Update documentation and release notes

CONTRIBUTING.md

@@ -44,12 +44,12 @@ this library's fields of application.
 [isocode639_1 url]: https://github.com/pemistahl/lingua-go/blob/main/isocode.go#L31
 [isocode639_3 url]: https://github.com/pemistahl/lingua-go/blob/main/isocode.go#L261
 [wikipedia isocodes list]: https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes
-[language url]: https://github.com/pemistahl/lingua-go/blob/main/language.go#L31
+[language url]: https://github.com/pemistahl/lingua-go/blob/main/language.go#L25
 [alphabet url]: https://github.com/pemistahl/lingua-go/blob/main/alphabet.go#L26
-[language method url]: https://github.com/pemistahl/lingua-go/blob/main/language.go#L607
+[language method url]: https://github.com/pemistahl/lingua-go/blob/main/language.go#L601
 [chars to languages mapping url]: https://github.com/pemistahl/lingua-go/blob/main/constant.go#L31
-[language model files writer url]: https://github.com/pemistahl/lingua-go/blob/main/writer.go#L55
-[test data files writer url]: https://github.com/pemistahl/lingua-go/blob/main/writer.go#L201
+[language model files writer url]: https://github.com/pemistahl/lingua-go/blob/main/writer.go#L56
+[test data files writer url]: https://github.com/pemistahl/lingua-go/blob/main/writer.go#L202
 [language models directory url]: https://github.com/pemistahl/lingua-go/tree/main/language-models
 [testdata directory url]: https://github.com/pemistahl/lingua-go/tree/main/cmd/language-testdata
 [accuracy reporter url]: https://github.com/pemistahl/lingua-go/blob/main/cmd/accuracy_reporter.go

README.md

@@ -1816,7 +1816,7 @@ Erroneously classified as Dutch: 0.20%, Latin: 0.10%
 
 ## 7. How to add it to your project?
 
-    go get github.com/pemistahl/lingua-go@v1.1.1
+    go get github.com/pemistahl/lingua-go
 
 ## 8. How to build?
 
@@ -2032,7 +2032,56 @@ build the detector from all supported languages. When you have knowledge about
 the texts you want to classify you can almost always rule out certain languages as impossible
 or unlikely to occur.
 
-### 9.6 Methods to build the LanguageDetector
+### 9.6 Detection of multiple languages in mixed-language texts
+
+In contrast to most other language detectors, *Lingua* is able to detect multiple languages 
+in mixed-language texts. This feature can yield quite reasonable results but it is still
+in an experimental state and therefore the detection result is highly dependent on the input
+text. It works best in high-accuracy mode with multiple long words for each language.
+The shorter the phrases and their words are, the less accurate are the results. Reducing the
+set of languages when building the language detector can also improve accuracy for this task
+if the languages occurring in the text are equal to the languages supported by the respective
+language detector instance.
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/pemistahl/lingua-go"
+)
+
+func main() {
+    languages := []lingua.Language{
+        lingua.English,
+        lingua.French,
+        lingua.German,
+    }
+
+    detector := lingua.NewLanguageDetectorBuilder().
+        FromLanguages(languages...).
+        Build()
+
+    sentence := "Parlez-vous français? " + 
+        "Ich spreche Französisch nur ein bisschen. " +
+        "A little bit is better than nothing."
+
+    for _, result := range detector.DetectMultipleLanguagesOf(sentence) {
+        fmt.Printf("%s: '%s'\n", result.Language(), sentence[result.StartIndex():result.EndIndex()])
+    }
+
+    // Output:
+    // French: 'Parlez-vous français? '
+    // German: 'Ich spreche Französisch nur ein bisschen. '
+    // English: 'A little bit is better than nothing.'
+}
+```
+
+In the example above, a slice of [`DetectionResult`](https://github.com/pemistahl/lingua-go/blob/main/result.go#L22)
+is returned. Each entry in the slice describes a contiguous single-language text section,
+providing start and end indices of the respective substring.
+
+### 9.7 Methods to build the LanguageDetector
 
 There might be classification tasks where you know beforehand that your language data is
 definitely not written in Latin, for instance. The detection accuracy can become better 
@@ -2062,9 +2111,9 @@ lingua.NewLanguageDetectorBuilder().FromIsoCodes639_1(lingua.EN, lingua.DE)
 lingua.NewLanguageDetectorBuilder().FromIsoCodes639_3(lingua.ENG, lingua.DEU)
 ```
 
-## 10. What's next for version 1.2.0?
+## 10. What's next for version 1.3.0?
 
-Take a look at the [planned issues](https://github.com/pemistahl/lingua-go/milestone/3).
+Take a look at the [planned issues](https://github.com/pemistahl/lingua-go/milestone/4).
 
 ## 11. Contributions
 

RELEASE_NOTES.md

@@ -1,3 +1,10 @@
+## Lingua 1.2.0 (released on 12 Dec 2022)
+
+### Features
+
+- The new method `LanguageDetector.DetectMultipleLanguagesOf()` has been
+  introduced. It allows to detect multiple languages in mixed-language text. (#9)
+
 ## Lingua 1.1.1 (released on 22 Nov 2022)
 
 ### Documentation

example_test.go

@@ -40,6 +40,31 @@ func Example_basic() {
 	// Output: English
 }
 
+func Example_multipleLanguagesDetection() {
+	languages := []lingua.Language{
+		lingua.English,
+		lingua.French,
+		lingua.German,
+	}
+
+	detector := lingua.NewLanguageDetectorBuilder().
+		FromLanguages(languages...).
+		Build()
+
+	sentence := "Parlez-vous français? " +
+		"Ich spreche Französisch nur ein bisschen. " +
+		"A little bit is better than nothing."
+
+	for _, result := range detector.DetectMultipleLanguagesOf(sentence) {
+		fmt.Printf("%s: '%s'\n", result.Language(), sentence[result.StartIndex():result.EndIndex()])
+	}
+
+	// Output:
+	// French: 'Parlez-vous français? '
+	// German: 'Ich spreche Französisch nur ein bisschen. '
+	// English: 'A little bit is better than nothing.'
+}
+
 // By default, Lingua returns the most likely language for a given input text.
 // However, there are certain words that are spelled the same in more than one
 // language. The word `prologue`, for instance, is both a valid English and

go.mod

@@ -3,7 +3,7 @@ module github.com/pemistahl/lingua-go
 go 1.18
 
 require (
-	github.com/pemistahl/lingua-go/serialization v0.0.0-00010101000000-000000000000
+	github.com/pemistahl/lingua-go/serialization v1.2.0
 	github.com/stretchr/testify v1.8.1
 	golang.org/x/exp v0.0.0-20221106115401-f9659909a136
 	google.golang.org/protobuf v1.28.1