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use toml::value::{Table, Value};
pub(crate) trait TomlExt {
fn read(&self, key: &str) -> Option<&Value>;
fn read_mut(&mut self, key: &str) -> Option<&mut Value>;
fn insert(&mut self, key: &str, value: Value);
fn delete(&mut self, key: &str) -> Option<Value>;
}
impl TomlExt for Value {
fn read(&self, key: &str) -> Option<&Value> {
if let Some((head, tail)) = split(key) {
self.get(head)?.read(tail)
} else {
self.get(key)
}
}
fn read_mut(&mut self, key: &str) -> Option<&mut Value> {
if let Some((head, tail)) = split(key) {
self.get_mut(head)?.read_mut(tail)
} else {
self.get_mut(key)
}
}
fn insert(&mut self, key: &str, value: Value) {
if !self.is_table() {
*self = Value::Table(Table::new());
}
let table = self.as_table_mut().expect("unreachable");
if let Some((head, tail)) = split(key) {
table
.entry(head)
.or_insert_with(|| Value::Table(Table::new()))
.insert(tail, value);
} else {
table.insert(key.to_string(), value);
}
}
fn delete(&mut self, key: &str) -> Option<Value> {
if let Some((head, tail)) = split(key) {
self.get_mut(head)?.delete(tail)
} else if let Some(table) = self.as_table_mut() {
table.remove(key)
} else {
None
}
}
}
fn split(key: &str) -> Option<(&str, &str)> {
let ix = key.find('.')?;
let (head, tail) = key.split_at(ix);
// splitting will leave the "."
let tail = &tail[1..];
Some((head, tail))
}
#[cfg(test)]
mod tests {
use super::*;
use std::str::FromStr;
#[test]
fn read_simple_table() {
let src = "[table]";
let value = Value::from_str(src).unwrap();
let got = value.read("table").unwrap();
assert!(got.is_table());
}
#[test]
fn read_nested_item() {
let src = "[table]\nnested=true";
let value = Value::from_str(src).unwrap();
let got = value.read("table.nested").unwrap();
assert_eq!(got, &Value::Boolean(true));
}
#[test]
fn insert_item_at_top_level() {
let mut value = Value::Table(Table::default());
let item = Value::Boolean(true);
value.insert("first", item.clone());
assert_eq!(value.get("first").unwrap(), &item);
}
#[test]
fn insert_nested_item() {
let mut value = Value::Table(Table::default());
let item = Value::Boolean(true);
value.insert("first.second", item.clone());
let inserted = value.read("first.second").unwrap();
assert_eq!(inserted, &item);
}
#[test]
fn delete_a_top_level_item() {
let src = "top = true";
let mut value = Value::from_str(src).unwrap();
let got = value.delete("top").unwrap();
assert_eq!(got, Value::Boolean(true));
}
#[test]
fn delete_a_nested_item() {
let src = "[table]\n nested = true";
let mut value = Value::from_str(src).unwrap();
let got = value.delete("table.nested").unwrap();
assert_eq!(got, Value::Boolean(true));
}
}
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