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|
mod vector_clock;
use std::fmt::Display;
use uuid::Uuid;
use crate::vector_clock::VectorClock;
use thiserror::Error;
#[derive(Error, Debug)]
pub enum Error {
#[error("object with ID {0} not found")]
NotFound(DerivedId),
}
#[derive(Default)]
pub struct Doc {
ops: Vec<Op>,
}
impl Doc {
pub fn append_op(&mut self, actor_id: &Uuid, payload: OpPayload) {
// Increment the last clock for the provided actor
let clock = self
.ops
.last()
.map(|Op { clock, .. }| clock.inc(actor_id))
// For an empty document, initialize a new clock
.unwrap_or_else(|| VectorClock::default().inc(actor_id));
self.ops.push(Op {
id: Uuid::now_v7(),
clock,
payload,
});
}
pub fn realize(&self) -> Result<RealizedDoc, Error> {
let mut realized = RealizedDoc::default();
for op in &self.ops {
op.apply(&mut realized)?;
}
Ok(realized)
}
}
#[derive(Debug)]
pub struct Op {
id: Uuid,
payload: OpPayload,
clock: VectorClock,
}
impl Op {
fn apply(&self, realized: &mut RealizedDoc) -> Result<(), Error> {
match &self.payload {
OpPayload::CreateGrid {
rows,
base_cells_per_row,
} => {
let rows = (0..*rows)
.map(|row_idx| {
let cells = (0..*base_cells_per_row)
.map(|cell_idx| Cell {
id: self.id.derive_id("cell", cell_idx),
})
.collect();
Row {
id: self.id.derive_id("row", row_idx),
cells,
}
})
.collect();
realized.grids.push(Grid {
id: self.id.derive_id("grid", 0),
rows,
});
}
OpPayload::ChangeSubdivisions {
grid_id,
row_id,
start_cell_id,
end_cell_id,
subdivisions,
} => {
let grid = realized
.grids
.iter_mut()
.find(|g| g.id == *grid_id)
.ok_or(Error::NotFound(grid_id.clone()))?;
let row = grid
.rows
.iter_mut()
.find(|r| r.id == *row_id)
.ok_or(Error::NotFound(row_id.clone()))?;
let start_cell_idx = row
.cells
.iter()
.position(|c| c.id == *start_cell_id)
.ok_or(Error::NotFound(start_cell_id.clone()))?;
let end_cell_idx = row
.cells
.iter()
.position(|c| c.id == *end_cell_id)
.ok_or(Error::NotFound(end_cell_id.clone()))?;
let (i, j) = if start_cell_idx <= end_cell_idx {
(start_cell_idx, end_cell_idx)
} else {
(end_cell_idx, start_cell_idx)
};
row.cells.splice(
i..(j + 1),
(0..*subdivisions).map(|subdivision_idx| Cell {
id: self.id.derive_id("cell", subdivision_idx),
}),
);
}
}
Ok(())
}
}
#[derive(Debug)]
pub enum OpPayload {
CreateGrid {
rows: usize,
base_cells_per_row: usize,
},
ChangeSubdivisions {
grid_id: DerivedId,
row_id: DerivedId,
start_cell_id: DerivedId,
end_cell_id: DerivedId,
subdivisions: usize,
},
}
#[derive(Default, Debug)]
pub struct RealizedDoc {
grids: Vec<Grid>,
}
#[derive(Debug)]
pub struct Grid {
id: DerivedId,
rows: Vec<Row>,
}
#[derive(Debug)]
pub struct Row {
id: DerivedId,
cells: Vec<Cell>,
}
#[derive(Debug)]
pub struct Cell {
id: DerivedId,
}
#[derive(PartialEq, Eq, Debug, Clone)]
pub struct DerivedId {
// TODO These IDs can be interned on the Doc
id: Uuid,
tag: &'static str,
index: usize,
}
impl Display for DerivedId {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}:{}:{}", self.id, self.tag, self.index)
}
}
trait DerivableId {
fn derive_id(&self, tag: &'static str, index: usize) -> DerivedId;
}
impl DerivableId for Uuid {
fn derive_id(&self, tag: &'static str, index: usize) -> DerivedId {
DerivedId {
id: self.clone(),
tag,
index,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn realize_doc() {
let actor_id = Uuid::now_v7();
let mut doc = Doc::default();
doc.append_op(
&actor_id,
OpPayload::CreateGrid {
rows: 4,
base_cells_per_row: 16,
},
);
{
let realized = doc.realize().unwrap();
assert!(realized.grids.len() == 1);
let grid = realized.grids.first().unwrap();
assert!(grid.rows.len() == 4);
let row = grid.rows.first().unwrap();
assert!(row.cells.len() == 16);
doc.append_op(
&actor_id,
OpPayload::ChangeSubdivisions {
grid_id: grid.id.clone(),
row_id: row.id.clone(),
start_cell_id: row.cells[0].id.clone(),
end_cell_id: row.cells[3].id.clone(),
subdivisions: 3,
},
);
}
{
let realized = doc.realize().unwrap();
assert_eq!(realized.grids[0].rows[0].cells.len(), 15);
assert_eq!(realized.grids[0].rows[1].cells.len(), 16);
let grid = &realized.grids[0];
let row = &grid.rows[0];
doc.append_op(
&actor_id,
OpPayload::ChangeSubdivisions {
grid_id: grid.id.clone(),
row_id: row.id.clone(),
start_cell_id: row.cells[0].id.clone(),
end_cell_id: row.cells.last().unwrap().id.clone(),
subdivisions: 12,
},
);
}
{
let realized = doc.realize().unwrap();
assert_eq!(realized.grids[0].rows[0].cells.len(), 12);
assert_eq!(realized.grids[0].rows[1].cells.len(), 16);
}
}
}
|
