feat: automatically add indent on entering in the empty block math (#646)

crates/tinymist-query/src/document_highlight.rs

@@ -1,6 +1,6 @@
 use typst_shim::syntax::LinkedNodeExt;
 
-use crate::{prelude::*, SemanticRequest};
+use crate::{prelude::*, syntax::node_ancestors, SemanticRequest};
 
 /// The [`textDocument/documentHighlight`] request
 ///
@@ -120,7 +120,7 @@ impl<'a, 'w> DocumentHighlightWorker<'a, 'w> {
         let _ = self.ctx;
 
         // find the nearest loop node
-        let loop_node = ancestors(node)
+        let loop_node = node_ancestors(node)
             .find(|node| matches!(node.kind(), SyntaxKind::ForLoop | SyntaxKind::WhileLoop))?;
 
         // find the first key word of the loop node
@@ -146,10 +146,6 @@ fn highlight_func_returns(
     None
 }
 
-fn ancestors<'a>(node: &'a LinkedNode<'a>) -> impl Iterator<Item = &'a LinkedNode<'a>> {
-    std::iter::successors(Some(node), |node| node.parent())
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

crates/tinymist-query/src/on_enter.rs

@@ -2,7 +2,7 @@
 
 use typst_shim::syntax::LinkedNodeExt;
 
-use crate::{prelude::*, SyntaxRequest};
+use crate::{prelude::*, syntax::node_ancestors, SyntaxRequest};
 
 /// The [`experimental/onEnter`] request is sent from client to server to handle
 /// the <kbd>Enter</kbd> key press.
@@ -45,6 +45,12 @@ impl SyntaxRequest for OnEnterRequest {
             return worker.enter_line_doc_comment(&leaf, cursor);
         }
 
+        let math_node =
+            node_ancestors(&leaf).find(|node| matches!(node.kind(), SyntaxKind::Equation));
+        if let Some(mn) = math_node {
+            return worker.enter_block_math(mn, cursor);
+        }
+
         None
     }
 }
@@ -55,6 +61,13 @@ struct OnEnterWorker<'a> {
 }
 
 impl OnEnterWorker<'_> {
+    fn indent_of(&self, of: usize) -> String {
+        let all_text = self.source.text();
+        let start = all_text[..of].rfind('\n').map(|e| e + 1);
+        let indent_size = all_text[start.unwrap_or_default()..of].chars().count();
+        " ".repeat(indent_size)
+    }
+
     fn enter_line_doc_comment(&self, leaf: &LinkedNode, cursor: usize) -> Option<Vec<TextEdit>> {
         let skipper = |n: &LinkedNode| {
             matches!(
@@ -84,8 +97,7 @@ impl OnEnterWorker<'_> {
             return None;
         }
 
-        // todo: indent
-        let indent = "";
+        let indent = self.indent_of(leaf.offset());
         // todo: remove_trailing_whitespace
 
         let rng = cursor..cursor;
@@ -97,4 +109,32 @@ impl OnEnterWorker<'_> {
 
         Some(vec![edit])
     }
+
+    fn enter_block_math(&self, math_node: &LinkedNode<'_>, cursor: usize) -> Option<Vec<TextEdit>> {
+        let o = math_node.range();
+        if !o.contains(&cursor) {
+            return None;
+        }
+
+        let all_text = self.source.text();
+        let math_text = &all_text[o.clone()];
+        let content = math_text.trim_start_matches('$').trim_end_matches('$');
+        if !content.trim().is_empty() {
+            return None;
+        }
+
+        let indent = self.indent_of(o.start);
+        let rng = cursor..cursor;
+        let edit = TextEdit {
+            range: typst_to_lsp::range(rng, self.source, self.position_encoding),
+            // todo: read indent configuration
+            new_text: if !content.contains('\n') {
+                format!("\n{indent}  $0\n{indent}")
+            } else {
+                format!("\n{indent}  $0")
+            },
+        };
+
+        Some(vec![edit])
+    }
 }

crates/tinymist-query/src/syntax/matcher.rs

@@ -44,6 +44,10 @@ pub(crate) fn find_expr_in_import(mut node: LinkedNode) -> Option<LinkedNode> {
     None
 }
 
+pub fn node_ancestors<'a>(node: &'a LinkedNode<'a>) -> impl Iterator<Item = &'a LinkedNode<'a>> {
+    std::iter::successors(Some(node), |node| node.parent())
+}
+
 fn is_mark(sk: SyntaxKind) -> bool {
     use SyntaxKind::*;
     matches!(