feat: added new source-maps plugin for loading files with existing so…

…urce maps.

packages/packem/package.json

@@ -364,6 +364,7 @@
         "@visulima/package": "3.1.5",
         "@visulima/pail": "2.1.11",
         "@visulima/path": "1.1.1",
+        "@visulima/source-map": "1.0.10",
         "@visulima/tsconfig": "1.1.1",
         "browserslist": "4.24.2",
         "defu": "6.1.4",

packages/packem/src/packem.ts

@@ -245,6 +245,7 @@ const generateOptions = (
                 exclude: EXCLUDE_REGEXP,
                 include: ALLOWED_TRANSFORM_EXTENSIONS_REGEX,
             },
+            sourcemap: {},
             sucrase: {
                 disableESTransforms: true,
                 enableLegacyBabel5ModuleInterop: false,

packages/packem/src/rollup/get-rollup-options.ts

@@ -56,6 +56,7 @@ import createSplitChunks from "./utils/chunks/create-split-chunks";
 import getChunkFilename from "./utils/get-chunk-filename";
 import getEntryFileNames from "./utils/get-entry-file-names";
 import resolveAliases from "./utils/resolve-aliases";
+import { sourcemapsPlugin } from "./plugins/source-maps";
 
 const sortUserPlugins = (plugins: RollupPlugins | undefined, type: "build" | "dts"): [Plugin[], Plugin[], Plugin[]] => {
     const prePlugins: Plugin[] = [];
@@ -453,6 +454,8 @@ export const getRollupOptions = async (context: BuildContext, fileCache: FileCac
         ].filter(Boolean),
 
         plugins: [
+            context.options.sourcemap && sourcemapsPlugin(context.options.rollup.sourcemap),
+
             cachingPlugin(resolveFileUrlPlugin(), fileCache),
             cachingPlugin(resolveTypescriptMjsCtsPlugin(), fileCache),
 
@@ -741,6 +744,8 @@ export const getRollupDtsOptions = async (context: BuildContext, fileCache: File
         ].filter(Boolean),
 
         plugins: [
+            context.options.sourcemap && sourcemapsPlugin(context.options.rollup.sourcemap),
+
             cachingPlugin(resolveFileUrlPlugin(), fileCache),
             cachingPlugin(resolveTypescriptMjsCtsPlugin(), fileCache),
 

packages/packem/src/rollup/plugins/source-maps.ts

@@ -0,0 +1,67 @@
+import type { FilterPattern } from "@rollup/pluginutils";
+import { createFilter } from "@rollup/pluginutils";
+import { readFile } from "@visulima/fs";
+import { loadSourceMap } from "@visulima/source-map";
+import type { ExistingRawSourceMap, Plugin, PluginContext } from "rollup";
+
+// eslint-disable-next-line import/no-unused-modules
+export interface SourcemapsPluginOptions {
+    exclude?: FilterPattern;
+    include?: FilterPattern;
+}
+
+export const sourcemapsPlugin = ({ exclude, include }: SourcemapsPluginOptions = {}): Plugin => {
+    // Create a filter function based on the include and exclude options
+    const filter = createFilter(include, exclude);
+
+    return {
+        async load(this: PluginContext, id: string) {
+            if (!filter(id)) {
+                return null;
+            }
+
+            let code: string;
+
+            try {
+                code = await readFile(id, { buffer: false });
+
+                this.addWatchFile(id);
+            } catch {
+                try {
+                    // If reading fails, try again without a query suffix that some plugins use
+                    const cleanId = id.replace(/\?.*$/, "");
+
+                    code = await readFile(cleanId, { buffer: false });
+
+                    this.addWatchFile(cleanId);
+                } catch {
+                    this.warn("Failed reading file");
+
+                    return null;
+                }
+            }
+
+            let map: ExistingRawSourceMap;
+
+            try {
+                // Try to resolve the source map for the code
+                const result = loadSourceMap(id);
+
+                // If the code contained no sourceMappingURL, return the code
+                if (result === undefined) {
+                    return code;
+                }
+
+                map = result as unknown as ExistingRawSourceMap;
+            } catch {
+                this.warn("Failed resolving source map");
+
+                return { code };
+            }
+
+            // Return the code and the map
+            return { code, map };
+        },
+        name: "packem:sourcemaps",
+    };
+};

packages/packem/src/types.ts

@@ -32,6 +32,7 @@ import type { SwcPluginConfig } from "./rollup/plugins/swc/types";
 import type { PatchTypesOptions } from "./rollup/plugins/typescript/patch-typescript-types";
 import type FileCache from "./utils/file-cache";
 import type { UrlOptions } from "./rollup/plugins/url";
+import type { SourcemapsPluginOptions } from "./rollup/plugins/source-maps";
 
 type DeepPartial<T> = { [P in keyof T]?: DeepPartial<T[P]> };
 
@@ -110,6 +111,7 @@ export interface RollupBuildOptions {
     url?: UrlOptions | false;
     wasm?: RollupWasmOptions | false;
     watch?: RollupOptions["watch"];
+    sourcemap?: SourcemapsPluginOptions
 }
 
 export type TypeDocumentOptions = {