1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

use crate::{
    js::{
        any::Any,
        js_string::JsStringRef,
        visitor::{to_visitor, Visitor},
    },
    mem::{
        flexible_array::{header::FlexibleArrayHeader, FlexibleArray},
        manager::Dealloc,
        ref_::Ref,
    },
};

use core::{
    fmt::{self, Write},
    result,
};

const ESCAPE_B: u8 = 0x08;
const ESCAPE_F: u8 = 0x0C;

pub trait WriteJson: Write {
    fn write_u4_hex(&mut self, v: u16) -> fmt::Result {
        self.write_char(b"0123456789ABCDEF"[v as usize & 0xF] as char)
    }
    fn write_js_escape(&mut self, c: u16) -> fmt::Result {
        self.write_str("\\u")?;
        self.write_u4_hex(c >> 12)?;
        self.write_u4_hex(c >> 8)?;
        self.write_u4_hex(c >> 4)?;
        self.write_u4_hex(c)
    }
    /// See https://www.json.org/json-en.html
    fn write_js_string(&mut self, s: &JsStringRef<impl Dealloc>) -> fmt::Result {
        self.write_char('"')?;
        for &c in s.items().iter() {
            if c < 0x80 {
                match c as u8 {
                    b'\\' => self.write_str(r#"\\"#)?,
                    b'"' => self.write_str(r#"\""#)?,
                    ESCAPE_B => self.write_str(r#"\b"#)?,
                    ESCAPE_F => self.write_str(r#"\f"#)?,
                    b'\n' => self.write_str(r#"\n"#)?,
                    b'\r' => self.write_str(r#"\r"#)?,
                    b'\t' => self.write_str(r#"\t"#)?,
                    c if c < 0x20 => self.write_js_escape(c as u16)?,
                    c => self.write_char(c as char)?,
                }
            } else {
                self.write_js_escape(c)?;
            }
        }
        self.write_char('"')
    }

    fn write_list<I>(
        &mut self,
        open: char,
        close: char,
        v: Ref<FlexibleArray<I, impl FlexibleArrayHeader>, impl Dealloc>,
        f: impl Fn(&mut Self, &I) -> fmt::Result,
    ) -> fmt::Result {
        let mut comma = "";
        self.write_char(open)?;
        for i in v.items().iter() {
            self.write_str(comma)?;
            f(self, i)?;
            comma = ",";
        }
        self.write_char(close)
    }

    fn write_json(&mut self, any: Any<impl Dealloc>) -> fmt::Result {
        match to_visitor(any) {
            // TODO: replace with proper JSON number serializer.
            Visitor::Number(n) => self.write_str(n.to_string().as_str()),
            Visitor::Null => self.write_str("null"),
            Visitor::Bool(b) => self.write_str(if b { "true" } else { "false" }),
            Visitor::String(s) => self.write_js_string(&s),
            Visitor::Object(o) => self.write_list('{', '}', o, |w, (k, v)| {
                w.write_js_string(k)?;
                w.write_char(':')?;
                w.write_json(v.clone())
            }),
            Visitor::Array(a) => self.write_list('[', ']', a, |w, i| w.write_json(i.clone())),
        }
    }
}

impl<T: Write> WriteJson for T {}

pub fn to_json(a: Any<impl Dealloc>) -> result::Result<String, fmt::Error> {
    let mut s = String::default();
    s.write_json(a)?;
    Ok(s)
}

#[cfg(test)]
mod test {
    use wasm_bindgen_test::wasm_bindgen_test;

    use crate::{
        js::{any::Any, any_cast::AnyCast, js_string::new_string, new::New, null::Null},
        mem::global::{Global, GLOBAL},
        serializer::WriteJson,
    };

    #[test]
    #[wasm_bindgen_test]
    fn test() {
        type A = Any<Global>;
        let s = new_string(
            GLOBAL,
            ['a' as u16, '\\' as u16, 'b' as u16, '"' as u16, 31],
        )
        .to_ref();
        let a = GLOBAL.new_js_array([
            1.0.move_to_any(),
            true.move_to_any(),
            Null().move_to_any(),
            GLOBAL.new_js_array([]),
            GLOBAL.new_js_string([]),
            GLOBAL.new_js_object([]),
            GLOBAL.new_js_object([(s, 2.0.move_to_any())]),
        ]);
        let mut s = String::new();
        s.write_json(a).unwrap();
        assert_eq!(s, r#"[1,true,null,[],"",{},{"a\\b\"\u001F":2}]"#);
    }
}