Hacky way to specify indent scopes per language via toml configs.

Can't do it via a scm query nicely because it returns an iterator over
all the matches, whereas we want to traverse the tree ourselves.

Can't extract the pattern data from a parsed query either.

Oh well, toml files for now.

7 files changed, 100 insertions, 45 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 1ecb20a5..b52c321d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -291,6 +291,7 @@ dependencies = [
  "serde",
  "smallvec",
  "tendril",
+ "toml",
  "tree-sitter",
  "unicode-segmentation",
  "unicode-width",
diff --git a/helix-core/Cargo.toml b/helix-core/Cargo.toml
index 7868ec58..33b59cb1 100644
--- a/helix-core/Cargo.toml
+++ b/helix-core/Cargo.toml
@@ -22,5 +22,6 @@ once_cell = "1.4"
 regex = "1"
 
 serde = { version = "1.0", features = ["derive"] }
+toml = "0.5"
 
 etcetera = "0.3"
diff --git a/helix-core/src/indent.rs b/helix-core/src/indent.rs
index ca042172..fc253f91 100644
--- a/helix-core/src/indent.rs
+++ b/helix-core/src/indent.rs
@@ -1,6 +1,6 @@
 use crate::{
     find_first_non_whitespace_char,
-    syntax::Syntax,
+    syntax::{IndentQuery, LanguageConfiguration, Syntax},
     tree_sitter::{Node, Tree},
     Rope, RopeSlice,
 };
@@ -43,40 +43,11 @@ fn get_highest_syntax_node_at_bytepos(syntax: &Syntax, pos: usize) -> Option<Nod
     Some(node)
 }
 
-fn calculate_indentation(node: Option<Node>, newline: bool) -> usize {
-    let mut increment: i32 = 0;
-
-    // Hardcoded for rust for now
-    let indent_scopes = &[
-        "while_expression",
-        "for_expression",
-        "loop_expression",
-        "if_expression",
-        "if_let_expression",
-        // "match_expression",
-        // "match_arm",
-        "tuple_expression",
-        "array_expression",
-        // indent_except_first_scopes
-        "use_list",
-        "block",
-        "match_block",
-        "arguments",
-        "parameters",
-        "declaration_list",
-        "field_declaration_list",
-        "field_initializer_list",
-        "struct_pattern",
-        "tuple_pattern",
-        "enum_variant_list",
-        // "function_item",
-        // "closure_expression",
-        "binary_expression",
-        "field_expression",
-        "where_clause",
-    ];
+fn calculate_indentation(query: &IndentQuery, node: Option<Node>, newline: bool) -> usize {
+    // NOTE: can't use contains() on query because of comparing Vec<String> and &str
+    // https://doc.rust-lang.org/std/vec/struct.Vec.html#method.contains
 
-    let outdent = &["where", "}", "]", ")"];
+    let mut increment: i32 = 0;
 
     let mut node = match node {
         Some(node) => node,
@@ -88,7 +59,7 @@ fn calculate_indentation(node: Option<Node>, newline: bool) -> usize {
     // if we're calculating indentation for a brand new line then the current node will become the
     // parent node. We need to take it's indentation level into account too.
     let node_kind = node.kind();
-    if newline && indent_scopes.contains(&node_kind) {
+    if newline && query.indent.contains(node_kind) {
         increment += 1;
     }
 
@@ -102,14 +73,14 @@ fn calculate_indentation(node: Option<Node>, newline: bool) -> usize {
         // })               <-- }) is two scopes
         let starts_same_line = start == prev_start;
 
-        if outdent.contains(&node.kind()) && !starts_same_line {
+        if query.outdent.contains(node.kind()) && !starts_same_line {
             // we outdent by skipping the rules for the current level and jumping up
             // node = parent;
             increment -= 1;
             // continue;
         }
 
-        if indent_scopes.contains(&parent_kind) // && not_first_or_last_sibling
+        if query.indent.contains(parent_kind) // && not_first_or_last_sibling
             && !starts_same_line
         {
             // println!("is_scope {}", parent_kind);
@@ -128,6 +99,7 @@ fn calculate_indentation(node: Option<Node>, newline: bool) -> usize {
 }
 
 fn suggested_indent_for_line(
+    language_config: &LanguageConfiguration,
     syntax: Option<&Syntax>,
     text: RopeSlice,
     line_num: usize,
@@ -137,7 +109,7 @@ fn suggested_indent_for_line(
     let current = indent_level_for_line(line, tab_width);
 
     if let Some(start) = find_first_non_whitespace_char(text, line_num) {
-        return suggested_indent_for_pos(syntax, text, start, false);
+        return suggested_indent_for_pos(Some(language_config), syntax, text, start, false);
     };
 
     // if the line is blank, indent should be zero
@@ -148,18 +120,24 @@ fn suggested_indent_for_line(
 // - it should return 0 when mass indenting stuff
 // - it should look up the wrapper node and count it too when we press o/O
 pub fn suggested_indent_for_pos(
+    language_config: Option<&LanguageConfiguration>,
     syntax: Option<&Syntax>,
     text: RopeSlice,
     pos: usize,
     new_line: bool,
 ) -> usize {
-    if let Some(syntax) = syntax {
+    if let (Some(query), Some(syntax)) = (
+        language_config.and_then(|config| config.indent_query()),
+        syntax,
+    ) {
         let byte_start = text.char_to_byte(pos);
         let node = get_highest_syntax_node_at_bytepos(syntax, byte_start);
 
+        // let config = load indentation query config from Syntax(should contain language_config)
+
         // TODO: special case for comments
         // TODO: if preserve_leading_whitespace
-        calculate_indentation(node, new_line)
+        calculate_indentation(query, node, new_line)
     } else {
         // TODO: heuristics for non-tree sitter grammars
         0
@@ -286,6 +264,7 @@ where
                     tab_width: 4,
                     unit: String::from("    "),
                 }),
+                indent_query: OnceCell::new(),
             }],
         });
 
@@ -304,7 +283,7 @@ where
             let line = text.line(i);
             let indent = indent_level_for_line(line, tab_width);
             assert_eq!(
-                suggested_indent_for_line(Some(&syntax), text, i, tab_width),
+                suggested_indent_for_line(&language_config, Some(&syntax), text, i, tab_width),
                 indent,
                 "line {}: {}",
                 i,
diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index 06f3399e..1b8e832b 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -4,7 +4,7 @@ pub use helix_syntax::{get_language, get_language_name, Lang};
 use std::{
     borrow::Cow,
     cell::RefCell,
-    collections::HashMap,
+    collections::{HashMap, HashSet},
     path::{Path, PathBuf},
     sync::Arc,
 };
@@ -41,6 +41,9 @@ pub struct LanguageConfiguration {
     pub language_server: Option<LanguageServerConfiguration>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub indent: Option<IndentationConfiguration>,
+
+    #[serde(skip)]
+    pub(crate) indent_query: OnceCell<Option<IndentQuery>>,
 }
 
 #[derive(Serialize, Deserialize)]
@@ -59,6 +62,17 @@ pub struct IndentationConfiguration {
     pub unit: String,
 }
 
+#[derive(Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct IndentQuery {
+    #[serde(default)]
+    #[serde(skip_serializing_if = "HashSet::is_empty")]
+    pub indent: HashSet<String>,
+    #[serde(default)]
+    #[serde(skip_serializing_if = "HashSet::is_empty")]
+    pub outdent: HashSet<String>,
+}
+
 fn read_query(language: &str, filename: &str) -> String {
     static INHERITS_REGEX: Lazy<Regex> =
         Lazy::new(|| Regex::new(r";+\s*inherits\s*:?\s*([a-z_,()]+)\s*").unwrap());
@@ -127,6 +141,20 @@ impl LanguageConfiguration {
             .clone()
     }
 
+    pub fn indent_query(&self) -> Option<&IndentQuery> {
+        self.indent_query
+            .get_or_init(|| {
+                let language = get_language_name(self.language_id).to_ascii_lowercase();
+
+                let root = crate::runtime_dir();
+                let path = root.join("queries").join(language).join("indents.toml");
+
+                let toml = std::fs::read(&path).ok()?;
+                toml::from_slice(&toml).ok()
+            })
+            .as_ref()
+    }
+
     pub fn scope(&self) -> &str {
         &self.scope
     }
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 4a42bbba..104df72f 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -1171,7 +1171,13 @@ fn open(cx: &mut Context, open: Open) {
             let index = doc.text().line_to_char(line).saturating_sub(1);
 
             // TODO: share logic with insert_newline for indentation
-            let indent_level = indent::suggested_indent_for_pos(doc.syntax(), text, index, true);
+            let indent_level = indent::suggested_indent_for_pos(
+                doc.language_config(),
+                doc.syntax(),
+                text,
+                index,
+                true,
+            );
             let indent = doc.indent_unit().repeat(indent_level);
             let mut text = String::with_capacity(1 + indent.len());
             text.push('\n');
@@ -1649,8 +1655,13 @@ pub mod insert {
             let curr = contents.char(pos);
 
             // TODO: offset range.head by 1? when calculating?
-            let indent_level =
-                indent::suggested_indent_for_pos(doc.syntax(), text, pos.saturating_sub(1), true);
+            let indent_level = indent::suggested_indent_for_pos(
+                doc.language_config(),
+                doc.syntax(),
+                text,
+                pos.saturating_sub(1),
+                true,
+            );
             let indent = doc.indent_unit().repeat(indent_level);
             let mut text = String::with_capacity(1 + indent.len());
             text.push('\n');
diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index 8d6144cf..814777f8 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -329,6 +329,11 @@ impl Document {
     }
 
     #[inline]
+    pub fn language_config(&self) -> Option<&LanguageConfiguration> {
+        self.language.as_deref()
+    }
+
+    #[inline]
     /// Current document version, incremented at each change.
     pub fn version(&self) -> i32 {
         self.version
diff --git a/runtime/queries/rust/indents.toml b/runtime/queries/rust/indents.toml
new file mode 100644
index 00000000..49c2c15e
--- /dev/null
+++ b/runtime/queries/rust/indents.toml
@@ -0,0 +1,30 @@
+indent = [
+ "while_expression",
+ "for_expression",
+ "loop_expression",
+ "if_expression",
+ "if_let_expression",
+ "tuple_expression",
+ "array_expression",
+ "use_list",
+ "block",
+ "match_block",
+ "arguments",
+ "parameters",
+ "declaration_list",
+ "field_declaration_list",
+ "field_initializer_list",
+ "struct_pattern",
+ "tuple_pattern",
+ "enum_variant_list",
+ "binary_expression",
+ "field_expression",
+ "where_clause"
+]
+
+outdent = [
+ "where",
+ "}",
+ "]",
+ ")"
+]