Tree validator for FileSystem Writer

Changes

2 changed files (+121/-0)

• filesystem_writer/validate_tree.test.ts (new)
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    + // SPDX-FileCopyrightText: 2024 Shota FUJI <pockawoooh@gmail.com> + // + // SPDX-License-Identifier: Apache-2.0 + + import { + assertEquals, + assertExists, + assertRejects, + } from "../deps/deno.land/std/assert/mod.ts"; + + import { MemoryFsWriter } from "./memory_fs.ts"; + import { validateTree } from "./validate_tree.ts"; + + Deno.test("Should prevents from writing file when there is a directory at the path", async () => { + const writer = validateTree(new MemoryFsWriter()); + + const enc = new TextEncoder(); + + await writer.write(["foo", "bar.txt"], enc.encode("Foo\n")); + + await assertRejects(async () => + await writer.write(["foo"], enc.encode("Bar\n")) + ); + }); + + Deno.test("Should prevents from writing directory when there is a file at the path", async () => { + const writer = validateTree(new MemoryFsWriter()); + + const enc = new TextEncoder(); + + await writer.write(["foo"], enc.encode("Foo\n")); + + await assertRejects(async () => + await writer.write(["foo", "bar.txt"], enc.encode("Bar\n")) + ); + }); + + Deno.test("Should not reject if there is no conflict", async () => { + const memoryWriter = new MemoryFsWriter(); + const writer = validateTree(memoryWriter); + + const enc = new TextEncoder(); + + await writer.write(["foo.txt"], enc.encode("Foo\n")); + await writer.write(["foo", "bar.txt"], enc.encode("Bar\n")); + + const dec = new TextDecoder(); + + const foo = memoryWriter.get(["foo.txt"]); + assertExists(foo); + + const bar = memoryWriter.get(["foo", "bar.txt"]); + assertExists(bar); + + assertEquals(dec.decode(foo), "Foo\n"); + assertEquals(dec.decode(bar), "Bar\n"); + });
• filesystem_writer/validate_tree.ts (new)
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    + // SPDX-FileCopyrightText: 2024 Shota FUJI <pockawoooh@gmail.com> + // + // SPDX-License-Identifier: Apache-2.0 + + import type { FileSystemWriter } from "./interface.ts"; + + const enum NodeType { + File, + Directory, + } + + function nodeTypeToString(nodeType: NodeType): string { + switch (nodeType) { + case NodeType.File: + return "file"; + case NodeType.Directory: + return "directory"; + } + } + + const SEP = "/"; + + /** + * Wraps the given FileSystem Writer and returns a new FileSystem Writer + * that checks tree structure so there won't be a directory and a file + * having same name. + */ + export function validateTree(childWriter: FileSystemWriter): FileSystemWriter { + const nodes = new Map<string, NodeType>(); + + return { + write(path, content, opts) { + setNodeTypeRecur(path, NodeType.File, nodes); + + return childWriter.write(path, content, opts); + }, + }; + } + + function setNodeTypeRecur( + path: readonly string[], + nodeType: NodeType, + map: Map<string, NodeType>, + ): void { + if (path.length === 0) { + return; + } + + const key = path.join(SEP); + + const found = map.get(key); + if (typeof found !== "undefined" && found !== nodeType) { + const ns = nodeTypeToString(nodeType); + const fs = nodeTypeToString(found); + + throw new Error( + `Attempt to write a ${ns} at "${key}", but there already is a ${fs}.`, + ); + } + + map.set(key, nodeType); + + return setNodeTypeRecur(path.slice(0, -1), NodeType.Directory, map); + }