toml: add encode<T> and decode<T> (#13244)

vlib/toml/tests/encode_and_decode_test.v

@@ -0,0 +1,58 @@
+import toml
+
+enum JobTitle {
+	manager
+	executive
+	worker
+}
+
+struct Employee {
+pub mut:
+	name     string
+	age      int
+	salary   f32
+	is_human bool
+	title    JobTitle
+}
+
+fn (e Employee) to_toml() string {
+	mut mp := map[string]toml.Any{}
+	mp['name'] = toml.Any(e.name)
+	mp['age'] = toml.Any(e.age)
+	mp['salary'] = toml.Any(e.salary)
+	mp['is_human'] = toml.Any(e.is_human)
+	mp['title'] = toml.Any(int(e.title))
+	return mp.to_toml()
+}
+
+fn (mut e Employee) from_toml(any toml.Any) {
+	mp := any.as_map()
+	e.name = mp['name'] or { toml.Any('') }.string()
+	e.age = mp['age'] or { toml.Any(0) }.int()
+	e.salary = mp['salary'] or { toml.Any(0) }.f32()
+	e.is_human = mp['is_human'] or { toml.Any(false) }.bool()
+	e.title = JobTitle(mp['title'] or { toml.Any(0) }.int())
+}
+
+fn test_encode_and_decode() {
+	x := Employee{'Peter', 28, 95000.5, true, .worker}
+	s := toml.encode<Employee>(x)
+	eprintln('Employee x: $s')
+	assert s == r'name = "Peter"
+age = 28
+salary = 95000.5
+is_human = true
+title = 2'
+
+	y := toml.decode<Employee>(s) or {
+		println(err)
+		assert false
+		return
+	}
+	eprintln('Employee y: $y')
+	assert y.name == 'Peter'
+	assert y.age == 28
+	assert y.salary == 95000.5
+	assert y.is_human == true
+	assert y.title == .worker
+}