Move LanguageRegistry into buffer

Co-Authored-By: Nathan Sobo <nathan@zed.dev>
Co-Authored-By: Max Brunsfeld <max@zed.dev>

buffer/src/language.rs

@@ -1,7 +1,7 @@
 use crate::{HighlightMap, SyntaxTheme};
 use parking_lot::Mutex;
 use serde::Deserialize;
-use std::str;
+use std::{path::Path, str, sync::Arc};
 use tree_sitter::{Language as Grammar, Query};
 pub use tree_sitter::{Parser, Tree};
 
@@ -25,6 +25,41 @@ pub struct Language {
     pub highlight_map: Mutex<HighlightMap>,
 }
 
+#[derive(Default)]
+pub struct LanguageRegistry {
+    languages: Vec<Arc<Language>>,
+}
+
+impl LanguageRegistry {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn add(&mut self, language: Arc<Language>) {
+        self.languages.push(language);
+    }
+
+    pub fn set_theme(&self, theme: &SyntaxTheme) {
+        for language in &self.languages {
+            language.set_theme(theme);
+        }
+    }
+
+    pub fn select_language(&self, path: impl AsRef<Path>) -> Option<&Arc<Language>> {
+        let path = path.as_ref();
+        let filename = path.file_name().and_then(|name| name.to_str());
+        let extension = path.extension().and_then(|name| name.to_str());
+        let path_suffixes = [extension, filename];
+        self.languages.iter().find(|language| {
+            language
+                .config
+                .path_suffixes
+                .iter()
+                .any(|suffix| path_suffixes.contains(&Some(suffix.as_str())))
+        })
+    }
+}
+
 impl Language {
     pub fn name(&self) -> &str {
         self.config.name.as_str()
@@ -38,3 +73,63 @@ impl Language {
         *self.highlight_map.lock() = HighlightMap::new(self.highlight_query.capture_names(), theme);
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_select_language() {
+        let grammar = tree_sitter_rust::language();
+        let registry = LanguageRegistry {
+            languages: vec![
+                Arc::new(Language {
+                    config: LanguageConfig {
+                        name: "Rust".to_string(),
+                        path_suffixes: vec!["rs".to_string()],
+                        ..Default::default()
+                    },
+                    grammar,
+                    highlight_query: Query::new(grammar, "").unwrap(),
+                    brackets_query: Query::new(grammar, "").unwrap(),
+                    highlight_map: Default::default(),
+                }),
+                Arc::new(Language {
+                    config: LanguageConfig {
+                        name: "Make".to_string(),
+                        path_suffixes: vec!["Makefile".to_string(), "mk".to_string()],
+                        ..Default::default()
+                    },
+                    grammar,
+                    highlight_query: Query::new(grammar, "").unwrap(),
+                    brackets_query: Query::new(grammar, "").unwrap(),
+                    highlight_map: Default::default(),
+                }),
+            ],
+        };
+
+        // matching file extension
+        assert_eq!(
+            registry.select_language("zed/lib.rs").map(|l| l.name()),
+            Some("Rust")
+        );
+        assert_eq!(
+            registry.select_language("zed/lib.mk").map(|l| l.name()),
+            Some("Make")
+        );
+
+        // matching filename
+        assert_eq!(
+            registry.select_language("zed/Makefile").map(|l| l.name()),
+            Some("Make")
+        );
+
+        // matching suffix that is not the full file extension or filename
+        assert_eq!(registry.select_language("zed/cars").map(|l| l.name()), None);
+        assert_eq!(
+            registry.select_language("zed/a.cars").map(|l| l.name()),
+            None
+        );
+        assert_eq!(registry.select_language("zed/sumk").map(|l| l.name()), None);
+    }
+}

buffer/src/lib.rs

@@ -15,7 +15,7 @@ use clock::ReplicaId;
 use gpui::{AppContext, Entity, ModelContext, MutableAppContext, Task};
 pub use highlight_map::{HighlightId, HighlightMap};
 use language::Tree;
-pub use language::{Language, LanguageConfig};
+pub use language::{Language, LanguageConfig, LanguageRegistry};
 use lazy_static::lazy_static;
 use operation_queue::OperationQueue;
 use parking_lot::Mutex;