51 lines
1.3 KiB
Go
51 lines
1.3 KiB
Go
package files
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import (
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"unicode/utf8"
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)
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func isBinary(content []byte, _ int) bool {
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maybeStr := string(content)
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runeCnt := utf8.RuneCount(content)
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runeIndex := 0
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gotRuneErrCnt := 0
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firstRuneErrIndex := -1
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const (
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// 8 and below are control chars (e.g. backspace, null, eof, etc)
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maxControlCharsCode = 8
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// 0xFFFD(65533) is the "error" Rune or "Unicode replacement character"
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// see https://golang.org/pkg/unicode/utf8/#pkg-constants
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unicodeReplacementChar = 0xFFFD
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)
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for _, b := range maybeStr {
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if b <= maxControlCharsCode {
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return true
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}
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if b == unicodeReplacementChar {
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// if it is not the last (utf8.UTFMax - x) rune
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if runeCnt > utf8.UTFMax && runeIndex < runeCnt-utf8.UTFMax {
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return true
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}
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// else it is the last (utf8.UTFMax - x) rune
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// there maybe Vxxx, VVxx, VVVx, thus, we may got max 3 0xFFFD rune (assume V is the byte we got)
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// for Chinese, it can only be Vxx, VVx, we may got max 2 0xFFFD rune
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gotRuneErrCnt++
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// mark the first time
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if firstRuneErrIndex == -1 {
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firstRuneErrIndex = runeIndex
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}
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}
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runeIndex++
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}
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// if last (utf8.UTFMax - x ) rune has the "error" Rune, but not all
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if firstRuneErrIndex != -1 && gotRuneErrCnt != runeCnt-firstRuneErrIndex {
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return true
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}
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return false
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}
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