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// Package chardet ports character set detection from ICU.
package chardet
import (
"errors"
"sort"
)
// Result contains all the information that charset detector gives.
type Result struct {
// IANA name of the detected charset.
Charset string
// IANA name of the detected language. It may be empty for some charsets.
Language string
// Confidence of the Result. Scale from 1 to 100. The bigger, the more confident.
Confidence int
}
// Detector implements charset detection.
type Detector struct {
recognizers []recognizer
stripTag bool
}
// List of charset recognizers
var recognizers = []recognizer{
newRecognizer_utf8(),
newRecognizer_utf16be(),
newRecognizer_utf16le(),
newRecognizer_utf32be(),
newRecognizer_utf32le(),
newRecognizer_8859_1_en(),
newRecognizer_8859_1_da(),
newRecognizer_8859_1_de(),
newRecognizer_8859_1_es(),
newRecognizer_8859_1_fr(),
newRecognizer_8859_1_it(),
newRecognizer_8859_1_nl(),
newRecognizer_8859_1_no(),
newRecognizer_8859_1_pt(),
newRecognizer_8859_1_sv(),
newRecognizer_8859_2_cs(),
newRecognizer_8859_2_hu(),
newRecognizer_8859_2_pl(),
newRecognizer_8859_2_ro(),
newRecognizer_8859_5_ru(),
newRecognizer_8859_6_ar(),
newRecognizer_8859_7_el(),
newRecognizer_8859_8_I_he(),
newRecognizer_8859_8_he(),
newRecognizer_windows_1251(),
newRecognizer_windows_1256(),
newRecognizer_KOI8_R(),
newRecognizer_8859_9_tr(),
newRecognizer_sjis(),
newRecognizer_gb_18030(),
newRecognizer_euc_jp(),
newRecognizer_euc_kr(),
newRecognizer_big5(),
newRecognizer_2022JP(),
newRecognizer_2022KR(),
newRecognizer_2022CN(),
newRecognizer_IBM424_he_rtl(),
newRecognizer_IBM424_he_ltr(),
newRecognizer_IBM420_ar_rtl(),
newRecognizer_IBM420_ar_ltr(),
}
// NewTextDetector creates a Detector for plain text.
func NewTextDetector() *Detector {
return &Detector{recognizers, false}
}
// NewHtmlDetector creates a Detector for Html.
func NewHtmlDetector() *Detector {
return &Detector{recognizers, true}
}
var (
NotDetectedError = errors.New("Charset not detected.")
)
// DetectBest returns the Result with highest Confidence.
func (d *Detector) DetectBest(b []byte) (r *Result, err error) {
var all []Result
if all, err = d.DetectAll(b); err == nil {
r = &all[0]
}
return
}
// DetectAll returns all Results which have non-zero Confidence. The Results are sorted by Confidence in descending order.
func (d *Detector) DetectAll(b []byte) ([]Result, error) {
input := newRecognizerInput(b, d.stripTag)
outputChan := make(chan recognizerOutput)
for _, r := range d.recognizers {
go matchHelper(r, input, outputChan)
}
outputs := make([]recognizerOutput, 0, len(d.recognizers))
for i := 0; i < len(d.recognizers); i++ {
o := <-outputChan
if o.Confidence > 0 {
outputs = append(outputs, o)
}
}
if len(outputs) == 0 {
return nil, NotDetectedError
}
sort.Sort(recognizerOutputs(outputs))
dedupOutputs := make([]Result, 0, len(outputs))
foundCharsets := make(map[string]struct{}, len(outputs))
for _, o := range outputs {
if _, found := foundCharsets[o.Charset]; !found {
dedupOutputs = append(dedupOutputs, Result(o))
foundCharsets[o.Charset] = struct{}{}
}
}
if len(dedupOutputs) == 0 {
return nil, NotDetectedError
}
return dedupOutputs, nil
}
func matchHelper(r recognizer, input *recognizerInput, outputChan chan<- recognizerOutput) {
outputChan <- r.Match(input)
}
type recognizerOutputs []recognizerOutput
func (r recognizerOutputs) Len() int { return len(r) }
func (r recognizerOutputs) Less(i, j int) bool { return r[i].Confidence > r[j].Confidence }
func (r recognizerOutputs) Swap(i, j int) { r[i], r[j] = r[j], r[i] }
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