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const std = @import("std");
const Allocator = std.mem.Allocator;
pub fn SparseSet(comptime T: type) type {
return struct {
sparse: std.ArrayList(usize),
dense: std.ArrayList(usize),
components: std.ArrayList(T),
pub fn init(allocator: Allocator) @This() {
return @This(){
.sparse = std.ArrayList(usize).init(allocator),
.dense = std.ArrayList(usize).init(allocator),
.components = std.ArrayList(T).init(allocator),
};
}
pub fn addEntity(self: *@This(), entity: usize, component: T) !void {
if (entity >= self.sparse.items.len) {
try self.sparse.resize(entity + 10);
}
self.sparse.items[entity] = self.dense.items.len;
try self.dense.append(entity);
try self.components.append(component);
}
pub fn removeEntity(self: *@This(), entity: usize) void {
const last_index = self.dense.getLast();
const dense_index = self.sparse.items[entity];
self.dense.swapRemove(dense_index);
self.components.swapRemove(dense_index);
self.sparse.items[last_index] = dense_index;
}
};
}
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