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//
// imag - the personal information management suite for the commandline
// Copyright (C) 2015-2020 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
//
use std::path::PathBuf;
use std::sync::Arc;
use std::fmt::Debug;
use failure::Fallible as Result;
use crate::storeid::StoreIdWithBase;
use crate::file_abstraction::FileAbstraction;
/// See documentation for PathIterator
pub(crate) trait PathIterBuilder : Debug {
fn build_iter(&self) -> Box<dyn Iterator<Item = Result<PathBuf>>>;
fn in_collection(&mut self, c: &str) -> Result<()>;
}
/// A wrapper for an iterator over `PathBuf`s
///
/// As the backend defines how "iterating over all entries" is implemented, this type holds a
/// `PathIterBuilder` internally. This type is used to create new iterator instances every time the
/// "settings" for how the iterator behaves are changed. This basically means: If the PathIterator
/// is requested to not iterate over a directory "a" but rather its subdirectory "a/b", the
/// implementation asks the `PathIterBuilder` to create a new iterator for that.
///
/// The `PathIterBuilder` can then yield a new iterator instance which is optimized for the new
/// requirements (which basically means: Construct a new WalkDir object which does traverse the
/// subdirectory instead of the parent).
///
/// This means quite a few allocations down the road, as the PathIterator itself is not generic, but
/// this seems to be the best way to implement this.
pub(crate) struct PathIterator<'a> {
iter_builder: Box<dyn PathIterBuilder>,
iter: Box<dyn Iterator<Item = Result<PathBuf>>>,
storepath: &'a PathBuf,
backend: Arc<dyn FileAbstraction>,
}
impl<'a> PathIterator<'a> {
pub fn new(iter_builder: Box<dyn PathIterBuilder>,
storepath: &'a PathBuf,
backend: Arc<dyn FileAbstraction>)
-> PathIterator<'a>
{
trace!("Generating iterator object with PathIterBuilder: {:?}", iter_builder);
let iter = iter_builder.build_iter();
PathIterator { iter_builder, iter, storepath, backend }
}
pub fn in_collection(mut self, c: &str) -> Result<Self> {
trace!("Generating iterator object for collection: {}", c);
self.iter_builder.in_collection(c)?;
self.iter = self.iter_builder.build_iter();
trace!("Set new iterator");
Ok(self)
}
/// Turn iterator into its internals
///
/// Used for `Entries::into_storeid_iter()`
///
/// # TODO
///
/// Revisit whether this can be done in a cleaner way. See commit message for why this is
/// needed.
pub(crate) fn into_inner(self) -> Box<dyn Iterator<Item = Result<PathBuf>>> {
self.iter
}
}
impl<'a> Iterator for PathIterator<'a> {
type Item = Result<StoreIdWithBase<'a>>;
fn next(&mut self) -> Option<Self::Item> {
while let Some(next) = self.iter.next() {
trace!("Iterating over item = {:?}", next);
match next {
Err(e) => return Some(Err(e)),
Ok(next) => match self.backend.is_file(&next) {
Err(e) => return Some(Err(e)),
Ok(true) => return Some(StoreIdWithBase::from_full_path(&self.storepath, next)),
Ok(false) => { continue },
}
}
}
None
}
}
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