Enum with data to HashMap

This crate provides a way to transform an enum with associated data into a hashmap. This idea came to me as I was working on my UI library.

I wanted to implement styling in a very flexible way. Essentially, every style property is optional unless it's defined. This would have been extremely annoying to implement with a struct as all properties would have had to be an Option. Instead, I just simply create my enum with associated data and transform it into a map. I can later easily access each value with an iterator and manipulate it however I want.

[dependencies]
enum2map = "0.1"

Examples

The way to use the crate is very simple. Define an enum with associated data and derive Enum2Map.

#[derive(Debug, PartialEq, Eq, Clone, Enum2Map)]
pub enum TestValue {
    Padding(usize),
    Margin(String),
}

Then you can use generic getters and setters or the getter and setter for each property with the new enum that was generated.

pub enum TestValueKey {
    Padding,
    Margin,
}

let mut map = TestValueMap::new();

map.get(TestValueKey::Margin);
map.get(TestValueKey::Padding);

map.get_or_default(TestValueKey::Padding);
map.get_or_default(TestValueKey::Padding);

map.set(TestValue::Padding(10));
map.set(TestValue::Margin("string test".to_string()));

As well as the getters and setters for each value in your enum:

map.set_padding(50);
map.set_margin("another test".to_string());

map.get_padding();
map.get_margin();

How it works

The derive will first generate the keys from the enum provided:

pub enum TestValueKey {
    Padding,
    Margin,
}

It will then generate a struct with the generic getters and setters you saw in the examples. It will also generate a getter and setter for each value in your enum. The API was written to follow the HashMap API as closely as I could.

pub struct TestValueMap {
    pub values: std::collections::HashMap<TestValueKey, TestValue>,
}
impl TestValueMap {
    pub fn new() -> Self {
        Self {
            values: std::collections::HashMap::new(),
        }
    }
    pub fn insert(&mut self, value: TestValue) -> Option<TestValue> {
        match value {
            TestValue::Padding(val) => {
                self.values.insert(TestValueKey::Padding, TestValue::Padding(val))
            }
            TestValue::Margin(val) => {
                self.values.insert(TestValueKey::Margin, TestValue::Margin(val))
            }
        }
    }
    pub fn get(&self, key: TestValueKey) -> Option<&TestValue> {
        self.values.get(&key)
    }
    pub fn get_or_default(&self, key: TestValueKey) -> TestValue {
        match self.values.get(&key) {
            Some(value) => value.clone(),
            None => {
                match key {
                    TestValueKey::Padding => TestValue::Padding(Default::default()),
                    TestValueKey::Margin => TestValue::Margin(Default::default()),
                }
            }
        }
    }
    pub fn set(&mut self, value: TestValue) -> Option<TestValue> {
        match value {
            TestValue::Padding(val) => {
                self.values.insert(TestValueKey::Padding, TestValue::Padding(val))
            }
            TestValue::Margin(val) => {
                self.values.insert(TestValueKey::Margin, TestValue::Margin(val))
            }
        }
    }
    pub fn get_padding(&self) -> usize {
        match self.values.get(&TestValueKey::Padding) {
            Some(TestValue::Padding(value)) => value.clone(),
            None => Default::default(),
            _ => {
                ::core::panicking::panic_fmt(
                    format_args!(
                        "Unexpected condition: Didn\'t find type {0} for {1}",
                        "usize",
                        "Padding",
                    ),
                );
            }
        }
    }
    pub fn get_margin(&self) -> String {
        match self.values.get(&TestValueKey::Margin) {
            Some(TestValue::Margin(value)) => value.clone(),
            None => Default::default(),
            _ => {
                ::core::panicking::panic_fmt(
                    format_args!(
                        "Unexpected condition: Didn\'t find type {0} for {1}",
                        "String",
                        "Margin",
                    ),
                );
            }
        }
    }
    pub fn set_padding(&mut self, val: usize) -> Option<usize> {
        if let Some(TestValue::Padding(old_value))
            = self.values.insert(TestValueKey::Padding, TestValue::Padding(val))
        {
            return Some(old_value);
        }
        None
    }
    pub fn set_margin(&mut self, val: String) -> Option<String> {
        if let Some(TestValue::Margin(old_value))
            = self.values.insert(TestValueKey::Margin, TestValue::Margin(val))
        {
            return Some(old_value);
        }
        None
    }
}

Future Work

• Better error handling.
• Handle cases where the enum has no associated data.
• Better documentation.