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pub mod walk;
use {SyntaxNodeRef, TextUnit, TextRange};
pub fn find_leaf_at_offset(node: SyntaxNodeRef, offset: TextUnit) -> LeafAtOffset {
let range = node.range();
assert!(
contains_offset_nonstrict(range, offset),
"Bad offset: range {:?} offset {:?}", range, offset
);
if range.is_empty() {
return LeafAtOffset::None;
}
if node.is_leaf() {
return LeafAtOffset::Single(node);
}
let mut children = node.children()
.filter(|child| {
let child_range = child.range();
!child_range.is_empty() && contains_offset_nonstrict(child_range, offset)
});
let left = children.next().unwrap();
let right = children.next();
assert!(children.next().is_none());
return if let Some(right) = right {
match (find_leaf_at_offset(left, offset), find_leaf_at_offset(right, offset)) {
(LeafAtOffset::Single(left), LeafAtOffset::Single(right)) =>
LeafAtOffset::Between(left, right),
_ => unreachable!()
}
} else {
find_leaf_at_offset(left, offset)
};
}
#[derive(Clone, Copy, Debug)]
pub enum LeafAtOffset<'a> {
None,
Single(SyntaxNodeRef<'a>),
Between(SyntaxNodeRef<'a>, SyntaxNodeRef<'a>)
}
impl<'a> LeafAtOffset<'a> {
pub fn right_biased(self) -> Option<SyntaxNodeRef<'a>> {
match self {
LeafAtOffset::None => None,
LeafAtOffset::Single(node) => Some(node),
LeafAtOffset::Between(_, right) => Some(right)
}
}
pub fn left_biased(self) -> Option<SyntaxNodeRef<'a>> {
match self {
LeafAtOffset::None => None,
LeafAtOffset::Single(node) => Some(node),
LeafAtOffset::Between(left, _) => Some(left)
}
}
}
impl<'f> Iterator for LeafAtOffset<'f> {
type Item = SyntaxNodeRef<'f>;
fn next(&mut self) -> Option<SyntaxNodeRef<'f>> {
match *self {
LeafAtOffset::None => None,
LeafAtOffset::Single(node) => { *self = LeafAtOffset::None; Some(node) }
LeafAtOffset::Between(left, right) => { *self = LeafAtOffset::Single(right); Some(left) }
}
}
}
pub fn find_covering_node(root: SyntaxNodeRef, range: TextRange) -> SyntaxNodeRef {
assert!(is_subrange(root.range(), range));
let (left, right) = match (
find_leaf_at_offset(root, range.start()).right_biased(),
find_leaf_at_offset(root, range.end()).left_biased()
) {
(Some(l), Some(r)) => (l, r),
_ => return root
};
common_ancestor(left, right)
}
fn common_ancestor<'a>(n1: SyntaxNodeRef<'a>, n2: SyntaxNodeRef<'a>) -> SyntaxNodeRef<'a> {
for p in ancestors(n1) {
if ancestors(n2).any(|a| a == p) {
return p;
}
}
panic!("Can't find common ancestor of {:?} and {:?}", n1, n2)
}
pub fn ancestors<'a>(node: SyntaxNodeRef<'a>) -> impl Iterator<Item=SyntaxNodeRef<'a>> {
Ancestors(Some(node))
}
#[derive(Debug)]
struct Ancestors<'a>(Option<SyntaxNodeRef<'a>>);
impl<'a> Iterator for Ancestors<'a> {
type Item = SyntaxNodeRef<'a>;
fn next(&mut self) -> Option<Self::Item> {
self.0.take().map(|n| {
self.0 = n.parent();
n
})
}
}
fn contains_offset_nonstrict(range: TextRange, offset: TextUnit) -> bool {
range.start() <= offset && offset <= range.end()
}
fn is_subrange(range: TextRange, subrange: TextRange) -> bool {
range.start() <= subrange.start() && subrange.end() <= range.end()
}
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