feat(language-server): add offset-preserving virtual HTML document

2026-08-18 20:34:24 +05:30
parent 7d481df652
commit 7301849a7f
2 changed files with 225 additions and 0 deletions
@@ -0,0 +1,109 @@
+import { expect, test } from "bun:test";
+import { isInsideHtml, viewRegions, virtualHtmlDocument } from "../src/html-regions.ts";
+
+function doc(text: string): { uri: string; text: string; version?: number } {
+  return { uri: `file:///${Math.random()}.wrn`, text };
+}
+
+const PAGE = `page Home {
+  view {
+    <div class="card">hello</div>
+  }
+}
+`;
+
+test("the virtual document preserves length and newline offsets", () => {
+  // This is what makes position mapping unnecessary. If it breaks, every
+  // feature reports positions off by some amount instead of failing loudly.
+  const source = doc(PAGE);
+  const virtual = virtualHtmlDocument(source);
+
+  expect(virtual.text.length).toBe(source.text.length);
+  expect(virtual.languageId).toBe("html");
+  for (let i = 0; i < source.text.length; i += 1) {
+    if (source.text[i] === "\n") expect(virtual.text[i]).toBe("\n");
+  }
+});
+
+test("markup survives into the virtual document and everything else is blanked", () => {
+  const virtual = virtualHtmlDocument(doc(PAGE));
+  expect(virtual.text).toContain('<div class="card">hello</div>');
+  expect(virtual.text).not.toContain("page Home");
+  expect(virtual.text).not.toContain("view");
+});
+
+test("an apostrophe in text content does not swallow later regions", () => {
+  // A scanner treating ' as a string delimiter anywhere considers the rest of
+  // the file one open string and loses every later region.
+  const source = `page A {
+  view {
+    <p>it's fine</p>
+  }
+}
+component B {
+  view {
+    <span>second</span>
+  }
+}
+`;
+  expect(viewRegions(source)).toHaveLength(2);
+  expect(virtualHtmlDocument(doc(source)).text).toContain("<span>second</span>");
+});
+
+test("interpolation braces nest without ending the region early", () => {
+  const source = `page A {
+  view {
+    <div class={cond ? "a" : "b"} data-x={{ a: 1 }}>after</div>
+  }
+}
+`;
+  const regions = viewRegions(source);
+  expect(regions).toHaveLength(1);
+  expect(virtualHtmlDocument(doc(source)).text).toContain("after</div>");
+});
+
+test("unparseable mid-edit markup still yields a region", () => {
+  // Completion fires exactly when the document does not parse.
+  const source = `page A {
+  view {
+    <div class="
+  }
+}
+`;
+  expect(viewRegions(source).length).toBe(1);
+});
+
+test("a file with no view block yields no regions and a fully blank document", () => {
+  const source = `page A {
+  functions {
+    function go() {}
+  }
+}
+`;
+  expect(viewRegions(source)).toEqual([]);
+  expect(virtualHtmlDocument(doc(source)).text.trim()).toBe("");
+});
+
+test("regions are cached per document version", () => {
+  // One keystroke fans out into completion, hover, and tag-close requests.
+  const first = doc(PAGE);
+  first.version = 1;
+  expect(isInsideHtml(first, PAGE.indexOf("<div"))).toBe(true);
+
+  // Same version, mutated text: the cached regions are reused, proving the
+  // scan did not run again.
+  first.text = "page A { }";
+  expect(isInsideHtml(first, PAGE.indexOf("<div"))).toBe(true);
+
+  first.version = 2;
+  expect(isInsideHtml(first, PAGE.indexOf("<div"))).toBe(false);
+});
+
+test("isInsideHtml distinguishes markup from surrounding code", () => {
+  const source = doc(PAGE);
+  const markupOffset = PAGE.indexOf("<div");
+  const keywordOffset = PAGE.indexOf("page");
+
+  expect(isInsideHtml(source, markupOffset)).toBe(true);
+  expect(isInsideHtml(source, keywordOffset)).toBe(false);
+});