bon_macros/parsing/
spanned_key.rs

1use crate::util::prelude::*;
2use darling::FromMeta;
3use std::fmt;
4use std::ops::{Deref, DerefMut};
5
6/// A type that stores the attribute key path information along with the parsed value.
7/// It is useful for error reporting. For example, if some key was unexpected, it's
8/// possible to point to the key's span in the error instead of the attribute's value.
9#[derive(Clone)]
10pub(crate) struct SpannedKey<T> {
11    pub(crate) key: syn::Ident,
12    pub(crate) value: T,
13}
14
15impl<T> SpannedKey<T> {
16    pub(crate) fn new(path: &syn::Path, value: T) -> Result<Self> {
17        Ok(Self {
18            key: path.require_ident()?.clone(),
19            value,
20        })
21    }
22
23    pub(crate) fn into_value(self) -> T {
24        self.value
25    }
26
27    pub(crate) fn key(&self) -> &syn::Ident {
28        &self.key
29    }
30
31    pub(crate) fn with_value<U>(self, value: U) -> SpannedKey<U> {
32        SpannedKey {
33            value,
34            key: self.key,
35        }
36    }
37
38    pub(crate) fn map_value<U>(self, map: impl FnOnce(T) -> U) -> SpannedKey<U> {
39        SpannedKey {
40            value: map(self.value),
41            key: self.key,
42        }
43    }
44}
45
46impl<T: Default> Default for SpannedKey<T> {
47    fn default() -> Self {
48        Self {
49            key: syn::Ident::new("__bon_autogenerated", Span::call_site()),
50            value: T::default(),
51        }
52    }
53}
54
55impl<T: FromMeta> FromMeta for SpannedKey<T> {
56    fn from_meta(meta: &syn::Meta) -> Result<Self> {
57        let value = T::from_meta(meta)?;
58        Self::new(meta.path(), value)
59    }
60}
61
62impl<T: fmt::Debug> fmt::Debug for SpannedKey<T> {
63    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
64        fmt::Debug::fmt(&self.value, f)
65    }
66}
67
68impl<T> Deref for SpannedKey<T> {
69    type Target = T;
70
71    fn deref(&self) -> &T {
72        &self.value
73    }
74}
75
76impl<T> DerefMut for SpannedKey<T> {
77    fn deref_mut(&mut self) -> &mut T {
78        &mut self.value
79    }
80}
bon_macros/parsing/spanned_key.rs

bon_macros/parsing/
spanned_key.rs
