@javelin/ecs/dist/esm/archetype.js

import { unpackSparseArray } from "@javelin/core";
import { getSchemaId, toComponentFromType, } from "./component";
import { normalizeType } from "./type";
function hydrateTableFromSnapshot(table, type) {
    return table.map((column, i) => {
        const schemaId = type[i];
        return column
            .slice()
            .map(component => toComponentFromType(component, schemaId));
    });
}
function createArchetypeStateFromSnapshot(snapshot) {
    const entities = Object.keys(snapshot.indices).map(Number);
    const indices = unpackSparseArray(snapshot.indices);
    const type = normalizeType(snapshot.type);
    const table = hydrateTableFromSnapshot(snapshot.table, type);
    return { entities, indices, type, table };
}
function createStore(options) {
    if ("snapshot" in options) {
        return createArchetypeStateFromSnapshot(options.snapshot);
    }
    const type = normalizeType(options.type);
    const table = type.map(() => []);
    return { entities: [], indices: [], type, table };
}
function invertSignature(signature) {
    return signature.reduce((a, x, i) => {
        a[x] = i;
        return a;
    }, []);
}
/**
 * Create an Archetype.
 * @param signature
 * @param table
 */
export function createArchetype(options) {
    const { table, indices, entities, type } = createStore(options);
    const typeInverse = invertSignature(type);
    function insert(entity, components) {
        for (let i = 0; i < components.length; i++) {
            const component = components[i];
            const schemaIndex = typeInverse[getSchemaId(component)];
            table[schemaIndex].push(component);
        }
        indices[entity] = entities.push(entity) - 1;
    }
    function remove(entity) {
        const length = entities.length;
        const index = indices[entity];
        const head = entities.pop();
        delete indices[entity];
        if (index === length - 1) {
            for (const column of table)
                column.pop();
        }
        else {
            for (const column of table) {
                column[index] = column.pop();
            }
            entities[index] = head;
            indices[head] = index;
        }
    }
    return {
        entities,
        indices,
        insert,
        remove,
        type,
        typeInverse,
        table,
    };
}
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