evalit 0.1.1

a toy interpreter
Documentation 
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use std::collections::HashMap;

use crate::{Object, RuntimeError, Value, ValueRef};

impl<K, V> Object for HashMap<K, V>
where
    K: Object + std::hash::Hash + std::cmp::Eq + Clone,
    V: Object + Clone,
{
    fn debug(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_map().entries(self.iter()).finish()
    }

    fn index_get(&self, index: &Value) -> Result<ValueRef, RuntimeError> {
        if let Some(key) = index.downcast_ref::<K>() {
            if let Some(value) = self.get(key) {
                return Ok(ValueRef::new(value.clone()));
            }

            return Ok(ValueRef::null());
        }

        Err(RuntimeError::invalid_operation(
            super::OperateKind::IndexGet,
            format!("cannot index hashmap with {index:?}"),
        ))
    }

    fn index_set(&mut self, index: &Value, value: ValueRef) -> Result<(), RuntimeError> {
        if let Some(key) = index.downcast_ref::<K>() {
            if let Some(value) = value.downcast_ref::<V>() {
                self.insert(key.clone(), value.clone());
                return Ok(());
            }
        }

        Err(RuntimeError::invalid_operation(
            super::OperateKind::IndexSet,
            format!("cannot index hashmap with {index:?}"),
        ))
    }
}

impl<K> Object for HashMap<K, ValueRef>
where
    K: Object + std::hash::Hash + std::cmp::Eq + Clone,
{
    fn debug(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_map().entries(self.iter()).finish()
    }

    fn index_get(&self, index: &Value) -> Result<ValueRef, RuntimeError> {
        if let Some(key) = index.downcast_ref::<K>() {
            if let Some(value) = self.get(key) {
                return Ok(value.clone());
            }

            // return Ok(Value::null());
            return Err(RuntimeError::key_not_found(index));
        }

        Err(RuntimeError::invalid_operation(
            super::OperateKind::IndexGet,
            format!("cannot index hashmap with {index:?}"),
        ))
    }

    fn index_set(&mut self, index: &Value, value: ValueRef) -> Result<(), RuntimeError> {
        if let Some(key) = index.downcast_ref::<K>() {
            self.insert(key.clone(), value);
            return Ok(());
        }

        Err(RuntimeError::invalid_operation(
            super::OperateKind::IndexSet,
            format!("cannot index hashmap with {index:?}"),
        ))
    }

    fn make_iterator(&self) -> Result<Box<dyn Iterator<Item = ValueRef>>, RuntimeError> {
        Ok(Box::new(self.clone().into_iter().map(|(k, v)| {
            ValueRef::new((ValueRef::new(k.clone()), v.clone()))
        })))
    }
}