Enable path completions for node12/nodenext (microsoft#47836)

* Enable path completions for node12/nodenext * Explicitly pull path completions from export maps when available * Explicitly handle pattern exports by stopping up to the star

Author: weswigham

src/services/stringCompletions.ts

@@ -368,9 +368,20 @@ namespace ts.Completions.StringCompletions {
 }
 }
 
+function isEmitResolutionKindUsingNodeModules(compilerOptions: CompilerOptions): boolean {
+return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeJs ||
+getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node12 ||
+getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext;
+}
+
+function isEmitModuleResolutionRespectingExportMaps(compilerOptions: CompilerOptions) {
+return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node12 ||
+getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext;
+}
+
 function getSupportedExtensionsForModuleResolution(compilerOptions: CompilerOptions): readonly Extension[][] {
 const extensions = getSupportedExtensions(compilerOptions);
-return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeJs ?
+return isEmitResolutionKindUsingNodeModules(compilerOptions) ?
 getSupportedExtensionsWithJsonIfResolveJsonModule(compilerOptions, extensions) :
 extensions;
 }
@@ -549,7 +560,7 @@ namespace ts.Completions.StringCompletions {
 
 getCompletionEntriesFromTypings(host, compilerOptions, scriptPath, fragmentDirectory, extensionOptions, result);
 
-if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeJs) {
+if (isEmitResolutionKindUsingNodeModules(compilerOptions)) {
 // If looking for a global package name, don't just include everything in `node_modules` because that includes dependencies' own dependencies.
 // (But do if we didn't find anything, e.g. 'package.json' missing.)
 let foundGlobal = false;
@@ -562,12 +573,65 @@ namespace ts.Completions.StringCompletions {
 }
 }
 if (!foundGlobal) {
-forEachAncestorDirectory(scriptPath, ancestor => {
+let ancestorLookup: (directory: string) => void | undefined = ancestor => {
 const nodeModules = combinePaths(ancestor, "node_modules");
 if (tryDirectoryExists(host, nodeModules)) {
 getCompletionEntriesForDirectoryFragment(fragment, nodeModules, extensionOptions, host, /*exclude*/ undefined, result);
 }
-});
+};
+if (fragmentDirectory && isEmitModuleResolutionRespectingExportMaps(compilerOptions)) {
+const nodeModulesDirectoryLookup = ancestorLookup;
+ancestorLookup = ancestor => {
+const components = getPathComponents(fragment);
+components.shift(); // shift off empty root
+let packagePath = components.shift();
+if (!packagePath) {
+return nodeModulesDirectoryLookup(ancestor);
+}
+if (startsWith(packagePath, "@")) {
+const subName = components.shift();
+if (!subName) {
+return nodeModulesDirectoryLookup(ancestor);
+}
+packagePath = combinePaths(packagePath, subName);
+}
+const packageFile = combinePaths(ancestor, "node_modules", packagePath, "package.json");
+if (tryFileExists(host, packageFile)) {
+const packageJson = readJson(packageFile, host as { readFile: (filename: string) => string | undefined });
+const exports = (packageJson as any).exports;
+if (exports) {
+if (typeof exports !== "object" || exports === null) { // eslint-disable-line no-null/no-null
+return; // null exports or entrypoint only, no sub-modules available
+}
+const keys = getOwnKeys(exports);
+const fragmentSubpath = components.join("/");
+const processedKeys = mapDefined(keys, k => {
+if (k === ".") return undefined;
+if (!startsWith(k, "./")) return undefined;
+const subpath = k.substring(2);
+if (!startsWith(subpath, fragmentSubpath)) return undefined;
+// subpath is a valid export (barring conditions, which we don't currently check here)
+if (!stringContains(subpath, "*")) {
+return subpath;
+}
+// pattern export - only return everything up to the `*`, so the user can autocomplete, then
+// keep filling in the pattern (we could speculatively return a list of options by hitting disk,
+// but conditions will make that somewhat awkward, as each condition may have a different set of possible
+// options for the `*`.
+return subpath.slice(0, subpath.indexOf("*"));
+});
+forEach(processedKeys, k => {
+if (k) {
+result.push(nameAndKind(k, ScriptElementKind.externalModuleName, /*extension*/ undefined));
+}
+});
+return;
+}
+}
+return nodeModulesDirectoryLookup(ancestor);
+};
+}
+forEachAncestorDirectory(scriptPath, ancestorLookup);
 }
 }
 

tests/baselines/reference/nodeNextPathCompletions.baseline

@@ -0,0 +1,29 @@
+[
+{
+"marker": {
+"fileName": "/src/foo.ts",
+"position": 30,
+"name": ""
+},
+"completionList": {
+"isGlobalCompletion": false,
+"isMemberCompletion": false,
+"isNewIdentifierLocation": true,
+"entries": [
+{
+"name": "dependency",
+"kind": "external module name",
+"kindModifiers": "",
+"sortText": "11",
+"displayParts": [
+{
+"text": "dependency",
+"kind": "text"
+}
+],
+"tags": []
+}
+]
+}
+}
+]

tests/cases/fourslash/server/nodeNextPathCompletions.ts

@@ -0,0 +1,43 @@
+/// <reference path="../fourslash.ts" />
+
+// @Filename: /node_modules/dependency/package.json
+//// {
+//// "type": "module",
+//// "name": "dependency",
+//// "version": "1.0.0",
+//// "exports": {
+//// ".": {
+//// "types": "./lib/index.d.ts"
+//// },
+//// "./lol": {
+//// "types": "./lib/lol.d.ts"
+//// },
+//// "./dir/*": "./lib/*"
+//// }
+//// }
+
+// @Filename: /node_modules/dependency/lib/index.d.ts
+//// export function fooFromIndex(): void;
+
+// @Filename: /node_modules/dependency/lib/lol.d.ts
+//// export function fooFromLol(): void;
+
+// @Filename: /package.json
+//// {
+//// "type": "module",
+//// "dependencies": {
+//// "dependency": "^1.0.0"
+//// }
+//// }
+
+// @Filename: /tsconfig.json
+//// { "compilerOptions": { "module": "nodenext" }, "files": ["./src/foo.ts"] }
+
+// @Filename: /src/foo.ts
+//// import { fooFromIndex } from "/**/";
+
+verify.baselineCompletions();
+edit.insert("dependency/");
+verify.completions({ exact: ["lol", "dir/"], isNewIdentifierLocation: true });
+edit.insert("l");
+verify.completions({ exact: ["lol"], isNewIdentifierLocation: true });