serde_path_to_error/
lib.rs

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1//! [![github]](https://github.com/dtolnay/path-to-error)&ensp;[![crates-io]](https://crates.io/crates/serde_path_to_error)&ensp;[![docs-rs]](https://docs.rs/serde_path_to_error)
2//!
3//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
4//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
5//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs
6//!
7//! <br>
8//!
9//! Find out the path at which a deserialization error occurred. This crate
10//! provides a wrapper that works with any existing Serde `Deserializer` and
11//! exposes the chain of field names leading to the error.
12//!
13//! # Example
14//!
15//! ```
16//! # use serde_derive::Deserialize;
17//! #
18//! use serde::Deserialize;
19//! use std::collections::BTreeMap as Map;
20//!
21//! #[derive(Deserialize)]
22//! struct Package {
23//!     name: String,
24//!     dependencies: Map<String, Dependency>,
25//! }
26//!
27//! #[derive(Deserialize)]
28//! struct Dependency {
29//!     version: String,
30//! }
31//!
32//! fn main() {
33//!     let j = r#"{
34//!         "name": "demo",
35//!         "dependencies": {
36//!             "serde": {
37//!                 "version": 1
38//!             }
39//!         }
40//!     }"#;
41//!
42//!     // Some Deserializer.
43//!     let jd = &mut serde_json::Deserializer::from_str(j);
44//!
45//!     let result: Result<Package, _> = serde_path_to_error::deserialize(jd);
46//!     match result {
47//!         Ok(_) => panic!("expected a type error"),
48//!         Err(err) => {
49//!             let path = err.path().to_string();
50//!             assert_eq!(path, "dependencies.serde.version");
51//!         }
52//!     }
53//! }
54//! ```
55
56#![doc(html_root_url = "https://docs.rs/serde_path_to_error/0.1.8")]
57#![allow(
58    clippy::doc_link_with_quotes, // https://github.com/rust-lang/rust-clippy/issues/8961
59    clippy::iter_not_returning_iterator, // https://github.com/rust-lang/rust-clippy/issues/8285
60    clippy::missing_errors_doc,
61    clippy::module_name_repetitions,
62    clippy::must_use_candidate,
63    clippy::new_without_default
64)]
65
66mod de;
67mod path;
68mod ser;
69mod wrap;
70
71use std::cell::Cell;
72use std::error::Error as StdError;
73use std::fmt::{self, Display};
74
75pub use crate::de::{deserialize, Deserializer};
76pub use crate::path::{Path, Segment, Segments};
77pub use crate::ser::{serialize, Serializer};
78
79/// Original deserializer error together with the path at which it occurred.
80#[derive(Clone, Debug)]
81pub struct Error<E> {
82    path: Path,
83    original: E,
84}
85
86impl<E> Error<E> {
87    /// Element path at which this deserialization error occurred.
88    pub fn path(&self) -> &Path {
89        &self.path
90    }
91
92    /// The Deserializer's underlying error that occurred.
93    pub fn into_inner(self) -> E {
94        self.original
95    }
96
97    /// Reference to the Deserializer's underlying error that occurred.
98    pub fn inner(&self) -> &E {
99        &self.original
100    }
101}
102
103impl<E: Display> Display for Error<E> {
104    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
105        write!(f, "{}: {}", self.path(), self.inner())
106    }
107}
108
109impl<E: StdError + 'static> StdError for Error<E> {
110    fn source(&self) -> Option<&(dyn StdError + 'static)> {
111        Some(self.inner())
112    }
113}
114
115/// State for bookkeeping across nested deserializer calls.
116///
117/// You don't need this if you are using `serde_path_to_error::deserializer`. If
118/// you are managing your own `Deserializer`, see the usage example on
119/// [`Deserializer`].
120pub struct Track {
121    path: Cell<Option<Path>>,
122}
123
124impl Track {
125    /// Empty state with no error having happened yet.
126    pub fn new() -> Self {
127        Track {
128            path: Cell::new(None),
129        }
130    }
131
132    /// Gets path at which the error occurred. Only meaningful after we know
133    /// that an error has occurred. Returns an empty path otherwise.
134    pub fn path(self) -> Path {
135        self.path.into_inner().unwrap_or_else(Path::empty)
136    }
137
138    #[inline]
139    fn trigger<E>(&self, chain: &Chain, err: E) -> E {
140        self.trigger_impl(chain);
141        err
142    }
143
144    fn trigger_impl(&self, chain: &Chain) {
145        self.path.set(Some(match self.path.take() {
146            Some(already_set) => already_set,
147            None => Path::from_chain(chain),
148        }));
149    }
150}
151
152#[derive(Clone)]
153enum Chain<'a> {
154    Root,
155    Seq {
156        parent: &'a Chain<'a>,
157        index: usize,
158    },
159    Map {
160        parent: &'a Chain<'a>,
161        key: String,
162    },
163    Struct {
164        parent: &'a Chain<'a>,
165        key: &'static str,
166    },
167    Enum {
168        parent: &'a Chain<'a>,
169        variant: String,
170    },
171    Some {
172        parent: &'a Chain<'a>,
173    },
174    NewtypeStruct {
175        parent: &'a Chain<'a>,
176    },
177    NewtypeVariant {
178        parent: &'a Chain<'a>,
179    },
180    NonStringKey {
181        parent: &'a Chain<'a>,
182    },
183}
serde_path_to_error/lib.rs

serde_path_to_error/
lib.rs
