Make the indent heuristic configurable

helix-core/src/indent.rs

@@ -6,7 +6,7 @@ use crate::{
     chars::{char_is_line_ending, char_is_whitespace},
     find_first_non_whitespace_char,
     graphemes::{grapheme_width, tab_width_at},
-    syntax::{LanguageConfiguration, RopeProvider, Syntax},
+    syntax::{IndentationHeuristic, LanguageConfiguration, RopeProvider, Syntax},
     tree_sitter::Node,
     Rope, RopeGraphemes, RopeSlice,
 };
@@ -931,6 +931,7 @@ pub fn treesitter_indent_for_pos<'a>(
 pub fn indent_for_newline(
     language_config: Option<&LanguageConfiguration>,
     syntax: Option<&Syntax>,
+    indent_heuristic: &IndentationHeuristic,
     indent_style: &IndentStyle,
     tab_width: usize,
     text: RopeSlice,
@@ -939,7 +940,12 @@ pub fn indent_for_newline(
     current_line: usize,
 ) -> String {
     let indent_width = indent_style.indent_width(tab_width);
-    if let (Some(query), Some(syntax)) = (
+    if let (
+        IndentationHeuristic::TreeSitter | IndentationHeuristic::Hybrid,
+        Some(query),
+        Some(syntax),
+    ) = (
+        indent_heuristic,
         language_config.and_then(|config| config.indent_query()),
         syntax,
     ) {
@@ -953,6 +959,7 @@ pub fn indent_for_newline(
             line_before_end_pos,
             true,
         ) {
+            if let IndentationHeuristic::Hybrid = indent_heuristic {
                 // We want to compute the indentation not only based on the
                 // syntax tree but also on the actual indentation of a previous
                 // line. This makes indentation computation more resilient to
@@ -998,6 +1005,7 @@ pub fn indent_for_newline(
                         break;
                     }
                 }
+            }
             return indent.to_string(indent_style, tab_width);
         };
     }

helix-core/src/syntax.rs

@@ -442,6 +442,22 @@ pub struct IndentationConfiguration {
     pub unit: String,
 }
 
+/// How the indentation for a newly inserted line should be determined.
+/// If the selected heuristic is not available (e.g. because the current
+/// language has no tree-sitter indent queries), a simpler one will be used.
+#[derive(Debug, Default, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum IndentationHeuristic {
+    /// Just copy the indentation of the line that the cursor is currently on.
+    Simple,
+    /// Use tree-sitter indent queries to compute the expected absolute indentation level of the new line.
+    TreeSitter,
+    /// Use tree-sitter indent queries to compute the expected difference in indentation between the new line
+    /// and the line before. Add this to the actual indentation level of the line before.
+    #[default]
+    Hybrid,
+}
+
 /// Configuration for auto pairs
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case", deny_unknown_fields, untagged)]

helix-term/src/commands.rs

@@ -3053,6 +3053,7 @@ fn insert_with_indent(cx: &mut Context, cursor_fallback: IndentFallbackPos) {
             let indent = indent::indent_for_newline(
                 language_config,
                 syntax,
+                &doc.config.load().indent_heuristic,
                 &doc.indent_style,
                 tab_width,
                 text,
@@ -3181,6 +3182,7 @@ fn open(cx: &mut Context, open: Open) {
         let indent = indent::indent_for_newline(
             doc.language_config(),
             doc.syntax(),
+            &doc.config.load().indent_heuristic,
             &doc.indent_style,
             doc.tab_width(),
             text,
@@ -3720,6 +3722,7 @@ pub mod insert {
                 let indent = indent::indent_for_newline(
                     doc.language_config(),
                     doc.syntax(),
+                    &doc.config.load().indent_heuristic,
                     &doc.indent_style,
                     doc.tab_width(),
                     text,

helix-view/src/editor.rs

@@ -42,7 +42,7 @@ use anyhow::{anyhow, bail, Error};
 pub use helix_core::diagnostic::Severity;
 use helix_core::{
     auto_pairs::AutoPairs,
-    syntax::{self, AutoPairConfig, SoftWrap},
+    syntax::{self, AutoPairConfig, IndentationHeuristic, SoftWrap},
     Change, LineEnding, NATIVE_LINE_ENDING,
 };
 use helix_core::{Position, Selection};
@@ -291,6 +291,9 @@ pub struct Config {
     pub insert_final_newline: bool,
     /// Enables smart tab
     pub smart_tab: Option<SmartTabConfig>,
+    /// Which indent heuristic to use when a new line is inserted
+    #[serde(default)]
+    pub indent_heuristic: IndentationHeuristic,
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize, Eq, PartialOrd, Ord)]
@@ -841,6 +844,7 @@ impl Default for Config {
             default_line_ending: LineEndingConfig::default(),
             insert_final_newline: true,
             smart_tab: Some(SmartTabConfig::default()),
+            indent_heuristic: IndentationHeuristic::default(),
         }
     }
 }