--- /dev/null
+use std::borrow::Cow;
+use std::cmp::Ordering;
+use std::fmt;
+
+use rustc_ast::ast::{self, UseTreeKind};
+use rustc_span::{
+ symbol::{self, sym},
+ BytePos, Span, DUMMY_SP,
+};
+
+use crate::comment::combine_strs_with_missing_comments;
+use crate::config::lists::*;
+use crate::config::{Edition, IndentStyle};
+use crate::lists::{
+ definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator,
+};
+use crate::rewrite::{Rewrite, RewriteContext};
+use crate::shape::Shape;
+use crate::source_map::SpanUtils;
+use crate::spanned::Spanned;
+use crate::utils::{is_same_visibility, mk_sp, rewrite_ident};
+use crate::visitor::FmtVisitor;
+
+/// Returns a name imported by a `use` declaration.
+/// E.g., returns `Ordering` for `std::cmp::Ordering` and `self` for `std::cmp::self`.
+pub(crate) fn path_to_imported_ident(path: &ast::Path) -> symbol::Ident {
+ path.segments.last().unwrap().ident
+}
+
+impl<'a> FmtVisitor<'a> {
+ pub(crate) fn format_import(&mut self, item: &ast::Item, tree: &ast::UseTree) {
+ let span = item.span();
+ let shape = self.shape();
+ let rw = UseTree::from_ast(
+ &self.get_context(),
+ tree,
+ None,
+ Some(item.vis.clone()),
+ Some(item.span.lo()),
+ Some(item.attrs.clone()),
+ )
+ .rewrite_top_level(&self.get_context(), shape);
+ match rw {
+ Some(ref s) if s.is_empty() => {
+ // Format up to last newline
+ let prev_span = mk_sp(self.last_pos, source!(self, span).lo());
+ let trimmed_snippet = self.snippet(prev_span).trim_end();
+ let span_end = self.last_pos + BytePos(trimmed_snippet.len() as u32);
+ self.format_missing(span_end);
+ // We have an excessive newline from the removed import.
+ if self.buffer.ends_with('\n') {
+ self.buffer.pop();
+ self.line_number -= 1;
+ }
+ self.last_pos = source!(self, span).hi();
+ }
+ Some(ref s) => {
+ self.format_missing_with_indent(source!(self, span).lo());
+ self.push_str(s);
+ self.last_pos = source!(self, span).hi();
+ }
+ None => {
+ self.format_missing_with_indent(source!(self, span).lo());
+ self.format_missing(source!(self, span).hi());
+ }
+ }
+ }
+}
+
+// Ordering of imports
+
+// We order imports by translating to our own representation and then sorting.
+// The Rust AST data structures are really bad for this. Rustfmt applies a bunch
+// of normalisations to imports and since we want to sort based on the result
+// of these (and to maintain idempotence) we must apply the same normalisations
+// to the data structures for sorting.
+//
+// We sort `self` and `super` before other imports, then identifier imports,
+// then glob imports, then lists of imports. We do not take aliases into account
+// when ordering unless the imports are identical except for the alias (rare in
+// practice).
+
+// FIXME(#2531): we should unify the comparison code here with the formatting
+// code elsewhere since we are essentially string-ifying twice. Furthermore, by
+// parsing to our own format on comparison, we repeat a lot of work when
+// sorting.
+
+// FIXME we do a lot of allocation to make our own representation.
+#[derive(Clone, Eq, PartialEq)]
+pub(crate) enum UseSegment {
+ Ident(String, Option<String>),
+ Slf(Option<String>),
+ Super(Option<String>),
+ Crate(Option<String>),
+ Glob,
+ List(Vec<UseTree>),
+}
+
+#[derive(Clone)]
+pub(crate) struct UseTree {
+ pub(crate) path: Vec<UseSegment>,
+ pub(crate) span: Span,
+ // Comment information within nested use tree.
+ pub(crate) list_item: Option<ListItem>,
+ // Additional fields for top level use items.
+ // Should we have another struct for top-level use items rather than reusing this?
+ visibility: Option<ast::Visibility>,
+ attrs: Option<Vec<ast::Attribute>>,
+}
+
+impl PartialEq for UseTree {
+ fn eq(&self, other: &UseTree) -> bool {
+ self.path == other.path
+ }
+}
+impl Eq for UseTree {}
+
+impl Spanned for UseTree {
+ fn span(&self) -> Span {
+ let lo = if let Some(ref attrs) = self.attrs {
+ attrs.iter().next().map_or(self.span.lo(), |a| a.span.lo())
+ } else {
+ self.span.lo()
+ };
+ mk_sp(lo, self.span.hi())
+ }
+}
+
+impl UseSegment {
+ // Clone a version of self with any top-level alias removed.
+ fn remove_alias(&self) -> UseSegment {
+ match *self {
+ UseSegment::Ident(ref s, _) => UseSegment::Ident(s.clone(), None),
+ UseSegment::Slf(_) => UseSegment::Slf(None),
+ UseSegment::Super(_) => UseSegment::Super(None),
+ UseSegment::Crate(_) => UseSegment::Crate(None),
+ _ => self.clone(),
+ }
+ }
+
+ fn from_path_segment(
+ context: &RewriteContext<'_>,
+ path_seg: &ast::PathSegment,
+ modsep: bool,
+ ) -> Option<UseSegment> {
+ let name = rewrite_ident(context, path_seg.ident);
+ if name.is_empty() || name == "{{root}}" {
+ return None;
+ }
+ Some(match name {
+ "self" => UseSegment::Slf(None),
+ "super" => UseSegment::Super(None),
+ "crate" => UseSegment::Crate(None),
+ _ => {
+ let mod_sep = if modsep { "::" } else { "" };
+ UseSegment::Ident(format!("{}{}", mod_sep, name), None)
+ }
+ })
+ }
+}
+
+pub(crate) fn merge_use_trees(use_trees: Vec<UseTree>, merge_by: SharedPrefix) -> Vec<UseTree> {
+ let mut result = Vec::with_capacity(use_trees.len());
+ for use_tree in use_trees {
+ if use_tree.has_comment() || use_tree.attrs.is_some() {
+ result.push(use_tree);
+ continue;
+ }
+
+ for flattened in use_tree.flatten() {
+ if let Some(tree) = result
+ .iter_mut()
+ .find(|tree| tree.share_prefix(&flattened, merge_by))
+ {
+ tree.merge(&flattened, merge_by);
+ } else {
+ result.push(flattened);
+ }
+ }
+ }
+ result
+}
+
+pub(crate) fn flatten_use_trees(use_trees: Vec<UseTree>) -> Vec<UseTree> {
+ use_trees
+ .into_iter()
+ .flat_map(UseTree::flatten)
+ .map(|mut tree| {
+ // If a path ends in `::self`, rewrite it to `::{self}`.
+ if let Some(UseSegment::Slf(..)) = tree.path.last() {
+ let self_segment = tree.path.pop().unwrap();
+ tree.path.push(UseSegment::List(vec![UseTree::from_path(
+ vec![self_segment],
+ DUMMY_SP,
+ )]));
+ }
+ tree
+ })
+ .collect()
+}
+
+impl fmt::Debug for UseTree {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ fmt::Display::fmt(self, f)
+ }
+}
+
+impl fmt::Debug for UseSegment {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ fmt::Display::fmt(self, f)
+ }
+}
+
+impl fmt::Display for UseSegment {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ match *self {
+ UseSegment::Glob => write!(f, "*"),
+ UseSegment::Ident(ref s, _) => write!(f, "{}", s),
+ UseSegment::Slf(..) => write!(f, "self"),
+ UseSegment::Super(..) => write!(f, "super"),
+ UseSegment::Crate(..) => write!(f, "crate"),
+ UseSegment::List(ref list) => {
+ write!(f, "{{")?;
+ for (i, item) in list.iter().enumerate() {
+ if i != 0 {
+ write!(f, ", ")?;
+ }
+ write!(f, "{}", item)?;
+ }
+ write!(f, "}}")
+ }
+ }
+ }
+}
+impl fmt::Display for UseTree {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ for (i, segment) in self.path.iter().enumerate() {
+ if i != 0 {
+ write!(f, "::")?;
+ }
+ write!(f, "{}", segment)?;
+ }
+ Ok(())
+ }
+}
+
+impl UseTree {
+ // Rewrite use tree with `use ` and a trailing `;`.
+ pub(crate) fn rewrite_top_level(
+ &self,
+ context: &RewriteContext<'_>,
+ shape: Shape,
+ ) -> Option<String> {
+ let vis = self.visibility.as_ref().map_or(Cow::from(""), |vis| {
+ crate::utils::format_visibility(context, &vis)
+ });
+ let use_str = self
+ .rewrite(context, shape.offset_left(vis.len())?)
+ .map(|s| {
+ if s.is_empty() {
+ s
+ } else {
+ format!("{}use {};", vis, s)
+ }
+ })?;
+ match self.attrs {
+ Some(ref attrs) if !attrs.is_empty() => {
+ let attr_str = attrs.rewrite(context, shape)?;
+ let lo = attrs.last().as_ref()?.span.hi();
+ let hi = self.span.lo();
+ let span = mk_sp(lo, hi);
+
+ let allow_extend = if attrs.len() == 1 {
+ let line_len = attr_str.len() + 1 + use_str.len();
+ !attrs.first().unwrap().is_doc_comment()
+ && context.config.inline_attribute_width() >= line_len
+ } else {
+ false
+ };
+
+ combine_strs_with_missing_comments(
+ context,
+ &attr_str,
+ &use_str,
+ span,
+ shape,
+ allow_extend,
+ )
+ }
+ _ => Some(use_str),
+ }
+ }
+
+ // FIXME: Use correct span?
+ // The given span is essentially incorrect, since we are reconstructing
+ // use-statements. This should not be a problem, though, since we have
+ // already tried to extract comment and observed that there are no comment
+ // around the given use item, and the span will not be used afterward.
+ fn from_path(path: Vec<UseSegment>, span: Span) -> UseTree {
+ UseTree {
+ path,
+ span,
+ list_item: None,
+ visibility: None,
+ attrs: None,
+ }
+ }
+
+ pub(crate) fn from_ast_with_normalization(
+ context: &RewriteContext<'_>,
+ item: &ast::Item,
+ ) -> Option<UseTree> {
+ match item.kind {
+ ast::ItemKind::Use(ref use_tree) => Some(
+ UseTree::from_ast(
+ context,
+ use_tree,
+ None,
+ Some(item.vis.clone()),
+ Some(item.span.lo()),
+ if item.attrs.is_empty() {
+ None
+ } else {
+ Some(item.attrs.clone())
+ },
+ )
+ .normalize(),
+ ),
+ _ => None,
+ }
+ }
+
+ fn from_ast(
+ context: &RewriteContext<'_>,
+ a: &ast::UseTree,
+ list_item: Option<ListItem>,
+ visibility: Option<ast::Visibility>,
+ opt_lo: Option<BytePos>,
+ attrs: Option<Vec<ast::Attribute>>,
+ ) -> UseTree {
+ let span = if let Some(lo) = opt_lo {
+ mk_sp(lo, a.span.hi())
+ } else {
+ a.span
+ };
+ let mut result = UseTree {
+ path: vec![],
+ span,
+ list_item,
+ visibility,
+ attrs,
+ };
+
+ let leading_modsep =
+ context.config.edition() >= Edition::Edition2018 && a.prefix.is_global();
+
+ let mut modsep = leading_modsep;
+
+ for p in &a.prefix.segments {
+ if let Some(use_segment) = UseSegment::from_path_segment(context, p, modsep) {
+ result.path.push(use_segment);
+ modsep = false;
+ }
+ }
+
+ match a.kind {
+ UseTreeKind::Glob => {
+ // in case of a global path and the glob starts at the root, e.g., "::*"
+ if a.prefix.segments.len() == 1 && leading_modsep {
+ result.path.push(UseSegment::Ident("".to_owned(), None));
+ }
+ result.path.push(UseSegment::Glob);
+ }
+ UseTreeKind::Nested(ref list) => {
+ // Extract comments between nested use items.
+ // This needs to be done before sorting use items.
+ let items: Vec<_> = itemize_list(
+ context.snippet_provider,
+ list.iter().map(|(tree, _)| tree),
+ "}",
+ ",",
+ |tree| tree.span.lo(),
+ |tree| tree.span.hi(),
+ |_| Some("".to_owned()), // We only need comments for now.
+ context.snippet_provider.span_after(a.span, "{"),
+ a.span.hi(),
+ false,
+ )
+ .collect();
+ // in case of a global path and the nested list starts at the root,
+ // e.g., "::{foo, bar}"
+ if a.prefix.segments.len() == 1 && leading_modsep {
+ result.path.push(UseSegment::Ident("".to_owned(), None));
+ }
+ result.path.push(UseSegment::List(
+ list.iter()
+ .zip(items.into_iter())
+ .map(|(t, list_item)| {
+ Self::from_ast(context, &t.0, Some(list_item), None, None, None)
+ })
+ .collect(),
+ ));
+ }
+ UseTreeKind::Simple(ref rename, ..) => {
+ // If the path has leading double colons and is composed of only 2 segments, then we
+ // bypass the call to path_to_imported_ident which would get only the ident and
+ // lose the path root, e.g., `that` in `::that`.
+ // The span of `a.prefix` contains the leading colons.
+ let name = if a.prefix.segments.len() == 2 && leading_modsep {
+ context.snippet(a.prefix.span).to_owned()
+ } else {
+ rewrite_ident(context, path_to_imported_ident(&a.prefix)).to_owned()
+ };
+ let alias = rename.and_then(|ident| {
+ if ident.name == sym::underscore_imports {
+ // for impl-only-use
+ Some("_".to_owned())
+ } else if ident == path_to_imported_ident(&a.prefix) {
+ None
+ } else {
+ Some(rewrite_ident(context, ident).to_owned())
+ }
+ });
+ let segment = match name.as_ref() {
+ "self" => UseSegment::Slf(alias),
+ "super" => UseSegment::Super(alias),
+ "crate" => UseSegment::Crate(alias),
+ _ => UseSegment::Ident(name, alias),
+ };
+
+ // `name` is already in result.
+ result.path.pop();
+ result.path.push(segment);
+ }
+ }
+ result
+ }
+
+ // Do the adjustments that rustfmt does elsewhere to use paths.
+ pub(crate) fn normalize(mut self) -> UseTree {
+ let mut last = self.path.pop().expect("Empty use tree?");
+ // Hack around borrow checker.
+ let mut normalize_sole_list = false;
+ let mut aliased_self = false;
+
+ // Remove foo::{} or self without attributes.
+ match last {
+ _ if self.attrs.is_some() => (),
+ UseSegment::List(ref list) if list.is_empty() => {
+ self.path = vec![];
+ return self;
+ }
+ UseSegment::Slf(None) if self.path.is_empty() && self.visibility.is_some() => {
+ self.path = vec![];
+ return self;
+ }
+ _ => (),
+ }
+
+ // Normalise foo::self -> foo.
+ if let UseSegment::Slf(None) = last {
+ if !self.path.is_empty() {
+ return self;
+ }
+ }
+
+ // Normalise foo::self as bar -> foo as bar.
+ if let UseSegment::Slf(_) = last {
+ match self.path.last() {
+ Some(UseSegment::Ident(_, None)) => {
+ aliased_self = true;
+ }
+ _ => {}
+ }
+ }
+
+ let mut done = false;
+ if aliased_self {
+ match self.path.last_mut() {
+ Some(UseSegment::Ident(_, ref mut old_rename)) => {
+ assert!(old_rename.is_none());
+ if let UseSegment::Slf(Some(rename)) = last.clone() {
+ *old_rename = Some(rename);
+ done = true;
+ }
+ }
+ _ => unreachable!(),
+ }
+ }
+
+ if done {
+ return self;
+ }
+
+ // Normalise foo::{bar} -> foo::bar
+ if let UseSegment::List(ref list) = last {
+ if list.len() == 1 && list[0].to_string() != "self" {
+ normalize_sole_list = true;
+ }
+ }
+
+ if normalize_sole_list {
+ match last {
+ UseSegment::List(list) => {
+ for seg in &list[0].path {
+ self.path.push(seg.clone());
+ }
+ return self.normalize();
+ }
+ _ => unreachable!(),
+ }
+ }
+
+ // Recursively normalize elements of a list use (including sorting the list).
+ if let UseSegment::List(list) = last {
+ let mut list = list.into_iter().map(UseTree::normalize).collect::<Vec<_>>();
+ list.sort();
+ last = UseSegment::List(list);
+ }
+
+ self.path.push(last);
+ self
+ }
+
+ fn has_comment(&self) -> bool {
+ self.list_item.as_ref().map_or(false, ListItem::has_comment)
+ }
+
+ fn same_visibility(&self, other: &UseTree) -> bool {
+ match (&self.visibility, &other.visibility) {
+ (
+ Some(ast::Visibility {
+ kind: ast::VisibilityKind::Inherited,
+ ..
+ }),
+ None,
+ )
+ | (
+ None,
+ Some(ast::Visibility {
+ kind: ast::VisibilityKind::Inherited,
+ ..
+ }),
+ )
+ | (None, None) => true,
+ (Some(ref a), Some(ref b)) => is_same_visibility(a, b),
+ _ => false,
+ }
+ }
+
+ fn share_prefix(&self, other: &UseTree, shared_prefix: SharedPrefix) -> bool {
+ if self.path.is_empty()
+ || other.path.is_empty()
+ || self.attrs.is_some()
+ || !self.same_visibility(other)
+ {
+ false
+ } else {
+ match shared_prefix {
+ SharedPrefix::Crate => self.path[0] == other.path[0],
+ SharedPrefix::Module => {
+ self.path[..self.path.len() - 1] == other.path[..other.path.len() - 1]
+ }
+ }
+ }
+ }
+
+ fn flatten(self) -> Vec<UseTree> {
+ if self.path.is_empty() {
+ return vec![self];
+ }
+ match self.path.clone().last().unwrap() {
+ UseSegment::List(list) => {
+ if list.len() == 1 && list[0].path.len() == 1 {
+ match list[0].path[0] {
+ UseSegment::Slf(..) => return vec![self],
+ _ => (),
+ };
+ }
+ let prefix = &self.path[..self.path.len() - 1];
+ let mut result = vec![];
+ for nested_use_tree in list {
+ for flattend in &mut nested_use_tree.clone().flatten() {
+ let mut new_path = prefix.to_vec();
+ new_path.append(&mut flattend.path);
+ result.push(UseTree {
+ path: new_path,
+ span: self.span,
+ list_item: None,
+ visibility: self.visibility.clone(),
+ attrs: None,
+ });
+ }
+ }
+
+ result
+ }
+ _ => vec![self],
+ }
+ }
+
+ fn merge(&mut self, other: &UseTree, merge_by: SharedPrefix) {
+ let mut prefix = 0;
+ for (a, b) in self.path.iter().zip(other.path.iter()) {
+ if *a == *b {
+ prefix += 1;
+ } else {
+ break;
+ }
+ }
+ if let Some(new_path) = merge_rest(&self.path, &other.path, prefix, merge_by) {
+ self.path = new_path;
+ self.span = self.span.to(other.span);
+ }
+ }
+}
+
+fn merge_rest(
+ a: &[UseSegment],
+ b: &[UseSegment],
+ mut len: usize,
+ merge_by: SharedPrefix,
+) -> Option<Vec<UseSegment>> {
+ if a.len() == len && b.len() == len {
+ return None;
+ }
+ if a.len() != len && b.len() != len {
+ if let UseSegment::List(ref list) = a[len] {
+ let mut list = list.clone();
+ merge_use_trees_inner(
+ &mut list,
+ UseTree::from_path(b[len..].to_vec(), DUMMY_SP),
+ merge_by,
+ );
+ let mut new_path = b[..len].to_vec();
+ new_path.push(UseSegment::List(list));
+ return Some(new_path);
+ }
+ } else if len == 1 {
+ let rest = if a.len() == len { &b[1..] } else { &a[1..] };
+ return Some(vec![
+ b[0].clone(),
+ UseSegment::List(vec![
+ UseTree::from_path(vec![UseSegment::Slf(None)], DUMMY_SP),
+ UseTree::from_path(rest.to_vec(), DUMMY_SP),
+ ]),
+ ]);
+ } else {
+ len -= 1;
+ }
+ let mut list = vec![
+ UseTree::from_path(a[len..].to_vec(), DUMMY_SP),
+ UseTree::from_path(b[len..].to_vec(), DUMMY_SP),
+ ];
+ list.sort();
+ let mut new_path = b[..len].to_vec();
+ new_path.push(UseSegment::List(list));
+ Some(new_path)
+}
+
+fn merge_use_trees_inner(trees: &mut Vec<UseTree>, use_tree: UseTree, merge_by: SharedPrefix) {
+ let similar_trees = trees
+ .iter_mut()
+ .filter(|tree| tree.share_prefix(&use_tree, merge_by));
+ if use_tree.path.len() == 1 && merge_by == SharedPrefix::Crate {
+ if let Some(tree) = similar_trees.min_by_key(|tree| tree.path.len()) {
+ if tree.path.len() == 1 {
+ return;
+ }
+ }
+ } else if let Some(tree) = similar_trees.max_by_key(|tree| tree.path.len()) {
+ if tree.path.len() > 1 {
+ tree.merge(&use_tree, merge_by);
+ return;
+ }
+ }
+ trees.push(use_tree);
+ trees.sort();
+}
+
+impl PartialOrd for UseSegment {
+ fn partial_cmp(&self, other: &UseSegment) -> Option<Ordering> {
+ Some(self.cmp(other))
+ }
+}
+impl PartialOrd for UseTree {
+ fn partial_cmp(&self, other: &UseTree) -> Option<Ordering> {
+ Some(self.cmp(other))
+ }
+}
+impl Ord for UseSegment {
+ fn cmp(&self, other: &UseSegment) -> Ordering {
+ use self::UseSegment::*;
+
+ fn is_upper_snake_case(s: &str) -> bool {
+ s.chars()
+ .all(|c| c.is_uppercase() || c == '_' || c.is_numeric())
+ }
+
+ match (self, other) {
+ (&Slf(ref a), &Slf(ref b))
+ | (&Super(ref a), &Super(ref b))
+ | (&Crate(ref a), &Crate(ref b)) => a.cmp(b),
+ (&Glob, &Glob) => Ordering::Equal,
+ (&Ident(ref ia, ref aa), &Ident(ref ib, ref ab)) => {
+ // snake_case < CamelCase < UPPER_SNAKE_CASE
+ if ia.starts_with(char::is_uppercase) && ib.starts_with(char::is_lowercase) {
+ return Ordering::Greater;
+ }
+ if ia.starts_with(char::is_lowercase) && ib.starts_with(char::is_uppercase) {
+ return Ordering::Less;
+ }
+ if is_upper_snake_case(ia) && !is_upper_snake_case(ib) {
+ return Ordering::Greater;
+ }
+ if !is_upper_snake_case(ia) && is_upper_snake_case(ib) {
+ return Ordering::Less;
+ }
+ let ident_ord = ia.cmp(ib);
+ if ident_ord != Ordering::Equal {
+ return ident_ord;
+ }
+ if aa.is_none() && ab.is_some() {
+ return Ordering::Less;
+ }
+ if aa.is_some() && ab.is_none() {
+ return Ordering::Greater;
+ }
+ aa.cmp(ab)
+ }
+ (&List(ref a), &List(ref b)) => {
+ for (a, b) in a.iter().zip(b.iter()) {
+ let ord = a.cmp(b);
+ if ord != Ordering::Equal {
+ return ord;
+ }
+ }
+
+ a.len().cmp(&b.len())
+ }
+ (&Slf(_), _) => Ordering::Less,
+ (_, &Slf(_)) => Ordering::Greater,
+ (&Super(_), _) => Ordering::Less,
+ (_, &Super(_)) => Ordering::Greater,
+ (&Crate(_), _) => Ordering::Less,
+ (_, &Crate(_)) => Ordering::Greater,
+ (&Ident(..), _) => Ordering::Less,
+ (_, &Ident(..)) => Ordering::Greater,
+ (&Glob, _) => Ordering::Less,
+ (_, &Glob) => Ordering::Greater,
+ }
+ }
+}
+impl Ord for UseTree {
+ fn cmp(&self, other: &UseTree) -> Ordering {
+ for (a, b) in self.path.iter().zip(other.path.iter()) {
+ let ord = a.cmp(b);
+ // The comparison without aliases is a hack to avoid situations like
+ // comparing `a::b` to `a as c` - where the latter should be ordered
+ // first since it is shorter.
+ if ord != Ordering::Equal && a.remove_alias().cmp(&b.remove_alias()) != Ordering::Equal
+ {
+ return ord;
+ }
+ }
+
+ self.path.len().cmp(&other.path.len())
+ }
+}
+
+fn rewrite_nested_use_tree(
+ context: &RewriteContext<'_>,
+ use_tree_list: &[UseTree],
+ shape: Shape,
+) -> Option<String> {
+ let mut list_items = Vec::with_capacity(use_tree_list.len());
+ let nested_shape = match context.config.imports_indent() {
+ IndentStyle::Block => shape
+ .block_indent(context.config.tab_spaces())
+ .with_max_width(context.config)
+ .sub_width(1)?,
+ IndentStyle::Visual => shape.visual_indent(0),
+ };
+ for use_tree in use_tree_list {
+ if let Some(mut list_item) = use_tree.list_item.clone() {
+ list_item.item = use_tree.rewrite(context, nested_shape);
+ list_items.push(list_item);
+ } else {
+ list_items.push(ListItem::from_str(use_tree.rewrite(context, nested_shape)?));
+ }
+ }
+ let has_nested_list = use_tree_list.iter().any(|use_segment| {
+ use_segment
+ .path
+ .last()
+ .map_or(false, |last_segment| match last_segment {
+ UseSegment::List(..) => true,
+ _ => false,
+ })
+ });
+
+ let remaining_width = if has_nested_list {
+ 0
+ } else {
+ shape.width.saturating_sub(2)
+ };
+
+ let tactic = definitive_tactic(
+ &list_items,
+ context.config.imports_layout(),
+ Separator::Comma,
+ remaining_width,
+ );
+
+ let ends_with_newline = context.config.imports_indent() == IndentStyle::Block
+ && tactic != DefinitiveListTactic::Horizontal;
+ let trailing_separator = if ends_with_newline {
+ context.config.trailing_comma()
+ } else {
+ SeparatorTactic::Never
+ };
+ let fmt = ListFormatting::new(nested_shape, context.config)
+ .tactic(tactic)
+ .trailing_separator(trailing_separator)
+ .ends_with_newline(ends_with_newline)
+ .preserve_newline(true)
+ .nested(has_nested_list);
+
+ let list_str = write_list(&list_items, &fmt)?;
+
+ let result = if (list_str.contains('\n') || list_str.len() > remaining_width)
+ && context.config.imports_indent() == IndentStyle::Block
+ {
+ format!(
+ "{{\n{}{}\n{}}}",
+ nested_shape.indent.to_string(context.config),
+ list_str,
+ shape.indent.to_string(context.config)
+ )
+ } else {
+ format!("{{{}}}", list_str)
+ };
+
+ Some(result)
+}
+
+impl Rewrite for UseSegment {
+ fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+ Some(match self {
+ UseSegment::Ident(ref ident, Some(ref rename)) => format!("{} as {}", ident, rename),
+ UseSegment::Ident(ref ident, None) => ident.clone(),
+ UseSegment::Slf(Some(ref rename)) => format!("self as {}", rename),
+ UseSegment::Slf(None) => "self".to_owned(),
+ UseSegment::Super(Some(ref rename)) => format!("super as {}", rename),
+ UseSegment::Super(None) => "super".to_owned(),
+ UseSegment::Crate(Some(ref rename)) => format!("crate as {}", rename),
+ UseSegment::Crate(None) => "crate".to_owned(),
+ UseSegment::Glob => "*".to_owned(),
+ UseSegment::List(ref use_tree_list) => rewrite_nested_use_tree(
+ context,
+ use_tree_list,
+ // 1 = "{" and "}"
+ shape.offset_left(1)?.sub_width(1)?,
+ )?,
+ })
+ }
+}
+
+impl Rewrite for UseTree {
+ // This does NOT format attributes and visibility or add a trailing `;`.
+ fn rewrite(&self, context: &RewriteContext<'_>, mut shape: Shape) -> Option<String> {
+ let mut result = String::with_capacity(256);
+ let mut iter = self.path.iter().peekable();
+ while let Some(ref segment) = iter.next() {
+ let segment_str = segment.rewrite(context, shape)?;
+ result.push_str(&segment_str);
+ if iter.peek().is_some() {
+ result.push_str("::");
+ // 2 = "::"
+ shape = shape.offset_left(2 + segment_str.len())?;
+ }
+ }
+ Some(result)
+ }
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub(crate) enum SharedPrefix {
+ Crate,
+ Module,
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+ use rustc_span::DUMMY_SP;
+
+ // Parse the path part of an import. This parser is not robust and is only
+ // suitable for use in a test harness.
+ fn parse_use_tree(s: &str) -> UseTree {
+ use std::iter::Peekable;
+ use std::mem::swap;
+ use std::str::Chars;
+
+ struct Parser<'a> {
+ input: Peekable<Chars<'a>>,
+ }
+
+ impl<'a> Parser<'a> {
+ fn bump(&mut self) {
+ self.input.next().unwrap();
+ }
+
+ fn eat(&mut self, c: char) {
+ assert!(self.input.next().unwrap() == c);
+ }
+
+ fn push_segment(
+ result: &mut Vec<UseSegment>,
+ buf: &mut String,
+ alias_buf: &mut Option<String>,
+ ) {
+ if !buf.is_empty() {
+ let mut alias = None;
+ swap(alias_buf, &mut alias);
+
+ match buf.as_ref() {
+ "self" => {
+ result.push(UseSegment::Slf(alias));
+ *buf = String::new();
+ *alias_buf = None;
+ }
+ "super" => {
+ result.push(UseSegment::Super(alias));
+ *buf = String::new();
+ *alias_buf = None;
+ }
+ "crate" => {
+ result.push(UseSegment::Crate(alias));
+ *buf = String::new();
+ *alias_buf = None;
+ }
+ _ => {
+ let mut name = String::new();
+ swap(buf, &mut name);
+ result.push(UseSegment::Ident(name, alias));
+ }
+ }
+ }
+ }
+
+ fn parse_in_list(&mut self) -> UseTree {
+ let mut result = vec![];
+ let mut buf = String::new();
+ let mut alias_buf = None;
+ while let Some(&c) = self.input.peek() {
+ match c {
+ '{' => {
+ assert!(buf.is_empty());
+ self.bump();
+ result.push(UseSegment::List(self.parse_list()));
+ self.eat('}');
+ }
+ '*' => {
+ assert!(buf.is_empty());
+ self.bump();
+ result.push(UseSegment::Glob);
+ }
+ ':' => {
+ self.bump();
+ self.eat(':');
+ Self::push_segment(&mut result, &mut buf, &mut alias_buf);
+ }
+ '}' | ',' => {
+ Self::push_segment(&mut result, &mut buf, &mut alias_buf);
+ return UseTree {
+ path: result,
+ span: DUMMY_SP,
+ list_item: None,
+ visibility: None,
+ attrs: None,
+ };
+ }
+ ' ' => {
+ self.bump();
+ self.eat('a');
+ self.eat('s');
+ self.eat(' ');
+ alias_buf = Some(String::new());
+ }
+ c => {
+ self.bump();
+ if let Some(ref mut buf) = alias_buf {
+ buf.push(c);
+ } else {
+ buf.push(c);
+ }
+ }
+ }
+ }
+ Self::push_segment(&mut result, &mut buf, &mut alias_buf);
+ UseTree {
+ path: result,
+ span: DUMMY_SP,
+ list_item: None,
+ visibility: None,
+ attrs: None,
+ }
+ }
+
+ fn parse_list(&mut self) -> Vec<UseTree> {
+ let mut result = vec![];
+ loop {
+ match self.input.peek().unwrap() {
+ ',' | ' ' => self.bump(),
+ '}' => {
+ return result;
+ }
+ _ => result.push(self.parse_in_list()),
+ }
+ }
+ }
+ }
+
+ let mut parser = Parser {
+ input: s.chars().peekable(),
+ };
+ parser.parse_in_list()
+ }
+
+ macro_rules! parse_use_trees {
+ ($($s:expr),* $(,)*) => {
+ vec![
+ $(parse_use_tree($s),)*
+ ]
+ }
+ }
+
+ macro_rules! test_merge {
+ ($by:ident, [$($input:expr),* $(,)*], [$($output:expr),* $(,)*]) => {
+ assert_eq!(
+ merge_use_trees(parse_use_trees!($($input,)*), SharedPrefix::$by),
+ parse_use_trees!($($output,)*),
+ );
+ }
+ }
+
+ #[test]
+ fn test_use_tree_merge_crate() {
+ test_merge!(
+ Crate,
+ ["a::b::{c, d}", "a::b::{e, f}"],
+ ["a::b::{c, d, e, f}"]
+ );
+ test_merge!(Crate, ["a::b::c", "a::b"], ["a::{b, b::c}"]);
+ test_merge!(Crate, ["a::b", "a::b"], ["a::b"]);
+ test_merge!(Crate, ["a", "a::b", "a::b::c"], ["a::{self, b, b::c}"]);
+ test_merge!(
+ Crate,
+ ["a", "a::b", "a::b::c", "a::b::c::d"],
+ ["a::{self, b, b::{c, c::d}}"]
+ );
+ test_merge!(
+ Crate,
+ ["a", "a::b", "a::b::c", "a::b"],
+ ["a::{self, b, b::c}"]
+ );
+ test_merge!(
+ Crate,
+ ["a::{b::{self, c}, d::e}", "a::d::f"],
+ ["a::{b::{self, c}, d::{e, f}}"]
+ );
+ test_merge!(
+ Crate,
+ ["a::d::f", "a::{b::{self, c}, d::e}"],
+ ["a::{b::{self, c}, d::{e, f}}"]
+ );
+ test_merge!(
+ Crate,
+ ["a::{c, d, b}", "a::{d, e, b, a, f}", "a::{f, g, c}"],
+ ["a::{a, b, c, d, e, f, g}"]
+ );
+ test_merge!(
+ Crate,
+ ["a::{self}", "b::{self as foo}"],
+ ["a::{self}", "b::{self as foo}"]
+ );
+ }
+
+ #[test]
+ fn test_use_tree_merge_module() {
+ test_merge!(
+ Module,
+ ["foo::b", "foo::{a, c, d::e}"],
+ ["foo::{a, b, c}", "foo::d::e"]
+ );
+
+ test_merge!(
+ Module,
+ ["foo::{a::b, a::c, d::e, d::f}"],
+ ["foo::a::{b, c}", "foo::d::{e, f}"]
+ );
+ }
+
+ #[test]
+ fn test_flatten_use_trees() {
+ assert_eq!(
+ flatten_use_trees(parse_use_trees!["foo::{a::{b, c}, d::e}"]),
+ parse_use_trees!["foo::a::b", "foo::a::c", "foo::d::e"]
+ );
+
+ assert_eq!(
+ flatten_use_trees(parse_use_trees!["foo::{self, a, b::{c, d}, e::*}"]),
+ parse_use_trees![
+ "foo::{self}",
+ "foo::a",
+ "foo::b::c",
+ "foo::b::d",
+ "foo::e::*"
+ ]
+ );
+ }
+
+ #[test]
+ fn test_use_tree_flatten() {
+ assert_eq!(
+ parse_use_tree("a::b::{c, d, e, f}").flatten(),
+ parse_use_trees!("a::b::c", "a::b::d", "a::b::e", "a::b::f",)
+ );
+
+ assert_eq!(
+ parse_use_tree("a::b::{c::{d, e, f}, g, h::{i, j, k}}").flatten(),
+ parse_use_trees![
+ "a::b::c::d",
+ "a::b::c::e",
+ "a::b::c::f",
+ "a::b::g",
+ "a::b::h::i",
+ "a::b::h::j",
+ "a::b::h::k",
+ ]
+ );
+ }
+
+ #[test]
+ fn test_use_tree_normalize() {
+ assert_eq!(parse_use_tree("a::self").normalize(), parse_use_tree("a"));
+ assert_eq!(
+ parse_use_tree("a::self as foo").normalize(),
+ parse_use_tree("a as foo")
+ );
+ assert_eq!(
+ parse_use_tree("a::{self}").normalize(),
+ parse_use_tree("a::{self}")
+ );
+ assert_eq!(parse_use_tree("a::{b}").normalize(), parse_use_tree("a::b"));
+ assert_eq!(
+ parse_use_tree("a::{b, c::self}").normalize(),
+ parse_use_tree("a::{b, c}")
+ );
+ assert_eq!(
+ parse_use_tree("a::{b as bar, c::self}").normalize(),
+ parse_use_tree("a::{b as bar, c}")
+ );
+ }
+
+ #[test]
+ fn test_use_tree_ord() {
+ assert!(parse_use_tree("a").normalize() < parse_use_tree("aa").normalize());
+ assert!(parse_use_tree("a").normalize() < parse_use_tree("a::a").normalize());
+ assert!(parse_use_tree("a").normalize() < parse_use_tree("*").normalize());
+ assert!(parse_use_tree("a").normalize() < parse_use_tree("{a, b}").normalize());
+ assert!(parse_use_tree("*").normalize() < parse_use_tree("{a, b}").normalize());
+
+ assert!(
+ parse_use_tree("aaaaaaaaaaaaaaa::{bb, cc, dddddddd}").normalize()
+ < parse_use_tree("aaaaaaaaaaaaaaa::{bb, cc, ddddddddd}").normalize()
+ );
+ assert!(
+ parse_use_tree("serde::de::{Deserialize}").normalize()
+ < parse_use_tree("serde_json").normalize()
+ );
+ assert!(parse_use_tree("a::b::c").normalize() < parse_use_tree("a::b::*").normalize());
+ assert!(
+ parse_use_tree("foo::{Bar, Baz}").normalize()
+ < parse_use_tree("{Bar, Baz}").normalize()
+ );
+
+ assert!(
+ parse_use_tree("foo::{qux as bar}").normalize()
+ < parse_use_tree("foo::{self as bar}").normalize()
+ );
+ assert!(
+ parse_use_tree("foo::{qux as bar}").normalize()
+ < parse_use_tree("foo::{baz, qux as bar}").normalize()
+ );
+ assert!(
+ parse_use_tree("foo::{self as bar, baz}").normalize()
+ < parse_use_tree("foo::{baz, qux as bar}").normalize()
+ );
+
+ assert!(parse_use_tree("foo").normalize() < parse_use_tree("Foo").normalize());
+ assert!(parse_use_tree("foo").normalize() < parse_use_tree("foo::Bar").normalize());
+
+ assert!(
+ parse_use_tree("std::cmp::{d, c, b, a}").normalize()
+ < parse_use_tree("std::cmp::{b, e, g, f}").normalize()
+ );
+ }
+}
projects / rustc.git / blobdiff