toml: add Any.default_to() method (#12506)

vlib/toml/any.v

@@ -149,18 +149,26 @@ pub fn (a Any) datetime() DateTime {
 	}
 }
 
+// default_to returns `value` if `a Any` is `Null`.
+// This can be used to set default values when retrieving
+// values. E.g.: `toml_doc.value('wrong.key').default_to(123).int()`
+pub fn (a Any) default_to(value Any) Any {
+	match a {
+		Null { return value }
+		else { return a }
+	}
+}
+
 // value queries a value from the map.
 // `key` should be in "dotted" form (`a.b.c`).
 // `key` supports quoted keys like `a."b.c"`.
-pub fn (m map[string]Any) value(key string) ?Any {
+pub fn (m map[string]Any) value(key string) Any {
-	key_split := parse_dotted_key(key) ?
+	key_split := parse_dotted_key(key) or { return Any(Null{}) }
 	return m.value_(key_split)
 }
 
-fn (m map[string]Any) value_(key []string) ?Any {
+fn (m map[string]Any) value_(key []string) Any {
-	value := m[key[0]] or {
+	value := m[key[0]] or { return Any(Null{}) }
-		return error(@MOD + '.' + @STRUCT + '.' + @FN + ' key "${key[0]}" does not exist')
-	}
 	// `match` isn't currently very suitable for these types of sum type constructs...
 	if value is map[string]Any {
 		if key.len <= 1 {

vlib/toml/tests/default_to_test.v

@@ -0,0 +1,9 @@
+import toml
+
+fn test_default_to() {
+	default_value := 4321
+	mut toml_txt := 'var = 1234'
+	toml_doc := toml.parse(toml_txt) or { panic(err) }
+	value := toml_doc.value('tar').default_to(default_value).int()
+	assert value == default_value
+}

vlib/toml/tests/table_test.v

@@ -61,31 +61,31 @@ fn test_tables() {
 
 	mut m := toml_doc.value('tbl') as map[string]toml.Any
 
-	value = m.value('a.b.c.d.e') or { panic(err) }
+	value = m.value('a.b.c.d.e')
 	assert value.int() == 1
 
-	value = m.value('x.a.b.c.d.e') or { panic(err) }
+	value = m.value('x.a.b.c.d.e')
 	assert value.int() == 1
 
 	arr := toml_doc.value('arr') as []toml.Any
 
 	for i := 0; i < arr.len; i++ {
 		entry := (arr[i] as map[string]toml.Any)
-		value = entry.value('t.a.b') or { panic(err) }
+		value = entry.value('t.a.b')
 		assert value.int() == i + 1
-		value = entry.value('T.a.b') or { panic(err) }
+		value = entry.value('T.a.b')
 		assert value.int() == i + 1
 	}
 
 	arr0 := arr[0] as map[string]toml.Any
-	value = arr0.value('t.a.b') or { panic(err) }
+	value = arr0.value('t.a.b')
 	assert value.int() == 1
-	value = arr0.value('T.a.b') or { panic(err) }
+	value = arr0.value('T.a.b')
 	assert value.int() == 1
 
 	arr1 := arr[1] as map[string]toml.Any
-	value = arr1.value('t.a.b') or { panic(err) }
+	value = arr1.value('t.a.b')
 	assert value.int() == 2
-	value = arr1.value('T.a.b') or { panic(err) }
+	value = arr1.value('T.a.b')
 	assert value.int() == 2
 }

vlib/toml/tests/toml_bom_test.v

@@ -25,7 +25,7 @@ fn test_toml_with_bom() {
 	assert title as string == 'TOML Example'
 
 	owner := toml_doc.value('owner') as map[string]toml.Any
-	any_name := owner.value('name') or { panic(err) }
+	any_name := owner.value('name')
 	assert any_name.string() == 'Tom Preston-Werner'
 
 	database := toml_doc.value('database') as map[string]toml.Any

vlib/toml/tests/toml_memory_corruption_test.v

@@ -10,7 +10,7 @@ fn test_toml_known_memory_corruption() {
 	toml_doc := toml.parse(toml_text) or { panic(err) }
 
 	owner := toml_doc.value('owner') as map[string]toml.Any
-	any_name := owner.value('name') or { panic(err) }
+	any_name := owner.value('name')
 	// This assert code path will cause the corruption.
 	assert any_name.string() == 'Tom Preston-Werner'