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tentative adding yaml support #2516

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139 changes: 139 additions & 0 deletions json/json.mbt
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,145 @@ pub fn stringify(
buf.to_string()
}

///|
/// Convert a JsonValue to YAML string format
pub fn to_yaml(self : JsonValue, indent~ : Int = 2) -> String {
let buf = StringBuilder::new(size_hint=0)
fn needs_quotes(s : String) -> Bool {
if s.is_empty() {
return true
}

// Check if string looks like a number, boolean, or null
match s {
"true" | "false" | "null" | "~" => true
_ => {
// Check if it starts with special characters
let first_char = s[0]
if first_char == '-' ||
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@Lampese Lampese Oct 30, 2025

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May be this style is better?

if first_char
    is ('-'
    | ':'
    | '['
    | '{'
    | '!'
    | '&'
    | '*'
    | '|'
    | '>'
    | '\''
    | '"'
    | '#'
    | '@'
    | '`'){
    return true
}

first_char == ':' ||
first_char == '[' ||
first_char == '{' ||
first_char == '!' ||
first_char == '&' ||
first_char == '*' ||
first_char == '|' ||
first_char == '>' ||
first_char == '\'' ||
first_char == '"' ||
first_char == '#' ||
first_char == '@' ||
first_char == '`' {
return true
}

// Check if string contains special characters that need quoting
for c in s {
match c {
':' | '#' | '\n' | '\r' | '\t' => return true
_ => continue
}
}

// Check if string could be parsed as a number
try {
let _ = @strconv.parse_double(s)
true
} catch {
_ => false
}
}
}
}

fn write_string_value(s : String) -> Unit {
if needs_quotes(s) {
// Use JSON-style escaping for quoted strings
buf.write_char('"')
buf.write_string(escape(s, escape_slash=false))
buf.write_char('"')
} else {
buf.write_string(s)
}
}

fn yaml_inner(
value : JsonValue,
level : Int,
is_array_element : Bool,
) -> Unit {
let indent_str = " ".repeat(indent * level)
match value {
Object(members) => {
if members.is_empty() {
buf.write_string("{}")
return
}
let mut first = true
for k, v in members {
if not(is_array_element) || not(first) {
buf.write_string(indent_str)
}
if first {
first = false
}
write_string_value(k)
match v {
Object(_) | Array(_) => {
buf.write_string(":")
buf.write_char('\n')
yaml_inner(v, level + 1, false)
}
_ => {
buf.write_string(": ")
yaml_inner(v, level, false)
buf.write_char('\n')
}
}
}
}
Array(arr) => {
if arr.is_empty() {
buf.write_string("[]")
return
}
for i, v in arr {
if i > 0 || not(is_array_element) {
buf.write_string(indent_str)
}
buf.write_string("- ")
match v {
Object(_) | Array(_) => yaml_inner(v, level + 1, true)
_ => {
yaml_inner(v, level, false)
buf.write_char('\n')
}
}
}
}
String(s) => write_string_value(s)
Number(n, repr~) =>
match repr {
None => buf.write_object(n)
Some(r) => buf.write_string(r)
}
True => buf.write_string("true")
False => buf.write_string("false")
Null => buf.write_string("null")
}
}

yaml_inner(self, 0, false)

// Remove trailing newline if present
let result = buf.to_string()
if result.has_suffix("\n") {
result.substring(end=result.length() - 1)
} else {
result
}
}

///|
fn escape(str : String, escape_slash~ : Bool) -> String {
fn to_hex_digit(i : Int) -> Char {
Expand Down
1 change: 1 addition & 0 deletions json/json.mbti
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@ fn Json::as_object(Self) -> Map[String, Self]?
fn Json::as_string(Self) -> String?
fn Json::item(Self, Int) -> Self?
fn Json::stringify(Self, escape_slash~ : Bool = .., indent~ : Int = ..) -> String
fn Json::to_yaml(Self, indent~ : Int = ..) -> String
fn Json::value(Self, String) -> Self?
impl Show for Json
impl ToJson for Json
Expand Down
185 changes: 185 additions & 0 deletions json/json_test.mbt
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Original file line number Diff line number Diff line change
Expand Up @@ -511,3 +511,188 @@ test "nested json" {
},
})
}

///|
test "to_yaml - null value" {
let json = Json::null()
inspect(json.to_yaml(), content="null")
}

///|
test "to_yaml - boolean values" {
let json_true = Json::boolean(true)
let json_false = Json::boolean(false)
inspect(json_true.to_yaml(), content="true")
inspect(json_false.to_yaml(), content="false")
}

///|
test "to_yaml - number values" {
let json = Json::number(42.5)
inspect(json.to_yaml(), content="42.5")
let json_with_repr = Json::number(1.0 / 0.0, repr="Infinity")
inspect(json_with_repr.to_yaml(), content="Infinity")
}

///|
test "to_yaml - string values" {
// Simple string
let json = Json::string("hello")
inspect(json.to_yaml(), content="hello")

// String that needs quotes (looks like number)
let json_num = Json::string("123")
inspect(json_num.to_yaml(), content="\"123\"")

// String that needs quotes (looks like boolean)
let json_bool = Json::string("true")
inspect(json_bool.to_yaml(), content="\"true\"")

// String with special characters
let json_special = Json::string("hello: world")
inspect(json_special.to_yaml(), content="\"hello: world\"")

// String with newline
let json_newline = Json::string("hello\nworld")
inspect(json_newline.to_yaml(), content="\"hello\\nworld\"")

// Empty string
let json_empty = Json::string("")
inspect(json_empty.to_yaml(), content="\"\"")
}

///|
test "to_yaml - empty array" {
let json = Json::array([])
inspect(json.to_yaml(), content="[]")
}

///|
test "to_yaml - simple array" {
let json = Json::array([
Json::number(1.0),
Json::string("hello"),
Json::boolean(true),
Json::null(),
])
let yaml = json.to_yaml()
inspect(yaml, content="- 1\n- hello\n- true\n- null")
}

///|
test "to_yaml - nested array" {
let json = Json::array([
Json::number(1.0),
Json::array([Json::number(2.0), Json::number(3.0)]),
Json::string("end"),
])
let yaml = json.to_yaml()
inspect(yaml, content="- 1\n- - 2\n - 3\n- end")
}

///|
test "to_yaml - empty object" {
let json = Json::object({})
inspect(json.to_yaml(), content="{}")
}

///|
test "to_yaml - simple object" {
let json = Json::object({
"name": Json::string("John"),
"age": Json::number(30.0),
"active": Json::boolean(true),
})
// Note: Map iteration order might not be guaranteed
let yaml = json.to_yaml()
assert_true(yaml.contains("name: John"))
assert_true(yaml.contains("age: 30"))
assert_true(yaml.contains("active: true"))
}

///|
test "to_yaml - nested object" {
let json = Json::object({
"person": Json::object({
"name": Json::string("John"),
"age": Json::number(30.0),
}),
"items": Json::array([Json::string("item1"), Json::string("item2")]),
})
let yaml = json.to_yaml()
inspect(yaml, content=(
#|person:
#| name: John
#| age: 30
#|items:
#| - item1
#| - item2
))
}

///|
test "to_yaml - array of objects" {
let json = Json::array([
Json::object({ "id": Json::number(1.0), "name": Json::string("First") }),
Json::object({ "id": Json::number(2.0), "name": Json::string("Second") }),
])
let yaml = json.to_yaml()
inspect(yaml, content=(
#|- id: 1
#| name: First
#|- id: 2
#| name: Second
))
}

///|
test "to_yaml - object with array inside" {
let json = Json::object({
"fruits": Json::array([
Json::string("apple"),
Json::string("banana"),
Json::string("orange"),
]),
})
let yaml = json.to_yaml()
inspect(yaml, content=(
#|fruits:
#| - apple
#| - banana
#| - orange
))
}

///|
test "to_yaml - custom indent" {
let json = Json::object({
"level1": Json::object({ "level2": Json::string("value") }),
})
let yaml_2 = json.to_yaml(indent=2)
let yaml_4 = json.to_yaml(indent=4)
inspect(yaml_2, content=(
#|level1:
#| level2: value

))
inspect(yaml_4, content=(
#|level1:
#| level2: value

))
}

///|
test "to_yaml - special string keys" {
let json = Json::object({
"123": Json::string("numeric key"),
"true": Json::string("boolean key"),
"key:with:colons": Json::string("special chars"),
})
let yaml = json.to_yaml()
inspect(yaml, content=(
#|"123": numeric key
#|"true": boolean key
#|"key:with:colons": special chars
))
}
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