103 lines
2.2 KiB
Go
103 lines
2.2 KiB
Go
package chardet
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import (
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"bytes"
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)
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var (
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utf16beBom = []byte{0xFE, 0xFF}
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utf16leBom = []byte{0xFF, 0xFE}
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utf32beBom = []byte{0x00, 0x00, 0xFE, 0xFF}
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utf32leBom = []byte{0xFF, 0xFE, 0x00, 0x00}
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)
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type recognizerUtf16be struct {
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}
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func newRecognizer_utf16be() *recognizerUtf16be {
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return &recognizerUtf16be{}
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}
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func (*recognizerUtf16be) Match(input *recognizerInput) (output recognizerOutput) {
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output = recognizerOutput{
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Charset: "UTF-16BE",
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}
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if bytes.HasPrefix(input.raw, utf16beBom) {
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output.Confidence = 100
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}
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return
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}
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type recognizerUtf16le struct {
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}
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func newRecognizer_utf16le() *recognizerUtf16le {
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return &recognizerUtf16le{}
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}
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func (*recognizerUtf16le) Match(input *recognizerInput) (output recognizerOutput) {
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output = recognizerOutput{
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Charset: "UTF-16LE",
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}
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if bytes.HasPrefix(input.raw, utf16leBom) && !bytes.HasPrefix(input.raw, utf32leBom) {
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output.Confidence = 100
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}
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return
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}
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type recognizerUtf32 struct {
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name string
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bom []byte
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decodeChar func(input []byte) uint32
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}
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func decodeUtf32be(input []byte) uint32 {
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return uint32(input[0])<<24 | uint32(input[1])<<16 | uint32(input[2])<<8 | uint32(input[3])
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}
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func decodeUtf32le(input []byte) uint32 {
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return uint32(input[3])<<24 | uint32(input[2])<<16 | uint32(input[1])<<8 | uint32(input[0])
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}
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func newRecognizer_utf32be() *recognizerUtf32 {
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return &recognizerUtf32{
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"UTF-32BE",
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utf32beBom,
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decodeUtf32be,
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}
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}
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func newRecognizer_utf32le() *recognizerUtf32 {
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return &recognizerUtf32{
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"UTF-32LE",
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utf32leBom,
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decodeUtf32le,
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}
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}
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func (r *recognizerUtf32) Match(input *recognizerInput) (output recognizerOutput) {
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output = recognizerOutput{
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Charset: r.name,
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}
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hasBom := bytes.HasPrefix(input.raw, r.bom)
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var numValid, numInvalid uint32
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for b := input.raw; len(b) >= 4; b = b[4:] {
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if c := r.decodeChar(b); c >= 0x10FFFF || (c >= 0xD800 && c <= 0xDFFF) {
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numInvalid++
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} else {
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numValid++
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}
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}
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if hasBom && numInvalid == 0 {
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output.Confidence = 100
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} else if hasBom && numValid > numInvalid*10 {
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output.Confidence = 80
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} else if numValid > 3 && numInvalid == 0 {
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output.Confidence = 100
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} else if numValid > 0 && numInvalid == 0 {
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output.Confidence = 80
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} else if numValid > numInvalid*10 {
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output.Confidence = 25
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}
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return
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}
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