Load customized themes in addition to defaults

- New themes in `$BAT_CONFIG_DIR/themes` are now loaded *in addition* to
  the default themes (they may also override).
- The `Default.tmTheme` symlink is not necessary anymore.

This relates to #172

README.md

@@ -188,18 +188,12 @@ cd "$BAT_CONFIG_DIR/themes"
 # Download a theme in '.tmTheme' format, for example:
 git clone https://github.com/greggb/sublime-snazzy
 
-# Create a link to specify the new default theme
-ln -sf "sublime-snazzy/Sublime Snazzy.tmTheme" Default.tmTheme
-
 # Update the binary cache
 bat cache --init
 ```
 
 Finally, use `bat --list-themes` to check if the new themes are available.
 
-**Note:** Unlike for syntax definitions, adding custom themes currently *removes all default
-themes*. If you want to go back to the default themes, call `bat cache --clear`.
-
 ### Using a different pager
 
 `bat` uses the pager that is specified in the `PAGER` environment variable. If this variable is not

assets/themes/Default.tmTheme

@@ -1 +0,0 @@
-sublime-monokai-extended/Monokai Extended.tmTheme

src/app.rs

@@ -9,6 +9,8 @@ use style::{OutputComponent, OutputComponents, OutputWrap};
 #[cfg(windows)]
 use ansi_term;
 
+use assets::BAT_THEME_DEFAULT;
+
 pub struct App {
     pub matches: ArgMatches<'static>,
     interactive_output: bool,
@@ -271,7 +273,7 @@ impl App {
                 .value_of("theme")
                 .map(String::from)
                 .or_else(|| env::var("BAT_THEME").ok())
-                .unwrap_or(String::from("Default")),
+                .unwrap_or(String::from(BAT_THEME_DEFAULT)),
             line_range: transpose(self.matches.value_of("line-range").map(LineRange::from))?,
         })
     }

src/assets.rs

@@ -16,6 +16,8 @@ lazy_static! {
         ProjectDirs::from("", "", crate_name!()).expect("Could not get home directory");
 }
 
+pub const BAT_THEME_DEFAULT: &str = "Monokai Extended";
+
 pub struct HighlightingAssets {
     pub syntax_set: SyntaxSet,
     pub theme_set: ThemeSet,
@@ -50,11 +52,8 @@ impl HighlightingAssets {
 
         let theme_dir = source_dir.join("themes");
 
-        if let Ok(theme_set) = ThemeSet::load_from_folder(&theme_dir) {
+        let res = extend_theme_set(&mut assets.theme_set, &theme_dir);
-            // TODO: If syntect would support this, it would be great to
+        if !res.is_ok() {
-            // load the new themes in addition to the ones in the binary.
-            assets.theme_set = theme_set;
-        } else {
             println!(
                 "No themes were found in '{}', using the default set",
                 theme_dir.to_string_lossy()
@@ -160,7 +159,7 @@ impl HighlightingAssets {
                     Yellow.paint("[bat warning]"),
                     theme
                 );
-                &self.theme_set.themes["Default"]
+                &self.theme_set.themes[BAT_THEME_DEFAULT]
             }
         }
     }
@@ -194,6 +193,21 @@ impl HighlightingAssets {
     }
 }
 
+// TODO: ideally, this function would be part of syntect's `ThemeSet`.
+fn extend_theme_set<P: AsRef<Path>>(theme_set: &mut ThemeSet, folder: P) -> Result<()> {
+    let paths = ThemeSet::discover_theme_paths(folder)?;
+    for p in &paths {
+        let theme = ThemeSet::get_theme(p)?;
+        let basename = p
+            .file_stem()
+            .and_then(|x| x.to_str())
+            .ok_or("Could not get theme basename")?;
+        theme_set.themes.insert(basename.to_owned(), theme);
+    }
+
+    Ok(())
+}
+
 fn theme_set_path() -> PathBuf {
     PROJECT_DIRS.cache_dir().join("themes.bin")
 }