snix_eval/value/
json.rs

1/// Implementation of Value serialisation *to* JSON.
2///
3/// This can not be implemented through standard serde-derive methods,
4/// as there is internal Nix logic that must happen within the
5/// serialisation methods.
6use super::{CoercionKind, Value};
7use crate::errors::ErrorKind;
8use crate::generators::{self, GenCo};
9use crate::NixContext;
10
11use bstr::ByteSlice;
12use serde_json::value::to_value;
13use serde_json::Value as Json; // name clash with *our* `Value`
14use serde_json::{Map, Number};
15
16impl Value {
17    /// Transforms the structure into a JSON
18    /// and accumulate all encountered context in the second's element
19    /// of the return type.
20    pub async fn into_contextful_json(self, co: &GenCo) -> Result<(Json, NixContext), ErrorKind> {
21        let self_forced = generators::request_force(co, self).await;
22        let mut context = NixContext::new();
23
24        let value = match self_forced {
25            Value::Null => Json::Null,
26            Value::Bool(b) => Json::Bool(b),
27            Value::Integer(i) => Json::Number(Number::from(i)),
28            Value::Float(f) => to_value(f)?,
29            Value::String(s) => {
30                context.mimic(&s);
31
32                Json::String(s.to_str()?.to_owned())
33            }
34
35            Value::Path(p) => {
36                let imported = generators::request_path_import(co, *p).await;
37                let path = imported.to_string_lossy().to_string();
38                context = context.append(crate::NixContextElement::Plain(path.clone()));
39                Json::String(path)
40            }
41
42            Value::List(l) => {
43                let mut out = Vec::with_capacity(l.len());
44
45                for val in l.into_iter() {
46                    let (json_item, ctx) = Box::pin(val.into_contextful_json(co)).await?;
47                    context.extend(ctx.into_iter());
48                    out.push(json_item);
49                }
50
51                Json::Array(out)
52            }
53
54            Value::Attrs(attrs) => {
55                // Attribute sets with a callable `__toString` attribute
56                // serialise to the string-coerced version of the result of
57                // calling that.
58                if attrs.select("__toString").is_some() {
59                    let span = generators::request_span(co).await;
60                    match Value::Attrs(attrs)
61                        .coerce_to_string_(
62                            co,
63                            CoercionKind {
64                                strong: false,
65                                import_paths: false,
66                            },
67                            span,
68                        )
69                        .await?
70                    {
71                        Value::Catchable(cek) => return Err(ErrorKind::CatchableError(*cek)),
72                        Value::String(s) => {
73                            // We need a fresh context here because `__toString` will discard
74                            // everything.
75                            let mut fresh = NixContext::new();
76                            fresh.mimic(&s);
77                            return Ok((Json::String(s.to_str()?.to_owned()), fresh));
78                        }
79                        _ => panic!("Value::coerce_to_string_() returned a non-string!"),
80                    }
81                }
82
83                // Attribute sets with an `outPath` attribute
84                // serialise to a JSON serialisation of that inner
85                // value (regardless of what it is!).
86                if let Some(out_path) = attrs.select("outPath") {
87                    let (json_out_path, ctx) =
88                        Box::pin(out_path.clone().into_contextful_json(co)).await?;
89                    context.extend(ctx.into_iter());
90                    return Ok((json_out_path, context));
91                }
92
93                let mut out = Map::with_capacity(attrs.len());
94                for (name, value) in attrs.into_iter_sorted() {
95                    let (json_value, ctx) = Box::pin(value.into_contextful_json(co)).await?;
96                    context.extend(ctx.into_iter());
97                    out.insert(name.to_str()?.to_owned(), json_value);
98                }
99
100                Json::Object(out)
101            }
102
103            Value::Catchable(c) => return Err(ErrorKind::CatchableError(*c)),
104
105            val @ Value::Closure(_)
106            | val @ Value::Thunk(_)
107            | val @ Value::Builtin(_)
108            | val @ Value::AttrNotFound
109            | val @ Value::Blueprint(_)
110            | val @ Value::DeferredUpvalue(_)
111            | val @ Value::UnresolvedPath(_)
112            | val @ Value::FinaliseRequest(_) => {
113                return Err(ErrorKind::NotSerialisableToJson(val.type_of()))
114            }
115        };
116        Ok((value, context))
117    }
118}
snix_eval/value/json.rs

snix_eval/value/
json.rs
