Added support for reading the long git sha1 and the current git tag.

example/Example.hx

@@ -20,6 +20,9 @@ class Example
 		var date = CompileTime.buildDate();						// Equivalent of writing `new Date(2012,11,25,20,48,15);`
 		var dateAsString = CompileTime.buildDateString();		// A string saying "2012-12-25 20:48:15"
 		var gitsha = CompileTime.buildGitCommitSha();			// A string that might say '104ad4e'
+		var gitshaLong = CompileTime.buildGitCommitShaLong();	// A string that might say '104ad4e8128dd7fae6d3f1c8a066e3570db99b2e'
+		var gitTagDesrc = CompileTime.buildGitTagDescription();	// A string that might say 'v1.0.2' or 'v1.0.2-104ad4e'
+		var gitTag = CompileTime.buildGitTag();					// A string that might say 'v1.0.2'
 		var file = CompileTime.readFile("README.md");			// Reads the contents of README.md as a String.
 		var name="Jason", age=25;
 		var greeting = CompileTime.interpolateFile("test.txt"); // Reads the contents of test.txt, and interpolates local values, similar to single quotes

src/CompileTime.hx

@@ -49,6 +49,39 @@ class CompileTime
         return toExpr(sha1);
     }
 
+    /** Returns a string of the current git full sha1 */
+    macro public static function buildGitCommitShaLong():ExprOf<String> {
+        var proc = new sys.io.Process('git', ['log', "--pretty=format:'%H'", '-n', '1']);
+        var sha1 = proc.stdout.readLine();
+        return toExpr(sha1);
+    }
+
+    /** Returns a string of the current git tag description.
+        If there is a tag on the current commit, the tag is returned.
+        If there is no tag on the current commit, a combination of `TAG-SHA1` from the latest tag is returned instead.
+        If there are no tags on the repository, `null` is returned instead. */
+    macro public static function buildGitTagDescription():ExprOf<String> {
+        var proc = new sys.io.Process('git', ['describe', '--tags']);
+        var tag = null;
+        try {
+            tag = proc.stdout.readLine();
+        }
+        catch (e: Dynamic) { }
+        return toExpr(tag);
+    }
+
+    /** Returns a string of the current git tag.
+        If there is no tag on the current commit, `null` is returned instead. */
+    macro public static function buildGitTag():ExprOf<String> {
+        var proc = new sys.io.Process('git', ['describe', '--tags', '--exact-match' ]);
+        var tag = null;
+        try {
+            tag = proc.stdout.readLine();
+        }
+        catch (e: Dynamic) { }
+        return toExpr(tag);
+    }
+
     /** Reads a file at compile time, and inserts the contents into your code as a string.  The file path is resolved using `Context.resolvePath`, so it will search all your class paths */
     macro public static function readFile(path:String):ExprOf<String> {
         return toExpr(loadFileAsString(path));