inject language based on file extension

Nodes can now be captured with "injection.extension". If this capture
contains a valid file extension known to Helix, then the content will
be highlighted as that language.

helix-core/src/syntax.rs

@@ -769,6 +769,7 @@ impl Syntax {
                         &layer.config.injections_query,
                         &mat,
                         source_slice,
+                        &self.loader,
                     );
 
                     // Explicitly remove this match so that none of its other captures will remain
@@ -809,6 +810,7 @@ impl Syntax {
                             combined_injections_query,
                             &mat,
                             source_slice,
+                            &self.loader,
                         );
                         if language_name.is_some() {
                             entry.0 = language_name;
@@ -1163,6 +1165,7 @@ pub struct HighlightConfiguration {
     non_local_variable_patterns: Vec<bool>,
     injection_content_capture_index: Option<u32>,
     injection_language_capture_index: Option<u32>,
+    injection_filename_capture_index: Option<u32>,
     local_scope_capture_index: Option<u32>,
     local_def_capture_index: Option<u32>,
     local_def_value_capture_index: Option<u32>,
@@ -1307,6 +1310,7 @@ impl HighlightConfiguration {
         // Store the numeric ids for all of the special captures.
         let mut injection_content_capture_index = None;
         let mut injection_language_capture_index = None;
+        let mut injection_filename_capture_index = None;
         let mut local_def_capture_index = None;
         let mut local_def_value_capture_index = None;
         let mut local_ref_capture_index = None;
@@ -1327,6 +1331,7 @@ impl HighlightConfiguration {
             match name.as_str() {
                 "injection.content" => injection_content_capture_index = i,
                 "injection.language" => injection_language_capture_index = i,
+                "injection.filename" => injection_filename_capture_index = i,
                 _ => {}
             }
         }
@@ -1342,6 +1347,7 @@ impl HighlightConfiguration {
             non_local_variable_patterns,
             injection_content_capture_index,
             injection_language_capture_index,
+            injection_filename_capture_index,
             local_scope_capture_index,
             local_def_capture_index,
             local_def_value_capture_index,
@@ -1814,9 +1820,11 @@ fn injection_for_match<'a>(
     query: &'a Query,
     query_match: &QueryMatch<'a, 'a>,
     source: RopeSlice<'a>,
+    loader: &Loader,
 ) -> (Option<Cow<'a, str>>, Option<Node<'a>>, IncludedChildren) {
     let content_capture_index = config.injection_content_capture_index;
     let language_capture_index = config.injection_language_capture_index;
+    let language_filename_index = config.injection_filename_capture_index;
 
     let mut language_name = None;
     let mut content_node = None;
@@ -1827,6 +1835,12 @@ fn injection_for_match<'a>(
             language_name = Some(name);
         } else if index == content_capture_index {
             content_node = Some(capture.node);
+        } else if index == language_filename_index {
+            let file = byte_range_to_str(capture.node.byte_range(), source);
+            let language = loader.language_config_for_file_name(Path::new(file.as_ref()));
+            if let Some(config) = language {
+                language_name = Some(Cow::from(config.language_id.clone()));
+            }
         }
     }
 

runtime/queries/nix/injections.scm

@@ -37,3 +37,10 @@
   (#match? @_path "^text$")
   (#set! injection.language "bash")
   (#set! injection.combined))
+
+((apply_expression
+   function: (apply_expression function: (_) @_func
+     argument: (string_expression (string_fragment) @injection.filename))
+   argument: (indented_string_expression (string_fragment) @injection.content))
+ (#match? @_func "(^|\\.)write(Text|Script(Bin)?)$")
+ (#set! injection.combined))