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|
use rustc_hash::FxHashSet;
use ra_syntax::{
ast,
AstNode,
File, TextRange, SyntaxNodeRef,
SyntaxKind,
Direction,
};
#[derive(Debug, PartialEq, Eq)]
pub enum FoldKind {
Comment,
Imports,
}
#[derive(Debug)]
pub struct Fold {
pub range: TextRange,
pub kind: FoldKind,
}
pub fn folding_ranges(file: &File) -> Vec<Fold> {
let mut res = vec![];
let mut group_members = FxHashSet::default();
for node in file.syntax().descendants() {
// Fold items that span multiple lines
if let Some(kind) = fold_kind(node.kind()) {
if has_newline(node) {
res.push(Fold { range: node.range(), kind });
}
}
// Also fold item *groups* that span multiple lines
// Note: we need to skip elements of the group that we have already visited,
// otherwise there will be folds for the whole group and for its sub groups
if group_members.contains(&node) {
continue;
}
if let Some(kind) = fold_kind(node.kind()) {
contiguous_range_for_group(node.kind(), node, &mut group_members)
.map(|range| res.push(Fold { range, kind }));
}
}
res
}
fn fold_kind(kind: SyntaxKind) -> Option<FoldKind> {
match kind {
SyntaxKind::COMMENT => Some(FoldKind::Comment),
SyntaxKind::USE_ITEM => Some(FoldKind::Imports),
_ => None
}
}
fn has_newline(
node: SyntaxNodeRef,
) -> bool {
for descendant in node.descendants() {
if let Some(ws) = ast::Whitespace::cast(descendant) {
if ws.has_newlines() {
return true;
}
} else if let Some(comment) = ast::Comment::cast(descendant) {
if comment.has_newlines() {
return true;
}
}
}
false
}
fn contiguous_range_for_group<'a>(
group_kind: SyntaxKind,
first: SyntaxNodeRef<'a>,
visited: &mut FxHashSet<SyntaxNodeRef<'a>>,
) -> Option<TextRange> {
visited.insert(first);
let mut last = first;
for node in first.siblings(Direction::Next) {
visited.insert(node);
if let Some(ws) = ast::Whitespace::cast(node) {
// There is a blank line, which means the group ends here
if ws.count_newlines_lazy().take(2).count() == 2 {
break;
}
// Ignore whitespace without blank lines
continue;
}
// The group ends when an element of a different kind is reached
if node.kind() != group_kind {
break;
}
// Keep track of the last node in the group
last = node;
}
if first != last {
Some(TextRange::from_to(
first.range().start(),
last.range().end(),
))
} else {
// The group consists of only one element, therefore it cannot be folded
None
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_fold_comments() {
let text = r#"
// Hello
// this is a multiline
// comment
//
// But this is not
fn main() {
// We should
// also
// fold
// this one.
}"#;
let file = File::parse(&text);
let folds = folding_ranges(&file);
assert_eq!(folds.len(), 2);
assert_eq!(folds[0].range.start(), 1.into());
assert_eq!(folds[0].range.end(), 46.into());
assert_eq!(folds[0].kind, FoldKind::Comment);
assert_eq!(folds[1].range.start(), 84.into());
assert_eq!(folds[1].range.end(), 137.into());
assert_eq!(folds[1].kind, FoldKind::Comment);
}
#[test]
fn test_fold_imports() {
let text = r#"
use std::str;
use std::vec;
use std::io as iop;
fn main() {
}"#;
let file = File::parse(&text);
let folds = folding_ranges(&file);
assert_eq!(folds.len(), 1);
assert_eq!(folds[0].range.start(), 1.into());
assert_eq!(folds[0].range.end(), 48.into());
assert_eq!(folds[0].kind, FoldKind::Imports);
}
}
|
