toml: add generic automatic decoding and encoding of simple structs, when they don't implement custom methods (#17970)

vlib/toml/tests/encode_and_decode_test.v

@@ -1,13 +1,40 @@
 import toml
 
 enum JobTitle {
-	manager
-	executive
 	worker
+	executive
+	manager
 }
 
+struct Pet {
+	name      string
+	nicknames []string
+	age       u64
+	income    int
+	height    f32
+	has_furr  bool
+	title     JobTitle
+	address   Address
+	// *¹ Currently it is only possible to decode a single nested struct generically.
+	// As soon as we decode another nested struct (e.g. within this struct, like `contact` below)
+	// or only one nested struct within another struct, it results in wrong values or errors.
+	// Related issue: https://github.com/vlang/v/issues/18110
+	// contact Contact
+}
+
+struct Address {
+	street string
+	city   string
+}
+
+// *¹
+/*
+struct Contact {
+	phone string
+}*/
+
 struct Employee {
-pub mut:
+mut:
 	name     string
 	age      int
 	salary   f32
@@ -15,13 +42,49 @@ pub mut:
 	title    JobTitle
 }
 
+struct Arrs {
+	strs  []string
+	bools []bool
+	ints  []int
+	i64s  []i64
+	u64s  []u64
+	f32s  []f32
+	f64s  []f64
+	dts   []toml.DateTime
+	dates []toml.Date
+	times []toml.Time
+}
+
+fn test_encode_and_decode() {
+	// *¹
+	// p := Pet{'Mr. Scratchy McEvilPaws', ['Freddy', 'Fred', 'Charles'], 8, -1, 0.8, true, .manager, Address{'1428 Elm Street', 'Springwood'}, Contact{'123-456-7890'}}
+	p := Pet{'Mr. Scratchy McEvilPaws', ['Freddy', 'Fred', 'Charles'], 8, -1, 0.8, true, .manager, Address{'1428 Elm Street', 'Springwood'}}
+	s := 'name = "Mr. Scratchy McEvilPaws"
+nicknames = [
+  "Freddy",
+  "Fred",
+  "Charles"
+]
+age = 8
+income = -1
+height = 0.8
+has_furr = true
+title = 2
+address = { street = "1428 Elm Street", city = "Springwood" }'
+	// contact = { phone = "123-456-7890" }' // *¹
+
+	assert toml.encode[Pet](p) == s
+	assert toml.decode[Pet](s)! == p
+}
+
 pub 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))
+	// Change some values to assert that the custom method is used instead of generic encoding.
+	mp['salary'] = toml.Any(f32(e.salary) + 5000.0)
+	mp['title'] = toml.Any(int(e.title) + 1)
 	return mp.to_toml()
 }
 
@@ -29,19 +92,20 @@ pub 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 = unsafe { JobTitle(mp['title'] or { toml.Any(0) }.int()) }
+	// Change some values to assert that the custom method is used instead of generic decoding.
+	e.salary = mp['salary'] or { toml.Any(0) }.f32() - 15000.0
+	e.title = unsafe { JobTitle(mp['title'] or { toml.Any(0) }.int() - 2) }
 }
 
-fn test_encode_and_decode() {
+fn test_custom_encode_and_decode() {
-	x := Employee{'Peter', 28, 95000.5, true, .worker}
+	x := Employee{'Peter', 28, 95000.5, true, .executive}
 	s := toml.encode[Employee](x)
 	eprintln('Employee x: ${s}')
 	assert s == r'name = "Peter"
 age = 28
-salary = 95000.5
 is_human = true
+salary = 100000.5
 title = 2'
 
 	y := toml.decode[Employee](s) or {
@@ -52,7 +116,64 @@ title = 2'
 	eprintln('Employee y: ${y}')
 	assert y.name == 'Peter'
 	assert y.age == 28
-	assert y.salary == 95000.5
+	assert y.salary == 85000.5
 	assert y.is_human == true
 	assert y.title == .worker
 }
+
+fn test_array_encode_decode() {
+	a := Arrs{
+		strs: ['foo', 'bar']
+		bools: [true, false]
+		ints: [-1, 2]
+		i64s: [i64(-2)]
+		u64s: [u64(123)]
+		f32s: [f32(1.0), f32(2.5)]
+		f64s: [100000.5, -123.0]
+		dts: [toml.DateTime{'1979-05-27T07:32:00Z'}, toml.DateTime{'1979-05-27T07:32:00Z'}]
+		dates: [toml.Date{'1979-05-27'}, toml.Date{'2022-12-31'}]
+		times: [toml.Time{'07:32:59'}, toml.Time{'17:32:04'}]
+	}
+
+	s := 'strs = [
+  "foo",
+  "bar"
+]
+bools = [
+  true,
+  false
+]
+ints = [
+  -1,
+  2
+]
+i64s = [
+  -2
+]
+u64s = [
+  123
+]
+f32s = [
+  1.0,
+  2.5
+]
+f64s = [
+  100000.5,
+  -123.0
+]
+dts = [
+  1979-05-27T07:32:00Z,
+  1979-05-27T07:32:00Z
+]
+dates = [
+  1979-05-27,
+  2022-12-31
+]
+times = [
+  07:32:59,
+  17:32:04
+]'
+
+	assert toml.encode[Arrs](a) == s
+	assert toml.decode[Arrs](s)! == a
+}

vlib/toml/toml.v

@@ -13,17 +13,99 @@ pub struct Null {
 }
 
 // decode decodes a TOML `string` into the target type `T`.
+// If `T` has a custom `.from_toml()` method, it will be used instead of the default.
 pub fn decode[T](toml_txt string) !T {
 	doc := parse_text(toml_txt)!
 	mut typ := T{}
-	typ.from_toml(doc.to_any())
+	$for method in T.methods {
+		$if method.name == 'from_toml' {
+			typ.$method(doc.to_any())
+			return typ
+		}
+	}
+	decode_struct[T](doc.to_any(), mut typ)
 	return typ
 }
 
+fn decode_struct[T](doc Any, mut typ T) {
+	$for field in T.fields {
+		value := doc.value(field.name)
+		$if field.is_enum {
+			typ.$(field.name) = value.int()
+		} $else $if field.typ is string {
+			typ.$(field.name) = value.string()
+		} $else $if field.typ is bool {
+			typ.$(field.name) = value.bool()
+		} $else $if field.typ is int {
+			typ.$(field.name) = value.int()
+		} $else $if field.typ is i64 {
+			typ.$(field.name) = value.i64()
+		} $else $if field.typ is u64 {
+			typ.$(field.name) = value.u64()
+		} $else $if field.typ is f32 {
+			typ.$(field.name) = value.f32()
+		} $else $if field.typ is f64 {
+			typ.$(field.name) = value.f64()
+		} $else $if field.typ is DateTime {
+			typ.$(field.name) = value.datetime()
+		} $else $if field.typ is Date {
+			typ.$(field.name) = value.date()
+		} $else $if field.typ is Time {
+			typ.$(field.name) = value.time()
+		} $else $if field.is_array {
+			arr := value.array()
+			match typeof(typ.$(field.name)).name {
+				'[]string' { typ.$(field.name) = arr.as_strings() }
+				'[]int' { typ.$(field.name) = arr.map(it.int()) }
+				'[]i64' { typ.$(field.name) = arr.map(it.i64()) }
+				'[]u64' { typ.$(field.name) = arr.map(it.u64()) }
+				'[]f32' { typ.$(field.name) = arr.map(it.f32()) }
+				'[]f64' { typ.$(field.name) = arr.map(it.f64()) }
+				'[]bool' { typ.$(field.name) = arr.map(it.bool()) }
+				'[]toml.DateTime' { typ.$(field.name) = arr.map(it.datetime()) }
+				'[]toml.Date' { typ.$(field.name) = arr.map(it.date()) }
+				'[]toml.Time' { typ.$(field.name) = arr.map(it.time()) }
+				else {}
+			}
+		} $else $if field.is_struct {
+			mut s := typ.$(field.name)
+			decode_struct(value, mut s)
+			typ.$(field.name) = s
+		}
+	}
+}
+
 // encode encodes the type `T` into a TOML string.
-// Currently encode expects the method `.to_toml()` exists on `T`.
+// If `T` has a custom `.to_toml()` method, it will be used instead of the default.
 pub fn encode[T](typ T) string {
-	return typ.to_toml()
+	$for method in T.methods {
+		$if method.name == 'to_toml' {
+			return typ.$method()
+		}
+	}
+	mp := encode_struct[T](typ)
+	return mp.to_toml()
+}
+
+fn encode_struct[T](typ T) map[string]Any {
+	mut mp := map[string]Any{}
+	$for field in T.fields {
+		value := typ.$(field.name)
+		$if field.is_enum {
+			mp[field.name] = Any(int(value))
+		} $else $if field.is_struct {
+			mp[field.name] = encode_struct(value)
+		} $else $if field.is_array {
+			mut arr := []Any{}
+			for v in value {
+				arr << Any(v)
+			}
+			mp[field.name] = arr
+		} $else {
+			mp[field.name] = Any(value)
+		}
+	}
+	return mp
 }
 
 // DateTime is the representation of an RFC 3339 datetime string.