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refactor: dedupe & simplify ty alias formatting
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@calebcartwright
calebcartwright committed Nov 6, 2021
1 parent 4d50e7c commit 19c5c74
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Showing 2 changed files with 96 additions and 149 deletions.
164 changes: 73 additions & 91 deletions src/items.rs
View file
Expand Up @@ -1185,18 +1185,6 @@ pub(crate) fn format_trait(
}
}

struct OpaqueTypeBounds<'a> {
generic_bounds: &'a ast::GenericBounds,
}

impl<'a> Rewrite for OpaqueTypeBounds<'a> {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
self.generic_bounds
.rewrite(context, shape)
.map(|s| format!("impl {}", s))
}
}

pub(crate) struct TraitAliasBounds<'a> {
generic_bounds: &'a ast::GenericBounds,
generics: &'a ast::Generics,
Expand Down Expand Up @@ -1518,17 +1506,79 @@ fn format_tuple_struct(
Some(result)
}

pub(crate) fn rewrite_type<R: Rewrite>(
context: &RewriteContext<'_>,
pub(crate) enum ItemVisitorKind<'a> {
Item(&'a ast::Item),
AssocTraitItem(&'a ast::AssocItem),
AssocImplItem(&'a ast::AssocItem),
ForeignItem(&'a ast::ForeignItem),
}

struct TyAliasRewriteInfo<'c, 'g>(
&'c RewriteContext<'c>,
Indent,
&'g ast::Generics,
symbol::Ident,
Span,
);

pub(crate) fn rewrite_type_alias<'a, 'b>(
ty_alias_kind: &ast::TyAliasKind,
context: &RewriteContext<'a>,
indent: Indent,
ident: symbol::Ident,
vis: &ast::Visibility,
generics: &ast::Generics,
visitor_kind: &ItemVisitorKind<'b>,
span: Span,
) -> Option<String> {
use ItemVisitorKind::*;

let ast::TyAliasKind(defaultness, ref generics, ref generic_bounds, ref ty) = *ty_alias_kind;
let ty_opt = ty.as_ref().map(|t| &**t);
let (ident, vis) = match visitor_kind {
Item(i) => (i.ident, &i.vis),
AssocTraitItem(i) | AssocImplItem(i) => (i.ident, &i.vis),
ForeignItem(i) => (i.ident, &i.vis),
};
let rw_info = &TyAliasRewriteInfo(context, indent, generics, ident, span);

// Type Aliases are formatted slightly differently depending on the context
// in which they appear, whether they are opaque, and whether they are associated.
// https://rustc-dev-guide.rust-lang.org/opaque-types-type-alias-impl-trait.html
// https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/items.md#type-aliases
match (visitor_kind, ty_opt) {
(Item(_), None) => {
let op_ty = OpaqueType { generic_bounds };
rewrite_ty(rw_info, Some(generic_bounds), Some(&op_ty), vis)
}
(Item(_), Some(ty)) => rewrite_ty(rw_info, Some(generic_bounds), Some(&*ty), vis),
(AssocImplItem(_), _) => {
let result = if let Some(ast::Ty {
kind: ast::TyKind::ImplTrait(_, ref generic_bounds),
..
}) = ty_opt
{
let op_ty = OpaqueType { generic_bounds };
rewrite_ty(rw_info, None, Some(&op_ty), &DEFAULT_VISIBILITY)
} else {
rewrite_ty(rw_info, None, ty.as_ref(), vis)
}?;
match defaultness {
ast::Defaultness::Default(..) => Some(format!("default {}", result)),
_ => Some(result),
}
}
(AssocTraitItem(_), _) | (ForeignItem(_), _) => {
rewrite_ty(rw_info, Some(generic_bounds), ty.as_ref(), vis)
}
}
}

fn rewrite_ty<R: Rewrite>(
rw_info: &TyAliasRewriteInfo<'_, '_>,
generic_bounds_opt: Option<&ast::GenericBounds>,
rhs: Option<&R>,
span: Span,
vis: &ast::Visibility,
) -> Option<String> {
let mut result = String::with_capacity(128);
let TyAliasRewriteInfo(context, indent, generics, ident, span) = *rw_info;
result.push_str(&format!("{}type ", format_visibility(context, vis)));
let ident_str = rewrite_ident(context, ident);

Expand Down Expand Up @@ -1616,28 +1666,6 @@ pub(crate) fn rewrite_type<R: Rewrite>(
}
}

pub(crate) fn rewrite_opaque_type(
context: &RewriteContext<'_>,
indent: Indent,
ident: symbol::Ident,
generic_bounds: &ast::GenericBounds,
generics: &ast::Generics,
vis: &ast::Visibility,
span: Span,
) -> Option<String> {
let opaque_type_bounds = OpaqueTypeBounds { generic_bounds };
rewrite_type(
context,
indent,
ident,
vis,
generics,
Some(generic_bounds),
Some(&opaque_type_bounds),
span,
)
}

fn type_annotation_spacing(config: &Config) -> (&str, &str) {
(
if config.space_before_colon() { " " } else { "" },
Expand Down Expand Up @@ -1863,54 +1891,18 @@ fn rewrite_static(
}
}
struct OpaqueType<'a> {
bounds: &'a ast::GenericBounds,
generic_bounds: &'a ast::GenericBounds,
}

impl<'a> Rewrite for OpaqueType<'a> {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
let shape = shape.offset_left(5)?; // `impl `
self.bounds
self.generic_bounds
.rewrite(context, shape)
.map(|s| format!("impl {}", s))
}
}

pub(crate) fn rewrite_impl_type(
ident: symbol::Ident,
vis: &ast::Visibility,
defaultness: ast::Defaultness,
ty_opt: Option<&ptr::P<ast::Ty>>,
generics: &ast::Generics,
context: &RewriteContext<'_>,
indent: Indent,
span: Span,
) -> Option<String> {
// Opaque type
let result = if let Some(rustc_ast::ast::Ty {
kind: ast::TyKind::ImplTrait(_, ref bounds),
..
}) = ty_opt.map(|t| &**t)
{
rewrite_type(
context,
indent,
ident,
&DEFAULT_VISIBILITY,
generics,
None,
Some(&OpaqueType { bounds }),
span,
)
} else {
rewrite_type(context, indent, ident, vis, generics, None, ty_opt, span)
}?;

match defaultness {
ast::Defaultness::Default(..) => Some(format!("default {}", result)),
_ => Some(result),
}
}

impl Rewrite for ast::FnRetTy {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
match *self {
Expand Down Expand Up @@ -3176,19 +3168,9 @@ impl Rewrite for ast::ForeignItem {
// 1 = ;
rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
}
ast::ForeignItemKind::TyAlias(ref ty_alias_kind) => {
let ast::TyAliasKind(_, ref generics, ref generic_bounds, ref type_default) =
**ty_alias_kind;
rewrite_type(
context,
shape.indent,
self.ident,
&self.vis,
generics,
Some(generic_bounds),
type_default.as_ref(),
self.span,
)
ast::ForeignItemKind::TyAlias(ref ty_alias) => {
let (kind, span) = (&ItemVisitorKind::ForeignItem(&self), self.span);
rewrite_type_alias(ty_alias, context, shape.indent, kind, span)
}
ast::ForeignItemKind::MacCall(ref mac) => {
rewrite_macro(mac, None, context, shape, MacroPosition::Item)
Expand Down
81 changes: 23 additions & 58 deletions src/visitor.rs
View file
Expand Up @@ -12,8 +12,7 @@ use crate::config::{BraceStyle, Config};
use crate::coverage::transform_missing_snippet;
use crate::items::{
format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item, rewrite_extern_crate,
rewrite_impl_type, rewrite_opaque_type, rewrite_type, FnBraceStyle, FnSig, StaticParts,
StructParts,
rewrite_type_alias, FnBraceStyle, FnSig, ItemVisitorKind, StaticParts, StructParts,
};
use crate::macros::{macro_style, rewrite_macro, rewrite_macro_def, MacroPosition};
use crate::modules::Module;
Expand Down Expand Up @@ -576,35 +575,8 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
}
}
ast::ItemKind::TyAlias(ref alias_kind) => {
let ast::TyAliasKind(_, ref generics, ref generic_bounds, ref ty) =
**alias_kind;
match ty {
Some(ty) => {
let rewrite = rewrite_type(
&self.get_context(),
self.block_indent,
item.ident,
&item.vis,
generics,
Some(generic_bounds),
Some(&*ty),
item.span,
);
self.push_rewrite(item.span, rewrite);
}
None => {
let rewrite = rewrite_opaque_type(
&self.get_context(),
self.block_indent,
item.ident,
generic_bounds,
generics,
&item.vis,
item.span,
);
self.push_rewrite(item.span, rewrite);
}
}
use ItemVisitorKind::Item;
self.visit_ty_alias_kind(alias_kind, &Item(&item), item.span);
}
ast::ItemKind::GlobalAsm(..) => {
let snippet = Some(self.snippet(item.span).to_owned());
Expand All @@ -627,6 +599,22 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
self.skip_context = skip_context_saved;
}

fn visit_ty_alias_kind(
&mut self,
ty_kind: &ast::TyAliasKind,
visitor_kind: &ItemVisitorKind<'_>,
span: Span,
) {
let rewrite = rewrite_type_alias(
ty_kind,
&self.get_context(),
self.block_indent,
visitor_kind,
span,
);
self.push_rewrite(span, rewrite);
}

pub(crate) fn visit_trait_item(&mut self, ti: &ast::AssocItem) {
skip_out_of_file_lines_range_visitor!(self, ti.span);

Expand Down Expand Up @@ -659,19 +647,8 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
}
}
ast::AssocItemKind::TyAlias(ref ty_alias_kind) => {
let ast::TyAliasKind(_, ref generics, ref generic_bounds, ref type_default) =
**ty_alias_kind;
let rewrite = rewrite_type(
&self.get_context(),
self.block_indent,
ti.ident,
&ti.vis,
generics,
Some(generic_bounds),
type_default.as_ref(),
ti.span,
);
self.push_rewrite(ti.span, rewrite);
use ItemVisitorKind::AssocTraitItem;
self.visit_ty_alias_kind(ty_alias_kind, &AssocTraitItem(&ti), ti.span);
}
ast::AssocItemKind::MacCall(ref mac) => {
self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
Expand Down Expand Up @@ -710,20 +687,8 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
}
ast::AssocItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
ast::AssocItemKind::TyAlias(ref ty_alias_kind) => {
let ast::TyAliasKind(defaultness, ref generics, _, ref ty) = **ty_alias_kind;
self.push_rewrite(
ii.span,
rewrite_impl_type(
ii.ident,
&ii.vis,
defaultness,
ty.as_ref(),
generics,
&self.get_context(),
self.block_indent,
ii.span,
),
);
use ItemVisitorKind::AssocImplItem;
self.visit_ty_alias_kind(ty_alias_kind, &AssocImplItem(&ii), ii.span);
}
ast::AssocItemKind::MacCall(ref mac) => {
self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
Expand Down

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