refactor(core): separate out location node functionality and integrate into v2 (#34119)

packages/core/src/effect/layer-node/layer-node-tree.ts

@@ -0,0 +1,118 @@
+import { Layer } from "effect"
+import { LayerNode } from "./layer-node"
+
+type AnyNode = LayerNode.Node<unknown, unknown, any>
+type RuntimeLayer = Layer.Layer<never, unknown, unknown>
+
+export function hoist<A, E, T extends LayerNode.Tag>(
+  root: LayerNode.Node<A, E, any>,
+  tag: T,
+): {
+  readonly node: LayerNode.Node<A, E>
+  readonly hoisted: LayerNode.Node<unknown, E>
+} {
+  const visited = new Map<AnyNode, AnyNode>()
+  const hoisted = new Map<string, AnyNode>()
+  const visiting = new Set<AnyNode>()
+  const stack: AnyNode[] = []
+
+  const visit = (node: AnyNode): AnyNode => {
+    if (node.kind === "group") {
+      return { ...node, dependencies: node.dependencies.map(visit) }
+    }
+
+    const existingNode = visited.get(node)
+    if (existingNode) return existingNode
+
+    if (node.tag === tag) {
+      const existing = hoisted.get(node.name)
+      if (existing && existing !== node) {
+        throw new Error(`Tag ${tag} has conflicting implementations for ${node.name}`)
+      }
+      hoisted.set(node.name, node)
+      const empty = LayerNode.group([])
+      visited.set(node, empty)
+      return empty
+    }
+    if (node.kind === "unbound") {
+      return node
+    }
+
+    if (visiting.has(node)) {
+      const start = stack.indexOf(node)
+      throw new Error(
+        `Cycle detected in layer tree: ${[...stack.slice(start), node].map((item) => item.name).join(" -> ")}`,
+      )
+    }
+    visiting.add(node)
+    stack.push(node)
+    try {
+      const dependencies = node.dependencies.map(visit)
+      const clone = { ...node, dependencies }
+      visited.set(node, clone)
+      return clone
+    } finally {
+      stack.pop()
+      visiting.delete(node)
+    }
+  }
+
+  return {
+    node: visit(root) as LayerNode.Node<A, E>,
+    hoisted: LayerNode.group(Array.from(hoisted.values())) as LayerNode.Node<unknown, E>,
+  }
+}
+
+export function compile<A, E>(
+  root: LayerNode.Node<A, E, any>,
+  replacements?: ReadonlyMap<Layer.Any, Layer.Any>,
+): Layer.Layer<A, E> {
+  const cache = new Map<AnyNode, RuntimeLayer>()
+  const compileNode = (node: AnyNode): RuntimeLayer => {
+    if (node.kind === "unbound") throw new Error(`Unbound layer node: ${node.name}`)
+    const cached = cache.get(node)
+    if (cached) return cached
+    const dependencies = node.dependencies.flatMap(flatten).map(compileNode)
+    const implementation = (replacements?.get(node.implementation!) ?? node.implementation!) as RuntimeLayer
+    const layer =
+      dependencies.length === 0
+        ? implementation
+        : implementation.pipe(Layer.provide(dependencies as [RuntimeLayer, ...RuntimeLayer[]]))
+    cache.set(node, layer)
+    return layer
+  }
+  const layers = flatten(root).map((node) => compileNode(node))
+  const layer = layers.reduce<RuntimeLayer>((result, layer) => layer.pipe(Layer.provideMerge(result)), Layer.empty)
+  return layer as Layer.Layer<A, E>
+}
+
+export function bind<A, E, T extends LayerNode.Tag | undefined>(
+  root: LayerNode.Node<A, E, T>,
+  source: AnyNode,
+  replacement: AnyNode,
+): LayerNode.Node<A, E, T> {
+  if (source.kind !== "unbound") throw new Error(`Cannot bind non-unbound layer node: ${source.name}`)
+  if (source.name !== replacement.name) {
+    throw new Error(`Cannot bind ${source.name} to ${replacement.name}`)
+  }
+  if (source.tag !== replacement.tag) {
+    throw new Error(`Cannot bind ${source.name} across tags`)
+  }
+  const visited = new Map<AnyNode, AnyNode>()
+  const visit = (node: AnyNode): AnyNode => {
+    if (node === source) return replacement
+    const existing = visited.get(node)
+    if (existing) return existing
+    if (node.kind === "unbound") return node
+    const clone = { ...node, dependencies: node.dependencies.map(visit) }
+    visited.set(node, clone)
+    return clone
+  }
+  return visit(root) as LayerNode.Node<A, E, T>
+}
+
+function flatten(node: AnyNode): readonly AnyNode[] {
+  return node.kind === "group" ? node.dependencies.flatMap(flatten) : [node]
+}
+
+export * as LayerNodeTree from "./layer-node-tree"