regexp: examples for Regexp.FindIndex and Regexp.FindAllSubmatchIndex methods

This commit adds examples that demonstrate usage in a practical way.

Change-Id: I105baf610764c14a2c247cfc0b0c06f27888d377
Reviewed-on: https://go-review.googlesource.com/78635
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/src/regexp/example_test.go b/src/regexp/example_test.go
index eb8cd4ea94..d65464665f 100644
--- a/src/regexp/example_test.go
+++ b/src/regexp/example_test.go
@@ -249,3 +249,45 @@ func ExampleRegexp_ExpandString() {
 	// option2=value2
 	// option3=value3
 }
+
+func ExampleRegexp_FindIndex() {
+	content := []byte(`
+	# comment line
+	option1: value1
+	option2: value2
+`)
+	// Regex pattern captures "key: value" pair from the content.
+	pattern := regexp.MustCompile(`(?m)(?P<key>\w+):\s+(?P<value>\w+)$`)
+
+	loc := pattern.FindIndex(content)
+	fmt.Println(loc)
+	fmt.Println(string(content[loc[0]:loc[1]]))
+	// Output:
+	// [18 33]
+	// option1: value1
+}
+func ExampleRegexp_FindAllSubmatchIndex() {
+	content := []byte(`
+	# comment line
+	option1: value1
+	option2: value2
+`)
+	// Regex pattern captures "key: value" pair from the content.
+	pattern := regexp.MustCompile(`(?m)(?P<key>\w+):\s+(?P<value>\w+)$`)
+	allIndexes := pattern.FindAllSubmatchIndex(content, -1)
+	for _, loc := range allIndexes {
+		fmt.Println(loc)
+		fmt.Println(string(content[loc[0]:loc[1]]))
+		fmt.Println(string(content[loc[2]:loc[3]]))
+		fmt.Println(string(content[loc[4]:loc[5]]))
+	}
+	// Output:
+	// [18 33 18 25 27 33]
+	// option1: value1
+	// option1
+	// value1
+	// [35 50 35 42 44 50]
+	// option2: value2
+	// option2
+	// value2
+}