Added an Antora extension file to enable using Git worktrees. Added a…

… build script that runs the necessary command line option to enable the extension. (#80)

build_local_site.sh

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+npx antora --extension ./linked-worktree-as-content-source.js playbook.yml

linked-worktree-as-content-source.js

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+'use strict'
+
+/* Copyright (c) 2022 OpenDevise, Inc.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License Version 2.0. If a copy of this license was not distributed
+ * with this file, you can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+const { promises: fsp } = require('fs')
+const ospath = require('path')
+
+/**
+ * Rewrites local content sources to support the use of linked worktrees.
+ *
+ * @author Dan Allen <dan@opendevise.com>
+ */
+module.exports.register = function () {
+  this.once('playbookBuilt', async ({ playbook }) => {
+    const expandPath = this.require('@antora/expand-path-helper')
+    for (const contentSource of playbook.content.sources) {
+      const { url, branches } = contentSource
+      if (url.charAt() !== '.') continue
+      const absdir = expandPath(url, { dot: playbook.dir })
+      const gitfile = ospath.join(absdir, '.git')
+      if (await fsp.stat(gitfile).then((stat) => !stat.isDirectory(), () => false)) {
+        const worktreeGitdir = await fsp.readFile(gitfile, 'utf8')
+          .then((contents) => contents.trimRight().substr(8))
+        const worktreeBranch = await fsp.readFile(ospath.join(worktreeGitdir, 'HEAD'), 'utf8')
+          .then((contents) => contents.trimRight().replace(/^ref: (?:refs\/heads\/)?/, ''))
+        const reldir = ospath.relative(
+          playbook.dir,
+          await fsp.readFile(ospath.join(worktreeGitdir, 'commondir'), 'utf8')
+            .then((contents) => {
+              const gitdir = ospath.join(worktreeGitdir, contents.trimRight())
+              return ospath.basename(gitdir) === '.git' ? ospath.dirname(gitdir) : gitdir
+            })
+        )
+        contentSource.url = reldir ? `.${ospath.sep}${reldir}` : '.'
+        if (!branches) continue
+        contentSource.branches = (branches.constructor === Array ? branches : [branches])
+          .map((pattern) => pattern.replaceAll('HEAD', worktreeBranch))
+      }
+    }
+  })
+}