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use std::collections::BTreeMap;
use std::fmt::{self, Debug, Display, Formatter, Write};
use std::iter::FromIterator;
use std::ops::{Add, AddAssign};
use std::rc::Rc;
use super::{Str, Value};
use crate::diag::StrResult;
/// Create a new [`Dict`] from key-value pairs.
#[allow(unused_macros)]
macro_rules! dict {
($($key:expr => $value:expr),* $(,)?) => {{
#[allow(unused_mut)]
let mut map = std::collections::BTreeMap::new();
$(map.insert($key.into(), $value.into());)*
$crate::eval::Dict::from_map(map)
}};
}
/// A dictionary from strings to values with clone-on-write value semantics.
#[derive(Default, Clone, PartialEq)]
pub struct Dict(Rc<BTreeMap<Str, Value>>);
impl Dict {
/// Create a new, empty dictionary.
pub fn new() -> Self {
Self::default()
}
/// Create a new dictionary from a mapping of strings to values.
pub fn from_map(map: BTreeMap<Str, Value>) -> Self {
Self(Rc::new(map))
}
/// Whether the dictionary is empty.
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// The number of pairs in the dictionary.
pub fn len(&self) -> i64 {
self.0.len() as i64
}
/// Borrow the value the given `key` maps to.
pub fn get(&self, key: Str) -> StrResult<&Value> {
self.0.get(&key).ok_or_else(|| missing_key(&key))
}
/// Mutably borrow the value the given `key` maps to.
///
/// This inserts the key with [`None`](Value::None) as the value if not
/// present so far.
pub fn get_mut(&mut self, key: Str) -> &mut Value {
Rc::make_mut(&mut self.0).entry(key.into()).or_default()
}
/// Insert a mapping from the given `key` to the given `value`.
pub fn insert(&mut self, key: Str, value: Value) {
Rc::make_mut(&mut self.0).insert(key.into(), value);
}
/// Clear the dictionary.
pub fn clear(&mut self) {
if Rc::strong_count(&mut self.0) == 1 {
Rc::make_mut(&mut self.0).clear();
} else {
*self = Self::new();
}
}
/// Iterate over pairs of references to the contained keys and values.
pub fn iter(&self) -> std::collections::btree_map::Iter<Str, Value> {
self.0.iter()
}
}
/// The missing key access error message.
#[cold]
fn missing_key(key: &Str) -> String {
format!("dictionary does not contain key: {}", key)
}
impl Debug for Dict {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.debug_map().entries(self.0.iter()).finish()
}
}
impl Display for Dict {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.write_char('(')?;
if self.is_empty() {
f.write_char(':')?;
}
for (i, (key, value)) in self.iter().enumerate() {
f.write_str(key)?;
f.write_str(": ")?;
Display::fmt(value, f)?;
if i + 1 < self.0.len() {
f.write_str(", ")?;
}
}
f.write_char(')')
}
}
impl Add for Dict {
type Output = Self;
fn add(mut self, rhs: Dict) -> Self::Output {
self += rhs;
self
}
}
impl AddAssign for Dict {
fn add_assign(&mut self, rhs: Dict) {
match Rc::try_unwrap(rhs.0) {
Ok(map) => self.extend(map),
Err(rc) => self.extend(rc.iter().map(|(k, v)| (k.clone(), v.clone()))),
}
}
}
impl Extend<(Str, Value)> for Dict {
fn extend<T: IntoIterator<Item = (Str, Value)>>(&mut self, iter: T) {
Rc::make_mut(&mut self.0).extend(iter);
}
}
impl FromIterator<(Str, Value)> for Dict {
fn from_iter<T: IntoIterator<Item = (Str, Value)>>(iter: T) -> Self {
Self(Rc::new(iter.into_iter().collect()))
}
}
impl IntoIterator for Dict {
type Item = (Str, Value);
type IntoIter = std::collections::btree_map::IntoIter<Str, Value>;
fn into_iter(self) -> Self::IntoIter {
match Rc::try_unwrap(self.0) {
Ok(map) => map.into_iter(),
Err(rc) => (*rc).clone().into_iter(),
}
}
}
impl<'a> IntoIterator for &'a Dict {
type Item = (&'a Str, &'a Value);
type IntoIter = std::collections::btree_map::Iter<'a, Str, Value>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
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