duster/src/renderer/context_element.rs

use crate::parser::Filter;
use crate::renderer::errors::RenderError;
use crate::renderer::errors::WalkError;
use std::any::Any;
use std::fmt::Debug;

pub trait ContextElement:
    Debug + Walkable + Renderable + Loopable + CloneIntoBoxedContextElement + CompareContextElement
{
}

pub trait Walkable {
    fn walk(&self, segment: &str) -> Result<&dyn ContextElement, WalkError>;
}

pub trait Renderable {
    fn render(&self, filters: &Vec<Filter>) -> Result<String, RenderError>;
}

pub trait Loopable {
    /// Return the elements for a Dust section
    ///
    /// Sections in dust are accomplished with the {#path} syntax. A
    /// section has a truthiness check performed on it. If that
    /// truthiness check fails, then it will render the
    /// else-block. Otherwise if its a scalar value it will render
    /// once with the context being the element at that path. Finally,
    /// if its an array-like value then it will render n-times, once
    /// for each element of the array.
    fn get_loop_elements(&self) -> Vec<&dyn ContextElement>;
}

pub trait CompareContextElement {
    fn to_any(&self) -> &dyn Any;

    fn equals(&self, other: &dyn ContextElement) -> bool;
}

pub trait CloneIntoBoxedContextElement {
    fn clone_to_box(&self) -> Box<dyn ContextElement>;
}

impl<C: 'static + ContextElement + Clone> CloneIntoBoxedContextElement for C {
    fn clone_to_box(&self) -> Box<dyn ContextElement> {
        Box::new(self.clone())
    }
}

impl<'a, 'b> PartialEq<&'b dyn ContextElement> for &'a dyn ContextElement {
    fn eq(&self, other: &&'b dyn ContextElement) -> bool {
        self.equals(*other)
    }
}