clone ligatures addon repo

2026-08-05 13:43:48 -07:00 · 2020-05-01 14:26:03 +05:30
parent 939de5d151
commit 15df03ba09
24 changed files with 3484 additions and 0 deletions
@@ -0,0 +1,14 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+insert_final_newline = true
+trim_trailing_whitespace = true
+end_of_line = lf
+
+[*.{j,t}s]
+max_line_length = 100
+
+[*.md]
+trim_trailing_whitespace = false
@@ -0,0 +1,18 @@
+---
+name: Bug report
+about: Create a bug report
+---
+
+<!-- ⚠️ Please search existing issues to avoid creating duplicates. ⚠️ -->
+<!-- Describe the bug here. -->
+
+## Details
+- Browser and browser and/or electron version: 
+- OS version: 
+- xterm.js version: 
+- xterm-addon-ligatures version: 
+
+### Steps to reproduce
+
+1. 
+2. 
@@ -0,0 +1,7 @@
+---
+name: Feature request
+about: Suggest a feature or enhancement
+---
+
+<!-- ⚠️ Please search existing issues to avoid creating duplicates. ⚠️ -->
+<!-- Describe the enhancement here. -->
@@ -0,0 +1,8 @@
+---
+name: Question
+about: The issue tracker is not for questions. Please ask questions on https://stackoverflow.com/questions/tagged/xtermjs or https://gitter.im/sourcelair/xterm.js.
+---
+
+🛑 The issue tracker is not for questions 🛑
+
+If you have a question, please ask it on https://stackoverflow.com/questions/tagged/xtermjs or https://gitter.im/sourcelair/xterm.js.
@@ -0,0 +1,13 @@
+node_modules/
+.nyc_output/
+coverage/
+
+lib/
+fonts/
+
+.env
+.vscode/
+*.swp
+*.tgz
+npm-debug.log*
+yarn-error.log*
@@ -0,0 +1,36 @@
+# Blacklist - exclude everything except npm defaults such as LICENSE, etc
+*
+!*/
+
+# Whitelist - entries to be included must be negated with "!"
+!*.js
+!*.json
+
+# Whitelist - lib/
+!lib/**/*.d.ts
+
+!lib/**/*.js
+!lib/**/*.js.map
+
+# Whitelist - src/
+!src/**/*.ts
+!src/**/*.d.ts
+
+!src/**/*.js
+!src/**/*.js.map
+
+# Whitelist - typings/
+!typings/**/*.d.ts
+
+# Blacklist - (normal behavior) these will override any whitelist
+*.test.ts
+*.test.d.ts
+*.test.js
+*.test.js.map
+
+docs/
+/.idea/
+.vscode/
+coverage/
+.nyc_output/
+fonts/
@@ -0,0 +1 @@
+Jeff Principe <princjef@gmail.com>
@@ -0,0 +1,73 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, gender identity and expression, level of experience,
+education, socio-economic status, nationality, personal appearance, race,
+religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting [@Tyriar](https://twitter.com/Tyriar) or [@pariskasid](https://twitter.com/pariskasid) on Twitter. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
@@ -0,0 +1,51 @@
+# How to contribute to xterm-addon-ligatures
+
+- [Opening issues for bug reports or feature requests](#opening-issues)
+- [Contributing code](#contributing-code)
+
+## Opening issues
+
+The preferred way to report bugs or request features is to use
+[GitHub issues](http://github.com/xtermjs/xterm-addon-ligatures/issues). Before
+opening an issue, read these pointers.
+
+### Opening issues effectively
+
+- Include information about **the browser in which the problem occurred**. Even
+  if you tested several browsers, and the problem occurred in all of them,
+  mention this fact in the bug report. Also include browser version numbers and
+  the operating system that you're on.
+
+- Mention which release of xterm.js and xterm-addon-ligatures you're using.
+  Preferably, try also with the current HEAD of the master branch, to ensure the
+  problem has not already been fixed.
+
+- Mention precisely what went wrong. What did you expect to happen? What
+  happened instead? Describe the exact steps a maintainer has to take to make
+  the problem occur.
+
+- Be polite. Issues with an indignant or belligerent tone tend to be moved to
+  the bottom of the pile.
+
+## Contributing code
+
+- Make sure you have a [GitHub account](https://github.com/join)
+- Fork [xterm-addon-ligatures](https://github.com/xtermjs/xterm-addon-ligatures/)
+  ([how to fork a repo](https://help.github.com/articles/fork-a-repo))
+- Make your changes
+- If your changes are easy to test or likely to regress, add tests. Tests go into corresponding `.test.ts` files.
+- Follow the general code style of the rest of the project (see below).
+- Submit a pull request
+([how to create a pull request](https://help.github.com/articles/fork-a-repo)).
+  Don't put more than one feature/fix in a single pull request.
+
+By contributing code to xterm-addon-ligatures you
+
+ - agree to license the contributed code under xterm-addon-ligatures's [MIT
+   license](LICENSE).
+
+ - confirm that you have the right to contribute and license the code
+   in question. (Either you hold all rights on the code, or the rights
+   holder has explicitly granted the right to use it like this,
+   through a compatible open source license or through a direct
+   agreement with you.)
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
@@ -0,0 +1,98 @@
+# xterm-addon-ligatures
+
+[![Build Status](https://dev.azure.com/xtermjs/xterm-addon-ligatures/_apis/build/status/xtermjs.xterm-addon-ligatures)](https://dev.azure.com/xtermjs/xterm-addon-ligatures/_build/latest?definitionId=4)
+[![Coverage Status](https://coveralls.io/repos/github/xtermjs/xterm-addon-ligatures/badge.svg?branch=refs%2Fheads%2Fmaster)](https://coveralls.io/github/xtermjs/xterm-addon-ligatures?branch=refs%2Fheads%2Fmaster)
+
+Add support for programming ligatures to [xterm.js][] when running in
+environments with access to [Node.js][] APIs (such as [Electron][]).
+
+## Requirements
+
+ * [Node.js][] 8.x or higher (present in [Electron][] 1.8.3 or higher)
+ * [xterm.js][] 4.0.0 or higher using the default canvas renderer
+
+## Usage
+
+Install in your project by running:
+
+```
+npm install xterm-addon-ligatures
+```
+
+Then, modify the location where you initialize the terminal to enable ligature
+support after opening. If you enable ligatures prior to opening the terminal,
+they will not function properly.
+
+Your code should look something like this:
+
+```js
+import { Terminal } from 'xterm';
+import * as ligatures from 'xterm-addon-ligatures';
+
+Terminal.applyAddon(ligatures);
+
+const terminal = new Terminal();
+terminal.open(document.getElementById('terminal-mount'));
+terminal.enableLigatures();
+```
+
+### Importing in TypeScript
+
+If you use TypeScript, you will need to cast the terminal variable as `any` when
+you enable ligatures because TypeScript does not know that the addon is
+available on the terminal object. It will look like this:
+
+```ts
+(terminal as any).enableLigatures()
+```
+
+Alternatively, you can import the addon directly as a function and pass the
+terminal as an argument:
+
+```js
+import { Terminal } from 'xterm';
+import { enableLigatures } from 'xterm-addon-ligatures';
+
+const terminal = new Terminal();
+terminal.open(document.getElementById('terminal-mount'));
+enableLigatures(terminal);
+```
+
+## How It Works
+
+In a browser environment, font ligature information is read directly by the web
+browser and used to render text correctly without any intervention from the
+developer. As of version 3, xterm.js uses the canvas to render characters
+individually, resulting in a significant performance boost. However, this means
+that it can no longer lean on the browser to determine when to draw font
+ligatures.
+
+This package locates the font file on disk for the font currently in use by the
+terminal and parses the ligature information out of it (via the
+[font-ligatures][] package). As text is rendered in xterm.js, this package
+annotates it with the locations of ligatures, allowing xterm.js to render it
+correctly.
+
+Since this package depends on being able to find and resolve a system font from
+disk, it has to have system access that isn't available in the web browser. As a
+result, this package is mainly useful in environments that combine browser and
+Node.js runtimes (such as [Electron][]).
+
+## Fonts
+
+This package makes use of the following fonts for testing:
+
+ * [Fira Code][] - [Licensed under the OFL][Fira Code License] by Nikita
+   Prokopov, Mozilla Foundation with reserved names Fira Code, Fira Mono, and
+   Fira Sans
+ * [Iosevka][] - [Licensed under the OFL][Iosevka License] by Belleve Invis with
+   reserved name Iosevka
+
+[xterm.js]: https://github.com/xtermjs/xterm.js
+[Electron]: https://electronjs.org/
+[Node.js]: https://nodejs.org/
+[font-ligatures]: https://github.com/princjef/font-ligatures
+[Fira Code]: https://github.com/tonsky/FiraCode
+[Fira Code License]: https://github.com/tonsky/FiraCode/blob/master/LICENSE
+[Iosevka]: https://github.com/be5invis/Iosevka
+[Iosevka License]: https://github.com/be5invis/Iosevka/blob/master/LICENSE.md
@@ -0,0 +1,76 @@
+# Node.js
+# Build a general Node.js application with npm.
+# Add steps that analyze code, save build artifacts, deploy, and more:
+# https://docs.microsoft.com/vsts/pipelines/languages/javascript
+
+jobs:
+- job: Linux
+  pool:
+    vmImage: 'ubuntu-16.04'
+  steps:
+  - task: NodeTool@0
+    inputs:
+      versionSpec: '8.x'
+    displayName: 'Install Node.js'
+  - task: geeklearningio.gl-vsts-tasks-yarn.yarn-installer-task.YarnInstaller@2
+    inputs:
+      versionSpec: "1.9.4"
+    displayName: 'Install Yarn'
+  - script: |
+      yarn
+    displayName: 'Install dependencies'
+  - script: |
+      yarn build
+    displayName: 'Build'
+  - script: |
+      yarn test
+    displayName: 'Test'
+  - script: |
+      yarn lint
+    displayName: 'Lint'
+  - script: |
+      export COVERALLS_GIT_BRANCH=$BUILD_SOURCEBRANCH
+      yarn coveralls
+    displayName: 'Publish coverage'
+
+- job: macOS
+  pool:
+    vmImage: 'xcode9-macos10.13'
+  steps:
+  - task: NodeTool@0
+    inputs:
+      versionSpec: '8.x'
+    displayName: 'Install Node.js'
+  - script: |
+      yarn
+    displayName: 'Install dependencies'
+  - script: |
+      yarn build
+    displayName: 'Build'
+  - script: |
+      yarn test
+    displayName: 'Test'
+  - script: |
+      yarn lint
+    displayName: 'Lint'
+
+- job: Windows
+  pool:
+    vmImage: 'vs2017-win2016'
+  steps:
+  - task: NodeTool@0
+    inputs:
+      versionSpec: '8.x'
+    displayName: 'Install Node.js'
+  - script: |
+      yarn
+    displayName: 'Install dependencies'
+  - script: |
+      yarn build
+    displayName: 'Build'
+  - script: |
+      yarn test
+    displayName: 'Test'
+  - script: |
+      yarn lint
+    displayName: 'Lint'
@@ -0,0 +1,70 @@
+const fs = require('fs');
+const path = require('path');
+const util = require('util');
+
+const axios = require('axios').default;
+const mkdirp = require('mkdirp');
+const yauzl = require('yauzl');
+
+const urls = {
+  fira: 'https://github.com/tonsky/FiraCode/raw/master/distr/otf/FiraCode-Regular.otf',
+  iosevka: 'https://github.com/be5invis/Iosevka/releases/download/v1.14.3/01-iosevka-1.14.3.zip'
+};
+
+const writeFile = util.promisify(fs.writeFile);
+const fontsFolder = path.join(__dirname, '../fonts');
+
+async function download() {
+  await mkdirp(fontsFolder);
+
+  await downloadFiraCode();
+  await downloadIosevka();
+
+  console.log('Loaded all fonts for testing')
+}
+
+async function downloadFiraCode() {
+  const file = path.join(fontsFolder, 'firaCode.otf');
+  if (await util.promisify(fs.exists)(file)) {
+    console.log('Fira Code already loaded');
+  } else {
+    console.log('Downloading Fira Code...');
+    await writeFile(
+      file,
+      (await axios.get(urls.fira, { responseType: 'arraybuffer' })).data
+    );
+  }
+}
+
+async function downloadIosevka() {
+  const file = path.join(fontsFolder, 'iosevka.ttf');
+  if (await util.promisify(fs.exists)(file)) {
+    console.log('Iosevka already loaded');
+  } else {
+    console.log('Downloading Iosevka...');
+    const iosevkaContents = (await axios.get(urls.iosevka, { responseType: 'arraybuffer' })).data;
+    const iosevkaZipfile = await util.promisify(yauzl.fromBuffer)(iosevkaContents);
+    await new Promise((resolve, reject) => {
+      iosevkaZipfile.on('entry', entry => {
+        if (entry.fileName === 'ttf/iosevka-regular.ttf') {
+          iosevkaZipfile.openReadStream(entry, (err, stream) => {
+            if (err) {
+              return reject(err);
+            }
+
+            const writeStream = fs.createWriteStream(file);
+            stream.pipe(writeStream);
+            writeStream.on('close', () => resolve());
+          });
+        }
+      });
+    });
+  }
+}
+
+download();
+
+process.on('unhandledRejection', e => {
+  console.error(e);
+  process.exit(1);
+});
@@ -0,0 +1,79 @@
+{
+  "name": "xterm-addon-ligatures",
+  "version": "0.2.1",
+  "description": "Add support for programming ligatures to xterm.js",
+  "homepage": "https://github.com/xtermjs/xterm-addon-ligatures#readme",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/xtermjs/xterm-addon-ligatures.git"
+  },
+  "bugs": {
+    "url": "https://github.com/xtermjs/xterm-addon-ligatures/issues"
+  },
+  "engines": {
+    "node": ">8.0.0"
+  },
+  "main": "lib/LigaturesAddon.js",
+  "types": "typings/xterm-addon-ligatures.d.ts",
+  "scripts": {
+    "prepare": "node bin/download-fonts.js",
+    "lint": "tslint --project tsconfig.json --fix",
+    "prebuild": "npm run lint",
+    "build": "tsc",
+    "watch": "tsc -w",
+    "pretest": "npm run build",
+    "test": "nyc mocha lib/**/*.test.js",
+    "coveralls": "nyc report --reporter=text-lcov | coveralls",
+    "prepublish": "npm run build"
+  },
+  "keywords": [
+    "font",
+    "ligature",
+    "xterm",
+    "xterm.js",
+    "terminal"
+  ],
+  "license": "MIT",
+  "dependencies": {
+    "font-finder": "^1.0.4",
+    "font-ligatures": "^1.3.2"
+  },
+  "devDependencies": {
+    "@types/chai": "^4.1.3",
+    "@types/mocha": "^5.2.0",
+    "@types/node": "^8.10.10",
+    "@types/sinon": "^5.0.1",
+    "axios": "^0.18.0",
+    "chai": "^4.1.2",
+    "coveralls": "^3.0.2",
+    "mkdirp": "^0.5.1",
+    "mocha": "^5.2.0",
+    "nyc": "^12.0.2",
+    "sinon": "^6.1.3",
+    "tslint": "^5.9.1",
+    "tslint-consistent-codestyle": "^1.13.0",
+    "typescript": "^2.8.3",
+    "xterm": "^3.6.0",
+    "yauzl": "^2.10.0"
+  },
+  "peerDependencies": {
+    "xterm": "^4.0.0"
+  },
+  "nyc": {
+    "sourceMap": true,
+    "reporter": [
+      "text",
+      "html",
+      "json"
+    ],
+    "include": [
+      "lib/**/*.js"
+    ],
+    "exclude": [
+      "lib/**/*.test.*",
+      "lib/**/*.integration.*",
+      "lib/**/*.d.ts",
+      "lib/**/*.map*"
+    ]
+  }
+}
@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) 2018 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { Terminal } from 'xterm';
+import { enableLigatures } from '.';
+
+export interface ITerminalAddon {
+  activate(terminal: Terminal): void;
+  dispose(): void;
+}
+
+export class LigaturesAddon implements ITerminalAddon {
+  constructor() {}
+
+  public activate(terminal: Terminal): void {
+    enableLigatures(terminal);
+  }
+
+  public dispose(): void {}
+}
+
@@ -0,0 +1,48 @@
+import * as fontFinder from 'font-finder';
+import * as fontLigatures from 'font-ligatures';
+
+import parse from './parse';
+
+let fontsPromise: Promise<fontFinder.FontList> | undefined = undefined;
+
+/**
+ * Loads the font ligature wrapper for the specified font family if it could be
+ * resolved, throwing if it is unable to find a suitable match.
+ * @param fontFamily The CSS font family definition to resolve
+ * @param cacheSize The size of the ligature cache to maintain if the font is resolved
+ */
+export default async function load(fontFamily: string, cacheSize: number): Promise<fontLigatures.Font | undefined> {
+  if (!fontsPromise) {
+    fontsPromise = fontFinder.list();
+  }
+
+  const fonts = await fontsPromise;
+  for (const family of parse(fontFamily)) {
+    // If we reach one of the generic font families, the font resolution
+    // will end for the browser and we can't determine the specific font
+    // used. Throw.
+    if (genericFontFamilies.includes(family)) {
+      return undefined;
+    }
+
+    if (fonts.hasOwnProperty(family) && fonts[family].length > 0) {
+      return await fontLigatures.loadFile(fonts[family][0].path, { cacheSize });
+    }
+  }
+
+  // If none of the fonts could resolve, throw an error
+  return undefined;
+}
+
+// https://drafts.csswg.org/css-fonts-4/#generic-font-families
+const genericFontFamilies = [
+  'serif',
+  'sans-serif',
+  'cursive',
+  'fantasy',
+  'monospace',
+  'system-ui',
+  'emoji',
+  'math',
+  'fangsong'
+];
@@ -0,0 +1,220 @@
+import * as path from 'path';
+import * as sinon from 'sinon';
+import { assert } from 'chai';
+import * as fontFinder from 'font-finder';
+import * as fontLigatures from 'font-ligatures';
+
+import * as ligatureSupport from '.';
+
+describe('xterm-addon-ligatures', () => {
+  let onRefresh: sinon.SinonStub;
+  let term: MockTerminal;
+
+  // -> forms a ligature in Fira Code and Iosevka, but www only forms a ligature
+  // in Fira Code
+  const input = 'a -> b www c';
+
+  before(() => {
+    sinon.stub(fontFinder, 'list').returns(Promise.resolve({
+      'Fira Code': [{
+        path: path.join(__dirname, '../fonts/firaCode.otf'),
+        style: fontFinder.Style.Regular,
+        type: fontFinder.Type.Monospace,
+        weight: 400
+      }],
+      'Iosevka': [{
+        path: path.join(__dirname, '../fonts/iosevka.ttf'),
+        style: fontFinder.Style.Regular,
+        type: fontFinder.Type.Monospace,
+        weight: 400
+      }],
+      'Nonexistant Font': [{
+        path: path.join(__dirname, '../fonts/nonexistant.ttf'),
+        style: fontFinder.Style.Regular,
+        type: fontFinder.Type.Monospace,
+        weight: 400
+      }]
+    } as fontFinder.FontList));
+  });
+
+  beforeEach(() => {
+    MockTerminal.applyAddon(ligatureSupport);
+    onRefresh = sinon.stub();
+    term = new MockTerminal(onRefresh);
+    (term as any).enableLigatures();
+  });
+
+  it('registers itself correctly', () => {
+    MockTerminal.applyAddon(ligatureSupport);
+    const term = new MockTerminal(sinon.spy());
+    assert.isUndefined(term.joiner);
+    (term as any).enableLigatures();
+    assert.isFunction(term.joiner);
+  });
+
+  it('registers itself correctly when called directly', () => {
+    const term = new MockTerminal(sinon.spy());
+    assert.isUndefined(term.joiner);
+    ligatureSupport.enableLigatures(term as any);
+    assert.isFunction(term.joiner);
+  });
+
+  it('returns an empty set of ranges on the first call while the font is loading', () => {
+    assert.deepEqual(term.joiner!(input), []);
+  });
+
+  it('returns the correct set of ranges once the font has loaded', done => {
+    assert.deepEqual(term.joiner!(input), []);
+    onRefresh.callsFake(() => {
+      assert.deepEqual(term.joiner!(input), [[2, 4], [7, 10]]);
+      done();
+    });
+  });
+
+  it('handles quoted font names', done => {
+    term.setOption('fontFamily', '"Fira Code", monospace');
+    assert.deepEqual(term.joiner!(input), []);
+    onRefresh.callsFake(() => {
+      assert.deepEqual(term.joiner!(input), [[2, 4], [7, 10]]);
+      done();
+    });
+  });
+
+  it('falls back to later fonts if earlier ones are not present', done => {
+    term.setOption('fontFamily', 'notinstalled, Fira Code, monospace');
+    assert.deepEqual(term.joiner!(input), []);
+    onRefresh.callsFake(() => {
+      assert.deepEqual(term.joiner!(input), [[2, 4], [7, 10]]);
+      done();
+    });
+  });
+
+  it('uses the current font value', done => {
+    // The first three calls are all synchronous so that we don't allow time for
+    // any fonts to load while we're switching things around
+    term.setOption('fontFamily', 'Fira Code');
+    assert.deepEqual(term.joiner!(input), []);
+    term.setOption('fontFamily', 'notinstalled');
+    assert.deepEqual(term.joiner!(input), []);
+    term.setOption('fontFamily', 'Iosevka');
+    assert.deepEqual(term.joiner!(input), []);
+    onRefresh.callsFake(() => {
+      assert.deepEqual(term.joiner!(input), [[2, 4]]);
+
+      // And switch it back to Fira Code for good measure
+      term.setOption('fontFamily', 'Fira Code');
+
+      // At this point, we haven't loaded the new font, so the result reverts
+      // back to empty until that happens
+      assert.deepEqual(term.joiner!(input), []);
+
+      onRefresh.callsFake(() => {
+        assert.deepEqual(term.joiner!(input), [[2, 4], [7, 10]]);
+        done();
+      });
+    });
+  });
+
+  it('allows multiple terminal instances that use different fonts', done => {
+    const onRefresh2 = sinon.stub();
+    const term2 = new MockTerminal(onRefresh2);
+    term2.setOption('fontFamily', 'Iosevka');
+    (term2 as any).enableLigatures();
+
+    assert.deepEqual(term.joiner!(input), []);
+    onRefresh.callsFake(() => {
+      assert.deepEqual(term.joiner!(input), [[2, 4], [7, 10]]);
+      assert.deepEqual(term2.joiner!(input), []);
+      onRefresh2.callsFake(() => {
+        assert.deepEqual(term2.joiner!(input), [[2, 4]]);
+        assert.deepEqual(term.joiner!(input), [[2, 4], [7, 10]]);
+        done();
+      });
+    });
+  });
+
+  it('fails if it finds but cannot load the font', async () => {
+    term.setOption('fontFamily', 'Nonexistant Font, monospace');
+    assert.deepEqual(term.joiner!(input), []);
+    await delay(500);
+    assert.isTrue(onRefresh.notCalled);
+    assert.throws(() => term.joiner!(input));
+  });
+
+  it('returns nothing if the font is not present on the system', async () => {
+    term.setOption('fontFamily', 'notinstalled');
+    assert.deepEqual(term.joiner!(input), []);
+    await delay(500);
+    assert.isTrue(onRefresh.notCalled);
+    assert.deepEqual(term.joiner!(input), []);
+  });
+
+  it('returns nothing if no specific font is specified', async () => {
+    term.setOption('fontFamily', 'monospace');
+    assert.deepEqual(term.joiner!(input), []);
+    await delay(500);
+    assert.isTrue(onRefresh.notCalled);
+    assert.deepEqual(term.joiner!(input), []);
+  });
+
+  it('returns nothing if no fonts are provided', async () => {
+    term.setOption('fontFamily', '');
+    assert.deepEqual(term.joiner!(input), []);
+    await delay(500);
+    assert.isTrue(onRefresh.notCalled);
+    assert.deepEqual(term.joiner!(input), []);
+  });
+
+  it('fails when given malformed inputs', async () => {
+    term.setOption('fontFamily', {} as any);
+    assert.deepEqual(term.joiner!(input), []);
+    await delay(500);
+    assert.isTrue(onRefresh.notCalled);
+    assert.throws(() => term.joiner!(input));
+  });
+
+  it('ensures no empty errors are thrown', async () => {
+    sinon.stub(fontLigatures, 'loadFile').callsFake(async () => { throw undefined; });
+    term.setOption('fontFamily', 'Iosevka');
+    assert.deepEqual(term.joiner!(input), []);
+    await delay(500);
+    assert.isTrue(onRefresh.notCalled);
+    assert.throws(() => term.joiner!(input), 'Failure while loading font');
+    (fontLigatures.loadFile as sinon.SinonStub).restore();
+  });
+});
+
+class MockTerminal {
+  static applyAddon(addon: any): void {
+    addon.apply(MockTerminal);
+  }
+
+  private _options: { [name: string]: string | number; } = {
+    fontFamily: 'Fira Code, monospace',
+    rows: 50
+  };
+  joiner?: (text: string) => [number, number][];
+  refresh: (start: number, end: number) => void;
+
+  constructor(onRefresh: (start: number, end: number) => void) {
+    this.refresh = onRefresh;
+  }
+
+  registerCharacterJoiner(handler: (text: string) => [number, number][]): number {
+    this.joiner = handler;
+    return 1;
+  }
+  deregisterCharacterJoiner(id: number): void {
+    this.joiner = undefined;
+  }
+  setOption(name: string, value: string | number): void {
+    this._options[name] = value;
+  }
+  getOption(name: string): string | number {
+    return this._options[name];
+  }
+}
+
+function delay(delayMs: number): Promise<void> {
+  return new Promise(resolve => setTimeout(resolve, delayMs));
+}
@@ -0,0 +1,92 @@
+import { Terminal } from 'xterm';
+import { Font } from 'font-ligatures';
+
+import load from './font';
+
+const enum LoadingState {
+  UNLOADED,
+  LOADING,
+  LOADED,
+  FAILED
+}
+
+// Caches 100K characters worth of ligatures. In practice this works out to
+// about 650 KB worth of cache, when a moderate number of ligatures are present.
+const CACHE_SIZE = 100000;
+
+/**
+ * Enable ligature support for the provided Terminal instance. To function
+ * properly, this must be called after `open()` is called on the therminal. If
+ * the font currently in use supports ligatures, the terminal will automatically
+ * start to render them.
+ * @param term Terminal instance from xterm.js
+ */
+export function enableLigatures(term: Terminal): void {
+  let currentFontName: string | undefined = undefined;
+  let font: Font | undefined = undefined;
+  let loadingState: LoadingState = LoadingState.UNLOADED;
+  let loadError: any | undefined = undefined;
+
+  term.registerCharacterJoiner((text: string): [number, number][] => {
+    // If the font hasn't been loaded yet, load it and return an empty result
+    const termFont = term.getOption('fontFamily');
+    if (
+      termFont &&
+      (loadingState === LoadingState.UNLOADED || currentFontName !== termFont)
+    ) {
+      font = undefined;
+      loadingState = LoadingState.LOADING;
+      currentFontName = termFont;
+      const currentCallFontName = currentFontName;
+
+      load(currentCallFontName, CACHE_SIZE)
+        .then(f => {
+          // Another request may have come in while we were waiting, so make
+          // sure our font is still vaild.
+          if (currentCallFontName === term.getOption('fontFamily')) {
+            loadingState = LoadingState.LOADED;
+            font = f;
+
+            // Only refresh things if we actually found a font
+            if (f) {
+              term.refresh(0, term.getOption('rows') - 1);
+            }
+          }
+        })
+        .catch(e => {
+          // Another request may have come in while we were waiting, so make
+          // sure our font is still vaild.
+          if (currentCallFontName === term.getOption('fontFamily')) {
+            loadingState = LoadingState.FAILED;
+            font = undefined;
+            loadError = e;
+          }
+        });
+    }
+
+    if (font && loadingState === LoadingState.LOADED) {
+      // We clone the entries to avoid the internal cache of the ligature finder
+      // getting messed up.
+      return font.findLigatureRanges(text).map<[number, number]>(
+        range => [range[0], range[1]]
+      );
+    } else if (loadingState === LoadingState.FAILED) {
+      throw loadError || new Error('Failure while loading font');
+    }
+
+    return [];
+  });
+}
+
+/**
+ * Add capabilities to the provided terminal class for enabling ligature
+ * support. After calling this function, an `enableLigatures()` method is
+ * available on the terminal class, which will enable ligature support when
+ * called.
+ * @param terminalConstructor Terminal class from xterm.js
+ */
+export function apply(terminalConstructor: typeof Terminal): void {
+  (<any>terminalConstructor.prototype).enableLigatures = function (): void {
+    enableLigatures(this);
+  };
+}
@@ -0,0 +1,70 @@
+import { assert } from 'chai';
+
+import parse from './parse';
+
+// TODO: integrate tests from http://test.csswg.org/suites/css-fonts-4_dev/nightly-unstable/
+describe('parse', () => {
+  it('parses individual families', () => {
+    assert.deepEqual(parse('monospace'), ['monospace']);
+  });
+
+  it('parses multiple families', () => {
+    assert.deepEqual(parse('Arial, Verdana, serif'), ['Arial', 'Verdana', 'serif']);
+  });
+
+  it('parses quoted families', () => {
+    assert.deepEqual(parse('"Times New Roman", serif'), ['Times New Roman', 'serif']);
+  });
+
+  it('parses single quoted families', () => {
+    assert.deepEqual(parse('\'Times New Roman\', serif'), ['Times New Roman', 'serif']);
+  });
+
+  it('parses families with spaces in their names', () => {
+    assert.deepEqual(parse('Times New Roman, serif'), ['Times New Roman', 'serif']);
+  });
+
+  it('collapses multiple spaces together in identifiers', () => {
+    assert.deepEqual(parse('Times   New Roman, serif'), ['Times New Roman', 'serif']);
+  });
+
+  it('does not collapse multiple spaces together in quoted strings', () => {
+    assert.deepEqual(parse('"Times   New Roman", serif'), ['Times   New Roman', 'serif']);
+  });
+
+  it('handles escaped characters in strings', () => {
+    assert.deepEqual(parse('"quote \\" slash \\\\ slashquote \\\\\\"", serif'), ['quote " slash \\ slashquote \\"', 'serif']);
+  });
+
+  it('fails if a family has an unterminated string', () => {
+    assert.throws(() => parse('"Unterminated, serif'));
+  });
+
+  it('handles unicode escape sequences', () => {
+    assert.deepEqual(parse('"space\\20 between", serif'), ['space between', 'serif']);
+  });
+
+  it('swallows only the first space after a unicode escape', () => {
+    assert.deepEqual(parse('"two-space\\20  between", serif'), ['two-space  between', 'serif']);
+  });
+
+  it('automatically ends the unicode escape after six digits', () => {
+    assert.deepEqual(parse('space\\000020between, serif'), ['space between', 'serif']);
+  });
+
+  it('handles unicode escapes at the end of the family', () => {
+    assert.deepEqual(parse('endswithbrace \\7b, serif'), ['endswithbrace {', 'serif']);
+  });
+
+  it('handles unicode escapes at the end of the input', () => {
+    assert.deepEqual(parse('endswithbrace \\7b'), ['endswithbrace {']);
+  });
+
+  it('handles other escaped characters in identifiers', () => {
+    assert.deepEqual(parse('has\\,comma'), ['has,comma']);
+  });
+
+  it('swallows escaped newlines in strings', () => {
+    assert.deepEqual(parse('"multi \\\nline", serif'), ['multi line', 'serif']);
+  });
+});
@@ -0,0 +1,174 @@
+interface IParseContext {
+  input: string;
+  offset: number;
+}
+
+/**
+ * Parses a CSS font family value, returning the component font families
+ * contained within.
+ *
+ * @param family The CSS font family input string to parse
+ */
+export default function parse(family: string): string[] {
+  if (typeof family !== 'string') {
+    throw new Error('Font family must be a string');
+  }
+
+  const context: IParseContext = {
+    input: family,
+    offset: 0
+  };
+
+  const families = [];
+  let currentFamily = '';
+
+  // Work through the input character by character until there are none left.
+  // This lexing and parsing in one pass.
+  while (context.offset < context.input.length) {
+    const char = context.input[context.offset++];
+    switch (char) {
+      // String
+      case '\'':
+      case '"':
+        currentFamily += parseString(context, char);
+        break;
+      // End of family
+      case ',':
+        families.push(currentFamily);
+        currentFamily = '';
+        break;
+      default:
+        // Identifiers (whitespace between families is swallowed)
+        if (!/\s/.test(char)) {
+          context.offset--;
+          currentFamily += parseIdentifier(context);
+          families.push(currentFamily);
+          currentFamily = '';
+        }
+    }
+  }
+
+  return families;
+}
+
+/**
+ * Parse a CSS string.
+ *
+ * @param context Parsing input and offset
+ * @param quoteChar The quote character for the string (' or ")
+ */
+function parseString(context: IParseContext, quoteChar: '\'' | '"'): string {
+  let str = '';
+  let escaped = false;
+  while (context.offset < context.input.length) {
+    const char = context.input[context.offset++];
+    if (escaped) {
+      if (/[0-9a-fA-F]/.test(char)) {
+        // Unicode escape
+        context.offset--;
+        str += parseUnicode(context);
+      } else if (char !== '\n') {
+        // Newlines are ignored if escaped. Other characters are used as is.
+        str += char;
+      }
+      escaped = false;
+    } else {
+      switch (char) {
+        // Terminated quote
+        case quoteChar:
+          return str;
+        // Begin escape
+        case '\\':
+          escaped = true;
+          break;
+        // Add character to string
+        default:
+          str += char;
+      }
+    }
+  }
+
+  throw new Error('Unterminated string');
+}
+
+/**
+ * Parse a CSS custom identifier.
+ *
+ * @param context Parsing input and offset
+ */
+function parseIdentifier(context: IParseContext): string {
+  let str = '';
+  let escaped = false;
+  while (context.offset < context.input.length) {
+    const char = context.input[context.offset++];
+    if (escaped) {
+      if (/[0-9a-fA-F]/.test(char)) {
+        // Unicode escape
+        context.offset--;
+        str += parseUnicode(context);
+      } else {
+        // Everything else is used as is
+        str += char;
+      }
+      escaped = false;
+    } else {
+      switch (char) {
+        // Begin escape
+        case '\\':
+          escaped = true;
+          break;
+        // Terminate identifier
+        case ',':
+          return str;
+        default:
+          if (/\s/.test(char)) {
+            // Whitespace is collapsed into a single space within an identifier
+            if (!str.endsWith(' ')) {
+              str += ' ';
+            }
+          } else {
+            // Add other characters directly
+            str += char;
+          }
+      }
+    }
+  }
+
+  return str;
+}
+
+/**
+ * Parse a CSS unicode escape.
+ *
+ * @param context Parsing input and offset
+ */
+function parseUnicode(context: IParseContext): string {
+  let str = '';
+  while (context.offset < context.input.length) {
+    const char = context.input[context.offset++];
+    if (/\s/.test(char)) {
+      // The first whitespace character after a unicode escape indicates the end
+      // of the escape and is swallowed.
+      return unicodeToString(str);
+    } else if (str.length >= 6 || !/[0-9a-fA-F]/.test(char)) {
+      // If the next character is not a valid hex digit or we have reached the
+      // maximum of 6 digits in the escape, terminate the escape.
+      context.offset--;
+      return unicodeToString(str);
+    }
+
+    // Otherwise, just add it to the escape
+    str += char;
+  }
+
+  return unicodeToString(str);
+}
+
+/**
+ * Convert a unicode code point from a hex string to a utf8 string.
+ *
+ * @param codePoint Unicode code point represented as a hex string
+ */
+function unicodeToString(codePoint: string): string {
+  return String.fromCodePoint(parseInt(codePoint, 16));
+}
--- a/Show More
+++ b/Show More