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feat(bt)!: Remove legacy tree definition format 

The `LegacyTreeDef` type and its normalization path have been removed.
All tree definitions must now use the factory functions (`leaf`,
`sequential`, `parallel`, `selector`, `random`, `repeat`). The
`TreeDef` type is now simply `TaskEntityDef`.
This commit is contained in:
hyper 2026-06-28 10:19:40 +08:00
parent ddde3f7597
commit 1253bf82d2
5 changed files with 133 additions and 180 deletions
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72
USAGE.md
View File

@ -393,32 +393,33 @@ Command entities are automatically destroyed after processing if they become bar
Behaviour trees control game flow by composing tasks into a tree. Each node in the tree is an ECS entity with a `Task` component. Parent-child relationships are `ChildOf` edges. This means you can query, observe, and serialize the tree just like any other ECS data.
`buildTree()` takes a declarative definition and materializes it into entities, returning a fully-wired `TaskRunner`.
`buildTree()` takes a task entity definition and materializes it into entities, returning a fully-wired `TaskRunner`. Task definitions are created with factories, and non-task child entities can be mixed in as metadata; the runner ignores those non-task children during execution.
```ts
import { buildTree, Cancel } from "ecs-observable/bt";
import { defineComponent, entity } from "ecs-observable";
import { buildTree, Cancel, leaf, parallel, repeat, sequential } from "ecs-observable/bt";
```
#### Leaf patterns
**One-shot** — just return. Implicit success.
```ts
{ kind: "leaf", run: () => { doWork(); } }
leaf(() => { doWork(); })
```
**Fail** — throw any error.
```ts
{ kind: "leaf", run: () => { throw new Error("bad"); } }
leaf(() => { throw new Error("bad"); })
```
**Cancel** — throw the `Cancel` symbol.
```ts
{ kind: "leaf", run: () => { throw Cancel; } }
leaf(() => { throw Cancel; })
```
**Ongoing** — generator function. Each `yield` suspends until next tick. The yielded value is the delay in ms (or nothing for next frame). Completion = success.
```ts
{ kind: "leaf", *run() {
leaf(function* tickTimer() {
while (true) {
const dt: number = yield; // delta time from runner.tick(dt)
timer.accumulator += dt;
@ -426,49 +427,54 @@ import { buildTree, Cancel } from "ecs-observable/bt";
// ... act ...
}
}
} }
})
```
#### Composite nodes
```ts
{ kind: "sequential", children: [a, b, c] } // left-to-right, all must succeed
{ kind: "selector", children: [a, b, c] } // left-to-right, first success wins
{ kind: "parallel", children: [a, b, c] } // all at once, all must succeed
{ kind: "random", children: [a, b, c] } // pick one child each activation
{ kind: "repeat", child: a } // decorator — re-run child forever
sequential([a, b, c]) // left-to-right, all must succeed
selector([a, b, c]) // left-to-right, first success wins
parallel([a, b, c]) // all at once, all must succeed
random([a, b, c]) // pick one child each activation
repeat(a) // decorator — re-run child forever
```
Non-task entity children are materialized but ignored by the runner:
```ts
const Label = defineComponent("label", { value: "" });
sequential([
entity(Label, { value: "main sequence" }),
leaf(handleInput),
leaf(render),
])
```
#### Full example
```ts
const runner = buildTree(world, {
kind: "parallel",
children: [
{
kind: "leaf",
*run() {
const runner = buildTree(
world,
parallel([
leaf(function* physicsLoop() {
while (true) {
const dt: number = yield;
updatePhysics(dt);
}
},
},
{
kind: "repeat",
child: {
kind: "sequential",
children: [
{ kind: "leaf", run: () => { handleInput(); } },
{ kind: "leaf", run: () => { render(); } },
],
},
},
],
});
}),
repeat(
sequential([
leaf(() => { handleInput(); }),
leaf(() => { render(); }),
]),
),
]),
);
// Kick off
runner.schedule((runner as any).root);
runner.schedule(runner.root!);
// Game loop
setInterval(() => runner.tick(16), 16);

53
examples/blackjack/main.ts
View File

@ -23,7 +23,13 @@
// npx tsx examples/blackjack/main.ts
import { World } from "../../src/index";
import { buildTree } from "../../src/bt/index";
import {
buildTree,
leaf,
parallel,
repeat,
sequential,
} from "../../src/bt/index";
import { CommandQueue } from "../../src/commands/index";
import {
@ -63,14 +69,12 @@ const commands = new CommandQueue(world);
registerCommands(world, commands, cards);
// ── Behaviour Tree ───────────────────────────────────
const runner = buildTree(world, {
kind: "parallel",
children: [
{
kind: "leaf",
*run() {
const runner = buildTree(
world,
parallel([
leaf(function* dealerPlay() {
while (true) {
const dt: number = yield;
yield;
const phase = world.getSingleton(GamePhase);
if (phase.phase !== "dealerTurn") continue;
@ -83,30 +87,19 @@ const runner = buildTree(world, {
resolveRound(world, cards);
}
}
},
},
{
kind: "repeat",
child: {
kind: "sequential",
children: [
{
kind: "leaf",
run: () => {
}),
repeat(
sequential([
leaf(() => {
commands.execute();
},
},
{
kind: "leaf",
run: () => {
}),
leaf(() => {
render(world, ui);
},
},
],
},
},
],
});
}),
]),
),
]),
);
// ── Input → Command mapping ──────────────────────────
const keyToCommand: Partial<Record<Key, typeof Hit>> = {

51
examples/tetris/main.ts
View File

@ -20,7 +20,13 @@
// npx tsx examples/tetris/main.ts
import { World } from "../../src/index";
import { buildTree } from "../../src/bt/index";
import {
buildTree,
leaf,
parallel,
repeat,
sequential,
} from "../../src/bt/index";
import { CommandQueue } from "../../src/commands/index";
import {
@ -64,12 +70,10 @@ registerCommands(world, commands, pieces);
pieces.spawnPiece();
// ── Behaviour Tree ───────────────────────────────────
const runner = buildTree(world, {
kind: "parallel",
children: [
{
kind: "leaf",
*run() {
const runner = buildTree(
world,
parallel([
leaf(function* gravityTick() {
while (true) {
const dt: number = yield;
if (world.hasSingleton(GameOver) || world.hasSingleton(Paused)) {
@ -90,30 +94,19 @@ const runner = buildTree(world, {
}
}
}
},
},
{
kind: "repeat",
child: {
kind: "sequential",
children: [
{
kind: "leaf",
run: () => {
}),
repeat(
sequential([
leaf(() => {
commands.execute();
},
},
{
kind: "leaf",
run: () => {
}),
leaf(() => {
render(world, ui);
},
},
],
},
},
],
});
}),
]),
),
]),
);
// ── Input → Command mapping ──────────────────────────
const keyToCommand: Partial<Record<Key, typeof MoveLeft>> = {

8
src/bt/index.ts
View File

@ -23,10 +23,4 @@ export {
random,
repeat,
} from "./tree-def";
export type {
TreeDef,
LegacyTreeDef,
TaskEntityDef,
LeafTaskMeta,
LeafFn,
} from "./tree-def";
export type { TreeDef, TaskEntityDef, LeafTaskMeta, LeafFn } from "./tree-def";

47
src/bt/tree-def.ts
View File

@ -22,15 +22,6 @@ export type LeafFn =
| ((world: World, dt: number) => void)
| (() => Generator<number | void, void, number>);
/** Legacy declarative behaviour-tree definition. */
export type LegacyTreeDef =
| { kind: "leaf"; run: LeafFn }
| { kind: "sequential"; children: LegacyTreeDef[] }
| { kind: "parallel"; children: LegacyTreeDef[] }
| { kind: "selector"; children: LegacyTreeDef[] }
| { kind: "random"; children: LegacyTreeDef[] }
| { kind: "repeat"; child: LegacyTreeDef };
export interface LeafTaskMeta {
readonly run: LeafFn;
}
@ -40,8 +31,8 @@ export type TaskEntityDef = EntityDef<
LeafTaskMeta | undefined
>;
/** Behaviour-tree definitions accepted by `buildTree`. */
export type TreeDef = LegacyTreeDef | TaskEntityDef;
/** Behaviour-tree definition accepted by `buildTree`. */
export type TreeDef = TaskEntityDef;
// ── Entity task factories ──────────────────────────────
@ -118,37 +109,14 @@ export function repeat(
// ── Builder ───────────────────────────────────────────
function isEntityDef(def: TreeDef | EntityDef): def is EntityDef {
return def.kind === "entity";
}
function normalizeLegacyTree(def: LegacyTreeDef): TaskEntityDef {
switch (def.kind) {
case "leaf":
return leaf(def.run);
case "repeat":
return repeat(normalizeLegacyTree(def.child));
case "sequential":
return sequential(def.children.map(normalizeLegacyTree));
case "parallel":
return parallel(def.children.map(normalizeLegacyTree));
case "selector":
return selector(def.children.map(normalizeLegacyTree));
case "random":
return random(def.children.map(normalizeLegacyTree));
}
}
/**
* Materialize a behaviour-tree definition into ECS entities and return a
* fully-wired `TaskRunner`.
*
* The preferred definition format is an `EntityDef` tree produced by the task
* factories (`leaf`, `sequential`, `parallel`, `selector`, `random`, `repeat`)
* and generic single-component entity factories. Non-task child entities are
* materialized into the ECS tree but ignored by `TaskRunner` execution.
*
* Legacy object definitions are still accepted for compatibility.
* Definitions are `EntityDef` trees produced by the task factories (`leaf`,
* `sequential`, `parallel`, `selector`, `random`, `repeat`) and generic
* single-component entity factories. Non-task child entities are materialized
* into the ECS tree but ignored by `TaskRunner` execution.
*
* Leaf `run` functions:
* - **Plain function** — runs once per tick. `return` = success. `throw` = fail.
@ -158,7 +126,6 @@ function normalizeLegacyTree(def: LegacyTreeDef): TaskEntityDef {
* Generator completion = success. `throw` = fail. `throw Cancel` = cancel.
*/
export function buildTree(world: World, def: TreeDef): TaskRunner {
const rootDef = isEntityDef(def) ? def : normalizeLegacyTree(def);
const leafHandlers = new Map<Entity, LeafFn>();
// Track generator iterators for multi-frame leaves
const generators = new Map<Entity, Generator<number | void, void, number>>();
@ -189,7 +156,7 @@ export function buildTree(world: World, def: TreeDef): TaskRunner {
return entity;
}
const root = build(rootDef);
const root = build(def);
if (!world.has(root, Task)) {
throw new Error("buildTree root must be a task entity");