indexcompression

Documentation

Overview

Example (DecodeIndexList)

fmt.Println(DecodeIndexList([]int32{5}, 4))
fmt.Println(DecodeIndexList([]int32{5}, 5))
fmt.Println(DecodeIndexList([]int32{5}, 6))
fmt.Println(DecodeIndexList([]int32{}, 1))
fmt.Println(DecodeIndexList([]int32{1, 5, 7, 12, 4, 10, 14}, 50))
fmt.Println(DecodeIndexList([]int32{1, 5, -1, 8, 12, 4, 10, 14}, 50))
fmt.Println(DecodeIndexList([]int32{1, 5, -4, 8, 12, 4, 10, 14}, 50))
fmt.Println(DecodeIndexList([]int32{-1, 5, -1, 8, 12, 4, 10, 14}, 50))
fmt.Println(DecodeIndexList([]int32{1, 5, -1, 8, 12, 4, 10, 14, -1}, 50))
fmt.Println(DecodeIndexList([]int32{1, -1, 4, -1, 8}, 50))
fmt.Println(DecodeIndexList([]int32{1, -1, 4, 6, -1, 5}, 50))
fmt.Println(DecodeIndexList([]int32{1, -1, 4, 6, -1, 6}, 50))
fmt.Println(DecodeIndexList([]int32{1, -1, 4, 6, -1, 7}, 50))
fmt.Println(DecodeIndexList([]int32{1, -1, 4, 6, -1, 8}, 50))
// We don't ensure there are no repeats or they're in order...
fmt.Println(DecodeIndexList([]int32{1, -1, 4, 2, -1, 8, 11, 13, -1, 16}, 50))
// Check that expansion going past array size is found
fmt.Println(DecodeIndexList([]int32{1, -1, 12}, 10))
// And specified value going past
fmt.Println(DecodeIndexList([]int32{1, 3, 5, 12, 2}, 10))
// Verify arraySizeOptional is optional!
fmt.Println(DecodeIndexList([]int32{1, 3, 5, 12, 2}, -1))

Output:

[] index 5 out of bounds: 4
[] index 5 out of bounds: 5
[5] <nil>
[] <nil>
[1 5 7 12 4 10 14] <nil>
[1 5 6 7 8 12 4 10 14] <nil>
[] invalid index: -4
[] indexes start with -1
[] indexes end with -1
[1 2 3 4 5 6 7 8] <nil>
[] invalid range: 6->5
[] invalid range: 6->6
[] invalid range: 6->7
[1 2 3 4 6 7 8] <nil>
[1 2 3 4 2 3 4 5 6 7 8 11 13 14 15 16] <nil>
[] index 12 out of bounds: 10
[] index 12 out of bounds: 10
[1 3 5 12 2] <nil>

Example (EncodeIndexList)

fmt.Println(EncodeIndexList([]uint32{9, 22, 8}))
fmt.Println(EncodeIndexList([]uint32{9, 7, 9, 8}))
fmt.Println(EncodeIndexList([]uint32{9, 7, 8, 7}))
fmt.Println(EncodeIndexList([]uint32{9, 7, 8, 8}))
fmt.Println(EncodeIndexList([]uint32{1002, 14, 1005, 15, 1003, 1004, 13, 16}))
fmt.Println(EncodeIndexList([]uint32{7, 8}))
fmt.Println(EncodeIndexList([]uint32{9, 7, 8}))
fmt.Println(EncodeIndexList([]uint32{1, 3, 5, 12, 2}))
fmt.Println(EncodeIndexList([]uint32{}))
fmt.Println(EncodeIndexList([]uint32{7}))
fmt.Println(EncodeIndexList([]uint32{7, 8, 2, 9, 10, 11, 12, 14, 13, 16}))
fmt.Println(EncodeIndexList([]uint32{1002, 14, 1005, 15, 1003, 1004, 13, 1100, 16}))
fmt.Println(EncodeIndexList([]int32{1002, 14, 1005, 15, 1003, 1004, 13, 1100, 16}))
fmt.Println(EncodeIndexList([]uint32{9, math.MaxInt32, 8}))
fmt.Println(EncodeIndexList([]uint32{9, math.MaxInt32 + 1, 8}))

Output:

[8 9 22] <nil>
[7 -1 9] <nil>
[7 -1 9] <nil>
[7 -1 9] <nil>
[13 -1 16 1002 -1 1005] <nil>
[7 8] <nil>
[7 -1 9] <nil>
[1 -1 3 5 12] <nil>
[] <nil>
[7] <nil>
[2 7 -1 14 16] <nil>
[13 -1 16 1002 -1 1005 1100] <nil>
[13 -1 16 1002 -1 1005 1100] <nil>
[8 9 2147483647] <nil>
[] index list had value > maxint

Index

• func DecodeIndexList(encodedIndexes []int32, arraySizeOptional int) ([]uint32, error)
• func EncodeIndexList[T uint32 | int32](indexes []T) ([]int32, error)

Examples

• Package (DecodeIndexList)
• Package (EncodeIndexList)

Functions

func DecodeIndexList

func DecodeIndexList(encodedIndexes []int32, arraySizeOptional int) ([]uint32, error)

Returns a list of unsigned indexes, and an error if: - A negative value is seen that is not -1 - <start idx>, -1, <end idx which is <= start idx>

func EncodeIndexList

func EncodeIndexList[T uint32 | int32](indexes []T) ([]int32, error)

Given a list of unsigned indexes, this SORTS them and encodes them such that runs of consecutive numbers like 4, 5, 6, 7 are replaced with the sequence 4, -1, 7 - thereby reducing storage size NOTE: even though it takes unsigned int32s, it cannot support values over maxint, it just takes unsigned to signify that an array index can't be negative