From b6f3e05063fb040e3d157d64d336b08e48e70515 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <LPSego3+dev@gmail.com>
Date: Sat, 5 Nov 2022 10:12:00 -0400
Subject: [PATCH] fix(template): use more robust template tag identification

---
 demo/samples.js                   |  41 ++++++--
 package.json                      |   2 +-
 src/index.js                      |  99 ++++++++++++++++++-
 tests-esm/unit/injections.test.js | 153 ++++++++++++++++++++++++++++++
 4 files changed, 284 insertions(+), 11 deletions(-)

diff --git a/demo/samples.js b/demo/samples.js
index f928c534..125b1e36 100644
--- a/demo/samples.js
+++ b/demo/samples.js
@@ -114,22 +114,51 @@ export const gjsTemplateOnly = {
   name: 'template-only .gjs',
   language: 'js',
   sample: `import { helper } from '@ember/component/helper';
-import { modifier } from 'ember-modifier';
+  import { modifier } from 'ember-modifier';
 
-const plusOne = helper(([num]) => num + 1);
+  const plusOne = helper(([num]) => num + 1);
 
-const setScrollPosition = modifier((element, [position]) => {
+  const setScrollPosition = modifier((element, [position]) => {
   element.scrollTop = position
-});
+  });
 
-<template>
+  <template>
   <div class="scroll-container" {{setScrollPosition @scrollPos}}>
     {{#each @items as |item index|}}
       Item #{{plusOne index}}: {{item}}
     {{/each}}
   </div>
+  </template>
+  `,
+};
+
+export const multipleTemplateOnly = {
+  name: 'multiple template-only .gjs',
+  language: 'js',
+  sample: `import WeatherSummary from './weather-summary.js';
+
+const Greeting = <template>
+  <p>Hello, {{@name}}!</p>
+</template>;
+
+function isBirthday(dateOfBirth) {
+  const now = new Date();
+  return (
+    dateOfBirth.getDate() === now.getDate() &&
+    dateOfBirth.getMonth() === now.getMonth()
+  );
+}
+
+<template>
+  <div>
+    <Greeting @name="Chris" />
+    {{#if (isBirthday @user.dateOfBirth)}}
+      <Celebration type='birthday' />
+    {{/if}}
+    <WeatherSummary />
+  </div>
 </template>
-`,
+  `,
 };
 
 /** @type { Sample } */
diff --git a/package.json b/package.json
index 13b6c384..3657fef1 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,7 @@
   "scripts": {
     "prepare": "node ./scripts/build.cjs",
     "build": "node ./scripts/build.cjs",
-    "debug": "npx html-pages .",
+    "debug": "npx html-pages . --no-cache",
     "lint:js": "eslint .",
     "lint:js:fix": "eslint . --fix",
     "lint": "pnpm lint:js && pnpm --filter '*' lint:js",
diff --git a/src/index.js b/src/index.js
index 9561e622..8484dff2 100644
--- a/src/index.js
+++ b/src/index.js
@@ -34,18 +34,109 @@ function registerJavaScriptInjections(hljs) {
 
   js = js.rawDefinition(hljs);
 
+  setupHBSLiteral(js);
+  swapXMLForGlimmer(js);
+  setupTemplateTag(js);
+
+  hljs.registerLanguage('javascript', () => js);
+}
+
+function setupHBSLiteral(js) {
   let cssIndex = js.contains.findIndex((rule) => rule?.begin === 'css`');
   let css = js.contains[cssIndex];
 
+  const HBS_TEMPLATE = hljs.inherit(css, { begin: /hbs`/ });
+
+  HBS_TEMPLATE.starts.subLanguage = 'glimmer';
+
+  js.contains.splice(cssIndex, 0, HBS_TEMPLATE);
+}
+
+function swapXMLForGlimmer(js) {
   // The default JSX grammar is actually just XML, which... is also wrong :D
   js.contains
     .flatMap((contains) => contains?.contains || contains)
     .filter((rule) => rule.subLanguage === 'xml')
     .forEach((rule) => (rule.subLanguage = 'glimmer'));
+}
 
-  const HBS_TEMPLATE = hljs.inherit(css, { begin: /hbs`/ });
+/**
+ * A lot of this is stolen from XML
+ */
+function setupTemplateTag(js) {
+  const GLIMMER_TEMPLATE_TAG = {
+    begin: /<template>/,
+    end: /<\/template>/,
+    /**
+     * @param {RegExpMatchArray} match
+     * @param {CallbackResponse} response
+     */
+    isTrulyOpeningTag: (match, response) => {
+      const afterMatchIndex = match[0].length + match.index;
+      const nextChar = match.input[afterMatchIndex];
 
-  HBS_TEMPLATE.starts.subLanguage = 'glimmer';
-  js.contains.splice(cssIndex, 0, HBS_TEMPLATE);
-  hljs.registerLanguage('javascript', () => js);
+      if (
+        // HTML should not include another raw `<` inside a tag
+        // nested type?
+        // `<Array<Array<number>>`, etc.
+        nextChar === '<' ||
+        // the , gives away that this is not HTML
+        // `<T, A extends keyof T, V>`
+        nextChar === ','
+      ) {
+        response.ignoreMatch();
+
+        return;
+      }
+
+      // `<something>`
+      // Quite possibly a tag, lets look for a matching closing tag...
+      if (nextChar === '>') {
+        // if we cannot find a matching closing tag, then we
+        // will ignore it
+        if (!hasClosingTag(match, { after: afterMatchIndex })) {
+          response.ignoreMatch();
+        }
+      }
+
+      // `<blah />` (self-closing)
+      // handled by simpleSelfClosing rule
+
+      // `<From extends string>`
+      // technically this could be HTML, but it smells like a type
+      let m;
+      const afterMatch = match.input.substring(afterMatchIndex);
+
+      // NOTE: This is ugh, but added specifically for https://github.com/highlightjs/highlight.js/issues/3276
+      if ((m = afterMatch.match(/^\s+extends\s+/))) {
+        if (m.index === 0) {
+          response.ignoreMatch();
+
+          // eslint-disable-next-line no-useless-return
+          return;
+        }
+      }
+    },
+  };
+
+  js.contains.unshift({
+    variants: [
+      {
+        begin: GLIMMER_TEMPLATE_TAG.begin,
+        // we carefully check the opening tag to see if it truly
+        // is a tag and not a false positive
+        'on:begin': GLIMMER_TEMPLATE_TAG.isTrulyOpeningTag,
+        end: GLIMMER_TEMPLATE_TAG.end,
+      },
+    ],
+    subLanguage: 'glimmer',
+    contains: [
+      {
+        begin: GLIMMER_TEMPLATE_TAG.begin,
+        end: GLIMMER_TEMPLATE_TAG.end,
+        skip: true,
+        contains: ['self'],
+      },
+    ],
+  });
 }
diff --git a/tests-esm/unit/injections.test.js b/tests-esm/unit/injections.test.js
index 1add28b7..924ce399 100644
--- a/tests-esm/unit/injections.test.js
+++ b/tests-esm/unit/injections.test.js
@@ -37,5 +37,158 @@ describe('Injections | JS', () => {
         `
       );
     });
+
+    test('implied default export', () => {
+      let result = parse(
+        stripIndent`
+          <template>
+            {{@name}}
+          </template>
+        `,
+        'js'
+      );
+
+      expect(result).toEqual(
+        tag('hljs-name', ['{{', tag('punctuation', '@'), tag('params', 'name'), '}}'])
+      );
+    });
+
+    test('explicit default export', () => {
+      let result = parse(
+        stripIndent`
+          export default <template>
+            {{@name}}
+          </template>
+        `,
+        'js'
+      );
+
+      expect(result).toEqual();
+    });
+
+    test('with imports', () => {
+      let result = parse(
+        stripIndent`
+          import Greeting from './greeting.js';
+          import WeatherSummary from './weather-summary.js';
+
+          <template>
+            <div>
+              <Greeting @name="Chris" />
+              <WeatherSummary />
+            </div>
+          </template>
+        `,
+        'js'
+      );
+
+      expect(result).toEqual();
+    });
+
+    test('a function exists above the template', () => {
+      let result = parse(
+        stripIndent`
+          import Greeting from './greeting.js';
+          import WeatherSummary from './weather-summary.js';
+
+          function isBirthday(dateOfBirth) {
+            const now = new Date();
+            return (
+              dateOfBirth.getDate() === now.getDate() &&
+              dateOfBirth.getMonth() === now.getMonth()
+            );
+          }
+
+          <template>
+            <div>
+              <Greeting @name="Chris" />
+              {{#if (isBirthday @user.dateOfBirth)}}
+                <Celebration type='birthday' />
+              {{/if}}
+              <WeatherSummary />
+            </div>
+          </template>
+        `,
+        'js'
+      );
+
+      expect(result).toEqual();
+    });
+
+    test('is embedded in a class', () => {
+      let result = parse(
+        stripIndent`
+          import Component from '@glimmer/component';
+          import { gt, lt } from '@glimmer/helper';
+
+          export default class WeatherSummary extends Component {
+            @tracked currentTemp;
+
+            interval;
+
+            getWeather = () => {
+              this.currentTemp = // something
+            }
+
+            constructor(owner, args) {
+              super(owner, args);
+              this.interval = setInterval(this.getWeather, 10000);
+            }
+
+            willDestroy() {
+              super.willDestroy();
+              clearInterval(this.interval);
+            }
+
+            <template>
+              <p>
+                The current temperature is {{this.currentTemp}}!
+                {{#if (lt 50 this.currentTemp)}}
+                  Brr! 🥶
+                {{else if (gt 80 this.currentTemp)}}
+                  Yikes! 🥵
+                {{/if}}
+              </p>
+            </template>
+          }
+        `,
+        'js'
+      );
+
+      expect(result).toEqual();
+    });
+
+    test('multiple components', () => {
+      let result = parse(
+        stripIndent`
+          import WeatherSummary from './weather-summary.js';
+
+          const Greeting = <template>
+            <p>Hello, {{@name}}!</p>
+          </template>;
+
+          function isBirthday(dateOfBirth) {
+            const now = new Date();
+            return (
+              dateOfBirth.getDate() === now.getDate() &&
+              dateOfBirth.getMonth() === now.getMonth()
+            );
+          }
+
+          <template>
+            <div>
+              <Greeting @name="Chris" />
+              {{#if (isBirthday @user.dateOfBirth)}}
+                <Celebration type='birthday' />
+              {{/if}}
+              <WeatherSummary />
+            </div>
+          </template>
+        `,
+        'js'
+      );
+
+      expect(result).toEqual();
+    });
   });
 });