cb7534dcdf
Allows to compress short arbitrary strings and returns a string using base64 url encoding. Generator for tables included and a few samples has been added. Add more to init.go Tested with fuzzing for crash resistance and symmetry, see fuzz.go
60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
package filename
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import (
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"encoding/base64"
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"encoding/binary"
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"github.com/klauspost/compress/huff0"
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)
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// Encode will encode the string and return a base64 (url) compatible version of it.
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// Calling Decode with the returned string should always succeed.
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// It is not a requirement that the input string is valid utf-8.
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func Encode(s string) string {
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initCoders()
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bestSize := len(s)
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bestTable := tableUncompressed
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org := []byte(s)
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bestOut := []byte(s)
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// Try all tables and choose the best
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for i, enc := range encTables[:] {
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if len(org) <= 1 || len(org) > maxLength {
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// Use the uncompressed
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break
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}
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if enc == nil {
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continue
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}
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// Try to encode using table.
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err := func() error {
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encTableLocks[i].Lock()
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defer encTableLocks[i].Unlock()
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out, _, err := huff0.Compress1X(org, enc)
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if err != nil {
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return err
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}
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if len(out) < bestSize {
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bestOut = bestOut[:len(out)]
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bestTable = i
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bestSize = len(out)
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copy(bestOut, out)
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}
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return nil
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}()
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// If input is a single byte repeated store as RLE or save uncompressed.
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if err == huff0.ErrUseRLE {
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if len(org) > 2 {
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// Encode as one byte repeated since it will be smaller than uncompressed.
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n := binary.PutUvarint(bestOut, uint64(len(org)))
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bestOut = bestOut[:n+1]
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bestOut[n] = org[0]
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bestSize = n + 1
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bestTable = tableRLE
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}
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break
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}
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}
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return string(encodeURL[bestTable]) + base64.URLEncoding.EncodeToString(bestOut)
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}
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