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use libsyntax2::{
File, TextUnit, AstNode, SyntaxNodeRef,
ast::{self, NameOwner},
algo::{
ancestors,
visit::{visitor_ctx, VisitorCtx},
walk::preorder,
},
};
use {
AtomEdit, find_node_at_offset,
};
#[derive(Debug)]
pub struct CompletionItem {
pub name: String,
}
pub fn scope_completion(file: &File, offset: TextUnit) -> Option<Vec<CompletionItem>> {
// Insert a fake ident to get a valid parse tree
let file = {
let edit = AtomEdit::insert(offset, "intellijRulezz".to_string());
// Don't bother with completion if incremental reparse fails
file.incremental_reparse(&edit)?
};
let name_ref = find_node_at_offset::<ast::NameRef>(file.syntax(), offset)?;
Some(complete(name_ref))
}
fn complete(name_ref: ast::NameRef) -> Vec<CompletionItem> {
let mut res = Vec::new();
for node in ancestors(name_ref.syntax()) {
process_scope(node, &mut res);
}
res
}
fn process_scope(node: SyntaxNodeRef, sink: &mut Vec<CompletionItem>) {
let _ = visitor_ctx(sink)
.visit::<ast::Block, _>(|block, sink| {
block.let_stmts()
.filter_map(|it| it.pat())
.for_each(move |it| process_pat(it, sink))
})
.visit::<ast::FnDef, _>(|fn_def, sink| {
fn_def.param_list().into_iter()
.flat_map(|it| it.params())
.filter_map(|it| it.pat())
.for_each(move |it| process_pat(it, sink))
})
.accept(node);
fn process_pat(pat: ast::Pat, sink: &mut Vec<CompletionItem>) {
let items = preorder(pat.syntax())
.filter_map(ast::BindPat::cast)
.filter_map(ast::BindPat::name)
.map(|name| CompletionItem { name: name.text().to_string() });
sink.extend(items);
}
}
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