commit f41d6f248a9388286bbaece5f2a5be3170159abc
Author: Aneurin Barker Snook <a@aneur.in>
Date:   Fri Oct 6 11:58:24 2023 +0100

    add workspace, validation

diff --git a/email.go b/email.go
new file mode 100644
index 0000000..2365d62
--- /dev/null
+++ b/email.go
@@ -0,0 +1,18 @@
+package validate
+
+import (
+	"errors"
+	"regexp"
+)
+
+// Based on https://stackoverflow.com/a/201378
+var emailRegexp = regexp.MustCompile("^(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|\"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*\")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9]))\\.){3}(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\\])$")
+
+// Email validates an email address.
+func Email(value string) error {
+	if !emailRegexp.MatchString(value) {
+		return errors.New("Invalid email address")
+	}
+
+	return nil
+}
diff --git a/email_test.go b/email_test.go
new file mode 100644
index 0000000..95415c3
--- /dev/null
+++ b/email_test.go
@@ -0,0 +1,27 @@
+package validate
+
+import "testing"
+
+func TestInvalidEmail(t *testing.T) {
+	valid := []string{
+		"testexample.com",
+	}
+
+	for _, email := range valid {
+		if err := Email(email); err == nil {
+			t.Errorf("%s is not a valid email", email)
+		}
+	}
+}
+
+func TestValidEmail(t *testing.T) {
+	valid := []string{
+		"test@example.com",
+	}
+
+	for _, email := range valid {
+		if err := Email(email); err != nil {
+			t.Errorf("%s is a valid email", email)
+		}
+	}
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..1a55cba
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/recipeer/go/validate
+
+go 1.21.1
diff --git a/uuid.go b/uuid.go
new file mode 100644
index 0000000..d6915e6
--- /dev/null
+++ b/uuid.go
@@ -0,0 +1,18 @@
+package validate
+
+import (
+	"errors"
+	"regexp"
+)
+
+var uuidRegexp = regexp.MustCompile("^[a-f0-9]{8}(-[a-f0-9]{4}){3}-[a-f0-9]{12}$")
+
+// UUID validates a UUID string.
+// The UUID must be formatted with separators.
+func UUID(value string) error {
+	if !uuidRegexp.MatchString(value) {
+		return errors.New("Invalid UUID")
+	}
+
+	return nil
+}
diff --git a/uuid_test.go b/uuid_test.go
new file mode 100644
index 0000000..665b9dc
--- /dev/null
+++ b/uuid_test.go
@@ -0,0 +1,32 @@
+package validate
+
+import "testing"
+
+func TestInvalidUUID(t *testing.T) {
+	invalid := []string{
+		"Not a UUID",
+		"00000000-00-0000-0000-00000000000000",
+		"00000000000000000000000000000000",
+		"01234567-89ab-cdef-ghij-klmnopqrstuv",
+	}
+
+	for _, uuid := range invalid {
+		if err := UUID(uuid); err == nil {
+			t.Errorf("%s is not a valid UUID", uuid)
+		}
+	}
+}
+
+func TestValidUUID(t *testing.T) {
+	valid := []string{
+		"00000000-0000-0000-0000-000000000000",
+		"01234567-89ab-cdef-0123-456789abcdef",
+		"abcdef01-2345-6789-abcd-ef0123456789",
+	}
+
+	for _, uuid := range valid {
+		if err := UUID(uuid); err != nil {
+			t.Errorf("%s is a valid UUID", uuid)
+		}
+	}
+}