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use std::collections::HashMap;
use libsyntax2::{
File, TextUnit, AstNode, SyntaxNodeRef, SyntaxNode, SmolStr,
ast::{self, NameOwner},
algo::{
ancestors,
walk::preorder,
generate,
},
};
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)?;
let fn_def = ancestors(name_ref.syntax()).filter_map(ast::FnDef::cast).next()?;
let scopes = compute_scopes(fn_def);
Some(complete(name_ref, &scopes))
}
fn complete(name_ref: ast::NameRef, scopes: &FnScopes) -> Vec<CompletionItem> {
scopes.scope_chain(name_ref.syntax())
.flat_map(|scope| scopes.entries(scope).iter())
.map(|entry| CompletionItem {
name: entry.name().to_string()
})
.collect()
}
fn compute_scopes(fn_def: ast::FnDef) -> FnScopes {
let mut scopes = FnScopes::new();
let root = scopes.root_scope();
fn_def.param_list().into_iter()
.flat_map(|it| it.params())
.filter_map(|it| it.pat())
.for_each(|it| scopes.add_bindings(root, it));
let mut scope = root;
if let Some(body) = fn_def.body() {
for stmt in body.statements() {
match stmt {
ast::Stmt::LetStmt(stmt) => {
scope = scopes.new_scope(scope);
if let Some(pat) = stmt.pat() {
scopes.add_bindings(scope, pat);
}
if let Some(expr) = stmt.initializer() {
scopes.set_scope(expr.syntax(), scope)
}
}
ast::Stmt::ExprStmt(expr) => {
scopes.set_scope(expr.syntax(), scope)
}
}
}
if let Some(expr) = body.expr() {
scopes.set_scope(expr.syntax(), scope)
}
}
scopes
}
type ScopeId = usize;
struct FnScopes {
scopes: Vec<ScopeData>,
scope_for: HashMap<SyntaxNode, ScopeId>,
}
impl FnScopes {
fn new() -> FnScopes {
FnScopes {
scopes: vec![],
scope_for: HashMap::new(),
}
}
fn root_scope(&mut self) -> ScopeId {
let res = self.scopes.len();
self.scopes.push(ScopeData { parent: None, entries: vec![] });
res
}
fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
let res = self.scopes.len();
self.scopes.push(ScopeData { parent: Some(parent), entries: vec![] });
res
}
fn add_bindings(&mut self, scope: ScopeId, pat: ast::Pat) {
let entries = preorder(pat.syntax())
.filter_map(ast::BindPat::cast)
.filter_map(ScopeEntry::new);
self.scopes[scope].entries.extend(entries);
}
fn set_scope(&mut self, node: SyntaxNodeRef, scope: ScopeId) {
self.scope_for.insert(node.owned(), scope);
}
fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
&self.scopes[scope].entries
}
fn scope_for(&self, node: SyntaxNodeRef) -> Option<ScopeId> {
ancestors(node)
.filter_map(|it| self.scope_for.get(&it.owned()).map(|&scope| scope))
.next()
}
fn scope_chain<'a>(&'a self, node: SyntaxNodeRef) -> impl Iterator<Item=ScopeId> + 'a {
generate(self.scope_for(node), move |&scope| self.scopes[scope].parent)
}
}
struct ScopeData {
parent: Option<ScopeId>,
entries: Vec<ScopeEntry>
}
struct ScopeEntry {
syntax: SyntaxNode
}
impl ScopeEntry {
fn new(pat: ast::BindPat) -> Option<ScopeEntry> {
if pat.name().is_some() {
Some(ScopeEntry { syntax: pat.syntax().owned() })
} else {
None
}
}
fn name(&self) -> SmolStr {
self.ast().name()
.unwrap()
.text()
}
fn ast(&self) -> ast::BindPat {
ast::BindPat::cast(self.syntax.borrowed())
.unwrap()
}
}
|
