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use ra_text_edit::AtomTextEdit;
use ra_syntax::{
AstNode, SyntaxNode, SourceFile, TextUnit, TextRange,
ast,
algo::{find_leaf_at_offset, find_covering_node, find_node_at_offset},
SyntaxKind::*,
};
use hir::source_binder;
use crate::{db, FilePosition, Cancelable};
/// `CompletionContext` is created early during completion to figure out, where
/// exactly is the cursor, syntax-wise.
#[derive(Debug)]
pub(super) struct CompletionContext<'a> {
pub(super) db: &'a db::RootDatabase,
pub(super) offset: TextUnit,
pub(super) leaf: &'a SyntaxNode,
pub(super) module: Option<hir::Module>,
pub(super) function: Option<hir::Function>,
pub(super) function_syntax: Option<&'a ast::FnDef>,
pub(super) use_item_syntax: Option<&'a ast::UseItem>,
pub(super) is_param: bool,
/// A single-indent path, like `foo`.
pub(super) is_trivial_path: bool,
/// If not a trivial, path, the prefix (qualifier).
pub(super) path_prefix: Option<hir::Path>,
pub(super) after_if: bool,
/// `true` if we are a statement or a last expr in the block.
pub(super) can_be_stmt: bool,
/// Something is typed at the "top" level, in module or impl/trait.
pub(super) is_new_item: bool,
/// The receiver if this is a field or method access, i.e. writing something.<|>
pub(super) dot_receiver: Option<&'a ast::Expr>,
/// If this is a method call in particular, i.e. the () are already there.
pub(super) is_method_call: bool,
}
impl<'a> CompletionContext<'a> {
pub(super) fn new(
db: &'a db::RootDatabase,
original_file: &'a SourceFile,
position: FilePosition,
) -> Cancelable<Option<CompletionContext<'a>>> {
let module = source_binder::module_from_position(db, position)?;
let leaf =
ctry!(find_leaf_at_offset(original_file.syntax(), position.offset).left_biased());
let mut ctx = CompletionContext {
db,
leaf,
offset: position.offset,
module,
function: None,
function_syntax: None,
use_item_syntax: None,
is_param: false,
is_trivial_path: false,
path_prefix: None,
after_if: false,
can_be_stmt: false,
is_new_item: false,
dot_receiver: None,
is_method_call: false,
};
ctx.fill(original_file, position.offset);
Ok(Some(ctx))
}
fn fill(&mut self, original_file: &'a SourceFile, offset: TextUnit) {
// Insert a fake ident to get a valid parse tree. We will use this file
// to determine context, though the original_file will be used for
// actual completion.
let file = {
let edit = AtomTextEdit::insert(offset, "intellijRulezz".to_string());
original_file.reparse(&edit)
};
// First, let's try to complete a reference to some declaration.
if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(file.syntax(), offset) {
// Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
// See RFC#1685.
if is_node::<ast::Param>(name_ref.syntax()) {
self.is_param = true;
return;
}
self.classify_name_ref(original_file, name_ref);
}
// Otherwise, see if this is a declaration. We can use heuristics to
// suggest declaration names, see `CompletionKind::Magic`.
if let Some(name) = find_node_at_offset::<ast::Name>(file.syntax(), offset) {
if is_node::<ast::Param>(name.syntax()) {
self.is_param = true;
return;
}
}
}
fn classify_name_ref(&mut self, original_file: &'a SourceFile, name_ref: &ast::NameRef) {
let name_range = name_ref.syntax().range();
let top_node = name_ref
.syntax()
.ancestors()
.take_while(|it| it.range() == name_range)
.last()
.unwrap();
match top_node.parent().map(|it| it.kind()) {
Some(SOURCE_FILE) | Some(ITEM_LIST) => {
self.is_new_item = true;
return;
}
_ => (),
}
self.use_item_syntax = self.leaf.ancestors().find_map(ast::UseItem::cast);
self.function_syntax = self
.leaf
.ancestors()
.take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
.find_map(ast::FnDef::cast);
match (&self.module, self.function_syntax) {
(Some(module), Some(fn_def)) => {
let function = source_binder::function_from_module(self.db, module, fn_def);
self.function = Some(function);
}
_ => (),
}
let parent = match name_ref.syntax().parent() {
Some(it) => it,
None => return,
};
if let Some(segment) = ast::PathSegment::cast(parent) {
let path = segment.parent_path();
if let Some(mut path) = hir::Path::from_ast(path) {
if !path.is_ident() {
path.segments.pop().unwrap();
self.path_prefix = Some(path);
return;
}
}
if path.qualifier().is_none() {
self.is_trivial_path = true;
// Find either enclosing expr statement (thing with `;`) or a
// block. If block, check that we are the last expr.
self.can_be_stmt = name_ref
.syntax()
.ancestors()
.find_map(|node| {
if let Some(stmt) = ast::ExprStmt::cast(node) {
return Some(stmt.syntax().range() == name_ref.syntax().range());
}
if let Some(block) = ast::Block::cast(node) {
return Some(
block.expr().map(|e| e.syntax().range())
== Some(name_ref.syntax().range()),
);
}
None
})
.unwrap_or(false);
if let Some(off) = name_ref.syntax().range().start().checked_sub(2.into()) {
if let Some(if_expr) =
find_node_at_offset::<ast::IfExpr>(original_file.syntax(), off)
{
if if_expr.syntax().range().end() < name_ref.syntax().range().start() {
self.after_if = true;
}
}
}
}
}
if let Some(field_expr) = ast::FieldExpr::cast(parent) {
// The receiver comes before the point of insertion of the fake
// ident, so it should have the same range in the non-modified file
self.dot_receiver = field_expr
.expr()
.map(|e| e.syntax().range())
.and_then(|r| find_node_with_range(original_file.syntax(), r));
}
if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
// As above
self.dot_receiver = method_call_expr
.expr()
.map(|e| e.syntax().range())
.and_then(|r| find_node_with_range(original_file.syntax(), r));
self.is_method_call = true;
}
}
}
fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<&N> {
let node = find_covering_node(syntax, range);
node.ancestors().find_map(N::cast)
}
fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
match node.ancestors().filter_map(N::cast).next() {
None => false,
Some(n) => n.syntax().range() == node.range(),
}
}
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