Add empty queries (match all entities)

src/ecs.ts

@@ -126,9 +126,6 @@ class ECS {
   }
 
   createQuery(...cmps: string[]): Query {
-    if(!cmps.length) {
-      throw new Error("empty query")
-    }
     const or = cmps.filter(c => c.includes(" ")).map(i => i.split(" "))
     cmps = cmps.filter(c => !c.includes(" "))
     const query = new Query([cmps, ...or].map(i => {

src/query.ts

@@ -7,13 +7,14 @@ class Query {
   mask: QueryMask
   archetypes: Archetype[] = []
 
-  constructor(q: [number[], number[]][]) {
+  constructor(q: [number[], number[]][] | undefined) {
     const updateMask = (cmps: number[], mask: Uint32Array) => {
       cmps.forEach(i => {
         mask[Math.floor(i / 32)] |= 1 << i % 32
       })
     }
     this.mask = []
+    q = q ?? []
     q.map((n, i) => {
       const crMask = (x: number) => new Uint32Array(Math.ceil((Math.max(0, ...n[x]) + 1) / 32))
       this.mask.push([crMask(0), crMask(1)])
@@ -23,13 +24,15 @@ class Query {
   }
 
   static match(target: Uint32Array, query: QueryMask) {
-    if(!Query.matchAll(target, query[0])) { // AND
-      return false
-    }
-    for(let q of query.slice(1)) { // OR
-      if(!Query.matchAny(target, q)) {
+    if(query.length) {
+      if(!Query.matchAll(target, query[0])) { // AND
         return false
       }
+      for(let q of query.slice(1)) { // OR
+        if(!Query.matchAny(target, q)) {
+          return false
+        }
+      }
     }
     return true
   }

test/ecs.test.js

@@ -77,10 +77,6 @@ describe("ECS", function() {
       expect(not.archetypes).to.eql([ecs._arch.get("0")])
     })
 
-    it("should throw error on no arguments", function() {
-      expect(() => ecs.createQuery()).to.throw()
-    })
-
     it("should throw error on invalid name", function() {
       ecs.defineComponent("right")
       expect(() => ecs.createQuery("wrong")).to.throw()

test/query.test.js

@@ -5,6 +5,7 @@ import {Query} from "../build/query"
 describe("Query", function() {
   describe("constructor", function() {
     it("should have appropriate mask", function() {
+      expect(new Query().mask).to.eql([])
       expect(new Query([[[3, 1, 4], [2, 6, 5]]]).mask).to.eql([[new Uint32Array([26]), new Uint32Array([100])]])
       expect(new Query([[[1, 2], [4]], [[0, 3, 5], []]]).mask).to.eql([
         [new Uint32Array([6]), new Uint32Array([16])],
@@ -14,6 +15,13 @@ describe("Query", function() {
   })
 
   describe("match", function() {
+    it("should match empty", function() {
+      const query = new Query().mask
+      for(let i = 0; i < 20; i++) {
+        expect(Query.match(new Uint32Array([Math.floor(Math.random() * 1000)]), query)).to.be.true
+      }
+    })
+
     it("should match AND", function() {
       const query = new Query([[[0, 2, 3], []]]).mask
       expect(Query.match(new Uint32Array([13]), query)).to.be.true