feat: add paths resolver

Author: thetutlage

package.json

@@ -12,6 +12,9 @@
     "!build/bin",
     "!build/tests"
   ],
+  "imports": {
+    "#src/*": "./src/*.ts"
+  },
   "exports": {
     ".": "./build/index.js",
     "./code_transformer": "./build/src/code_transformer/main.js",

src/paths_resolver.ts

@@ -0,0 +1,43 @@
+/*
+ * @adonisjs/assembler
+ *
+ * (c) AdonisJS
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+import { fileURLToPath } from 'node:url'
+
+/**
+ * Encapsulates the API to resolve import specifiers with the ability
+ * to define customer resolver.
+ */
+export class PathsResolver {
+  #resolvedPaths: Record<string, string> = {}
+  #resolver: (specifier: string) => string = (specifier) => import.meta.resolve(specifier)
+
+  /**
+   * Define a custom resolver that resolves a path
+   */
+  use(resolver: (specifier: string) => string) {
+    this.#resolver = resolver
+  }
+
+  /**
+   * Resolve import specifier
+   */
+  resolve(specifier: string) {
+    if (specifier.startsWith('./') || specifier.startsWith('../')) {
+      throw new Error('Cannot resolve relative paths')
+    }
+
+    const cached = this.#resolvedPaths[specifier]
+    if (cached) {
+      return cached
+    }
+
+    this.#resolvedPaths[specifier] = fileURLToPath(this.#resolver(specifier))
+    return this.#resolvedPaths[specifier]
+  }
+}

tests/paths_resolver.spec.ts

@@ -0,0 +1,41 @@
+/*
+ * @adonisjs/assembler
+ *
+ * (c) AdonisJS
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+import { test } from '@japa/runner'
+import { PathsResolver } from '../src/paths_resolver.ts'
+import { join } from 'node:path'
+
+test.group('Paths resolver', () => {
+  test('throw error when trying to resolve a relative path', () => {
+    const resolver = new PathsResolver()
+    resolver.resolve('./routes_scanner.spec.ts')
+  }).throws('Cannot resolve relative paths')
+
+  test('resolve subpath import specifier', ({ assert }) => {
+    const resolver = new PathsResolver()
+    assert.equal(
+      resolver.resolve('#src/file_system'),
+      join(import.meta.dirname, '..', 'src', 'file_system.ts')
+    )
+  })
+
+  test('resolve package export specifier', ({ assert }) => {
+    const resolver = new PathsResolver()
+    assert.equal(
+      resolver.resolve('@adonisjs/assembler/code_transformer'),
+      join(import.meta.dirname, '..', 'build', 'src', 'code_transformer/main.js')
+    )
+  })
+
+  test('use custom resolver', ({ assert }) => {
+    const resolver = new PathsResolver()
+    resolver.use((specifier) => `file:///${specifier.replace('#', '')}`)
+    assert.equal(resolver.resolve('#src/file_system'), '/src/file_system')
+  })
+})