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//! ```
//! #[macro_use]
//! extern crate serde_derive;
//!
//! extern crate toml;
//! use toml::spanned::Spanned;
//!
//! #[derive(Deserialize)]
//! struct Value {
//! s: Spanned<String>,
//! }
//!
//! fn main() {
//! let t = "s = \"value\"\n";
//!
//! let u: Value = toml::from_str(t).unwrap();
//!
//! assert_eq!(u.s.start, 4);
//! assert_eq!(u.s.end, 11);
//! }
//! ```
use serde::{de, ser};
use std::fmt;
#[doc(hidden)]
pub const NAME: &'static str = "$__toml_private_Spanned";
#[doc(hidden)]
pub const START: &'static str = "$__toml_private_start";
#[doc(hidden)]
pub const END: &'static str = "$__toml_private_end";
#[doc(hidden)]
pub const VALUE: &'static str = "$__toml_private_value";
macro_rules! key_deserialize {
($ident:ident, $field:expr, $name:expr) => {
struct $ident;
impl<'de> de::Deserialize<'de> for $ident {
fn deserialize<D>(deserializer: D) -> Result<$ident, D::Error>
where D: de::Deserializer<'de>
{
struct FieldVisitor;
impl<'de> de::Visitor<'de> for FieldVisitor {
type Value = ();
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a valid spanned field")
}
fn visit_str<E>(self, s: &str) -> Result<(), E>
where E: de::Error
{
if s == $field {
Ok(())
} else {
Err(de::Error::custom(
concat!("expected spanned field `", $name, "`")))
}
}
}
deserializer.deserialize_identifier(FieldVisitor)?;
Ok($ident)
}
}
}
}
/// A spanned value, indicating the range at which it is defined in the source.
#[derive(Debug)]
pub struct Spanned<T> {
/// The start range.
pub start: usize,
/// The end range (exclusive).
pub end: usize,
/// The spanned value.
pub value: T,
}
impl<'de, T> de::Deserialize<'de> for Spanned<T>
where T: de::Deserialize<'de>
{
fn deserialize<D>(deserializer: D) -> Result<Spanned<T>, D::Error>
where D: de::Deserializer<'de>
{
struct SpannedVisitor<T>(::std::marker::PhantomData<T>);
impl<'de, T> de::Visitor<'de> for SpannedVisitor<T>
where T: de::Deserialize<'de>
{
type Value = Spanned<T>;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a TOML spanned")
}
fn visit_map<V>(self, mut visitor: V) -> Result<Spanned<T>, V::Error>
where V: de::MapAccess<'de>
{
let start = visitor.next_key::<StartKey>()?;
if start.is_none() {
return Err(de::Error::custom("spanned start key not found"))
}
let start: usize = visitor.next_value()?;
let end = visitor.next_key::<EndKey>()?;
if end.is_none() {
return Err(de::Error::custom("spanned end key not found"))
}
let end: usize = visitor.next_value()?;
let value = visitor.next_key::<ValueKey>()?;
if value.is_none() {
return Err(de::Error::custom("spanned value key not found"))
}
let value: T = visitor.next_value()?;
Ok(Spanned {
start: start,
end: end,
value: value
})
}
}
key_deserialize!(StartKey, START, "start");
key_deserialize!(EndKey, END, "end");
key_deserialize!(ValueKey, VALUE, "value");
let visitor = SpannedVisitor(::std::marker::PhantomData);
static FIELDS: [&'static str; 3] = [START, END, VALUE];
deserializer.deserialize_struct(NAME, &FIELDS, visitor)
}
}
impl<T: ser::Serialize> ser::Serialize for Spanned<T> {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: ser::Serializer,
{
self.value.serialize(serializer)
}
}
|
