strings: add examples for Lines, SplitSeq, SplitAfterSeq, FieldsSeq and FieldsFuncSeq

Change-Id: I1e5085ff2ed7f3d75ac3dc34ab72be6b55729fb7
Reviewed-on: https://go-review.googlesource.com/c/go/+/647575
Auto-Submit: Ian Lance Taylor <iant@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: cuishuang

src/strings/example_test.go

@@ -458,3 +458,93 @@ func ExampleToValidUTF8() {
 	// abc
 	// abc
 }
+
+func ExampleLines() {
+	text := "Hello\nWorld\nGo Programming\n"
+	for line := range strings.Lines(text) {
+		fmt.Printf("%q\n", line)
+	}
+
+	// Output:
+	// "Hello\n"
+	// "World\n"
+	// "Go Programming\n"
+}
+
+func ExampleSplitSeq() {
+	s := "a,b,c,d"
+	for part := range strings.SplitSeq(s, ",") {
+		fmt.Printf("%q\n", part)
+	}
+
+	// Output:
+	// "a"
+	// "b"
+	// "c"
+	// "d"
+}
+
+func ExampleSplitAfterSeq() {
+	s := "a,b,c,d"
+	for part := range strings.SplitAfterSeq(s, ",") {
+		fmt.Printf("%q\n", part)
+	}
+
+	// Output:
+	// "a,"
+	// "b,"
+	// "c,"
+	// "d"
+}
+
+func ExampleFieldsSeq() {
+	text := "The quick brown fox"
+	fmt.Println("Split string into fields:")
+	for word := range strings.FieldsSeq(text) {
+		fmt.Printf("%q\n", word)
+	}
+
+	textWithSpaces := "  lots   of   spaces  "
+	fmt.Println("\nSplit string with multiple spaces:")
+	for word := range strings.FieldsSeq(textWithSpaces) {
+		fmt.Printf("%q\n", word)
+	}
+
+	// Output:
+	// Split string into fields:
+	// "The"
+	// "quick"
+	// "brown"
+	// "fox"
+	//
+	// Split string with multiple spaces:
+	// "lots"
+	// "of"
+	// "spaces"
+}
+
+func ExampleFieldsFuncSeq() {
+	text := "The quick brown fox"
+	fmt.Println("Split on whitespace(similar to FieldsSeq):")
+	for word := range strings.FieldsFuncSeq(text, unicode.IsSpace) {
+		fmt.Printf("%q\n", word)
+	}
+
+	mixedText := "abc123def456ghi"
+	fmt.Println("\nSplit on digits:")
+	for word := range strings.FieldsFuncSeq(mixedText, unicode.IsDigit) {
+		fmt.Printf("%q\n", word)
+	}
+
+	// Output:
+	// Split on whitespace(similar to FieldsSeq):
+	// "The"
+	// "quick"
+	// "brown"
+	// "fox"
+	//
+	// Split on digits:
+	// "abc"
+	// "def"
+	// "ghi"
+}