GO by example, part 5

5-go-by-example/49-regex.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+)
+
+// Go offers built-in support for regular expressions
+func main() {
+	// test whether a pattern matches a string
+	match, _ := regexp.MatchString("p([a-z]+)ch", "peach")
+	fmt.Println(match)
+
+	// compile an optimized Regexp struct
+	r, _ := regexp.Compile("p([a-z]+)ch")
+
+	// match test like earlier
+	fmt.Println(r.MatchString("peach"))
+
+	// finds the match for the regex
+	fmt.Println(r.FindString("peach punch"))
+
+	// finds the first match but returns the start and end indexes for the match instead of the matching text
+	fmt.Println("idx:", r.FindStringIndex("peach punch"))
+
+	// include information about both the whole-pattern matches and the submatches within those matches
+	fmt.Println(r.FindStringSubmatch("peach punch"))
+
+	// information about the indexes of matches and submatches
+	fmt.Println(r.FindStringSubmatchIndex("peach punch"))
+
+	// apply to all matches in the input, not just the first
+	fmt.Println(r.FindAllString("peach punch pinch", -1))
+
+	// the All variants are available for the other functions too
+	fmt.Println("all:", r.FindAllStringSubmatchIndex(
+		"peach punch pinch", -1))
+
+	// providing a non-negative integer as the second argument to these functions will limit the number of matches
+	fmt.Println(r.FindAllString("peach punch pinch", 2))
+
+	// provide []byte arguments and drop String from the function name
+	fmt.Println(r.Match([]byte("peach")))
+
+	// MustCompile panics instead of returning an error, which makes it safer to use for global variables
+	r = regexp.MustCompile("p([a-z]+)ch")
+	fmt.Println("regexp:", r)
+
+	// replace subsets of strings with other values
+	fmt.Println(r.ReplaceAllString("a peach", "<fruit>"))
+
+	// transform matched text with a given functions
+	in := []byte("a peach")
+	out := r.ReplaceAllFunc(in, bytes.ToUpper)
+	fmt.Println(string(out))
+}