Refactor show syntax tree action

editors/code/src/commands/syntax_tree.ts

@@ -0,0 +1,106 @@
+import * as vscode from 'vscode';
+import * as lc from 'vscode-languageclient';
+
+import { Ctx, Cmd } from '../ctx';
+
+// Opens the virtual file that will show the syntax tree
+//
+// The contents of the file come from the `TextDocumentContentProvider`
+export function syntaxTree(ctx: Ctx): Cmd {
+    const stcp = new SyntaxTreeContentProvider(ctx);
+
+    ctx.pushCleanup(
+        vscode.workspace.registerTextDocumentContentProvider(
+            'rust-analyzer',
+            stcp,
+        ),
+    );
+
+    vscode.workspace.onDidChangeTextDocument(
+        (event: vscode.TextDocumentChangeEvent) => {
+            const doc = event.document;
+            if (doc.languageId !== 'rust') return;
+            afterLs(() => stcp.eventEmitter.fire(stcp.uri));
+        },
+        ctx.subscriptions,
+    );
+
+    vscode.window.onDidChangeActiveTextEditor(
+        (editor: vscode.TextEditor | undefined) => {
+            if (!editor || editor.document.languageId !== 'rust') return;
+            stcp.eventEmitter.fire(stcp.uri);
+        },
+        ctx.subscriptions,
+    );
+
+    return async () => {
+        const editor = vscode.window.activeTextEditor;
+        const rangeEnabled = !!(editor && !editor.selection.isEmpty);
+
+        const uri = rangeEnabled
+            ? vscode.Uri.parse(`${stcp.uri.toString()}?range=true`)
+            : stcp.uri;
+
+        const document = await vscode.workspace.openTextDocument(uri);
+
+        stcp.eventEmitter.fire(uri);
+
+        return vscode.window.showTextDocument(
+            document,
+            vscode.ViewColumn.Two,
+            true,
+        );
+    };
+}
+
+// We need to order this after LS updates, but there's no API for that.
+// Hence, good old setTimeout.
+function afterLs(f: () => any) {
+    setTimeout(f, 10);
+}
+
+interface SyntaxTreeParams {
+    textDocument: lc.TextDocumentIdentifier;
+    range?: lc.Range;
+}
+
+export class SyntaxTreeContentProvider
+    implements vscode.TextDocumentContentProvider {
+    ctx: Ctx;
+    uri = vscode.Uri.parse('rust-analyzer://syntaxtree');
+    eventEmitter = new vscode.EventEmitter<vscode.Uri>();
+    syntaxTree: string = 'Not available';
+
+    constructor(ctx: Ctx) {
+        this.ctx = ctx;
+    }
+
+    provideTextDocumentContent(uri: vscode.Uri): vscode.ProviderResult<string> {
+        const editor = vscode.window.activeTextEditor;
+        if (editor == null) return '';
+
+        let range: lc.Range | undefined;
+
+        // When the range based query is enabled we take the range of the selection
+        if (uri.query === 'range=true') {
+            range = editor.selection.isEmpty
+                ? undefined
+                : this.ctx.client.code2ProtocolConverter.asRange(
+                      editor.selection,
+                  );
+        }
+
+        const request: SyntaxTreeParams = {
+            textDocument: { uri: editor.document.uri.toString() },
+            range,
+        };
+        return this.ctx.client.sendRequest<string>(
+            'rust-analyzer/syntaxTree',
+            request,
+        );
+    }
+
+    get onDidChange(): vscode.Event<vscode.Uri> {
+        return this.eventEmitter.event;
+    }
+}