50: Regular expression examples

Author: symonk

regex/main.go

@@ -8,6 +8,18 @@ import (
 // Go offers built in support for regular expressions
 func Run() {
 	fmt.Println(stringContainsAnyMatch("^hello.*", "hello world"))
+	pattern := compiledPattern("^f")
+	fmt.Println(pattern.MatchString("fo"))
+	fmt.Println(pattern.MatchString("oof"))
+	// matches `f` only.
+	fmt.Println(pattern.FindString("foolproof"))
+	pattern = compiledPattern("hello.*")
+	// [3-14] index matching
+	fmt.Println("index: ", pattern.FindStringIndex("ok hello there"))
+	// Find information around full matches and sub matches within those full matches
+	fmt.Println(pattern.FindStringSubmatch("ok hello world test"))
+	// Replace all occurrences
+	replaceAllOccurrences("hello[0-9]", "hello1, hello2, hello3, helloX, helloY", "<replaced>")
 }
 
 // Check if a string has any matches of a given pattern.
@@ -18,3 +30,14 @@ func stringContainsAnyMatch(pattern string, str string) bool {
 	}
 	return match
 }
+
+// Compiles are pattern for reuse. Panics if invalid pattern.
+func compiledPattern(pattern string) *regexp.Regexp {
+	return regexp.MustCompile(pattern)
+}
+
+func replaceAllOccurrences(pattern string, s string, r string) {
+	p := regexp.MustCompile(pattern)
+	result := p.ReplaceAllString(s, r)
+	fmt.Printf("Replaced %s with %s: %s\n", s, r, result)
+}