refactor(tree): Extract leaf schemas into their own module (#20289)

Extracted from #20271

packages/dds/tree/src/simple-tree/leafNodeSchema.ts

@@ -0,0 +1,70 @@
+/*!
+ * Copyright (c) Microsoft Corporation and contributors. All rights reserved.
+ * Licensed under the MIT License.
+ */
+
+import { assert } from "@fluidframework/core-utils";
+import { TreeNodeSchemaIdentifier, TreeValue } from "../core/index.js";
+import { leaf } from "../domains/index.js";
+import {
+	LeafNodeSchema as FlexLeafNodeSchema,
+	FlexTreeNode,
+	isFlexTreeNode,
+	valueSchemaAllows,
+} from "../feature-libraries/index.js";
+import { NodeKind, TreeNodeSchema, TreeNodeSchemaNonClass } from "./schemaTypes.js";
+import { setFlexSchemaFromClassSchema } from "./toFlexSchema.js";
+
+type UnbrandedName<T extends FlexLeafNodeSchema> = T["name"] extends TreeNodeSchemaIdentifier<
+	infer Name extends string
+>
+	? Name
+	: T["name"];
+
+/**
+ * Instances of this class are schema for leaf nodes.
+ * @remarks
+ * Unlike other schema, leaf schema are class instances instead of classes themselves.
+ * This is because the instance type (the tree node type) for leaves are not objects,
+ * so those instances can't be instances of a schema based class.
+ * @privateRemarks
+ * This class refers to the underlying flex tree schema in its constructor, so this class can't be included in the package API.
+ */
+class LeafNodeSchema<T extends FlexLeafNodeSchema>
+	implements TreeNodeSchemaNonClass<UnbrandedName<T>, NodeKind.Leaf, TreeValue<T["info"]>>
+{
+	public readonly identifier: UnbrandedName<T>;
+	public readonly kind = NodeKind.Leaf;
+	public readonly info: T["info"];
+	public readonly implicitlyConstructable = true as const;
+	public create(data: TreeValue<T["info"]> | FlexTreeNode): TreeValue<T["info"]> {
+		if (isFlexTreeNode(data)) {
+			const value = data.value;
+			assert(valueSchemaAllows(this.info, value), "invalid value");
+			return value;
+		}
+		return data;
+	}
+
+	public constructor(schema: T) {
+		setFlexSchemaFromClassSchema(this, schema);
+		this.identifier = schema.name as UnbrandedName<T>;
+		this.info = schema.info;
+	}
+}
+
+/**
+ * Wrapper around LeafNodeSchema's constructor that provides the return type that is desired in the package public API.
+ */
+function makeLeaf<T extends FlexLeafNodeSchema>(
+	schema: T,
+): TreeNodeSchema<UnbrandedName<T>, NodeKind.Leaf, TreeValue<T["info"]>, TreeValue<T["info"]>> {
+	return new LeafNodeSchema(schema);
+}
+
+// Leaf schema shared between all SchemaFactory instances.
+export const stringSchema = makeLeaf(leaf.string);
+export const numberSchema = makeLeaf(leaf.number);
+export const booleanSchema = makeLeaf(leaf.boolean);
+export const nullSchema = makeLeaf(leaf.null);
+export const handleSchema = makeLeaf(leaf.handle);

packages/dds/tree/src/simple-tree/schemaFactory.ts

@@ -6,10 +6,8 @@
 import { assert, unreachableCase } from "@fluidframework/core-utils";
 import { UsageError } from "@fluidframework/telemetry-utils";
 import { TreeNodeSchemaIdentifier, TreeValue } from "../core/index.js";
-import { leaf } from "../domains/index.js";
 import {
 	FlexFieldNodeSchema,
-	LeafNodeSchema as FlexLeafNodeSchema,
 	FlexMapNodeSchema,
 	FlexObjectNodeSchema,
 	FlexTreeNode,
@@ -18,9 +16,15 @@ import {
 	isLazy,
 	markEager,
 	typeNameSymbol,
-	valueSchemaAllows,
 } from "../feature-libraries/index.js";
 import { RestrictiveReadonlyRecord, getOrCreate, isReadonlyArray } from "../util/index.js";
+import {
+	booleanSchema,
+	handleSchema,
+	nullSchema,
+	numberSchema,
+	stringSchema,
+} from "./leafNodeSchema.js";
 import {
 	arrayNodePrototypeProperties,
 	createArrayNodeProxy,
@@ -45,62 +49,13 @@ import {
 	TreeMapNode,
 	TreeNodeSchema,
 	TreeNodeSchemaClass,
-	TreeNodeSchemaNonClass,
 	WithType,
 	type,
 } from "./schemaTypes.js";
-import { getFlexSchema, setFlexSchemaFromClassSchema } from "./toFlexSchema.js";
+import { getFlexSchema } from "./toFlexSchema.js";
 import { TreeArrayNode } from "./treeArrayNode.js";
 import { TreeNode } from "./types.js";
 
-/**
- * Instances of this class are schema for leaf nodes.
- * @remarks
- * Unlike other schema, leaf schema are class instances instead of classes themselves.
- * This is because the instance type (the tree node type) for leaves are not objects,
- * so those instances can't be instances of a schema based class.
- * @privateRemarks
- * This class refers to the underlying flex tree schema in its constructor, so this class can't be included in the package API.
- */
-class LeafNodeSchema<T extends FlexLeafNodeSchema>
-	implements TreeNodeSchemaNonClass<UnbrandedName<T>, NodeKind.Leaf, TreeValue<T["info"]>>
-{
-	public readonly identifier: UnbrandedName<T>;
-	public readonly kind = NodeKind.Leaf;
-	public readonly info: T["info"];
-	public readonly implicitlyConstructable = true as const;
-	public create(data: TreeValue<T["info"]> | FlexTreeNode): TreeValue<T["info"]> {
-		if (isFlexTreeNode(data)) {
-			const value = data.value;
-			assert(valueSchemaAllows(this.info, value), "invalid value");
-			return value;
-		}
-		return data;
-	}
-
-	public constructor(schema: T) {
-		setFlexSchemaFromClassSchema(this, schema);
-		this.identifier = schema.name as UnbrandedName<T>;
-		this.info = schema.info;
-	}
-}
-
-/**
- * Wrapper around LeafNodeSchema's constructor that provides the return type that is desired in the package public API.
- */
-function makeLeaf<T extends FlexLeafNodeSchema>(
-	schema: T,
-): TreeNodeSchema<UnbrandedName<T>, NodeKind.Leaf, TreeValue<T["info"]>, TreeValue<T["info"]>> {
-	return new LeafNodeSchema(schema);
-}
-
-// Leaf schema shared between all SchemaFactory instances.
-const stringSchema = makeLeaf(leaf.string);
-const numberSchema = makeLeaf(leaf.number);
-const booleanSchema = makeLeaf(leaf.boolean);
-const nullSchema = makeLeaf(leaf.null);
-const handleSchema = makeLeaf(leaf.handle);
-
 /**
  * Gets the leaf domain schema compatible with a given {@link TreeValue}.
  */
@@ -124,12 +79,6 @@ export function schemaFromValue(value: TreeValue): TreeNodeSchema {
 	}
 }
 
-type UnbrandedName<T extends FlexLeafNodeSchema> = T["name"] extends TreeNodeSchemaIdentifier<
-	infer Name extends string
->
-	? Name
-	: T["name"];
-
 /**
  * The name of a schema produced by {@link SchemaFactory}, including its optional scope prefix.
  *