silphius/app/ecs/query.js
2024-06-15 19:41:58 -05:00

85 lines
2.0 KiB
JavaScript

export default class Query {
$$criteria = {with: [], without: []};
$$index = new Set();
constructor(parameters, Components) {
for (let i = 0; i < parameters.length; ++i) {
const parameter = parameters[i];
switch (parameter.charCodeAt(0)) {
case '!'.charCodeAt(0):
this.$$criteria.without.push(Components[parameter.slice(1)]);
break;
default:
this.$$criteria.with.push(Components[parameter]);
break;
}
}
}
get count() {
return this.$$index.size;
}
deindex(entityIds) {
for (let i = 0; i < entityIds.length; ++i) {
this.$$index.delete(entityIds[i]);
}
}
reindex(entityIds) {
if (0 === this.$$criteria.with.length && 0 === this.$$criteria.without.length) {
for (const entityId of entityIds) {
this.$$index.add(entityId);
}
return;
}
for (const entityId of entityIds) {
let should = true;
for (let j = 0; j < this.$$criteria.with.length; ++j) {
if ('undefined' === typeof this.$$criteria.with[j].get(entityId)) {
should = false;
break;
}
}
if (should) {
for (let j = 0; j < this.$$criteria.without.length; ++j) {
if ('undefined' !== typeof this.$$criteria.without[j].get(entityId)) {
should = false;
break;
}
}
}
if (should) {
this.$$index.add(entityId);
}
else if (!should) {
this.$$index.delete(entityId);
}
}
}
select() {
const it = this.$$index.values();
const value = [];
return {
[Symbol.iterator]() {
return this;
},
next: () => {
const result = it.next();
if (result.done) {
return {done: true, value: undefined};
}
for (let i = 0; i < this.$$criteria.with.length; ++i) {
value[i] = this.$$criteria.with[i].get(result.value);
}
value[this.$$criteria.with.length] = result.value;
return {done: false, value};
},
};
}
}