Add clean-cache command

Author: vv9k

CHANGELOG.md

@@ -6,6 +6,7 @@
 * Rewrite core functionality by using cached state instead of relying on the file system.
   WARNING! this version is completely different functionally from the older one and the tags have to be recreated
   after updating it. [#30](https://github.com/wojciechkepka/wutag/pull/30)
+* Add `clean-cache` subcommand that cleans the cached tag registry from the filesystem.
 
 
 # 0.3.0

src/app.rs

@@ -101,6 +101,14 @@ impl App {
             Command::Cp(ref opts) => self.cp(opts),
             Command::Edit(ref opts) => self.edit(opts),
             Command::PrintCompletions(ref opts) => self.print_completions(opts),
+            Command::CleanCache => self.clean_cache(),
+        }
+    }
+
+    fn clean_cache(&mut self) {
+        self.registry.clear();
+        if let Err(e) = self.registry.save() {
+            println!("{:?}", e);
         }
     }
 

src/opt.rs

@@ -155,4 +155,6 @@ pub enum Command {
     Edit(EditOpts),
     /// Prints completions for the specified shell to stdout.
     PrintCompletions(CompletionsOpts),
+    /// Clean the cached tag registry.
+    CleanCache,
 }

src/registry.rs

@@ -57,6 +57,12 @@ impl TagRegistry {
         fs::write(&self.path, &serialized).context("failed to save registry")
     }
 
+    /// Clears this tag registry by removing all entries and tags.
+    pub fn clear(&mut self) {
+        self.tags.clear();
+        self.entries.clear();
+    }
+
     /// Updates the entry or adds it if it is not present.
     pub fn add_or_update_entry(&mut self, entry: EntryData) -> EntryId {
         let pos = self