rust-analyzer/crates/ide_db/src/helpers/insert_use.rs
2021-01-16 19:33:36 +02:00

601 lines
22 KiB
Rust

//! Handle syntactic aspects of inserting a new `use`.
use std::{cmp::Ordering, iter::successors};
use crate::RootDatabase;
use hir::Semantics;
use itertools::{EitherOrBoth, Itertools};
use syntax::{
algo::SyntaxRewriter,
ast::{
self,
edit::{AstNodeEdit, IndentLevel},
make, AstNode, AttrsOwner, PathSegmentKind, VisibilityOwner,
},
AstToken, InsertPosition, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxToken,
};
use test_utils::mark;
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct InsertUseConfig {
pub merge: Option<MergeBehavior>,
pub prefix_kind: hir::PrefixKind,
}
#[derive(Debug, Clone)]
pub enum ImportScope {
File(ast::SourceFile),
Module(ast::ItemList),
}
impl ImportScope {
pub fn from(syntax: SyntaxNode) -> Option<Self> {
if let Some(module) = ast::Module::cast(syntax.clone()) {
module.item_list().map(ImportScope::Module)
} else if let this @ Some(_) = ast::SourceFile::cast(syntax.clone()) {
this.map(ImportScope::File)
} else {
ast::ItemList::cast(syntax).map(ImportScope::Module)
}
}
/// Determines the containing syntax node in which to insert a `use` statement affecting `position`.
pub fn find_insert_use_container(
position: &SyntaxNode,
sema: &Semantics<'_, RootDatabase>,
) -> Option<Self> {
sema.ancestors_with_macros(position.clone()).find_map(Self::from)
}
pub fn as_syntax_node(&self) -> &SyntaxNode {
match self {
ImportScope::File(file) => file.syntax(),
ImportScope::Module(item_list) => item_list.syntax(),
}
}
fn indent_level(&self) -> IndentLevel {
match self {
ImportScope::File(file) => file.indent_level(),
ImportScope::Module(item_list) => item_list.indent_level() + 1,
}
}
fn first_insert_pos(&self) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
match self {
ImportScope::File(_) => (InsertPosition::First, AddBlankLine::AfterTwice),
// don't insert the imports before the item list's opening curly brace
ImportScope::Module(item_list) => item_list
.l_curly_token()
.map(|b| (InsertPosition::After(b.into()), AddBlankLine::Around))
.unwrap_or((InsertPosition::First, AddBlankLine::AfterTwice)),
}
}
fn insert_pos_after_last_inner_element(&self) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
self.as_syntax_node()
.children_with_tokens()
.filter(|child| match child {
NodeOrToken::Node(node) => is_inner_attribute(node.clone()),
NodeOrToken::Token(token) => is_inner_comment(token.clone()),
})
.last()
.map(|last_inner_element| {
(InsertPosition::After(last_inner_element.into()), AddBlankLine::BeforeTwice)
})
.unwrap_or_else(|| self.first_insert_pos())
}
}
fn is_inner_attribute(node: SyntaxNode) -> bool {
ast::Attr::cast(node).map(|attr| attr.kind()) == Some(ast::AttrKind::Inner)
}
fn is_inner_comment(token: SyntaxToken) -> bool {
ast::Comment::cast(token).and_then(|comment| comment.kind().doc)
== Some(ast::CommentPlacement::Inner)
}
/// Insert an import path into the given file/node. A `merge` value of none indicates that no import merging is allowed to occur.
pub fn insert_use<'a>(
scope: &ImportScope,
path: ast::Path,
merge: Option<MergeBehavior>,
) -> SyntaxRewriter<'a> {
let _p = profile::span("insert_use");
let mut rewriter = SyntaxRewriter::default();
let use_item = make::use_(None, make::use_tree(path.clone(), None, None, false));
// merge into existing imports if possible
if let Some(mb) = merge {
for existing_use in scope.as_syntax_node().children().filter_map(ast::Use::cast) {
if let Some(merged) = try_merge_imports(&existing_use, &use_item, mb) {
rewriter.replace(existing_use.syntax(), merged.syntax());
return rewriter;
}
}
}
// either we weren't allowed to merge or there is no import that fits the merge conditions
// so look for the place we have to insert to
let (insert_position, add_blank) = find_insert_position(scope, path);
let indent = if let ident_level @ 1..=usize::MAX = scope.indent_level().0 as usize {
Some(make::tokens::whitespace(&" ".repeat(4 * ident_level)).into())
} else {
None
};
let to_insert: Vec<SyntaxElement> = {
let mut buf = Vec::new();
match add_blank {
AddBlankLine::Before | AddBlankLine::Around => {
buf.push(make::tokens::single_newline().into())
}
AddBlankLine::BeforeTwice => buf.push(make::tokens::blank_line().into()),
_ => (),
}
if add_blank.has_before() {
if let Some(indent) = indent.clone() {
mark::hit!(insert_use_indent_before);
buf.push(indent);
}
}
buf.push(use_item.syntax().clone().into());
match add_blank {
AddBlankLine::After | AddBlankLine::Around => {
buf.push(make::tokens::single_newline().into())
}
AddBlankLine::AfterTwice => buf.push(make::tokens::blank_line().into()),
_ => (),
}
// only add indentation *after* our stuff if there's another node directly after it
if add_blank.has_after() && matches!(insert_position, InsertPosition::Before(_)) {
if let Some(indent) = indent {
mark::hit!(insert_use_indent_after);
buf.push(indent);
}
} else if add_blank.has_after() && matches!(insert_position, InsertPosition::After(_)) {
mark::hit!(insert_use_no_indent_after);
}
buf
};
match insert_position {
InsertPosition::First => {
rewriter.insert_many_as_first_children(scope.as_syntax_node(), to_insert)
}
InsertPosition::Last => return rewriter, // actually unreachable
InsertPosition::Before(anchor) => rewriter.insert_many_before(&anchor, to_insert),
InsertPosition::After(anchor) => rewriter.insert_many_after(&anchor, to_insert),
}
rewriter
}
fn eq_visibility(vis0: Option<ast::Visibility>, vis1: Option<ast::Visibility>) -> bool {
match (vis0, vis1) {
(None, None) => true,
// FIXME: Don't use the string representation to check for equality
// spaces inside of the node would break this comparison
(Some(vis0), Some(vis1)) => vis0.to_string() == vis1.to_string(),
_ => false,
}
}
fn eq_attrs(
attrs0: impl Iterator<Item = ast::Attr>,
attrs1: impl Iterator<Item = ast::Attr>,
) -> bool {
let attrs0 = attrs0.map(|attr| attr.to_string());
let attrs1 = attrs1.map(|attr| attr.to_string());
attrs0.eq(attrs1)
}
pub fn try_merge_imports(
lhs: &ast::Use,
rhs: &ast::Use,
merge_behavior: MergeBehavior,
) -> Option<ast::Use> {
// don't merge imports with different visibilities
if !eq_visibility(lhs.visibility(), rhs.visibility()) {
return None;
}
if !eq_attrs(lhs.attrs(), rhs.attrs()) {
return None;
}
let lhs_tree = lhs.use_tree()?;
let rhs_tree = rhs.use_tree()?;
let merged = try_merge_trees(&lhs_tree, &rhs_tree, merge_behavior)?;
Some(lhs.with_use_tree(merged))
}
pub fn try_merge_trees(
lhs: &ast::UseTree,
rhs: &ast::UseTree,
merge: MergeBehavior,
) -> Option<ast::UseTree> {
let lhs_path = lhs.path()?;
let rhs_path = rhs.path()?;
let (lhs_prefix, rhs_prefix) = common_prefix(&lhs_path, &rhs_path)?;
let (lhs, rhs) = if is_simple_path(lhs)
&& is_simple_path(rhs)
&& lhs_path == lhs_prefix
&& rhs_path == rhs_prefix
{
(lhs.clone(), rhs.clone())
} else {
(lhs.split_prefix(&lhs_prefix), rhs.split_prefix(&rhs_prefix))
};
recursive_merge(&lhs, &rhs, merge)
}
/// Recursively "zips" together lhs and rhs.
fn recursive_merge(
lhs: &ast::UseTree,
rhs: &ast::UseTree,
merge: MergeBehavior,
) -> Option<ast::UseTree> {
let mut use_trees = lhs
.use_tree_list()
.into_iter()
.flat_map(|list| list.use_trees())
// we use Option here to early return from this function(this is not the same as a `filter` op)
.map(|tree| match merge.is_tree_allowed(&tree) {
true => Some(tree),
false => None,
})
.collect::<Option<Vec<_>>>()?;
use_trees.sort_unstable_by(|a, b| path_cmp_for_sort(a.path(), b.path()));
for rhs_t in rhs.use_tree_list().into_iter().flat_map(|list| list.use_trees()) {
if !merge.is_tree_allowed(&rhs_t) {
return None;
}
let rhs_path = rhs_t.path();
match use_trees.binary_search_by(|lhs_t| {
let (lhs_t, rhs_t) = match lhs_t
.path()
.zip(rhs_path.clone())
.and_then(|(lhs, rhs)| common_prefix(&lhs, &rhs))
{
Some((lhs_p, rhs_p)) => (lhs_t.split_prefix(&lhs_p), rhs_t.split_prefix(&rhs_p)),
None => (lhs_t.clone(), rhs_t.clone()),
};
path_cmp_bin_search(lhs_t.path(), rhs_t.path())
}) {
Ok(idx) => {
let lhs_t = &mut use_trees[idx];
let lhs_path = lhs_t.path()?;
let rhs_path = rhs_path?;
let (lhs_prefix, rhs_prefix) = common_prefix(&lhs_path, &rhs_path)?;
if lhs_prefix == lhs_path && rhs_prefix == rhs_path {
let tree_is_self = |tree: ast::UseTree| {
tree.path().as_ref().map(path_is_self).unwrap_or(false)
};
// check if only one of the two trees has a tree list, and whether that then contains `self` or not.
// If this is the case we can skip this iteration since the path without the list is already included in the other one via `self`
let tree_contains_self = |tree: &ast::UseTree| {
tree.use_tree_list()
.map(|tree_list| tree_list.use_trees().any(tree_is_self))
.unwrap_or(false)
};
match (tree_contains_self(&lhs_t), tree_contains_self(&rhs_t)) {
(true, false) => continue,
(false, true) => {
*lhs_t = rhs_t;
continue;
}
_ => (),
}
// glob imports arent part of the use-tree lists so we need to special handle them here as well
// this special handling is only required for when we merge a module import into a glob import of said module
// see the `merge_self_glob` or `merge_mod_into_glob` tests
if lhs_t.star_token().is_some() || rhs_t.star_token().is_some() {
*lhs_t = make::use_tree(
make::path_unqualified(make::path_segment_self()),
None,
None,
false,
);
use_trees.insert(idx, make::glob_use_tree());
continue;
}
if lhs_t.use_tree_list().is_none() && rhs_t.use_tree_list().is_none() {
continue;
}
}
let lhs = lhs_t.split_prefix(&lhs_prefix);
let rhs = rhs_t.split_prefix(&rhs_prefix);
match recursive_merge(&lhs, &rhs, merge) {
Some(use_tree) => use_trees[idx] = use_tree,
None => return None,
}
}
Err(_)
if merge == MergeBehavior::Last
&& use_trees.len() > 0
&& rhs_t.use_tree_list().is_some() =>
{
return None
}
Err(idx) => {
use_trees.insert(idx, rhs_t);
}
}
}
Some(lhs.with_use_tree_list(make::use_tree_list(use_trees)))
}
/// Traverses both paths until they differ, returning the common prefix of both.
fn common_prefix(lhs: &ast::Path, rhs: &ast::Path) -> Option<(ast::Path, ast::Path)> {
let mut res = None;
let mut lhs_curr = first_path(&lhs);
let mut rhs_curr = first_path(&rhs);
loop {
match (lhs_curr.segment(), rhs_curr.segment()) {
(Some(lhs), Some(rhs)) if lhs.syntax().text() == rhs.syntax().text() => (),
_ => break res,
}
res = Some((lhs_curr.clone(), rhs_curr.clone()));
match lhs_curr.parent_path().zip(rhs_curr.parent_path()) {
Some((lhs, rhs)) => {
lhs_curr = lhs;
rhs_curr = rhs;
}
_ => break res,
}
}
}
fn is_simple_path(use_tree: &ast::UseTree) -> bool {
use_tree.use_tree_list().is_none() && use_tree.star_token().is_none()
}
fn path_is_self(path: &ast::Path) -> bool {
path.segment().and_then(|seg| seg.self_token()).is_some() && path.qualifier().is_none()
}
#[inline]
fn first_segment(path: &ast::Path) -> Option<ast::PathSegment> {
first_path(path).segment()
}
fn first_path(path: &ast::Path) -> ast::Path {
successors(Some(path.clone()), ast::Path::qualifier).last().unwrap()
}
fn segment_iter(path: &ast::Path) -> impl Iterator<Item = ast::PathSegment> + Clone {
// cant make use of SyntaxNode::siblings, because the returned Iterator is not clone
successors(first_segment(path), |p| p.parent_path().parent_path().and_then(|p| p.segment()))
}
fn path_len(path: ast::Path) -> usize {
segment_iter(&path).count()
}
/// Orders paths in the following way:
/// the sole self token comes first, after that come uppercase identifiers, then lowercase identifiers
// FIXME: rustfmt sorts lowercase idents before uppercase, in general we want to have the same ordering rustfmt has
// which is `self` and `super` first, then identifier imports with lowercase ones first, then glob imports and at last list imports.
// Example foo::{self, foo, baz, Baz, Qux, *, {Bar}}
fn path_cmp_for_sort(a: Option<ast::Path>, b: Option<ast::Path>) -> Ordering {
match (a, b) {
(None, None) => Ordering::Equal,
(None, Some(_)) => Ordering::Less,
(Some(_), None) => Ordering::Greater,
(Some(ref a), Some(ref b)) => match (path_is_self(a), path_is_self(b)) {
(true, true) => Ordering::Equal,
(true, false) => Ordering::Less,
(false, true) => Ordering::Greater,
(false, false) => path_cmp_short(a, b),
},
}
}
/// Path comparison func for binary searching for merging.
fn path_cmp_bin_search(lhs: Option<ast::Path>, rhs: Option<ast::Path>) -> Ordering {
match (lhs.as_ref().and_then(first_segment), rhs.as_ref().and_then(first_segment)) {
(None, None) => Ordering::Equal,
(None, Some(_)) => Ordering::Less,
(Some(_), None) => Ordering::Greater,
(Some(ref a), Some(ref b)) => path_segment_cmp(a, b),
}
}
/// Short circuiting comparison, if both paths are equal until one of them ends they are considered
/// equal
fn path_cmp_short(a: &ast::Path, b: &ast::Path) -> Ordering {
let a = segment_iter(a);
let b = segment_iter(b);
// cmp_by would be useful for us here but that is currently unstable
// cmp doesnt work due the lifetimes on text's return type
a.zip(b)
.find_map(|(a, b)| match path_segment_cmp(&a, &b) {
Ordering::Equal => None,
ord => Some(ord),
})
.unwrap_or(Ordering::Equal)
}
/// Compares to paths, if one ends earlier than the other the has_tl parameters decide which is
/// greater as a a path that has a tree list should be greater, while one that just ends without
/// a tree list should be considered less.
fn use_tree_path_cmp(a: &ast::Path, a_has_tl: bool, b: &ast::Path, b_has_tl: bool) -> Ordering {
let a_segments = segment_iter(a);
let b_segments = segment_iter(b);
// cmp_by would be useful for us here but that is currently unstable
// cmp doesnt work due the lifetimes on text's return type
a_segments
.zip_longest(b_segments)
.find_map(|zipped| match zipped {
EitherOrBoth::Both(ref a, ref b) => match path_segment_cmp(a, b) {
Ordering::Equal => None,
ord => Some(ord),
},
EitherOrBoth::Left(_) if !b_has_tl => Some(Ordering::Greater),
EitherOrBoth::Left(_) => Some(Ordering::Less),
EitherOrBoth::Right(_) if !a_has_tl => Some(Ordering::Less),
EitherOrBoth::Right(_) => Some(Ordering::Greater),
})
.unwrap_or(Ordering::Equal)
}
fn path_segment_cmp(a: &ast::PathSegment, b: &ast::PathSegment) -> Ordering {
let a = a.kind().and_then(|kind| match kind {
PathSegmentKind::Name(name_ref) => Some(name_ref),
_ => None,
});
let b = b.kind().and_then(|kind| match kind {
PathSegmentKind::Name(name_ref) => Some(name_ref),
_ => None,
});
a.as_ref().map(ast::NameRef::text).cmp(&b.as_ref().map(ast::NameRef::text))
}
/// What type of merges are allowed.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum MergeBehavior {
/// Merge everything together creating deeply nested imports.
Full,
/// Only merge the last import level, doesn't allow import nesting.
Last,
}
impl MergeBehavior {
#[inline]
fn is_tree_allowed(&self, tree: &ast::UseTree) -> bool {
match self {
MergeBehavior::Full => true,
// only simple single segment paths are allowed
MergeBehavior::Last => {
tree.use_tree_list().is_none() && tree.path().map(path_len) <= Some(1)
}
}
}
}
#[derive(Eq, PartialEq, PartialOrd, Ord)]
enum ImportGroup {
// the order here defines the order of new group inserts
Std,
ExternCrate,
ThisCrate,
ThisModule,
SuperModule,
}
impl ImportGroup {
fn new(path: &ast::Path) -> ImportGroup {
let default = ImportGroup::ExternCrate;
let first_segment = match first_segment(path) {
Some(it) => it,
None => return default,
};
let kind = first_segment.kind().unwrap_or(PathSegmentKind::SelfKw);
match kind {
PathSegmentKind::SelfKw => ImportGroup::ThisModule,
PathSegmentKind::SuperKw => ImportGroup::SuperModule,
PathSegmentKind::CrateKw => ImportGroup::ThisCrate,
PathSegmentKind::Name(name) => match name.text().as_str() {
"std" => ImportGroup::Std,
"core" => ImportGroup::Std,
_ => ImportGroup::ExternCrate,
},
PathSegmentKind::Type { .. } => unreachable!(),
}
}
}
#[derive(PartialEq, Eq)]
enum AddBlankLine {
Before,
BeforeTwice,
Around,
After,
AfterTwice,
}
impl AddBlankLine {
fn has_before(&self) -> bool {
matches!(self, AddBlankLine::Before | AddBlankLine::BeforeTwice | AddBlankLine::Around)
}
fn has_after(&self) -> bool {
matches!(self, AddBlankLine::After | AddBlankLine::AfterTwice | AddBlankLine::Around)
}
}
fn find_insert_position(
scope: &ImportScope,
insert_path: ast::Path,
) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
let group = ImportGroup::new(&insert_path);
let path_node_iter = scope
.as_syntax_node()
.children()
.filter_map(|node| ast::Use::cast(node.clone()).zip(Some(node)))
.flat_map(|(use_, node)| {
let tree = use_.use_tree()?;
let path = tree.path()?;
let has_tl = tree.use_tree_list().is_some();
Some((path, has_tl, node))
});
// Iterator that discards anything thats not in the required grouping
// This implementation allows the user to rearrange their import groups as this only takes the first group that fits
let group_iter = path_node_iter
.clone()
.skip_while(|(path, ..)| ImportGroup::new(path) != group)
.take_while(|(path, ..)| ImportGroup::new(path) == group);
// track the last element we iterated over, if this is still None after the iteration then that means we never iterated in the first place
let mut last = None;
// find the element that would come directly after our new import
let post_insert = group_iter.inspect(|(.., node)| last = Some(node.clone())).find(
|&(ref path, has_tl, _)| {
use_tree_path_cmp(&insert_path, false, path, has_tl) != Ordering::Greater
},
);
match post_insert {
// insert our import before that element
Some((.., node)) => (InsertPosition::Before(node.into()), AddBlankLine::After),
// there is no element after our new import, so append it to the end of the group
None => match last {
Some(node) => (InsertPosition::After(node.into()), AddBlankLine::Before),
// the group we were looking for actually doesnt exist, so insert
None => {
// similar concept here to the `last` from above
let mut last = None;
// find the group that comes after where we want to insert
let post_group = path_node_iter
.inspect(|(.., node)| last = Some(node.clone()))
.find(|(p, ..)| ImportGroup::new(p) > group);
match post_group {
Some((.., node)) => {
(InsertPosition::Before(node.into()), AddBlankLine::AfterTwice)
}
// there is no such group, so append after the last one
None => match last {
Some(node) => {
(InsertPosition::After(node.into()), AddBlankLine::BeforeTwice)
}
// there are no imports in this file at all
None => scope.insert_pos_after_last_inner_element(),
},
}
}
},
}
}
#[cfg(test)]
mod tests;