duster/src/renderer/parameters_context.rs

use crate::parser::Filter;
use crate::parser::KVPair;
use crate::parser::OwnedLiteral;
use crate::parser::RValue;
use crate::renderer::breadcrumb_tree::BreadcrumbTreeElement;
use crate::renderer::context_element::CompareContextElement;
use crate::renderer::context_element::ContextElement;
use crate::renderer::context_element::IceResult;
use crate::renderer::context_element::IntoContextElement;
use crate::renderer::tree_walking::walk_path;
use crate::renderer::DustRenderer;
use crate::renderer::Loopable;
use crate::renderer::RenderError;
use crate::renderer::Renderable;
use crate::renderer::Truthiness;
use crate::renderer::WalkError;
use crate::renderer::Walkable;
use std::borrow::Borrow;
use std::cmp::Ordering;
use std::collections::HashMap;
use std::rc::Rc;

#[derive(Debug)]
pub struct ParametersContext<'a> {
    params: HashMap<&'a str, BreadcrumbTreeElement<'a>>,
}

impl<'a> ParametersContext<'a> {
    pub fn new(
        renderer: &DustRenderer,
        breadcrumbs: &'a Vec<BreadcrumbTreeElement<'a>>,
        params: &'a Vec<KVPair>,
    ) -> Self {
        // If the parameter is a Path, then we resolve it immediately
        // to a context element because those are resolved using the
        // breadcrumbs at the time of assignment.
        //
        // If the parameter is a template (for example `foo="{bar}"`)
        // then those are resolved at the time of access rather than
        // the time of assignment, so we leave them into their
        // original IntoContextElement state.
        let rendered_params: HashMap<&'a str, BreadcrumbTreeElement<'a>> = params
            .iter()
            .map(|kvpair| {
                let k = kvpair.key;
                let v: Option<BreadcrumbTreeElement<'a>> = match &kvpair.value {
                    RValue::RVLiteral(owned_literal) => {
                        Some(BreadcrumbTreeElement::from_borrowed(&kvpair.value))
                    }
                    RValue::RVPath(path) => kvpair
                        .value
                        .into_context_element(renderer, breadcrumbs)
                        .map(std::convert::From::from),
                    RValue::RVTemplate(template) => {
                        Some(BreadcrumbTreeElement::from_borrowed(&kvpair.value))
                    }
                };
                v.map(|some_v| (k, some_v))
            })
            // TODO: Should a None value here be the same as a key not existing, or should we store the Nones?
            .filter_map(|pair| pair)
            .collect();

        ParametersContext {
            params: rendered_params,
        }
    }
}

impl<'a> IntoContextElement for ParametersContext<'a> {
    fn into_context_element<'b>(
        &'b self,
        renderer: &DustRenderer,
        breadcrumbs: &'b Vec<BreadcrumbTreeElement<'b>>,
    ) -> Option<IceResult<'b>> {
        panic!("into_context_element cannot be called on pseudo elements");
    }
}

impl<'a> Walkable for ParametersContext<'a> {
    fn walk(&self, segment: &str) -> Result<&dyn IntoContextElement, WalkError> {
        self.params
            .get(segment)
            .map(|bte| bte.borrow())
            .ok_or(WalkError::CantWalk)
    }

    fn is_pseudo_element(&self) -> bool {
        true
    }
}

impl<'a> IntoContextElement for RValue<'a> {
    fn into_context_element<'b>(
        &'b self,
        renderer: &DustRenderer,
        breadcrumbs: &'b Vec<BreadcrumbTreeElement<'b>>,
    ) -> Option<IceResult<'b>> {
        match self {
            RValue::RVLiteral(owned_literal) => Some(IceResult::from_borrowed(owned_literal)),
            RValue::RVPath(path) => walk_path(breadcrumbs, &path.keys)
                .map(|ice| ice.into_context_element(renderer, breadcrumbs))
                .ok()
                .flatten(),
            RValue::RVTemplate(template) => renderer
                .render_partial_name(template, breadcrumbs)
                .map(|rendered| OwnedLiteral::LString(rendered))
                .ok()
                .map(|owned_literal| IceResult::from_owned(owned_literal)),
        }
    }
}

impl<'a> Walkable for RValue<'a> {
    fn walk(&self, segment: &str) -> Result<&dyn IntoContextElement, WalkError> {
        Err(WalkError::CantWalk)
    }
}

impl ContextElement for OwnedLiteral {}

impl Truthiness for OwnedLiteral {
    fn is_truthy(&self) -> bool {
        match self {
            OwnedLiteral::LString(text) => !text.is_empty(),
            OwnedLiteral::LPositiveInteger(num) => true,
        }
    }
}

impl Renderable for OwnedLiteral {
    fn render(&self, _filters: &Vec<Filter>) -> Result<String, RenderError> {
        match self {
            OwnedLiteral::LString(text) => Ok(text.clone()),
            OwnedLiteral::LPositiveInteger(num) => Ok(num.to_string()),
        }
    }
}

impl Loopable for OwnedLiteral {
    fn get_loop_elements(&self) -> Vec<&dyn ContextElement> {
        Vec::new()
    }
}

impl Walkable for OwnedLiteral {
    fn walk(&self, segment: &str) -> Result<&dyn IntoContextElement, WalkError> {
        Err(WalkError::CantWalk)
    }
}

impl CompareContextElement for OwnedLiteral {
    fn equals(&self, other: &dyn ContextElement) -> bool {
        // println!("equals literal {:?} | {:?}", self, other);
        // If its an OwnedLiteral then compare them directly,
        // otherwise defer to the other type's implementation of
        // CompareContextElement since the end user could add any
        // type.
        match other.to_any().downcast_ref::<Self>() {
            None => other.equals(self),
            Some(other_literal) => match (self, other_literal) {
                (OwnedLiteral::LString(self_text), OwnedLiteral::LString(other_text)) => {
                    self_text == other_text
                }
                (OwnedLiteral::LPositiveInteger(self_num), OwnedLiteral::LString(other_text)) => {
                    &self_num.to_string() == other_text
                }
                (OwnedLiteral::LString(self_text), OwnedLiteral::LPositiveInteger(other_num)) => {
                    self_text == &other_num.to_string()
                }
                (
                    OwnedLiteral::LPositiveInteger(self_num),
                    OwnedLiteral::LPositiveInteger(other_num),
                ) => self_num == other_num,
            },
        }
    }

    fn partial_compare(&self, other: &dyn ContextElement) -> Option<Ordering> {
        // println!("partial_compare literal {:?} | {:?}", self, other);
        // If its an OwnedLiteral then compare them directly,
        // otherwise defer to the other type's implementation of
        // CompareContextElement since the end user could add any
        // type.
        match other.to_any().downcast_ref::<Self>() {
            None => match other.partial_compare(self) {
                None => None,
                Some(ord) => match ord {
                    Ordering::Equal => Some(Ordering::Equal),
                    Ordering::Greater => Some(Ordering::Less),
                    Ordering::Less => Some(Ordering::Greater),
                },
            },
            Some(other_literal) => match (self, other_literal) {
                (OwnedLiteral::LString(self_text), OwnedLiteral::LString(other_text)) => {
                    self_text.partial_cmp(other_text)
                }
                (OwnedLiteral::LPositiveInteger(self_num), OwnedLiteral::LString(other_text)) => {
                    self_num.to_string().partial_cmp(other_text)
                }
                (OwnedLiteral::LString(self_text), OwnedLiteral::LPositiveInteger(other_num)) => {
                    self_text.partial_cmp(&other_num.to_string())
                }
                (
                    OwnedLiteral::LPositiveInteger(self_num),
                    OwnedLiteral::LPositiveInteger(other_num),
                ) => self_num.partial_cmp(other_num),
            },
        }
    }
}