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94 lines
2.8 KiB
Rust
94 lines
2.8 KiB
Rust
//! Operations related to retrieving `items` from the current `Segmentation`
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//!
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//! A `Segmentation` is a aggregation of items into many `Segments`.
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//! These operations allow retreiving the individual items for all
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//! segments in the `Segmentation.
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use eyre::Result;
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use super::types::LoadingState;
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use super::{engine::Action, Engine};
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use crate::database::{
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query::{Field, Filter, Query},
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query_result::QueryRow,
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};
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use std::ops::Range;
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/// Return the `items` in the current `Segmentation`
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///
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/// If the items don't exist in the cache, they will be queried
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/// asynchronously from the database. The return value distinguishes
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/// between `Loaded` and `Loading` items.
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///
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/// # Arguments
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///
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/// * `engine` - The engine to use for retrieving data
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/// * `range` - The range of items to retrieve. If `None` then all items will be retrieved
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pub fn items(engine: &mut Engine, range: Option<Range<usize>>) -> Result<Vec<Option<QueryRow>>> {
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// build an array with either empty values or values from our cache.
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let mut rows = Vec::new();
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// The given range or all items
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let range = range.unwrap_or_else(|| Range {
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start: 0,
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end: count(engine),
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});
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let mut missing_data = false;
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for index in range.clone() {
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let entry = engine.item_cache.get(&index);
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let entry = match entry {
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Some(LoadingState::Loaded(n)) => Some((*n).clone()),
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Some(LoadingState::Loading) => None,
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None => {
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// for simplicity, we keep the "something is missing" state separate
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missing_data = true;
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// Mark the row as being loaded
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engine.item_cache.put(index, LoadingState::Loading);
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None
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}
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};
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rows.push(entry);
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}
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// Only if at least some data is missing do we perform the request
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if missing_data && !range.is_empty() {
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let request = make_query(engine, range);
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engine.link.request(&request, Action::LoadItems)?;
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}
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Ok(rows)
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}
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/// The total amount of elements in the current `Segmentation`
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///
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/// # Arguments
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///
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/// * `engine` - The engine to use for retrieving data
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pub fn count(engine: &Engine) -> usize {
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let segmentation = match engine.segmentations.last() {
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Some(n) => n,
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None => return 0,
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};
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segmentation.element_count()
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}
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/// Make the query for retrieving items
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fn make_query(engine: &Engine, range: Range<usize>) -> Query {
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let mut filters = Vec::new();
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for entry in &engine.search_stack {
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filters.push(Filter::Like(entry.clone()));
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}
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Query::Normal {
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filters,
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fields: vec![
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Field::SenderDomain,
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Field::SenderLocalPart,
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Field::Subject,
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Field::Path,
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Field::Timestamp,
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],
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range,
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}
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}
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