//! FIXME: write short doc here use std::ops::RangeInclusive; use itertools::Itertools; use ra_text_edit::TextEditBuilder; use rustc_hash::FxHashMap; use crate::{ AstNode, Direction, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxNodePtr, TextRange, TextUnit, }; /// Returns ancestors of the node at the offset, sorted by length. This should /// do the right thing at an edge, e.g. when searching for expressions at `{ /// <|>foo }` we will get the name reference instead of the whole block, which /// we would get if we just did `find_token_at_offset(...).flat_map(|t| /// t.parent().ancestors())`. pub fn ancestors_at_offset( node: &SyntaxNode, offset: TextUnit, ) -> impl Iterator<Item = SyntaxNode> { node.token_at_offset(offset) .map(|token| token.parent().ancestors()) .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len()) } /// Finds a node of specific Ast type at offset. Note that this is slightly /// imprecise: if the cursor is strictly between two nodes of the desired type, /// as in /// /// ```no-run /// struct Foo {}|struct Bar; /// ``` /// /// then the shorter node will be silently preferred. pub fn find_node_at_offset<N: AstNode>(syntax: &SyntaxNode, offset: TextUnit) -> Option<N> { ancestors_at_offset(syntax, offset).find_map(N::cast) } /// Finds the first sibling in the given direction which is not `trivia` pub fn non_trivia_sibling(element: SyntaxElement, direction: Direction) -> Option<SyntaxElement> { return match element { NodeOrToken::Node(node) => node.siblings_with_tokens(direction).skip(1).find(not_trivia), NodeOrToken::Token(token) => token.siblings_with_tokens(direction).skip(1).find(not_trivia), }; fn not_trivia(element: &SyntaxElement) -> bool { match element { NodeOrToken::Node(_) => true, NodeOrToken::Token(token) => !token.kind().is_trivia(), } } } pub fn find_covering_element(root: &SyntaxNode, range: TextRange) -> SyntaxElement { root.covering_element(range) } #[derive(Debug, PartialEq, Eq, Clone, Copy)] pub enum InsertPosition<T> { First, Last, Before(T), After(T), } pub struct TreeDiff { replacements: FxHashMap<SyntaxElement, SyntaxElement>, } impl TreeDiff { pub fn into_text_edit(&self, builder: &mut TextEditBuilder) { for (from, to) in self.replacements.iter() { builder.replace(from.text_range(), to.to_string()) } } } /// Finds minimal the diff, which, applied to `from`, will result in `to`. /// /// Specifically, returns a map whose keys are descendants of `from` and values /// are descendants of `to`, such that `replace_descendants(from, map) == to`. /// /// A trivial solution is a singletom map `{ from: to }`, but this function /// tries to find a more fine-grained diff. pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff { let mut buf = FxHashMap::default(); // FIXME: this is both horrible inefficient and gives larger than // necessary diff. I bet there's a cool algorithm to diff trees properly. go(&mut buf, from.clone().into(), to.clone().into()); return TreeDiff { replacements: buf }; fn go( buf: &mut FxHashMap<SyntaxElement, SyntaxElement>, lhs: SyntaxElement, rhs: SyntaxElement, ) { if lhs.kind() == rhs.kind() && lhs.text_range().len() == rhs.text_range().len() { if match (&lhs, &rhs) { (NodeOrToken::Node(lhs), NodeOrToken::Node(rhs)) => { lhs.green() == rhs.green() || lhs.text() == rhs.text() } (NodeOrToken::Token(lhs), NodeOrToken::Token(rhs)) => lhs.text() == rhs.text(), _ => false, } { return; } } if let (Some(lhs), Some(rhs)) = (lhs.as_node(), rhs.as_node()) { if lhs.children_with_tokens().count() == rhs.children_with_tokens().count() { for (lhs, rhs) in lhs.children_with_tokens().zip(rhs.children_with_tokens()) { go(buf, lhs, rhs) } return; } } buf.insert(lhs, rhs); } } /// Adds specified children (tokens or nodes) to the current node at the /// specific position. /// /// This is a type-unsafe low-level editing API, if you need to use it, /// prefer to create a type-safe abstraction on top of it instead. pub fn insert_children( parent: &SyntaxNode, position: InsertPosition<SyntaxElement>, to_insert: &mut dyn Iterator<Item = SyntaxElement>, ) -> SyntaxNode { let mut delta = TextUnit::default(); let to_insert = to_insert.map(|element| { delta += element.text_range().len(); to_green_element(element) }); let old_children = parent.green().children(); let new_children = match &position { InsertPosition::First => { to_insert.chain(old_children.iter().cloned()).collect::<Box<[_]>>() } InsertPosition::Last => old_children.iter().cloned().chain(to_insert).collect::<Box<[_]>>(), InsertPosition::Before(anchor) | InsertPosition::After(anchor) => { let take_anchor = if let InsertPosition::After(_) = position { 1 } else { 0 }; let split_at = position_of_child(parent, anchor.clone()) + take_anchor; let (before, after) = old_children.split_at(split_at); before .iter() .cloned() .chain(to_insert) .chain(after.iter().cloned()) .collect::<Box<[_]>>() } }; with_children(parent, new_children) } /// Replaces all nodes in `to_delete` with nodes from `to_insert` /// /// This is a type-unsafe low-level editing API, if you need to use it, /// prefer to create a type-safe abstraction on top of it instead. pub fn replace_children( parent: &SyntaxNode, to_delete: RangeInclusive<SyntaxElement>, to_insert: &mut dyn Iterator<Item = SyntaxElement>, ) -> SyntaxNode { let start = position_of_child(parent, to_delete.start().clone()); let end = position_of_child(parent, to_delete.end().clone()); let old_children = parent.green().children(); let new_children = old_children[..start] .iter() .cloned() .chain(to_insert.map(to_green_element)) .chain(old_children[end + 1..].iter().cloned()) .collect::<Box<[_]>>(); with_children(parent, new_children) } /// Replaces descendants in the node, according to the mapping. /// /// This is a type-unsafe low-level editing API, if you need to use it, prefer /// to create a type-safe abstraction on top of it instead. pub fn replace_descendants( parent: &SyntaxNode, map: &FxHashMap<SyntaxElement, SyntaxElement>, ) -> SyntaxNode { // FIXME: this could be made much faster. let new_children = parent.children_with_tokens().map(|it| go(map, it)).collect::<Box<[_]>>(); return with_children(parent, new_children); fn go( map: &FxHashMap<SyntaxElement, SyntaxElement>, element: SyntaxElement, ) -> NodeOrToken<rowan::GreenNode, rowan::GreenToken> { if let Some(replacement) = map.get(&element) { return match replacement { NodeOrToken::Node(it) => NodeOrToken::Node(it.green().clone()), NodeOrToken::Token(it) => NodeOrToken::Token(it.green().clone()), }; } match element { NodeOrToken::Token(it) => NodeOrToken::Token(it.green().clone()), NodeOrToken::Node(it) => { NodeOrToken::Node(replace_descendants(&it, map).green().clone()) } } } } fn with_children( parent: &SyntaxNode, new_children: Box<[NodeOrToken<rowan::GreenNode, rowan::GreenToken>]>, ) -> SyntaxNode { let len = new_children.iter().map(|it| it.text_len()).sum::<TextUnit>(); let new_node = rowan::GreenNode::new(rowan::cursor::SyntaxKind(parent.kind() as u16), new_children); let new_root_node = parent.replace_with(new_node); let new_root_node = SyntaxNode::new_root(new_root_node); // FIXME: use a more elegant way to re-fetch the node (#1185), make // `range` private afterwards let mut ptr = SyntaxNodePtr::new(parent); ptr.range = TextRange::offset_len(ptr.range().start(), len); ptr.to_node(&new_root_node) } fn position_of_child(parent: &SyntaxNode, child: SyntaxElement) -> usize { parent .children_with_tokens() .position(|it| it == child) .expect("element is not a child of current element") } fn to_green_element(element: SyntaxElement) -> NodeOrToken<rowan::GreenNode, rowan::GreenToken> { match element { NodeOrToken::Node(it) => it.green().clone().into(), NodeOrToken::Token(it) => it.green().clone().into(), } }