1/*!
2# Error types for XML parsing
3
4This module contains the error types used throughout the `xso` crate.
5*/
6
7// Copyright (c) 2024 Jonas Schäfer <jonas@zombofant.net>
8//
9// This Source Code Form is subject to the terms of the Mozilla Public
10// License, v. 2.0. If a copy of the MPL was not distributed with this
11// file, You can obtain one at http://mozilla.org/MPL/2.0/.
12
13use alloc::{
14 boxed::Box,
15 string::{String, ToString},
16};
17use core::fmt;
18
19use rxml::Error as XmlError;
20
21/// Opaque string error.
22///
23/// This is exclusively used in the `From<&Error> for Error` implementation
24/// in order to type-erase and "clone" the TextParseError.
25///
26/// That implementation, in turn, is primarily used by the
27/// `AsXml for Result<T, E>` implementation. We intentionally do not implement
28/// `Clone` using this type because it'd lose type information (which you
29/// don't expect a clone to do).
30#[derive(Debug)]
31struct OpaqueError(String);
32
33impl fmt::Display for OpaqueError {
34 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
35 f.write_str(&self.0)
36 }
37}
38
39impl core::error::Error for OpaqueError {}
40
41/// Error variants generated while parsing or serialising XML data.
42#[derive(Debug)]
43pub enum Error {
44 /// Invalid XML data encountered
45 XmlError(XmlError),
46
47 /// Attempt to parse text data failed with the provided nested error.
48 TextParseError(Box<dyn core::error::Error + Send + Sync + 'static>),
49
50 /// Generic, unspecified other error.
51 Other(&'static str),
52
53 /// An element header did not match an expected element.
54 ///
55 /// This error condition is only generated when the top-level element
56 /// passed to [`transform`][`crate::transform`] or similar does not match
57 /// the type.
58 TypeMismatch,
59}
60
61impl Error {
62 /// Convenience function to create a [`Self::TextParseError`] variant.
63 ///
64 /// This includes the `Box::new(.)` call, making it directly usable as
65 /// argument to [`Result::map_err`].
66 pub fn text_parse_error<T: core::error::Error + Send + Sync + 'static>(e: T) -> Self {
67 Self::TextParseError(Box::new(e))
68 }
69}
70
71/// "Clone" an [`Error`] while discarding some information.
72///
73/// This discards the specific type information from the
74/// [`TextParseError`][`Self::TextParseError`] variant and it may discard
75/// more information in the future.
76impl From<&Error> for Error {
77 fn from(other: &Error) -> Self {
78 match other {
79 Self::XmlError(e) => Self::XmlError(*e),
80 Self::TextParseError(e) => Self::TextParseError(Box::new(OpaqueError(e.to_string()))),
81 Self::Other(e) => Self::Other(e),
82 Self::TypeMismatch => Self::TypeMismatch,
83 }
84 }
85}
86
87impl fmt::Display for Error {
88 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
89 match self {
90 Self::XmlError(ref e) => write!(f, "xml parse error: {}", e),
91 Self::TextParseError(ref e) => write!(f, "text parse error: {}", e),
92 Self::TypeMismatch => f.write_str("mismatch between expected and actual XML data"),
93 Self::Other(msg) => f.write_str(msg),
94 }
95 }
96}
97
98impl core::error::Error for Error {
99 fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
100 match self {
101 Self::XmlError(ref e) => Some(e),
102 Self::TextParseError(ref e) => Some(&**e),
103 _ => None,
104 }
105 }
106}
107
108impl From<rxml::Error> for Error {
109 fn from(other: rxml::Error) -> Error {
110 Error::XmlError(other)
111 }
112}
113
114impl From<rxml::strings::Error> for Error {
115 fn from(other: rxml::strings::Error) -> Error {
116 Error::XmlError(other.into())
117 }
118}
119
120impl From<core::convert::Infallible> for Error {
121 fn from(other: core::convert::Infallible) -> Self {
122 match other {}
123 }
124}
125
126/// Error returned from
127/// [`FromXml::from_events`][`crate::FromXml::from_events`].
128#[derive(Debug)]
129pub enum FromEventsError {
130 /// The `name` and/or `attrs` passed to `FromXml::from_events` did not
131 /// match the element's type.
132 Mismatch {
133 /// The `name` passed to `from_events`.
134 name: rxml::QName,
135
136 /// The `attrs` passed to `from_events`.
137 attrs: rxml::AttrMap,
138 },
139
140 /// The `name` and `attrs` passed to `FromXml::from_events` matched the
141 /// element's type, but the data was invalid. Details are in the inner
142 /// error.
143 Invalid(Error),
144}
145
146impl From<Error> for FromEventsError {
147 fn from(other: Error) -> Self {
148 Self::Invalid(other)
149 }
150}
151
152impl From<core::convert::Infallible> for FromEventsError {
153 fn from(other: core::convert::Infallible) -> Self {
154 match other {}
155 }
156}
157
158impl fmt::Display for FromEventsError {
159 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
160 match self {
161 Self::Mismatch { .. } => f.write_str("element header did not match"),
162 Self::Invalid(ref e) => fmt::Display::fmt(e, f),
163 }
164 }
165}
166
167impl core::error::Error for FromEventsError {
168 fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
169 match self {
170 Self::Mismatch { .. } => None,
171 Self::Invalid(ref e) => Some(e),
172 }
173 }
174}
175
176impl From<Error> for Result<minidom::Element, Error> {
177 fn from(other: Error) -> Self {
178 Self::Err(other)
179 }
180}
181
182/// Error returned by the `TryFrom<Element>` implementations.
183#[derive(Debug)]
184pub enum FromElementError {
185 /// The XML element header did not match the expectations of the type
186 /// implementing `TryFrom`.
187 ///
188 /// Contains the original `Element` unmodified.
189 Mismatch(minidom::Element),
190
191 /// During processing of the element, an (unrecoverable) error occurred.
192 Invalid(Error),
193}
194
195impl fmt::Display for FromElementError {
196 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
197 match self {
198 Self::Mismatch(ref el) => write!(
199 f,
200 "expected different XML element (got {} in namespace {})",
201 el.name(),
202 el.ns()
203 ),
204 Self::Invalid(ref e) => fmt::Display::fmt(e, f),
205 }
206 }
207}
208
209impl core::error::Error for FromElementError {
210 fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
211 match self {
212 Self::Mismatch(_) => None,
213 Self::Invalid(ref e) => Some(e),
214 }
215 }
216}
217
218impl From<Result<minidom::Element, Error>> for FromElementError {
219 fn from(other: Result<minidom::Element, Error>) -> Self {
220 match other {
221 Ok(v) => Self::Mismatch(v),
222 Err(e) => Self::Invalid(e),
223 }
224 }
225}
226
227impl From<Error> for FromElementError {
228 fn from(other: Error) -> Self {
229 Self::Invalid(other)
230 }
231}
232
233impl From<FromElementError> for Error {
234 fn from(other: FromElementError) -> Self {
235 match other {
236 FromElementError::Invalid(e) => e,
237 FromElementError::Mismatch(..) => Self::TypeMismatch,
238 }
239 }
240}
241
242impl From<core::convert::Infallible> for FromElementError {
243 fn from(other: core::convert::Infallible) -> Self {
244 match other {}
245 }
246}