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use std::borrow::Cow;
use std::collections::BTreeMap;

/// Trait for working with generic map data structures.
pub trait BDictAccess<K, V> {
    /// Convert the dictionary to an unordered list of key/value pairs.
    fn to_list(&self) -> Vec<(&K, &V)>;

    /// Lookup a value in the dictionary.
    fn lookup(&self, key: &[u8]) -> Option<&V>;

    /// Lookup a mutable value in the dictionary.
    fn lookup_mut(&mut self, key: &[u8]) -> Option<&mut V>;

    /// Insert a key/value pair into the dictionary.
    fn insert(&mut self, key: K, value: V) -> Option<V>;

    /// Remove a value from the dictionary and return it.
    fn remove(&mut self, key: &[u8]) -> Option<V>;
}

impl<'a, V> BDictAccess<&'a [u8], V> for BTreeMap<&'a [u8], V> {
    fn to_list(&self) -> Vec<(&&'a [u8], &V)> {
        self.iter().map(|(k, v)| (k, v)).collect()
    }

    fn lookup(&self, key: &[u8]) -> Option<&V> {
        self.get(key)
    }

    fn lookup_mut(&mut self, key: &[u8]) -> Option<&mut V> {
        self.get_mut(key)
    }

    fn insert(&mut self, key: &'a [u8], value: V) -> Option<V> {
        self.insert(key, value)
    }

    fn remove(&mut self, key: &[u8]) -> Option<V> {
        self.remove(key)
    }
}

impl<'a, V> BDictAccess<Cow<'a, [u8]>, V> for BTreeMap<Cow<'a, [u8]>, V> {
    fn to_list(&self) -> Vec<(&Cow<'a, [u8]>, &V)> {
        self.iter().map(|(k, v)| (k, v)).collect()
    }

    fn lookup(&self, key: &[u8]) -> Option<&V> {
        self.get(key)
    }

    fn lookup_mut(&mut self, key: &[u8]) -> Option<&mut V> {
        self.get_mut(key)
    }

    fn insert(&mut self, key: Cow<'a, [u8]>, value: V) -> Option<V> {
        self.insert(key, value)
    }

    fn remove(&mut self, key: &[u8]) -> Option<V> {
        self.remove(key)
    }
}