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use crate::{
syntax::Syntax,
tree_sitter::{Node, Tree},
Rope, RopeSlice, State,
};
pub const TAB_WIDTH: usize = 4;
fn indent_level_for_line(line: RopeSlice) -> usize {
let mut len = 0;
for ch in line.chars() {
match ch {
'\t' => len += TAB_WIDTH,
' ' => len += 1,
_ => break,
}
}
len / TAB_WIDTH
}
/// Find the highest syntax node at position.
/// This is to identify the column where this node (e.g., an HTML closing tag) ends.
fn get_highest_syntax_node_at_bytepos(syntax: &Syntax, pos: usize) -> Option<Node> {
let tree = syntax.root_layer.tree.as_ref().unwrap();
let mut node = match tree.root_node().named_descendant_for_byte_range(pos, pos) {
Some(node) => node,
None => return None,
};
while let Some(parent) = node.parent() {
if parent.start_byte() == node.start_byte() {
node = parent
} else {
break;
}
}
Some(node)
}
fn walk(node: Option<Node>) -> usize {
let node = match node {
Some(node) => node,
None => return 0,
};
let parent = match node.parent() {
Some(node) => node,
None => return 0,
};
let mut increment = 0;
let not_first_or_last_sibling = node.next_sibling().is_some() && node.prev_sibling().is_some();
let is_scope = true;
if not_first_or_last_sibling && is_scope {
increment += 1;
}
walk(Some(parent)) + increment
}
// for_line_at_col
fn suggested_indent_for_line(state: &State, line_num: usize) -> usize {
let line = state.doc.line(line_num);
let current = indent_level_for_line(line);
let mut byte_start = state.doc.line_to_byte(line_num);
// find first non-whitespace char
for ch in line.chars() {
// TODO: could use memchr with chunks?
if ch != ' ' && ch != '\t' {
break;
}
byte_start += 1;
}
if let Some(syntax) = &state.syntax {
let node = get_highest_syntax_node_at_bytepos(state.syntax.as_ref().unwrap(), byte_start);
// let indentation = walk()
// special case for comments
// if preserve_leading_whitespace
unimplemented!()
} else {
// TODO: case for non-tree sitter grammars
0
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn indent_level() {
let line = Rope::from(" fn new"); // 8 spaces
assert_eq!(indent_level_for_line(line.slice(..)), 2);
let line = Rope::from("\t\t\tfn new"); // 3 tabs
assert_eq!(indent_level_for_line(line.slice(..)), 3);
// mixed indentation
let line = Rope::from("\t \tfn new"); // 1 tab, 4 spaces, tab
assert_eq!(indent_level_for_line(line.slice(..)), 3);
}
}
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