(feat) rewrite svelte2tsx (#1237)

Goal: Get rid of a tsx-style transformation and simplify transformations along the way
#1077
#1256
#1149

Advantages:

-   no messing with projects who use JSX for some other reason and then have conflicting JSX definitions
-   TS control flow easier to keep flowing
-   overall easier transformations of Svelte specific syntax like await, each etc.
-   better type inference in some cases, for example around svelte:component

This includes:

-   rewriting the html2jsx part of svelte2tsx
-   adjusting the language server to the new transformation
-   adding a toggle to language-server and vs code extension to turn on the new transformation. Default "off" for now, with the plan to switch it to "on" and then removing the old transformation altogether
-   ensuring tests run with both new and old transformation
-   adjusting the TypeScript plugin. It uses the new transformation already now since it's not easily possible to add an option (on/off). Should be low-impact since TS doesn't need to know much about the contents of a Svelte file, only its public API

Look at the PR of this commit to see more explanations with some of the entry points of the new transformation.

Author: dummdidumm

.eslintignore

@@ -4,3 +4,4 @@ packages/svelte2tsx/test/**/*
 packages/svelte2tsx/index.*
 declare module '*.svelte'
 packages/svelte2tsx/svelte-shims.d.ts
+packages/svelte2tsx/svelte-jsx.d.ts

.prettierignore

@@ -1,6 +1,6 @@
 packages/svelte2tsx/*.d.ts
-packages/svelte2tsx/test/*/samples/*/*sx
-packages/svelte2tsx/test/*/samples/*/*.svelte
+packages/svelte2tsx/repl/*
+packages/svelte2tsx/test/*/samples/**/*
 packages/svelte2tsx/test/sourcemaps/samples/*
 packages/svelte2tsx/test/emitDts/samples/*/expected/**
 packages/language-server/test/**/*.svelte

packages/language-server/package.json

@@ -5,7 +5,7 @@
     "main": "dist/src/index.js",
     "typings": "dist/src/index",
     "scripts": {
-        "test": "cross-env TS_NODE_TRANSPILE_ONLY=true mocha --require ts-node/register \"test/**/*.ts\"",
+        "test": "cross-env TS_NODE_TRANSPILE_ONLY=true mocha --require ts-node/register \"test/**/*.ts\" --exclude \"test/**/*.d.ts\"",
         "build": "tsc",
         "prepublishOnly": "npm run build",
         "watch": "tsc -w"
@@ -57,7 +57,7 @@
         "source-map": "^0.7.3",
         "svelte": "^3.46.1",
         "svelte-preprocess": "~4.10.1",
-        "svelte2tsx": "~0.4.0",
+        "svelte2tsx": "~0.5.0",
         "typescript": "*",
         "vscode-css-languageservice": "~5.1.0",
         "vscode-emmet-helper": "~2.6.0",

packages/language-server/src/lib/documents/utils.ts

@@ -344,6 +344,19 @@ export function getNodeIfIsInStartTag(html: HTMLDocument, offset: number): Node
     }
 }
 
+/**
+ * Returns `true` if `offset` is a html tag and within the name of the start tag or end tag
+ */
+export function isInHTMLTagRange(html: HTMLDocument, offset: number): boolean {
+    const node = html.findNodeAt(offset);
+    return (
+        !!node.tag &&
+        node.tag[0] === node.tag[0].toLowerCase() &&
+        (node.start + node.tag.length + 1 >= offset ||
+            (!!node.endTagStart && node.endTagStart <= offset))
+    );
+}
+
 /**
  * Gets word range at position.
  * Delimiter is by default a whitespace, but can be adjusted.

packages/language-server/src/ls-config.ts

@@ -45,6 +45,7 @@ const defaultLSConfig: LSConfig = {
     },
     svelte: {
         enable: true,
+        useNewTransformation: false,
         compilerWarnings: {},
         diagnostics: { enable: true },
         rename: { enable: true },
@@ -176,6 +177,7 @@ export type CompilerWarningsSettings = Record<string, 'ignore' | 'error'>;
 
 export interface LSSvelteConfig {
     enable: boolean;
+    useNewTransformation: boolean;
     compilerWarnings: CompilerWarningsSettings;
     diagnostics: {
         enable: boolean;

packages/language-server/src/plugins/PluginHost.ts

@@ -28,9 +28,9 @@ import {
     TextEdit,
     WorkspaceEdit
 } from 'vscode-languageserver';
-import { DocumentManager } from '../lib/documents';
+import { DocumentManager, getNodeIfIsInHTMLStartTag } from '../lib/documents';
 import { Logger } from '../logger';
-import { regexLastIndexOf } from '../utils';
+import { isNotNullOrUndefined, regexLastIndexOf } from '../utils';
 import {
     AppCompletionItem,
     FileRename,
@@ -115,18 +115,54 @@ export class PluginHost implements LSProvider, OnWatchFileChanges {
     ): Promise<CompletionList> {
         const document = this.getDocument(textDocument.uri);
 
-        const completions = (
-            await this.execute<CompletionList>(
-                'getCompletions',
-                [document, position, completionContext, cancellationToken],
-                ExecuteMode.Collect,
-                'high'
-            )
-        ).filter((completion) => completion != null);
+        const completions = await Promise.all(
+            this.plugins.map(async (plugin) => {
+                const result = await this.tryExecutePlugin(
+                    plugin,
+                    'getCompletions',
+                    [document, position, completionContext, cancellationToken],
+                    null
+                );
+                if (result) {
+                    return { result: result as CompletionList, plugin: plugin.__name };
+                }
+            })
+        ).then((completions) => completions.filter(isNotNullOrUndefined));
+
+        const html = completions.find((completion) => completion.plugin === 'html');
+        const ts = completions.find((completion) => completion.plugin === 'ts');
+        if (html && ts && getNodeIfIsInHTMLStartTag(document.html, document.offsetAt(position))) {
+            // Completion in a component or html start tag and both html and ts
+            // suggest something -> filter out all duplicates from TS completions
+            const htmlCompletions = new Set(html.result.items.map((item) => item.label));
+            ts.result.items = ts.result.items.filter((item) => {
+                const label = item.label;
+                if (htmlCompletions.has(label)) {
+                    return false;
+                }
+                if (label[0] === '"' && label[label.length - 1] === '"') {
+                    if (htmlCompletions.has(label.slice(1, -1))) {
+                        // "aria-label" -> aria-label -> exists in html completions
+                        return false;
+                    }
+                }
+                if (label.startsWith('on')) {
+                    if (htmlCompletions.has('on:' + label.slice(2))) {
+                        // onclick -> on:click -> exists in html completions
+                        return false;
+                    }
+                }
+                // adjust sort text so it does appear after html completions
+                item.sortText = 'Z' + (item.sortText || '');
+                return true;
+            });
+        }
 
-        let flattenedCompletions = flatten(completions.map((completion) => completion.items));
+        let flattenedCompletions = flatten(
+            completions.map((completion) => completion.result.items)
+        );
         const isIncomplete = completions.reduce(
-            (incomplete, completion) => incomplete || completion.isIncomplete,
+            (incomplete, completion) => incomplete || completion.result.isIncomplete,
             false as boolean
         );
 

packages/language-server/src/plugins/css/CSSPlugin.ts

@@ -54,6 +54,7 @@ export class CSSPlugin
         DocumentSymbolsProvider,
         SelectionRangeProvider
 {
+    __name = 'css';
     private configManager: LSConfigManager;
     private cssDocuments = new WeakMap<Document, CSSDocument>();
     private triggerCharacters = ['.', ':', '-', '/'];

packages/language-server/src/plugins/html/HTMLPlugin.ts

@@ -37,6 +37,7 @@ import { possiblyComponent } from '../../utils';
 export class HTMLPlugin
     implements HoverProvider, CompletionsProvider, RenameProvider, LinkedEditingRangesProvider
 {
+    __name = 'html';
     private configManager: LSConfigManager;
     private lang = getLanguageService({
         customDataProviders: [svelteHtmlDataProvider],

packages/language-server/src/plugins/interfaces.ts

@@ -226,4 +226,4 @@ export type Plugin = Partial<
         OnWatchFileChanges &
         SelectionRangeProvider &
         UpdateTsOrJsFile
->;
+> & { __name: string };

packages/language-server/src/plugins/svelte/SveltePlugin.ts

@@ -41,6 +41,7 @@ export class SveltePlugin
         CodeActionsProvider,
         SelectionRangeProvider
 {
+    __name = 'svelte';
     private docManager = new Map<Document, SvelteDocument>();
 
     constructor(private configManager: LSConfigManager) {}

packages/language-server/src/plugins/typescript/DocumentSnapshot.ts

@@ -78,6 +78,8 @@ export interface SnapshotFragment extends DocumentMapper {
  */
 export interface SvelteSnapshotOptions {
     transformOnTemplateError: boolean;
+    useNewTransformation: boolean;
+    typingsNamespace: string;
 }
 
 export namespace DocumentSnapshot {
@@ -159,13 +161,21 @@ function preprocessSvelteFile(document: Document, options: SvelteSnapshotOptions
         getScriptKindFromAttributes(document.scriptInfo?.attributes ?? {}),
         getScriptKindFromAttributes(document.moduleScriptInfo?.attributes ?? {})
     ].includes(ts.ScriptKind.TSX)
-        ? ts.ScriptKind.TSX
+        ? options.useNewTransformation
+            ? ts.ScriptKind.TS
+            : ts.ScriptKind.TSX
+        : options.useNewTransformation
+        ? ts.ScriptKind.JS
         : ts.ScriptKind.JSX;
 
     try {
         const tsx = svelte2tsx(text, {
             filename: document.getFilePath() ?? undefined,
-            isTsFile: scriptKind === ts.ScriptKind.TSX,
+            isTsFile: options.useNewTransformation
+                ? scriptKind === ts.ScriptKind.TS
+                : scriptKind === ts.ScriptKind.TSX,
+            mode: options.useNewTransformation ? 'ts' : 'tsx',
+            typingsNamespace: options.useNewTransformation ? options.typingsNamespace : undefined,
             emitOnTemplateError: options.transformOnTemplateError,
             namespace: document.config?.compilerOptions?.namespace,
             accessors:
@@ -388,7 +398,7 @@ export class SvelteSnapshotFragment implements SnapshotFragment {
     constructor(
         private readonly mapper: DocumentMapper,
         public readonly text: string,
-        private readonly parent: Document,
+        public readonly parent: Document,
         private readonly url: string
     ) {}
 

packages/language-server/src/plugins/typescript/LSAndTSDocResolver.ts

@@ -70,6 +70,7 @@ export class LSAndTSDocResolver {
         return {
             ambientTypesSource: this.isSvelteCheck ? 'svelte-check' : 'svelte2tsx',
             createDocument: this.createDocument,
+            useNewTransformation: this.configManager.getConfig().svelte.useNewTransformation,
             transformOnTemplateError: !this.isSvelteCheck,
             globalSnapshotsManager: this.globalSnapshotsManager,
             notifyExceedSizeLimit: this.notifyExceedSizeLimit