Account for detached HEAD and TSDoc for type definitions

Author: AbhyudayaSharma

macro.d.ts

@@ -1,16 +1,47 @@
+/**
+ * A Babel plugin macro giving access to git information at compile time.
+ */
 declare module "react-git-info/macro" {
+  /**
+   * Information about a git commit.
+   */
   export interface GitCommitInformation {
+    /**
+     * Date of the commit as a string in strict ISO 8601 format.
+     */
     readonly date: string;
+    /**
+     * Full hash of the latest commit on the active branch.
+     */
     readonly hash: string;
+    /**
+     * Raw commit message.
+     */
     readonly message: string;
+    /**
+     * Abbreviated commit hash with length defined as `core.abbrev` in
+     * {@link https://git-scm.com/docs/git-config | git-config}.
+     */
     readonly shortHash: string;
   }
 
   export interface GitInformation {
+    /**
+     * Tags pointing to the current commit.
+     */
     readonly tags: string[];
-    readonly branch: string;
+    /**
+     * The current git branch. `undefined` if the repository is in a detached HEAD state.
+     */
+    readonly branch?: string;
+    /**
+     * Information about the commit pointed to by `HEAD`.
+     */
     readonly commit: GitCommitInformation;
   }
 
+  /**
+   * Returns information about the current Git state.
+   */
   export default function GitInfo(): GitInformation;
 }

src/GitInfo.macro.js

@@ -20,8 +20,10 @@ const parseRefs = (refs) => {
   let branch = undefined;
   const tags = [];
   refs.split(', ').map((item) => {
-    const isBranch = item.match(/HEAD -> (.*)/);
-    const isTag = item.match(/tag: (.*)/);
+    // if HEAD is not detached, the branch is printed out as `HEAD -> branch_name`.
+    // if HEAD is detached, the output becomes `HEAD`.
+    const isBranch = item.match(/^HEAD -> (.*)$/);
+    const isTag = item.match(/^tag: (.*)$/);
 
     if (isTag && isTag.length > 1) {
       tags.push(isTag[1]);
@@ -30,10 +32,6 @@ const parseRefs = (refs) => {
     }
   });
 
-  if (!branch) {
-    throw Error('Unable to get parse branch from the log result.');
-  }
-
   return [branch, tags];
 };