package util
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import(
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"github.com/pierrec/lz4"
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"github.com/long/test/logger"
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)
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// 1. oldstring element is not in new : abandon(delete)
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// 2. new element is not in oldstring : add(add)
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func Difference(oldstring []string, newstring []string) map[string]string {
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var diff = make(map[string]string)
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// Loop two times, first to find oldstring strings not in newstring,
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// second loop to find newstring strings not in oldstring
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for i := 0; i < 2; i++ {
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for _, s1 := range oldstring {
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found := false
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for _, s2 := range newstring {
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if s1 == s2 {
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found = true
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break
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}
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}
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// String not found. We add it to return slice
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if !found && i == 0 {
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diff[s1] = "delete"
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}
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if !found && i != 0 {
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diff[s1] = "add"
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}
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}
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// Swap the slices, only if it was the first loop
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if i == 0 {
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oldstring, newstring = newstring, oldstring
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}
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}
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return diff
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}
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// UnCompress uncompress
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func UnCompress(in []byte) ([]byte, error) {
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out := make([]byte, 10*len(in))
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n, err := lz4.UncompressBlock(in, out)
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if err != nil {
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logger.Error("uncompress error: ", err)
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return nil, err
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}
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out = out[:n] // uncompressed data
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return out, nil
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}
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// Compress compress
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func Compress(in []byte) ([]byte, error) {
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out := make([]byte, len(in))
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ht := make([]int, 64<<10) // buffer for the compression table
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n, err := lz4.CompressBlock(in, out, ht)
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if err != nil {
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logger.Error("compress: ", err)
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return nil, err
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}
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if n >= len(in) {
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logger.Error("image is not compressible")
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}
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out = out[:n] // compressed data
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return out, nil
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}
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