doublets-decorators 0.1.0-alpha.3

Decorators for doublets
Documentation 
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use std::borrow::BorrowMut;
use std::default::default;
use std::marker::PhantomData;
use std::ops::Try;

use doublets::data::LinksConstants;
use doublets::data::ToQuery;
use doublets::num::LinkType;

use doublets::{Doublets, Error, Link};

pub struct UsagesValidator<T: LinkType, L: Doublets<T>> {
    links: L,

    _phantom: PhantomData<T>,
}

impl<T: LinkType, L: Doublets<T>> UsagesValidator<T, L> {
    pub fn new(links: L) -> Self {
        Self {
            links,
            _phantom: default(),
        }
    }
}

impl<T: LinkType, L: Doublets<T>> Doublets<T> for UsagesValidator<T, L> {
    fn constants(&self) -> LinksConstants<T> {
        self.links.constants()
    }

    fn count_by(&self, query: impl ToQuery<T>) -> T {
        self.links.count_by(query)
    }

    fn create_by_with<F, R>(&mut self, query: impl ToQuery<T>, handler: F) -> Result<R, Error<T>>
    where
        F: FnMut(Link<T>, Link<T>) -> R,
        R: Try<Output = ()>,
    {
        self.links.create_by_with(query, handler)
    }

    fn try_each_by<F, R>(&self, restrictions: impl ToQuery<T>, handler: F) -> R
    where
        F: FnMut(Link<T>) -> R,
        R: Try<Output = ()>,
    {
        self.links.try_each_by(restrictions, handler)
    }

    fn update_by_with<F, R>(
        &mut self,
        query: impl ToQuery<T>,
        replacement: impl ToQuery<T>,
        handler: F,
    ) -> Result<R, Error<T>>
    where
        F: FnMut(Link<T>, Link<T>) -> R,
        R: Try<Output = ()>,
    {
        let links = self.links.borrow_mut();
        let query = query.to_query();
        let index = query[links.constants().index_part.as_()];
        let usages = links.usages(index)?;
        if usages.is_empty() {
            links.update_by_with(query, replacement, handler)
        } else {
            let usages: Result<_, Error<T>> = usages
                .into_iter()
                .map(|index| links.try_get_link(index))
                .collect();
            Err(Error::HasUsages(usages?))
        }
    }

    fn delete_by_with<F, R>(&mut self, query: impl ToQuery<T>, handler: F) -> Result<R, Error<T>>
    where
        F: FnMut(Link<T>, Link<T>) -> R,
        R: Try<Output = ()>,
    {
        let links = self.links.borrow_mut();
        let query = query.to_query();
        let index = query[links.constants().index_part.as_()];
        let usages = links.usages(index)?;
        if usages.is_empty() {
            links.delete_by_with(query, handler)
        } else {
            let usages: Result<_, Error<T>> = usages
                .into_iter()
                .map(|index| links.try_get_link(index))
                .collect();
            Err(Error::HasUsages(usages?))
        }
    }
}