lusingander · lusingander · Oct 19, 2024 · Oct 19, 2024 · Oct 19, 2024
diff --git a/README.md b/README.md
@@ -150,24 +150,41 @@ date_format = "%Y-%m-%d %H:%M:%S"
 # type: bool
 highlight = false
 # The name of the color theme to use for syntax highlighting in the object preview.
-# By default the following themes are available:
-# - base16-ocean.dark
-# - base16-eighties.dark
-# - base16-mocha.dark
-# - base16-ocean.light
-#   - https://github.com/SublimeText/Spacegray
-# - InspiredGitHub
-#   - https://github.com/sethlopez/InspiredGitHub.tmtheme
-# - Solarized (dark)
-# - Solarized (light)
-# Also, by creating `xxx.tmTheme` in `$STU_ROOT_DIR/preview_theme/`, you can use `xxx` and load it.
 # type: string
 highlight_theme = "base16-ocean.dark"
 # Whether image file preview is enabled in the object preview.
 # type: bool
 image = false
 ```
 
+### Syntax highlighting
+
+In the object preview, Syntax highlighting using syntect is available. To enable this, set `preview.highlight = true` in the config file.
+
+#### Color themes
+
+You can change the color theme by specifying the theme name in `preview.highlight_theme`.
+
+By default the following themes are available:
+
+- base16-ocean.dark
+- base16-eighties.dark
+- base16-mocha.dark
+- base16-ocean.light
+  - https://github.com/SublimeText/Spacegray
+- InspiredGitHub
+  - https://github.com/sethlopez/InspiredGitHub.tmtheme
+- Solarized (dark)
+- Solarized (light)
+
+Also, by creating `xxx.tmTheme` in `$STU_ROOT_DIR/preview_theme/`, you can use `xxx` and load it.
+
+#### Syntax definitions
+
+You can add syntax definitions for file types that are not supported by default. You can use it by creating a `.sublime-syntax` file in `$STU_ROOT_DIR/preview_syntax/`.
+
+https://www.sublimetext.com/docs/syntax.html
+
 ## Features / Screenshots
 
 ### Bucket list

diff --git a/src/config.rs b/src/config.rs
@@ -11,6 +11,7 @@ const ERROR_LOG_FILE_NAME: &str = "error.log";
 const DEBUG_LOG_FILE_NAME: &str = "debug.log";
 const DOWNLOAD_DIR: &str = "download";
 const PREVIEW_THEME_DIR: &str = "preview_theme";
+const PREVIEW_SYNTAX_DIR: &str = "preview_syntax";
 const CACHE_FILE_NAME: &str = "cache.txt";
 
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -164,6 +165,12 @@ impl Config {
         Ok(String::from(path.to_string_lossy()))
     }
 
+    pub fn preview_syntax_dir_path() -> anyhow::Result<String> {
+        let dir = Config::get_app_base_dir()?;
+        let path = dir.join(PREVIEW_SYNTAX_DIR);
+        Ok(String::from(path.to_string_lossy()))
+    }
+
     fn get_app_base_dir() -> anyhow::Result<PathBuf> {
         match env::var(STU_ROOT_DIR_ENV_VAR) {
             Ok(dir) => Ok(PathBuf::from(dir)),

diff --git a/src/widget/text_preview.rs b/src/widget/text_preview.rs
@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 use ansi_to_tui::IntoText;
 use once_cell::sync::Lazy;
 use ratatui::{
@@ -22,7 +24,22 @@ use crate::{
     widget::{ScrollLines, ScrollLinesOptions, ScrollLinesState},
 };
 
-static SYNTAX_SET: Lazy<SyntaxSet> = Lazy::new(SyntaxSet::load_defaults_newlines);
+static SYNTAX_SET: Lazy<SyntaxSet> = Lazy::new(|| {
+    if let Ok(path) = Config::preview_syntax_dir_path() {
+        let path = PathBuf::from(path); // fixme: remove when function returns pathbuf directly
+        if path.exists() {
+            // SyntaxSetBuilder::build is terribly slow in debug build...
+            // To avoid unnecessary processing, we won't use the builder if the syntax directory doesn't exist...
+            let mut builder = SyntaxSet::load_defaults_newlines().into_builder();
+            builder.add_from_folder(path, true).unwrap();
+            builder.build()
+        } else {
+            SyntaxSet::load_defaults_newlines()
+        }
+    } else {
+        SyntaxSet::load_defaults_newlines()
+    }
+});
 static DEFAULT_THEME_SET: Lazy<ThemeSet> = Lazy::new(ThemeSet::load_defaults);
 static USER_THEME_SET: Lazy<ThemeSet> = Lazy::new(|| {
     Config::preview_theme_dir_path()