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|
use crate::{
syntax::Syntax,
tree_sitter::{Node, Tree},
Rope, RopeSlice, State,
};
/// To determine indentation of a newly inserted line, figure out the indentation at the last col
/// of the previous line.
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;
// Hardcoded for rust for now
let indent_scopes = &[
"block",
"function_item",
"closure_expression",
"while_expression",
"for_expression",
"loop_expression",
"if_expression",
"if_let_expression",
"binary_expression",
"match_expression",
"match_arm",
//
"struct_item",
"enum_item",
"impl_item",
//
"mod_item",
];
// let indent_except_first_scopes = &[];
let not_first_sibling = node.next_sibling().is_some();
let not_last_sibling = node.prev_sibling().is_some();
let not_first_or_last_sibling = not_first_sibling && not_last_sibling;
let parent_kind = parent.kind();
let is_scope = indent_scopes.iter().any(|scope| scope == &parent_kind);
// && not_first_or_last_sibling
if is_scope {
increment += 1
}
// if last_scope && increment > 0 && ...{ ignore }
walk(Some(parent)) + increment
}
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 start = state.doc.line_to_char(line_num);
// find first non-whitespace char
for ch in line.chars() {
// TODO: could use memchr with chunks?
if ch != ' ' && ch != '\t' {
break;
}
start += 1;
}
suggested_indent_for_pos(state, start)
}
pub fn suggested_indent_for_pos(state: &State, pos: usize) -> usize {
if let Some(syntax) = &state.syntax {
let byte_start = state.doc.char_to_byte(pos);
let node = get_highest_syntax_node_at_bytepos(syntax, byte_start);
let indentation = walk(node);
// special case for comments
// if preserve_leading_whitespace
indentation
} else {
// TODO: case for non-tree sitter grammars
0
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_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);
}
#[test]
fn test_suggested_indent_for_line() {
let doc = Rope::from(
"mod test {
fn hello_world() {
1 + 1
}
}
",
);
let mut state = State::new(doc);
state.set_language("source.rust", &[]);
assert_eq!(suggested_indent_for_line(&state, 0), 0); // mod
assert_eq!(suggested_indent_for_line(&state, 1), 1); // fn
assert_eq!(suggested_indent_for_line(&state, 2), 2); // 1 + 1
assert_eq!(suggested_indent_for_line(&state, 4), 1); // }
assert_eq!(suggested_indent_for_line(&state, 5), 0); // }
}
}
|
