = b2.ViewsFromToRelIndex(0, 0)
Check(t, 1, len(v11))
Check(t, 0, len(v22))
CheckArr(t, []int{1}, v11)
v11, v22 = b2.ViewsFromTo(0, 1)
v11, v22 = b2.ViewsFromToRelIndex(0, 1)
Check(t, 2, len(v11))
Check(t, 0, len(v22))
CheckArr(t, []int{1, 2}, v11)
v11, v22 = b2.ViewsFromTo(0, 3)
v11, v22 = b2.ViewsFromToRelIndex(0, 3)
Check(t, 4, len(v11))
Check(t, 0, len(v22))
CheckArr(t, []int{1, 2, 3, 4}, v11)
v11, v22 = b2.ViewsFromTo(0, 4)
v11, v22 = b2.ViewsFromToRelIndex(0, 4)
Check(t, 4, len(v11))
Check(t, 0, len(v22))
CheckArr(t, []int{1, 2, 3, 4}, v11)
v11, v22 = b2.ViewsFromTo(0, 40)
v11, v22 = b2.ViewsFromToRelIndex(0, 40)
Check(t, 4, len(v11))
Check(t, 0, len(v22))
CheckArr(t, []int{1, 2, 3, 4}, v11)
v11, v22 = b2.ViewsFromTo(3, 40)
v11, v22 = b2.ViewsFromToRelIndex(3, 40)
Check(t, 1, len(v11))
Check(t, 0, len(v22))
CheckArr(t, []int{4}, v11)
b2.Write(5, 6)
v11, v22 = b2.ViewsFromTo(3, 40)
v11, v22 = b2.ViewsFromToRelIndex(3, 40)
Check(t, 0, len(v11))
Check(t, 1, len(v22))
CheckArr(t, []int{6}, v22)
v11, v22 = b2.ViewsFromTo(1, 2)
v11, v22 = b2.ViewsFromToRelIndex(1, 2)
Check(t, 1, len(v11))
Check(t, 1, len(v22))
CheckArr(t, []int{4}, v11)
CheckArr(t, []int{5}, v22)
v11, v22 = b2.ViewsFromTo(0, 1)
v11, v22 = b2.ViewsFromToRelIndex(0, 1)
Check(t, 2, len(v11))
Check(t, 0, len(v22))
CheckArr(t, []int{3, 4}, v11)
v11, v22 = b2.ViewsFromTo(0, 2)
v11, v22 = b2.ViewsFromToRelIndex(0, 2)
Check(t, 2, len(v11))
Check(t, 1, len(v22))
CheckArr(t, []int{3, 4}, v11)
CheckArr(t, []int{5}, v22)
v11, v22 = b2.ViewsFromTo(0, 3)
v11, v22 = b2.ViewsFromToRelIndex(0, 3)
Check(t, 2, len(v11))
Check(t, 2, len(v22))
CheckArr(t, []int{3, 4}, v11)
CheckArr(t, []int{5, 6}, v22)
v11, v22 = b2.ViewsFromTo(2, 3)
v11, v22 = b2.ViewsFromToRelIndex(2, 3)
Check(t, 0, len(v11))
Check(t, 2, len(v22))
CheckArr(t, []int{5, 6}, v22)