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//! Error values produces when extracting configurations.
use std::fmt::{self, Display};
use std::borrow::Cow;
use serde::{ser, de};
use crate::{Figment, Profile, Metadata, value::Tag};
/// A simple alias to `Result` with an error type of [`Error`].
pub type Result<T> = std::result::Result<T, Error>;
/// An error that occured while producing data or extracting a configuration.
///
/// # Constructing Errors
///
/// An `Error` will generally be constructed indirectly via its implementations
/// of serde's [`de::Error`] and [`ser::Error`], that is, as a result of
/// serialization or deserialization errors. When implementing [`Provider`],
/// however, it may be necessary to construct an `Error` directly.
///
/// [`Provider`]: crate::Provider
///
/// Broadly, there are two ways to construct an `Error`:
///
/// * Via an error message, since `Error` impls `From<String>`:
///
/// ```
/// use figment::Error;
///
/// Error::from("whoops, something went wrong!".to_string());
/// ```
///
/// * Via a [`Kind`], since `Error` impls `From<Kind>`:
///
/// ```
/// use figment::{error::{Error, Kind}, value::Value};
///
/// let value = Value::serialize(&100).unwrap();
/// if !value.as_str().is_some() {
/// let kind = Kind::InvalidType(value.to_actual(), "string".into());
/// let error = Error::from(kind);
/// }
/// ```
///
/// As always, `?` can be used to automatically convert into an `Error` using
/// the available `From` implementations:
///
/// ```
/// use std::fs::File;
///
/// fn try_read() -> Result<(), figment::Error> {
/// let x = File::open("/tmp/foo.boo").map_err(|e| e.to_string())?;
/// Ok(())
/// }
/// ```
///
/// # Display
///
/// By default, `Error` uses all of the available information about the error,
/// including the `Metadata`, `path`, and `profile` to display a message that
/// resembles the following, where `$` is `error.` for some `error: Error`:
///
/// ```text
/// $kind: `$metadata.interpolate($path)` in $($metadata.sources())*
/// ```
///
/// Concretely, such an error may look like:
///
/// ```text
/// invalid type: found sequence, expected u16: `staging.port` in TOML file Config.toml
/// ```
///
/// # Iterator
///
/// An `Error` may contain more than one error. To process all errors, iterate
/// over an `Error`:
///
/// ```rust
/// fn with_error(error: figment::Error) {
/// for error in error {
/// println!("error: {}", error);
/// }
/// }
/// ```
#[derive(Clone, Debug, PartialEq)]
pub struct Error {
/// The tag of the value that errored. We use this to lookup the `metadata`.
tag: Tag,
/// The profile that was selected when the error occured, if any.
pub profile: Option<Profile>,
/// The metadata for the provider of the value that errored, if known.
pub metadata: Option<Metadata>,
/// The path to the configuration key that errored, if known.
pub path: Vec<String>,
/// The error kind.
pub kind: Kind,
prev: Option<Box<Error>>,
}
/// An error kind, encapsulating serde's [`serde::de::Error`].
#[derive(Clone, Debug, PartialEq)]
pub enum Kind {
/// A custom error message.
Message(String),
/// An invalid type: (actual, expected). See
/// [`serde::de::Error::invalid_type()`].
InvalidType(Actual, String),
/// An invalid value: (actual, expected). See
/// [`serde::de::Error::invalid_value()`].
InvalidValue(Actual, String),
/// Too many or too few items: (actual, expected). See
/// [`serde::de::Error::invalid_length()`].
InvalidLength(usize, String),
/// A variant with an unrecognized name: (actual, expected). See
/// [`serde::de::Error::unknown_variant()`].
UnknownVariant(String, &'static [&'static str]),
/// A field with an unrecognized name: (actual, expected). See
/// [`serde::de::Error::unknown_field()`].
UnknownField(String, &'static [&'static str]),
/// A field was missing: (name). See [`serde::de::Error::missing_field()`].
MissingField(Cow<'static, str>),
/// A field appeared more than once: (name). See
/// [`serde::de::Error::duplicate_field()`].
DuplicateField(&'static str),
/// The `isize` was not in range of any known sized signed integer.
ISizeOutOfRange(isize),
/// The `usize` was not in range of any known sized unsigned integer.
USizeOutOfRange(usize),
/// The serializer or deserializer does not support the `Actual` type.
Unsupported(Actual),
/// The type `.0` cannot be used for keys, need a `.1`.
UnsupportedKey(Actual, Cow<'static, str>),
}
impl Error {
pub(crate) fn prefixed(mut self, path: &str) -> Self {
self.path.insert(0, path.into());
self
}
pub(crate) fn chain(self, mut error: Error) -> Self {
error.prev = Some(Box::new(self));
error
}
pub(crate) fn retagged(mut self, tag: Tag) -> Self {
if self.tag.is_default() {
self.tag = tag;
}
self
}
pub(crate) fn resolved(mut self, config: &Figment) -> Self {
let mut error = Some(&mut self);
while let Some(e) = error {
e.metadata = config.get_metadata(e.tag).cloned();
e.profile = e.tag.profile()
.or_else(|| Some(config.profile().clone()));
error = e.prev.as_deref_mut();
}
self
}
}
impl Error {
/// Returns `true` if the error's kind is `MissingField`.
///
/// # Example
///
/// ```rust
/// use figment::error::{Error, Kind};
///
/// let error = Error::from(Kind::MissingField("path".into()));
/// assert!(error.missing());
/// ```
pub fn missing(&self) -> bool {
matches!(self.kind, Kind::MissingField(..))
}
/// Append the string `path` to the error's path.
///
/// # Example
///
/// ```rust
/// use figment::Error;
///
/// let error = Error::from("an error message".to_string())
/// .with_path("some_path");
/// ```
pub fn with_path(mut self, path: &str) -> Self {
self.path.push(path.into());
self
}
/// Returns the number of errors represented by `self`.
///
/// # Example
///
/// ```rust
/// use figment::{Figment, providers::{Format, Toml}};
///
/// figment::Jail::expect_with(|jail| {
/// jail.create_file("Base.toml", r#"
/// # oh no, an unclosed array!
/// cat = [1
/// "#)?;
///
/// jail.create_file("Release.toml", r#"
/// # and now an unclosed string!?
/// cat = "
/// "#)?;
///
/// let figment = Figment::from(Toml::file("Base.toml"))
/// .merge(Toml::file("Release.toml"));
///
/// let error = figment.extract_inner::<String>("cat").unwrap_err();
/// assert_eq!(error.count(), 2);
///
/// Ok(())
/// });
/// ```
pub fn count(&self) -> usize {
1 + self.prev.as_ref().map_or(0, |e| e.count())
}
}
/// An iterator over all errors in an [`Error`].
pub struct IntoIter(Option<Error>);
impl Iterator for IntoIter {
type Item = Error;
fn next(&mut self) -> Option<Self::Item> {
if let Some(mut error) = self.0.take() {
self.0 = error.prev.take().map(|e| *e);
Some(error)
} else {
None
}
}
}
impl IntoIterator for Error {
type Item = Error;
type IntoIter = IntoIter;
fn into_iter(self) -> Self::IntoIter {
IntoIter(Some(self))
}
}
/// A type that enumerates all of serde's types, used to indicate that a value
/// of the given type was received.
#[allow(missing_docs)]
#[derive(Clone, Debug, PartialEq)]
pub enum Actual {
Bool(bool),
Unsigned(u128),
Signed(i128),
Float(f64),
Char(char),
Str(String),
Bytes(Vec<u8>),
Unit,
Option,
NewtypeStruct,
Seq,
Map,
Enum,
UnitVariant,
NewtypeVariant,
TupleVariant,
StructVariant,
Other(String),
}
impl fmt::Display for Actual {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Actual::Bool(v) => write!(f, "bool {}", v),
Actual::Unsigned(v) => write!(f, "unsigned int `{}`", v),
Actual::Signed(v) => write!(f, "signed int `{}`", v),
Actual::Float(v) => write!(f, "float `{}`", v),
Actual::Char(v) => write!(f, "char {:?}", v),
Actual::Str(v) => write!(f, "string {:?}", v),
Actual::Bytes(v) => write!(f, "bytes {:?}", v),
Actual::Unit => write!(f, "unit"),
Actual::Option => write!(f, "option"),
Actual::NewtypeStruct => write!(f, "new-type struct"),
Actual::Seq => write!(f, "sequence"),
Actual::Map => write!(f, "map"),
Actual::Enum => write!(f, "enum"),
Actual::UnitVariant => write!(f, "unit variant"),
Actual::NewtypeVariant => write!(f, "new-type variant"),
Actual::TupleVariant => write!(f, "tuple variant"),
Actual::StructVariant => write!(f, "struct variant"),
Actual::Other(v) => v.fmt(f),
}
}
}
impl From<de::Unexpected<'_>> for Actual {
fn from(value: de::Unexpected<'_>) -> Actual {
match value {
de::Unexpected::Bool(v) => Actual::Bool(v),
de::Unexpected::Unsigned(v) => Actual::Unsigned(v as u128),
de::Unexpected::Signed(v) => Actual::Signed(v as i128),
de::Unexpected::Float(v) => Actual::Float(v),
de::Unexpected::Char(v) => Actual::Char(v),
de::Unexpected::Str(v) => Actual::Str(v.into()),
de::Unexpected::Bytes(v) => Actual::Bytes(v.into()),
de::Unexpected::Unit => Actual::Unit,
de::Unexpected::Option => Actual::Option,
de::Unexpected::NewtypeStruct => Actual::NewtypeStruct,
de::Unexpected::Seq => Actual::Seq,
de::Unexpected::Map => Actual::Map,
de::Unexpected::Enum => Actual::Enum,
de::Unexpected::UnitVariant => Actual::UnitVariant,
de::Unexpected::NewtypeVariant => Actual::NewtypeVariant,
de::Unexpected::TupleVariant => Actual::TupleVariant,
de::Unexpected::StructVariant => Actual::StructVariant,
de::Unexpected::Other(v) => Actual::Other(v.into())
}
}
}
impl de::Error for Error {
fn custom<T: Display>(msg: T) -> Self {
Kind::Message(msg.to_string()).into()
}
fn invalid_type(unexp: de::Unexpected, exp: &dyn de::Expected) -> Self {
Kind::InvalidType(unexp.into(), exp.to_string()).into()
}
fn invalid_value(unexp: de::Unexpected, exp: &dyn de::Expected) -> Self {
Kind::InvalidValue(unexp.into(), exp.to_string()).into()
}
fn invalid_length(len: usize, exp: &dyn de::Expected) -> Self {
Kind::InvalidLength(len, exp.to_string()).into()
}
fn unknown_variant(variant: &str, expected: &'static [&'static str]) -> Self {
Kind::UnknownVariant(variant.into(), expected).into()
}
fn unknown_field(field: &str, expected: &'static [&'static str]) -> Self {
Kind::UnknownField(field.into(), expected).into()
}
fn missing_field(field: &'static str) -> Self {
Kind::MissingField(field.into()).into()
}
fn duplicate_field(field: &'static str) -> Self {
Kind::DuplicateField(field).into()
}
}
impl ser::Error for Error {
fn custom<T: Display>(msg: T) -> Self {
Kind::Message(msg.to_string()).into()
}
}
impl From<Kind> for Error {
fn from(kind: Kind) -> Error {
Error {
tag: Tag::Default,
path: vec![],
profile: None,
metadata: None,
prev: None,
kind,
}
}
}
impl From<String> for Error {
fn from(string: String) -> Error {
Kind::Message(string).into()
}
}
impl Display for Kind {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
Kind::Message(msg) => f.write_str(&msg),
Kind::InvalidType(v, exp) => {
write!(f, "invalid type: found {}, expected {}", v, exp)
}
Kind::InvalidValue(v, exp) => {
write!(f, "invalid value {}, expected {}", v, exp)
},
Kind::InvalidLength(v, exp) => {
write!(f, "invalid length {}, expected {}", v, exp)
},
Kind::UnknownVariant(v, exp) => {
write!(f, "unknown variant: found `{}`, expected `{}`", v, OneOf(exp))
}
Kind::UnknownField(v, exp) => {
write!(f, "unknown field: found `{}`, expected `{}`", v, OneOf(exp))
}
Kind::MissingField(v) => {
write!(f, "missing field `{}`", v)
}
Kind::DuplicateField(v) => {
write!(f, "duplicate field `{}`", v)
}
Kind::ISizeOutOfRange(v) => {
write!(f, "signed integer `{}` is out of range", v)
}
Kind::USizeOutOfRange(v) => {
write!(f, "unsigned integer `{}` is out of range", v)
}
Kind::Unsupported(v) => {
write!(f, "unsupported type `{}`", v)
}
Kind::UnsupportedKey(a, e) => {
write!(f, "unsupported type `{}` for key: must be `{}`", a, e)
}
}
}
}
impl Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.kind.fmt(f)?;
if let (Some(profile), Some(md)) = (&self.profile, &self.metadata) {
if !self.path.is_empty() {
let key = md.interpolate(profile, &self.path);
write!(f, " for key {:?}", key)?;
}
}
if let Some(md) = &self.metadata {
if let Some(source) = &md.source {
write!(f, " in {} {}", source, md.name)?;
} else {
write!(f, " in {}", md.name)?;
}
}
if let Some(prev) = &self.prev {
write!(f, "\n{}", prev)?;
}
Ok(())
}
}
impl std::error::Error for Error {}
/// A structure that implements [`de::Expected`] signaling that one of the types
/// in the slice was expected.
pub struct OneOf(pub &'static [&'static str]);
impl fmt::Display for OneOf {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self.0.len() {
0 => write!(f, "none"),
1 => write!(f, "`{}`", self.0[0]),
2 => write!(f, "`{}` or `{}`", self.0[0], self.0[1]),
_ => {
write!(f, "one of ")?;
for (i, alt) in self.0.iter().enumerate() {
if i > 0 { write!(f, ", ")?; }
write!(f, "`{}`", alt)?;
}
Ok(())
}
}
}
}
impl de::Expected for OneOf {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(self, f)
}
}