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use std::error::Error as StdError;
use std::fmt;
use std::iter::{self, Iterator};
use std::string::ToString;
use std::vec;
pub type Result<T> = ::std::result::Result<T, Error>;
#[derive(Debug)]
#[cfg_attr(test, derive(Clone, PartialEq, Eq))]
pub struct Error {
kind: ErrorKind,
locations: Vec<String>,
}
impl Error {
fn new(kind: ErrorKind) -> Self {
Error {
kind: kind,
locations: Vec::new(),
}
}
pub fn custom<T: fmt::Display>(msg: T) -> Self {
Error::new(ErrorKind::Custom(msg.to_string()))
}
pub fn duplicate_field(name: &str) -> Self {
Error::new(ErrorKind::DuplicateField(name.into()))
}
pub fn missing_field(name: &str) -> Self {
Error::new(ErrorKind::MissingField(name.into()))
}
pub fn unknown_field(name: &str) -> Self {
Error::new(ErrorKind::UnknownField(name.into()))
}
pub fn unsupported_format(format: &str) -> Self {
Error::new(ErrorKind::UnexpectedFormat(format.into()))
}
pub fn unexpected_type(ty: &str) -> Self {
Error::new(ErrorKind::UnexpectedType(ty.into()))
}
pub fn unknown_value(value: &str) -> Self {
Error::new(ErrorKind::UnknownValue(value.into()))
}
pub fn too_few_items(min: usize) -> Self {
Error::new(ErrorKind::TooFewItems(min))
}
pub fn too_many_items(max: usize) -> Self {
Error::new(ErrorKind::TooManyItems(max))
}
pub fn multiple(mut errors: Vec<Error>) -> Self {
if errors.len() > 1 {
Error::new(ErrorKind::Multiple(errors))
} else if errors.len() == 1 {
errors
.pop()
.expect("Error array of length 1 has a first item")
} else {
panic!("Can't deal with 0 errors")
}
}
pub fn flatten(self) -> Self {
Error::multiple(self.to_vec())
}
fn to_vec(self) -> Vec<Self> {
if let ErrorKind::Multiple(errors) = self.kind {
let mut flat = Vec::new();
for error in errors {
flat.extend(error.prepend_at(self.locations.clone()).to_vec());
}
flat
} else {
vec![self]
}
}
pub fn at<T: fmt::Display>(mut self, location: T) -> Self {
self.locations.insert(0, location.to_string());
self
}
pub fn len(&self) -> usize {
self.kind.len()
}
fn prepend_at(mut self, mut locations: Vec<String>) -> Self {
if !locations.is_empty() {
locations.extend(self.locations);
self.locations = locations;
}
self
}
#[cfg(test)]
pub(crate) fn location(&self) -> Vec<&str> {
self.locations.iter().map(|i| i.as_str()).collect()
}
}
impl StdError for Error {
fn description(&self) -> &str {
&self.kind.description()
}
fn cause(&self) -> Option<&StdError> {
None
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.kind)?;
if !self.locations.is_empty() {
write!(f, " at {}", self.locations.join("/"))?;
}
Ok(())
}
}
impl IntoIterator for Error {
type Item = Error;
type IntoIter = IntoIter;
fn into_iter(self) -> IntoIter {
if let ErrorKind::Multiple(errors) = self.kind {
IntoIter {
inner: IntoIterEnum::Multiple(errors.into_iter()),
}
} else {
IntoIter {
inner: IntoIterEnum::Single(iter::once(self)),
}
}
}
}
enum IntoIterEnum {
Single(iter::Once<Error>),
Multiple(vec::IntoIter<Error>),
}
impl Iterator for IntoIterEnum {
type Item = Error;
fn next(&mut self) -> Option<Self::Item> {
match *self {
IntoIterEnum::Single(ref mut content) => content.next(),
IntoIterEnum::Multiple(ref mut content) => content.next(),
}
}
}
pub struct IntoIter {
inner: IntoIterEnum,
}
impl Iterator for IntoIter {
type Item = Error;
fn next(&mut self) -> Option<Error> {
self.inner.next()
}
}
type FieldName = String;
type MetaFormat = String;
#[derive(Debug)]
#[cfg_attr(test, derive(Clone, PartialEq, Eq))]
enum ErrorKind {
Custom(String),
DuplicateField(FieldName),
MissingField(FieldName),
UnknownField(FieldName),
UnexpectedFormat(MetaFormat),
UnexpectedType(String),
UnknownValue(String),
TooFewItems(usize),
TooManyItems(usize),
Multiple(Vec<Error>),
#[doc(hidden)]
__NonExhaustive,
}
impl ErrorKind {
pub fn description(&self) -> &str {
use self::ErrorKind::*;
match *self {
Custom(ref s) => s,
DuplicateField(_) => "Duplicate field",
MissingField(_) => "Missing field",
UnknownField(_) => "Unexpected field",
UnexpectedFormat(_) => "Unexpected meta-item format",
UnexpectedType(_) => "Unexpected literal type",
UnknownValue(_) => "Unknown literal value",
TooFewItems(_) => "Too few items",
TooManyItems(_) => "Too many items",
Multiple(_) => "Multiple errors",
__NonExhaustive => unreachable!(),
}
}
pub fn len(&self) -> usize {
if let ErrorKind::Multiple(ref items) = *self {
items.iter().map(Error::len).sum()
} else {
1
}
}
}
impl fmt::Display for ErrorKind {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::ErrorKind::*;
match *self {
Custom(ref s) => s.fmt(f),
DuplicateField(ref field) => write!(f, "Duplicate field `{}`", field),
MissingField(ref field) => write!(f, "Missing field `{}`", field),
UnknownField(ref field) => write!(f, "Unexpected field `{}`", field),
UnexpectedFormat(ref format) => write!(f, "Unexpected meta-item format `{}`", format),
UnexpectedType(ref ty) => write!(f, "Unexpected literal type `{}`", ty),
UnknownValue(ref val) => write!(f, "Unknown literal value `{}`", val),
TooFewItems(ref min) => write!(f, "Too few items: Expected at least {}", min),
TooManyItems(ref max) => write!(f, "Too many items: Expected no more than {}", max),
Multiple(ref items) if items.len() == 1 => items[0].fmt(f),
Multiple(ref items) => {
write!(f, "Multiple errors: (")?;
let mut first = true;
for item in items {
if !first {
write!(f, ", ")?;
} else {
first = false;
}
item.fmt(f)?;
}
write!(f, ")")
}
__NonExhaustive => unreachable!(),
}
}
}
#[cfg(test)]
mod tests {
use super::Error;
#[test]
fn flatten_noop() {
let err = Error::duplicate_field("hello").at("world");
assert_eq!(err.clone().flatten(), err);
}
#[test]
fn flatten_simple() {
let err = Error::multiple(vec![
Error::unknown_field("hello").at("world"),
Error::missing_field("hell_no").at("world"),
]).at("foo")
.flatten();
assert!(err.location().is_empty());
let mut err_iter = err.into_iter();
let first = err_iter.next();
assert!(first.is_some());
assert_eq!(first.unwrap().location(), vec!["foo", "world"]);
let second = err_iter.next();
assert!(second.is_some());
assert_eq!(second.unwrap().location(), vec!["foo", "world"]);
assert!(err_iter.next().is_none());
}
#[test]
fn len_single() {
let err = Error::duplicate_field("hello");
assert_eq!(1, err.len());
}
#[test]
fn len_multiple() {
let err = Error::multiple(vec![
Error::duplicate_field("hello"),
Error::missing_field("hell_no"),
]);
assert_eq!(2, err.len());
}
#[test]
fn len_nested() {
let err = Error::multiple(vec![
Error::duplicate_field("hello"),
Error::multiple(vec![
Error::duplicate_field("hi"),
Error::missing_field("bye"),
Error::multiple(vec![Error::duplicate_field("whatsup")]),
]),
]);
assert_eq!(4, err.len());
}
}