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//
// imag - the personal information management suite for the commandline
// Copyright (C) 2015-2019 Matthias Beyer <mail@beyermatthias.de> and contributors
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; version
// 2.1 of the License.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
//! Iterator helpers for external linking stuff
//!
//! Contains also helpers to filter iterators for external/internal links
//!
//!
//! # Warning
//!
//! This module uses `internal::Link` as link type, so we operate on _store ids_ here.
//!
//! Not to confuse with `external::Link` which is a real `FileLockEntry` under the hood.
//!
use libimagentrylink::link::Link;
use libimagentrylink::iter::LinkIter;
use libimagstore::store::Store;
use failure::Fallible as Result;
use failure::ResultExt;
use failure::Error;
use url::Url;
/// Helper for building `OnlyUrlIter` and `NoUrlIter`
///
/// The boolean value defines, how to interpret the `is_external_link_storeid()` return value
/// (here as "pred"):
///
/// ```ignore
/// pred | bool | xor | take?
/// ---- | ---- | --- | ----
/// 0 | 0 | 0 | 1
/// 0 | 1 | 1 | 0
/// 1 | 0 | 1 | 0
/// 1 | 1 | 0 | 1
/// ```
///
/// If `bool` says "take if return value is false", we take the element if the `pred` returns
/// false... and so on.
///
/// As we can see, the operator between these two operants is `!(a ^ b)`.
pub struct UrlFilterIter(LinkIter, bool);
impl Iterator for UrlFilterIter {
type Item = Link;
fn next(&mut self) -> Option<Self::Item> {
use crate::util::is_external_link_storeid;
while let Some(elem) = self.0.next() {
trace!("Check whether is external: {:?}", elem);
if !(self.1 ^ is_external_link_storeid(&elem)) {
trace!("Is external id: {:?}", elem);
return Some(elem);
}
}
None
}
}
/// Helper trait to be implemented on `LinkIter` to select or deselect all external links
///
/// # See also
///
/// Also see `OnlyUrlIter` and `NoUrlIter` and the helper traits/functions
/// `OnlyInteralLinks`/`only_links()` and `OnlyUrlLinks`/`only_urls()`.
pub trait SelectUrl {
fn select_urls(self, b: bool) -> UrlFilterIter;
}
impl SelectUrl for LinkIter {
fn select_urls(self, b: bool) -> UrlFilterIter {
UrlFilterIter(self, b)
}
}
pub struct OnlyUrlIter(UrlFilterIter);
impl OnlyUrlIter {
pub fn new(li: LinkIter) -> OnlyUrlIter {
OnlyUrlIter(UrlFilterIter(li, true))
}
pub fn urls(self, store: &Store) -> UrlIter<'_> {
UrlIter(self, store)
}
}
impl Iterator for OnlyUrlIter {
type Item = Link;
fn next(&mut self) -> Option<Self::Item> {
self.0.next()
}
}
pub struct NoUrlIter(UrlFilterIter);
impl NoUrlIter {
pub fn new(li: LinkIter) -> NoUrlIter {
NoUrlIter(UrlFilterIter(li, false))
}
}
impl Iterator for NoUrlIter {
type Item = Link;
fn next(&mut self) -> Option<Self::Item> {
self.0.next()
}
}
pub trait OnlyUrlLinks : Sized {
fn only_urls(self) -> OnlyUrlIter ;
fn no_links(self) -> OnlyUrlIter {
self.only_urls()
}
}
impl OnlyUrlLinks for LinkIter {
fn only_urls(self) -> OnlyUrlIter {
OnlyUrlIter::new(self)
}
}
pub trait OnlyInternalLinks : Sized {
fn only_links(self) -> NoUrlIter;
fn no_urls(self) -> NoUrlIter {
self.only_links()
}
}
impl OnlyInternalLinks for LinkIter {
fn only_links(self) -> NoUrlIter {
NoUrlIter::new(self)
}
}
pub struct UrlIter<'a>(OnlyUrlIter, &'a Store);
impl<'a> Iterator for UrlIter<'a> {
type Item = Result<Url>;
fn next(&mut self) -> Option<Self::Item> {
use crate::link::Link;
loop {
let next = self.0
.next()
.map(|id| {
debug!("Retrieving entry for id: '{:?}'", id);
self.1
.retrieve(id.clone())
.with_context(|e| format!("Retrieving entry for id: '{:?}' failed: {}", id, e))
.map_err(From::from)
.and_then(|f| {
debug!("Store::retrieve({:?}) succeeded", id);
debug!("getting uri link from file now");
f.get_url()
.context("Error happened while getting link URI from FLE")
.with_context(|e| format!("URL -> Err = {:?}", e))
.map_err(Error::from)
})
});
match next {
Some(Ok(Some(link))) => return Some(Ok(link)),
Some(Ok(None)) => continue,
Some(Err(e)) => return Some(Err(e)),
None => return None
}
}
}
}
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