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Split impl at 'for' if a line break is needed (#1148)

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* Split impl at 'for' if a line break is needed

* Fix formatting

* Improve comments

* Skip second try if there is no 'for'

* Restore intentional trailing whitespace

* Change test source to be incorrectly formatted

* Restore more missing trailing whitespace

* Remove too much whitespace...

Really should learn how to use git revert.
This commit is contained in:
dawirstejeck 2016-09-06 07:11:56 +02:00 committed by Nick Cameron
parent df173c2885
commit a5d7073bf5
3 changed files with 87 additions and 47 deletions
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127
src/items.rs
View File

@ -446,58 +446,21 @@ fn format_variant(&self, field: &ast::Variant) -> Option<String> {
}
pub fn format_impl(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
if let ast::ItemKind::Impl(unsafety,
polarity,
ref generics,
ref trait_ref,
ref self_ty,
ref items) = item.node {
if let ast::ItemKind::Impl(_, _, ref generics, ref trait_ref, _, ref items) = item.node {
let mut result = String::new();
result.push_str(&*format_visibility(&item.vis));
result.push_str(format_unsafety(unsafety));
result.push_str("impl");
// First try to format the ref and type without a split at the 'for'.
let mut ref_and_type = try_opt!(format_impl_ref_and_type(context, item, offset, false));
let lo = context.codemap.span_after(item.span, "impl");
let hi = match *trait_ref {
Some(ref tr) => tr.path.span.lo,
None => self_ty.span.lo,
};
let generics_str = try_opt!(rewrite_generics(context,
generics,
offset,
context.config.max_width,
offset + result.len(),
mk_sp(lo, hi)));
result.push_str(&generics_str);
// FIXME might need to linebreak in the impl header, here would be a
// good place.
result.push(' ');
if polarity == ast::ImplPolarity::Negative {
result.push_str("!");
}
if let Some(ref trait_ref) = *trait_ref {
let budget = try_opt!(context.config.max_width.checked_sub(result.len()));
let indent = offset + result.len();
result.push_str(&*try_opt!(trait_ref.rewrite(context, budget, indent)));
result.push_str(" for ");
}
let mut used_space = result.len();
if generics.where_clause.predicates.is_empty() {
// If there is no where clause adapt budget for type formatting to take space and curly
// brace into account.
match context.config.item_brace_style {
BraceStyle::AlwaysNextLine => {}
BraceStyle::PreferSameLine => used_space += 2,
BraceStyle::SameLineWhere => used_space += 2,
// If there is a line break present in the first result format it again
// with a split at the 'for'. Skip this if there is no trait ref and
// therefore no 'for'.
if let Some(_) = *trait_ref {
if ref_and_type.contains('\n') {
ref_and_type = try_opt!(format_impl_ref_and_type(context, item, offset, true));
}
}
let budget = try_opt!(context.config.max_width.checked_sub(used_space));
let indent = offset + result.len();
result.push_str(&*try_opt!(self_ty.rewrite(context, budget, indent)));
result.push_str(&ref_and_type);
let where_budget = try_opt!(context.config.max_width.checked_sub(last_line_width(&result)));
let where_clause_str = try_opt!(rewrite_where_clause(context,
@ -594,6 +557,76 @@ fn is_impl_single_line(context: &RewriteContext,
!contains_comment(&snippet[open_pos..]))
}
fn format_impl_ref_and_type(context: &RewriteContext,
item: &ast::Item,
offset: Indent,
split_at_for: bool)
-> Option<String> {
if let ast::ItemKind::Impl(unsafety, polarity, ref generics, ref trait_ref, ref self_ty, _) =
item.node {
let mut result = String::new();
result.push_str(&*format_visibility(&item.vis));
result.push_str(format_unsafety(unsafety));
result.push_str("impl");
let lo = context.codemap.span_after(item.span, "impl");
let hi = match *trait_ref {
Some(ref tr) => tr.path.span.lo,
None => self_ty.span.lo,
};
let generics_str = try_opt!(rewrite_generics(context,
generics,
offset,
context.config.max_width,
offset + result.len(),
mk_sp(lo, hi)));
result.push_str(&generics_str);
result.push(' ');
if polarity == ast::ImplPolarity::Negative {
result.push('!');
}
if let Some(ref trait_ref) = *trait_ref {
let budget = try_opt!(context.config.max_width.checked_sub(result.len()));
let indent = offset + result.len();
result.push_str(&*try_opt!(trait_ref.rewrite(context, budget, indent)));
if split_at_for {
result.push('\n');
// Add indentation of one additional tab.
let width = context.block_indent.width() + context.config.tab_spaces;
let for_indent = Indent::new(0, width);
result.push_str(&for_indent.to_string(context.config));
result.push_str("for ");
} else {
result.push_str(" for ");
}
}
let mut used_space = last_line_width(&result);
if generics.where_clause.predicates.is_empty() {
// If there is no where clause adapt budget for type formatting to take space and curly
// brace into account.
match context.config.item_brace_style {
BraceStyle::AlwaysNextLine => {}
BraceStyle::PreferSameLine => used_space += 2,
BraceStyle::SameLineWhere => used_space += 2,
}
}
let budget = try_opt!(context.config.max_width.checked_sub(used_space));
let indent = offset + result.len();
result.push_str(&*try_opt!(self_ty.rewrite(context, budget, indent)));
Some(result)
} else {
unreachable!();
}
}
pub fn format_struct(context: &RewriteContext,
item_name: &str,
ident: ast::Ident,

3
tests/source/impls.rs
View File

@ -100,3 +100,6 @@ impl<T> PartialEq for S<T> where T: PartialEq { }
impl<BorrowType, K, V, NodeType, HandleType> Handle<NodeRef<BorrowType, K, V, NodeType>, HandleType> {
}
impl<BorrowType, K, V, NodeType, HandleType> PartialEq for Handle<NodeRef<BorrowType, K, V, NodeType>, HandleType> {
}

4
tests/target/impls.rs
View File

@ -128,3 +128,7 @@ impl<T> PartialEq for S<T> where T: PartialEq {}
impl<BorrowType, K, V, NodeType, HandleType> Handle<NodeRef<BorrowType, K, V, NodeType>,
HandleType> {
}
impl<BorrowType, K, V, NodeType, HandleType> PartialEq
for Handle<NodeRef<BorrowType, K, V, NodeType>, HandleType> {
}