125 lines
2.9 KiB
Go
125 lines
2.9 KiB
Go
package main
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import (
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"bufio"
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"bytes"
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"fmt"
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"io/ioutil"
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"log"
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"os"
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"regexp"
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"strconv"
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)
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var re *regexp.Regexp
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func main() {
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var input []byte
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var noDecompress bool
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var printSize bool
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if len(os.Args) > 1 {
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for i := 1; i < len(os.Args); i++ {
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if os.Args[i][0] != '-' {
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// Assume it's a filename
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// Read from the given filename
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input = fileToByteSlice(os.Args[1])
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} else {
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switch os.Args[i] {
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case "-size":
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printSize = true
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case "-dry":
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// -dry implies printSize
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printSize = true
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noDecompress = true
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}
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}
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}
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}
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if len(input) == 0 {
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// Must be stdin
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input = stdinToByteSlice()
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}
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input = bytes.TrimSpace(input)
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// re matches compression markers and submatches the values we care about
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re = regexp.MustCompile(`\((\d*)x(\d*)\)`)
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if noDecompress {
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cnt := depthDecompressLength(input)
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fmt.Println("Total Decompressed Bytes:", cnt)
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os.Exit(0)
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}
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output := depthDecompress(input)
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fmt.Println(string(output))
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if printSize {
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fmt.Println("Total Decompressed Bytes:", len(output))
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}
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}
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// depthDecompressLength counts how many uncompressed bytes are
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// in the byte slice by unravelling the compression levels
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// recursively
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func depthDecompressLength(cmp []byte) uint64 {
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mrkParts := re.FindStringSubmatch(string(cmp))
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if len(mrkParts) < 3 {
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// No compressionmarker, just return cmp length
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return uint64(len(cmp))
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}
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marker, mrkBytes, mrkDupe := []byte(mrkParts[0]), atoi(mrkParts[1]), atoi(mrkParts[2])
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mrkPos := bytes.Index(cmp, marker)
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if mrkPos > 0 {
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cmp = cmp[mrkPos:]
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}
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recurBytes := bytes.TrimPrefix(cmp, marker)[:mrkBytes]
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remainder := bytes.TrimPrefix(cmp, append(marker, recurBytes...))
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return uint64(mrkPos) + (depthDecompressLength(recurBytes) * uint64(mrkDupe)) + depthDecompressLength(remainder)
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}
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func depthDecompress(cmp []byte) []byte {
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mrkParts := re.FindStringSubmatch(string(cmp))
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if len(mrkParts) < 3 {
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// No compression marker, just return cmp length
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return cmp
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}
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marker, mrkBytes, mrkDupe := []byte(mrkParts[0]), atoi(mrkParts[1]), atoi(mrkParts[2])
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mrkPos := bytes.Index(cmp, marker)
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var ret []byte
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if mrkPos > 0 {
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ret = cmp[:mrkPos]
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cmp = cmp[mrkPos:]
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}
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recurBytes := bytes.TrimPrefix(cmp, marker)[:mrkBytes]
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remainder := bytes.TrimPrefix(cmp, append(marker, recurBytes...))
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ret = append(ret, bytes.Repeat(depthDecompress(recurBytes), mrkDupe)...)
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return append(ret, depthDecompress(remainder)...)
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}
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func fileToByteSlice(fn string) []byte {
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var c []byte
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var err error
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c, err = ioutil.ReadFile(fn)
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if err != nil {
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fmt.Println("Unable to read file: " + fn)
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os.Exit(1)
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}
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return c
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}
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func stdinToByteSlice() []byte {
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var input string
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scanner := bufio.NewScanner(os.Stdin)
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for scanner.Scan() {
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input += scanner.Text()
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}
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return []byte(input)
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}
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func atoi(i string) int {
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var ret int
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var err error
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if ret, err = strconv.Atoi(i); err != nil {
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log.Fatal("Invalid Atoi")
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}
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return ret
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}
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