From 787b059948718d182d39c13c7f3f5af96e2ff888 Mon Sep 17 00:00:00 2001
From: Geoff Johnstone <qwerty@acm.org>
Date: Fri, 31 Dec 2010 16:44:17 +0000
Subject: [PATCH] Autodetect output format from filename.

---
 src/net/ametros/dive/Main.java | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/net/ametros/dive/Main.java b/src/net/ametros/dive/Main.java
index cfddb93..907e9be 100644
--- a/src/net/ametros/dive/Main.java
+++ b/src/net/ametros/dive/Main.java
@@ -94,9 +94,7 @@ public class Main
   public static void main (String[] args) throws Exception
   {
     final OptionParser op = new OptionParser();
-    op.acceptsAll (L("f", "format"), "Output format: html, xhtml, xls or xml").
-      withRequiredArg().defaultsTo ("xls");
-
+    op.acceptsAll (L("f", "format"), "Output format: html, xhtml, xls or xml");
     op.acceptsAll (L("o", "output"), "Output filename").
       withRequiredArg().ofType (File.class);
 
@@ -106,7 +104,25 @@ public class Main
     try
     {
       options = op.parse (args);
-      writer = getWriter ((String)options.valueOf ("format"));
+
+      final String format;
+      if (options.has ("format"))
+        format = (String)options.valueOf ("format");
+      else if (!options.has ("output"))
+        throw new IllegalArgumentException ("Cannot guess output format " +
+                                            "without an output filename");
+      else
+      {
+        final File file = (File)options.valueOf ("output");
+        final String name = file.getName();
+        final int dot = name.lastIndexOf ('.');
+        if (-1 == dot)
+          throw new IllegalArgumentException ("Cannot guess output format");
+
+        format = name.substring (dot + 1);
+      }
+
+      writer = getWriter (format);
     }
     catch (Exception e)
     {
-- 
2.11.4.GIT