From d45107797858e9e4e09224a45c78cd564298bddf Mon Sep 17 00:00:00 2001
From: Nikita Revenco <154856872+NikitaRevenco@users.noreply.github.com>
Date: Mon, 3 Feb 2025 13:34:52 +0000
Subject: [PATCH] feat: add typable command to get injection layer for current
 range

---
 helix-core/src/comment.rs        | 49 +++++++++-----------------------
 helix-core/src/syntax.rs         | 31 ++++++++++++++++++++
 helix-term/src/commands/typed.rs | 34 ++++++++++++++++++++++
 3 files changed, 78 insertions(+), 36 deletions(-)

diff --git a/helix-core/src/comment.rs b/helix-core/src/comment.rs
index ec57a4ef9..ef9131a53 100644
--- a/helix-core/src/comment.rs
+++ b/helix-core/src/comment.rs
@@ -30,43 +30,20 @@ pub fn get_injected_tokens(
     start: usize,
     end: usize,
 ) -> (Option<Vec<String>>, Option<Vec<BlockCommentToken>>) {
-    let mut best_fit = None;
-    let mut min_gap = usize::MAX;
-
     // Find the injection with the most tightly encompassing range.
-    if let Some(syntax) = &syntax {
-        for (layer_id, layer) in &syntax.layers {
-            for ts_range in &layer.ranges {
-                let is_encompassing = ts_range.start_byte <= start && ts_range.end_byte >= end;
-                if is_encompassing {
-                    let this_gap = ts_range.end_byte - ts_range.start_byte;
-                    if this_gap < min_gap
-                                // ignore the "comment" language family
-                                // as that would mean we can't uncomment anything, or
-                                // the comments would be incorrect.
-                                //
-                                // Since uncommenting would attempt to use the comment
-                                // language's non-existing comment tokens
-                                // TODO: add this as a language configuration key?
-                                && !matches!(syntax.layer_config(layer_id).language_name.as_ref(), "jsdoc" | "comment")
-                    {
-                        best_fit = Some(layer_id);
-                        min_gap = this_gap;
-                    }
-                }
-            }
-        }
-
-        if let Some(best_fit) = best_fit {
-            let config = syntax.layer_config(best_fit);
-            return (
-                config.comment_tokens.clone(),
-                config.block_comment_tokens.clone(),
-            );
-        }
-    }
-
-    (None, None)
+    syntax
+        .and_then(|syntax| {
+            syntax
+                .injection_for_range(start, end)
+                .map(|language_id| syntax.layer_config(language_id))
+                .map(|config| {
+                    (
+                        config.comment_tokens.clone(),
+                        config.block_comment_tokens.clone(),
+                    )
+                })
+        })
+        .unwrap_or_default()
 }
 
 /// Given text, a comment token, and a set of line indices, returns the following:
diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index 8f6184330..11201b26b 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -1437,6 +1437,37 @@ impl Syntax {
         Arc::clone(&loader.language_configs[language_id])
     }
 
+    /// For a given range in the document, get the most tightly encompassing
+    /// injection layer corresponding to that range.
+    pub fn injection_for_range(&self, from: usize, to: usize) -> Option<LayerId> {
+        let mut best_fit = None;
+        let mut min_gap = usize::MAX;
+
+        for (layer_id, layer) in &self.layers {
+            for ts_range in &layer.ranges {
+                let is_encompassing = ts_range.start_byte <= from && ts_range.end_byte >= to;
+                if is_encompassing {
+                    let this_gap = ts_range.end_byte - ts_range.start_byte;
+                    if this_gap < min_gap
+                                // ignore the "comment" language family
+                                // as that would mean we can't uncomment anything, or
+                                // the comments would be incorrect.
+                                //
+                                // Since uncommenting would attempt to use the comment
+                                // language's non-existing comment tokens
+                                // TODO: add this as a language configuration key?
+                                && !matches!(self.layer_config(layer_id).language_name.as_ref(), "jsdoc" | "comment")
+                    {
+                        best_fit = Some(layer_id);
+                        min_gap = this_gap;
+                    }
+                }
+            }
+        }
+
+        best_fit
+    }
+
     pub fn tree(&self) -> &Tree {
         self.layers[self.root].tree()
     }
diff --git a/helix-term/src/commands/typed.rs b/helix-term/src/commands/typed.rs
index 1d57930cc..b23bfb319 100644
--- a/helix-term/src/commands/typed.rs
+++ b/helix-term/src/commands/typed.rs
@@ -1604,6 +1604,33 @@ fn tree_sitter_scopes(
     Ok(())
 }
 
+fn tree_sitter_injection(
+    cx: &mut compositor::Context,
+    _args: &[Cow<str>],
+    event: PromptEvent,
+) -> anyhow::Result<()> {
+    if event != PromptEvent::Validate {
+        return Ok(());
+    }
+
+    let (view, doc) = current!(cx.editor);
+
+    let syntax = doc
+        .syntax()
+        .context("No tree-sitter grammar found for this file.")?;
+
+    let range = doc.selection(view.id).primary();
+
+    let language_name = syntax
+        .injection_for_range(range.from(), range.to())
+        .map(|language_id| syntax.layer_config(language_id).language_name.clone())
+        .context("No injection layer found for the current range.")?;
+
+    cx.editor.set_status(language_name);
+
+    Ok(())
+}
+
 fn tree_sitter_highlight_name(
     cx: &mut compositor::Context,
     _args: Args,
@@ -3134,6 +3161,13 @@ pub const TYPABLE_COMMAND_LIST: &[TypableCommand] = &[
             ..Signature::DEFAULT
         },
     },
+    TypableCommand {
+        name: "tree-sitter-injection",
+        aliases: &[],
+        doc: "Display injected language for the primary range.",
+        fun: tree_sitter_injection,
+        signature: CommandSignature::none(),
+    },
     TypableCommand {
         name: "debug-start",
         aliases: &["dbg"],