[Concept] Regular Expressions-add exercise templates

docs/exercises.md

@@ -49,6 +49,14 @@ title: Exercises
     <li>25_range_iterators - Range over Iterators</li>
     <li>26_errors - Error Handling</li>
     <li>27_custom_errors - Custom Errors</li>
+    <li>28_defer - Defer</li>
+    <li>29_go_routines - Go Routines</li>
+    <li>30_channels - Channels</li>
+    <li>31_mutexes - Mutexes</li>
+    <li>32_sorting - Sorting</li>
+    <li>33_string_formatting - String Formatting</li>
+    <li>34_channel_buffering - Channel Buffering</li>
+    <li>41_regex - Regular Expressions</li>
     <li>36_json - JSON Processing</li>
     <li>37_xml - XML Processing</li>
   </ul>

internal/exercises/catalog.yaml

@@ -169,6 +169,11 @@ concepts:
   test_regex: ".*"
   hints:
     - Use `make(chan T, N)` to create a buffered channel and `<-` to send and receive on it.
+- slug: 35_channel_sync
+  title: Channel Synchronization
+  test_regex: ".*"
+  hints:
+    - Use a buffered boolean channel and wait till go routine completes.
 - slug: 39_channel_directions
   title: Channel Directions
   test_regex: ".*"
@@ -178,11 +183,18 @@ concepts:
     - Send 50 jobs to the worker pool.
     - Receive results from the worker pool and store them in a `rs` slice.
     - Enforce type safety by specifying the channel directions in worker function.
-- slug: 35_channel_sync
-  title: Channel Synchronization
-  test_regex: ".*"
-  hints:
-    - Use a buffered boolean channel and wait till go routine completes.
+- slug: 41_regex
+  title: Regular Expressions
+  test_regex: ".*"
+  hints:
+    - Use regexp.MustCompile to create compiled regular expressions.
+    - Use MatchString to test if a string matches a pattern.
+    - Use FindAllString to extract all matches from text.
+    - Use ReplaceAllString to replace matches with new text.
+    - "Email regex: ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}$"
+    - "Phone regex: ^\\(\\d{3}\\) \\d{3}-\\d{4}$"
+    - "Number regex: \\d+\\.?\\d*"
+    - "Vowel regex: [aeiouAEIOU]"
 - slug: 37_xml
   title: XML Encoding and Decoding
   test_regex: ".*"

internal/exercises/solutions/41_regex/regex.go

@@ -0,0 +1,35 @@
+package regex
+
+import "regexp"
+
+// IsValidEmail returns true if the email address is valid.
+func IsValidEmail(email string) bool {
+	pattern := `^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$`
+	re := regexp.MustCompile(pattern)
+	return re.MatchString(email)
+}
+
+// ExtractNumbers returns all numbers found in the input string.
+func ExtractNumbers(text string) []string {
+	pattern := `\d+\.?\d*`
+	re := regexp.MustCompile(pattern)
+	matches := re.FindAllString(text, -1)
+	if matches == nil {
+		return []string{}
+	}
+	return matches
+}
+
+// ReplaceVowels replaces all vowels with asterisks.
+func ReplaceVowels(text string) string {
+	pattern := `[aeiouAEIOU]`
+	re := regexp.MustCompile(pattern)
+	return re.ReplaceAllString(text, "*")
+}
+
+// IsPhoneNumber returns true if the phone number matches format (XXX) XXX-XXXX.
+func IsPhoneNumber(phone string) bool {
+	pattern := `^\(\d{3}\) \d{3}-\d{4}$`
+	re := regexp.MustCompile(pattern)
+	return re.MatchString(phone)
+}

internal/exercises/templates/41_regex/regex.go

@@ -0,0 +1,37 @@
+package regex
+
+// Task:
+// Implement regular expression functions using Go's regexp package.
+//
+// 1. Implement IsValidEmail to validate email addresses using regex.
+// 2. Implement ExtractNumbers to extract all numbers from a string.
+// 3. Implement ReplaceVowels to replace all vowels with asterisks.
+// 4. Implement IsPhoneNumber to validate phone numbers in format (XXX) XXX-XXXX.
+
+// IsValidEmail should return true if the email address is valid.
+// A valid email should have the format: [email protected]
+func IsValidEmail(email string) bool {
+	// TODO: implement using regexp.MustCompile and MatchString
+	return false
+}
+
+// ExtractNumbers should return all numbers found in the input string.
+// Numbers can be integers or decimals (e.g., "123", "45.67").
+func ExtractNumbers(text string) []string {
+	// TODO: implement using regexp.FindAllString
+	return nil
+}
+
+// ReplaceVowels should replace all vowels (a, e, i, o, u) with asterisks.
+// Case-insensitive replacement.
+func ReplaceVowels(text string) string {
+	// TODO: implement using regexp.MustCompile and ReplaceAllString
+	return ""
+}
+
+// IsPhoneNumber should return true if the phone number matches format (XXX) XXX-XXXX.
+// Example: (123) 456-7890
+func IsPhoneNumber(phone string) bool {
+	// TODO: implement using regexp.MustCompile and MatchString
+	return false
+}

internal/exercises/templates/41_regex/regex_test.go

@@ -0,0 +1,99 @@
+package regex
+
+import "testing"
+
+func TestIsValidEmail(t *testing.T) {
+	tests := []struct {
+		email    string
+		expected bool
+	}{
+		{"[email protected]", true},
+		{"[email protected]", true},
+		{"invalid-email", false},
+		{"@domain.com", false},
+		{"user@", false},
+		{"user@domain", false},
+		{"", false},
+	}
+
+	for _, test := range tests {
+		result := IsValidEmail(test.email)
+		if result != test.expected {
+			t.Errorf("IsValidEmail(%q) = %v, want %v", test.email, result, test.expected)
+		}
+	}
+}
+
+func TestExtractNumbers(t *testing.T) {
+	tests := []struct {
+		text     string
+		expected []string
+	}{
+		{"I have 123 apples and 45.67 oranges", []string{"123", "45.67"}},
+		{"The price is $99.99", []string{"99.99"}},
+		{"No numbers here", []string{}},
+		{"123", []string{"123"}},
+		{"12.34.56", []string{"12.34", "56"}},
+		{"", []string{}},
+	}
+
+	for _, test := range tests {
+		result := ExtractNumbers(test.text)
+		if len(result) != len(test.expected) {
+			t.Errorf("ExtractNumbers(%q) length = %d, want %d", test.text, len(result), len(test.expected))
+			continue
+		}
+		for i, num := range result {
+			if num != test.expected[i] {
+				t.Errorf("ExtractNumbers(%q)[%d] = %q, want %q", test.text, i, num, test.expected[i])
+			}
+		}
+	}
+}
+
+func TestReplaceVowels(t *testing.T) {
+	tests := []struct {
+		text     string
+		expected string
+	}{
+		{"hello", "h*ll*"},
+		{"HELLO", "H*LL*"},
+		{"Hello World", "H*ll* W*rld"},
+		{"bcdfg", "bcdfg"},
+		{"", ""},
+		{"aeiou", "*****"},
+		{"AEIOU", "*****"},
+	}
+
+	for _, test := range tests {
+		result := ReplaceVowels(test.text)
+		if result != test.expected {
+			t.Errorf("ReplaceVowels(%q) = %q, want %q", test.text, result, test.expected)
+		}
+	}
+}
+
+func TestIsPhoneNumber(t *testing.T) {
+	tests := []struct {
+		phone    string
+		expected bool
+	}{
+		{"(123) 456-7890", true},
+		{"(555) 123-4567", true},
+		{"(000) 000-0000", true},
+		{"123-456-7890", false},
+		{"(123)456-7890", false},
+		{"(123) 4567890", false},
+		{"123 456 7890", false},
+		{"(123) 456-789", false},
+		{"(12) 456-7890", false},
+		{"", false},
+	}
+
+	for _, test := range tests {
+		result := IsPhoneNumber(test.phone)
+		if result != test.expected {
+			t.Errorf("IsPhoneNumber(%q) = %v, want %v", test.phone, result, test.expected)
+		}
+	}
+}