Allow iteration over available file names

Your example program included an unimplemented `entries` method.  I
chose not to implement `entries` because iterating over it would require
decompressing any large files stored in the map.

Instead, I've provided a `file_names` API that provides just the names
of the files in the map, which the caller can look up (and potentially
decompress) if they wish.

I implemented a custom iterator wrapper to hide the implementation
details from the caller.

1 files changed, 4 insertions, 1 deletions

diff --git a/example/src/main.rs b/example/src/main.rs
index 9ca782c..e1a4931 100644
--- a/example/src/main.rs
+++ b/example/src/main.rs
@@ -4,7 +4,10 @@ extern crate phf;
 include!(concat!(env!("OUT_DIR"), "/data.rs"));
 
 fn main() {
-    println!("{:?}", FILES.get("data/foo"))
+    println!("{:?}", FILES.get("data/foo"));
+    for name in FILES.file_names() {
+        println!("Found: {}", name);
+    }
     // for (k, v) in FILES.entries() {
     //    println!("{}: {} bytes", k, v.len());
     // }