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use std::fmt::{self, Display};
use std::slice;
use super::Chain;
/// Path to the error value in the input, like `dependencies.serde.typo1`.
///
/// Use `path.to_string()` to get a string representation of the path with
/// segments separated by periods, or use `path.iter()` to iterate over
/// individual segments of the path.
#[derive(Clone, Debug)]
pub struct Path {
segments: Vec<Segment>,
}
/// Single segment of a path.
#[derive(Clone, Debug)]
pub enum Segment {
Seq { index: usize },
Map { key: String },
Enum { variant: String },
Unknown,
}
impl Path {
/// Returns an iterator with element type [`&Segment`][Segment].
pub fn iter(&self) -> Segments {
Segments {
iter: self.segments.iter(),
}
}
}
impl<'a> IntoIterator for &'a Path {
type Item = &'a Segment;
type IntoIter = Segments<'a>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
/// Iterator over segments of a path.
pub struct Segments<'a> {
iter: slice::Iter<'a, Segment>,
}
impl<'a> Iterator for Segments<'a> {
type Item = &'a Segment;
fn next(&mut self) -> Option<Self::Item> {
self.iter.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a> DoubleEndedIterator for Segments<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.next_back()
}
}
impl<'a> ExactSizeIterator for Segments<'a> {
fn len(&self) -> usize {
self.iter.len()
}
}
impl Display for Path {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
if self.segments.is_empty() {
return formatter.write_str(".");
}
let mut separator = "";
for segment in self {
match segment {
Segment::Seq { index } => {
write!(formatter, "[{}]", index)?;
}
Segment::Map { key } | Segment::Enum { variant: key } => {
write!(formatter, "{}{}", separator, key)?;
}
Segment::Unknown => {
write!(formatter, "{}?", separator)?;
}
}
separator = ".";
}
Ok(())
}
}
impl Path {
pub(crate) fn empty() -> Self {
Path {
segments: Vec::new(),
}
}
pub(crate) fn from_chain(mut chain: &Chain) -> Self {
let mut segments = Vec::new();
loop {
match chain {
Chain::Root => break,
Chain::Seq { parent, index } => {
segments.push(Segment::Seq { index: *index });
chain = parent;
}
Chain::Map { parent, key } => {
segments.push(Segment::Map { key: key.clone() });
chain = parent;
}
Chain::Struct { parent, key } => {
let key = *key;
segments.push(Segment::Map {
key: key.to_owned(),
});
chain = parent;
}
Chain::Enum { parent, variant } => {
segments.push(Segment::Enum {
variant: variant.clone(),
});
chain = parent;
}
Chain::Some { parent }
| Chain::NewtypeStruct { parent }
| Chain::NewtypeVariant { parent } => {
chain = parent;
}
Chain::NonStringKey { parent } => {
segments.push(Segment::Unknown);
chain = parent;
}
}
}
segments.reverse();
Path { segments }
}
pub(crate) fn is_only_unknown(&self) -> bool {
self.segments.iter().all(Segment::is_unknown)
}
}
impl Segment {
fn is_unknown(&self) -> bool {
match self {
Segment::Unknown => true,
_ => false,
}
}
}