Moving Table to utils. Fixing couple of small things

This commit is contained in:
Tomusdrw 2016-02-18 19:30:58 +01:00 committed by Tomasz Drwięga
parent 5869dc8273
commit 4bf77c03f5
2 changed files with 123 additions and 0 deletions

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@ -144,6 +144,7 @@ pub mod network;
pub mod log; pub mod log;
pub mod panics; pub mod panics;
pub mod keys; pub mod keys;
pub mod table;
pub use common::*; pub use common::*;
pub use misc::*; pub use misc::*;

122
util/src/table.rs Normal file
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@ -0,0 +1,122 @@
// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity 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 General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! A collection associating pair of keys (row and column) with a single value.
use std::hash::Hash;
use std::collections::HashMap;
/// Structure to hold double-indexed values
///
/// You can obviously use `HashMap<(Row,Col), Val>`, but this structure gives
/// you better access to all `Columns` in Specific `Row`. Namely you can get sub-hashmap
/// `HashMap<Col, Val>` for specific `Row`
pub struct Table<Row, Col, Val>
where Row: Eq + Hash + Clone,
Col: Eq + Hash {
map: HashMap<Row, HashMap<Col, Val>>,
}
impl<Row, Col, Val> Table<Row, Col, Val>
where Row: Eq + Hash + Clone,
Col: Eq + Hash {
/// Creates new Table
pub fn new() -> Table<Row, Col, Val> {
Table {
map: HashMap::new(),
}
}
/// Removes all elements from this Table
pub fn clear(&mut self) {
self.map.clear();
}
/// Returns length of the Table (number of (row, col, val) tuples)
pub fn len(&self) -> usize {
self.map.iter().fold(0, |acc, (_k, v)| acc + v.len())
}
/// Check if there is any element in this Table
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// Get mutable reference for single Table row.
pub fn get_row_mut(&mut self, row: &Row) -> Option<&mut HashMap<Col, Val>> {
self.map.get_mut(row)
}
/// Checks if row is defined for that table (note that even if defined it might be empty)
pub fn has_row(&self, row: &Row) -> bool {
self.map.contains_key(row)
}
/// Get immutable reference for single row in this Table
pub fn get_row(&self, row: &Row) -> Option<&HashMap<Col, Val>> {
self.map.get(row)
}
/// Get element in cell described by `(row, col)`
pub fn get(&self, row: &Row, col: &Col) -> Option<&Val> {
self.map.get(row).and_then(|r| r.get(col))
}
/// Remove value from specific cell
///
/// It will remove the row if it's the last value in it
pub fn remove(&mut self, row: &Row, col: &Col) -> Option<Val> {
let (val, is_empty) = {
let row_map = self.map.get_mut(row);
if let None = row_map {
return None;
}
let mut row_map = row_map.unwrap();
let val = row_map.remove(col);
(val, row_map.is_empty())
};
// Clean row
if is_empty {
self.map.remove(row);
}
val
}
/// Remove given row from Table if there are no values defined in it
///
/// When using `#get_row_mut` it may happen that all values from some row are drained.
/// Table however will not be aware that row is empty.
/// You can use this method to explicitly remove row entry from the Table.
pub fn clear_if_empty(&mut self, row: &Row) {
let is_empty = self.map.get(row).map_or(false, |m| m.is_empty());
if is_empty {
self.map.remove(row);
}
}
/// Inserts new value to specified cell
///
/// Returns previous value (if any)
pub fn insert(&mut self, row: Row, col: Col, val: Val) -> Option<Val> {
if !self.map.contains_key(&row) {
let m = HashMap::new();
self.map.insert(row.clone(), m);
}
let mut columns = self.map.get_mut(&row).unwrap();
columns.insert(col, val)
}
}