item.rs

use crate::algorithm::Printer;
use crate::iter::IterDelimited;
use crate::INDENT;
use proc_macro2::TokenStream;
use syn::{
    Fields, FnArg, ForeignItem, ForeignItemFn, ForeignItemMacro, ForeignItemStatic,
    ForeignItemType, ImplItem, ImplItemConst, ImplItemMacro, ImplItemMethod, ImplItemType, Item,
    ItemConst, ItemEnum, ItemExternCrate, ItemFn, ItemForeignMod, ItemImpl, ItemMacro, ItemMacro2,
    ItemMod, ItemStatic, ItemStruct, ItemTrait, ItemTraitAlias, ItemType, ItemUnion, ItemUse, Pat,
    Receiver, Signature, Stmt, TraitItem, TraitItemConst, TraitItemMacro, TraitItemMethod,
    TraitItemType, Type, UseGlob, UseGroup, UseName, UsePath, UseRename, UseTree,
};

impl Printer {
    pub fn item(&mut self, item: &Item) {
        match item {
            Item::Const(item) => self.item_const(item),
            Item::Enum(item) => self.item_enum(item),
            Item::ExternCrate(item) => self.item_extern_crate(item),
            Item::Fn(item) => self.item_fn(item),
            Item::ForeignMod(item) => self.item_foreign_mod(item),
            Item::Impl(item) => self.item_impl(item),
            Item::Macro(item) => self.item_macro(item),
            Item::Macro2(item) => self.item_macro2(item),
            Item::Mod(item) => self.item_mod(item),
            Item::Static(item) => self.item_static(item),
            Item::Struct(item) => self.item_struct(item),
            Item::Trait(item) => self.item_trait(item),
            Item::TraitAlias(item) => self.item_trait_alias(item),
            Item::Type(item) => self.item_type(item),
            Item::Union(item) => self.item_union(item),
            Item::Use(item) => self.item_use(item),
            Item::Verbatim(item) => self.item_verbatim(item),
            #[cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
            _ => unimplemented!("unknown Item"),
        }
    }

    fn item_const(&mut self, item: &ItemConst) {
        self.outer_attrs(&item.attrs);
        self.cbox(0);
        self.visibility(&item.vis);
        self.word("const ");
        self.ident(&item.ident);
        self.word(": ");
        self.ty(&item.ty);
        self.word(" = ");
        self.neverbreak();
        self.expr(&item.expr);
        self.word(";");
        self.end();
        self.hardbreak();
    }

    fn item_enum(&mut self, item: &ItemEnum) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        self.word("enum ");
        self.ident(&item.ident);
        self.generics(&item.generics);
        self.where_clause_for_body(&item.generics.where_clause);
        self.word("{");
        self.hardbreak_if_nonempty();
        for variant in &item.variants {
            self.variant(variant);
            self.word(",");
            self.hardbreak();
        }
        self.offset(-INDENT);
        self.end();
        self.word("}");
        self.hardbreak();
    }

    fn item_extern_crate(&mut self, item: &ItemExternCrate) {
        self.outer_attrs(&item.attrs);
        self.visibility(&item.vis);
        self.word("extern crate ");
        self.ident(&item.ident);
        if let Some((_as_token, rename)) = &item.rename {
            self.word(" as ");
            self.ident(rename);
        }
        self.word(";");
        self.hardbreak();
    }

    fn item_fn(&mut self, item: &ItemFn) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        self.signature(&item.sig);
        self.where_clause_for_body(&item.sig.generics.where_clause);
        self.word("{");
        self.hardbreak_if_nonempty();
        self.inner_attrs(&item.attrs);
        for stmt in &item.block.stmts {
            self.stmt(stmt);
        }
        self.offset(-INDENT);
        self.end();
        self.word("}");
        self.hardbreak();
    }

    fn item_foreign_mod(&mut self, item: &ItemForeignMod) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.abi(&item.abi);
        self.word("{");
        self.hardbreak_if_nonempty();
        self.inner_attrs(&item.attrs);
        for foreign_item in &item.items {
            self.foreign_item(foreign_item);
        }
        self.offset(-INDENT);
        self.end();
        self.word("}");
        self.hardbreak();
    }

    fn item_impl(&mut self, item: &ItemImpl) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.ibox(-INDENT);
        self.cbox(INDENT);
        if item.defaultness.is_some() {
            self.word("default ");
        }
        if item.unsafety.is_some() {
            self.word("unsafe ");
        }
        self.word("impl");
        self.generics(&item.generics);
        self.end();
        self.nbsp();
        if let Some((negative_polarity, path, _for_token)) = &item.trait_ {
            if negative_polarity.is_some() {
                self.word("!");
            }
            self.path(path);
            self.space();
            self.word("for ");
        }
        self.ty(&item.self_ty);
        self.end();
        self.where_clause_for_body(&item.generics.where_clause);
        self.word("{");
        self.hardbreak_if_nonempty();
        self.inner_attrs(&item.attrs);
        for impl_item in &item.items {
            self.impl_item(impl_item);
        }
        self.offset(-INDENT);
        self.end();
        self.word("}");
        self.hardbreak();
    }

    fn item_macro(&mut self, item: &ItemMacro) {
        self.outer_attrs(&item.attrs);
        self.mac(&item.mac, item.ident.as_ref());
        self.mac_semi_if_needed(&item.mac.delimiter);
        self.hardbreak();
    }

    fn item_macro2(&mut self, item: &ItemMacro2) {
        unimplemented!("Item::Macro2 `macro {} {}`", item.ident, item.rules);
    }

    fn item_mod(&mut self, item: &ItemMod) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        self.word("mod ");
        self.ident(&item.ident);
        if let Some((_brace, items)) = &item.content {
            self.word(" {");
            self.hardbreak_if_nonempty();
            self.inner_attrs(&item.attrs);
            for item in items {
                self.item(item);
            }
            self.offset(-INDENT);
            self.end();
            self.word("}");
        } else {
            self.word(";");
            self.end();
        }
        self.hardbreak();
    }

    fn item_static(&mut self, item: &ItemStatic) {
        self.outer_attrs(&item.attrs);
        self.cbox(0);
        self.visibility(&item.vis);
        self.word("static ");
        if item.mutability.is_some() {
            self.word("mut ");
        }
        self.ident(&item.ident);
        self.word(": ");
        self.ty(&item.ty);
        self.word(" = ");
        self.neverbreak();
        self.expr(&item.expr);
        self.word(";");
        self.end();
        self.hardbreak();
    }

    fn item_struct(&mut self, item: &ItemStruct) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        self.word("struct ");
        self.ident(&item.ident);
        self.generics(&item.generics);
        match &item.fields {
            Fields::Named(fields) => {
                self.where_clause_for_body(&item.generics.where_clause);
                self.word("{");
                self.hardbreak_if_nonempty();
                for field in &fields.named {
                    self.field(field);
                    self.word(",");
                    self.hardbreak();
                }
                self.offset(-INDENT);
                self.end();
                self.word("}");
            }
            Fields::Unnamed(fields) => {
                self.fields_unnamed(fields);
                self.where_clause_semi(&item.generics.where_clause);
                self.end();
            }
            Fields::Unit => {
                self.where_clause_semi(&item.generics.where_clause);
                self.end();
            }
        }
        self.hardbreak();
    }

    fn item_trait(&mut self, item: &ItemTrait) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        if item.unsafety.is_some() {
            self.word("unsafe ");
        }
        if item.auto_token.is_some() {
            self.word("auto ");
        }
        self.word("trait ");
        self.ident(&item.ident);
        self.generics(&item.generics);
        for supertrait in item.supertraits.iter().delimited() {
            if supertrait.is_first {
                self.word(": ");
            } else {
                self.word(" + ");
            }
            self.type_param_bound(&supertrait);
        }
        self.where_clause_for_body(&item.generics.where_clause);
        self.word("{");
        self.hardbreak_if_nonempty();
        self.inner_attrs(&item.attrs);
        for trait_item in &item.items {
            self.trait_item(trait_item);
        }
        self.offset(-INDENT);
        self.end();
        self.word("}");
        self.hardbreak();
    }

    fn item_trait_alias(&mut self, item: &ItemTraitAlias) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        self.word("trait ");
        self.ident(&item.ident);
        self.generics(&item.generics);
        self.word(" = ");
        self.neverbreak();
        for bound in item.bounds.iter().delimited() {
            if !bound.is_first {
                self.space();
                self.word("+ ");
            }
            self.type_param_bound(&bound);
        }
        self.where_clause_semi(&item.generics.where_clause);
        self.end();
        self.hardbreak();
    }

    fn item_type(&mut self, item: &ItemType) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        self.word("type ");
        self.ident(&item.ident);
        self.generics(&item.generics);
        self.where_clause_oneline(&item.generics.where_clause);
        self.word("= ");
        self.neverbreak();
        self.ibox(-INDENT);
        self.ty(&item.ty);
        self.end();
        self.word(";");
        self.end();
        self.hardbreak();
    }

    fn item_union(&mut self, item: &ItemUnion) {
        self.outer_attrs(&item.attrs);
        self.cbox(INDENT);
        self.visibility(&item.vis);
        self.word("union ");
        self.ident(&item.ident);
        self.generics(&item.generics);
        self.where_clause_for_body(&item.generics.where_clause);
        self.word("{");
        self.hardbreak_if_nonempty();
        for field in &item.fields.named {
            self.field(field);
            self.word(",");
            self.hardbreak();
        }
        self.offset(-INDENT);
        self.end();
        self.word("}");
        self.hardbreak();
    }

    fn item_use(&mut self, item: &ItemUse) {
        self.outer_attrs(&item.attrs);
        self.visibility(&item.vis);
        self.word("use ");
        if item.leading_colon.is_some() {
            self.word("::");
        }
        self.use_tree(&item.tree);
        self.word(";");
        self.hardbreak();
    }

    #[cfg(not(feature = "verbatim"))]
    fn item_verbatim(&mut self, item: &TokenStream) {
        if !item.is_empty() {
            unimplemented!("Item::Verbatim `{}`", item);
        }
        self.hardbreak();
    }

    #[cfg(feature = "verbatim")]
    fn item_verbatim(&mut self, tokens: &TokenStream) {
        use syn::parse::{Parse, ParseStream, Result};
        use syn::{Attribute, Token};

        enum ItemVerbatim {
            Empty,
            UnsafeForeignMod(ItemForeignMod),
        }

        impl Parse for ItemVerbatim {
            fn parse(input: ParseStream) -> Result<Self> {
                if input.is_empty() {
                    Ok(ItemVerbatim::Empty)
                } else {
                    let attrs = input.call(Attribute::parse_outer)?;
                    input.parse::<Token![unsafe]>()?;
                    let module: ItemForeignMod = input.parse()?;
                    Ok(ItemVerbatim::UnsafeForeignMod(ItemForeignMod {
                        attrs,
                        ..module
                    }))
                }
            }
        }

        let item: ItemVerbatim = match syn::parse2(tokens.clone()) {
            Ok(item) => item,
            Err(_) => unimplemented!("Item::Verbatim `{}`", tokens),
        };

        match item {
            ItemVerbatim::Empty => {}
            ItemVerbatim::UnsafeForeignMod(item) => {
                self.outer_attrs(&item.attrs);
                self.cbox(INDENT);
                self.word("unsafe ");
                self.abi(&item.abi);
                self.word("{");
                self.hardbreak_if_nonempty();
                self.inner_attrs(&item.attrs);
                for foreign_item in &item.items {
                    self.foreign_item(foreign_item);
                }
                self.offset(-INDENT);
                self.end();
                self.word("}");
            }
        }

        self.hardbreak();
    }

    fn use_tree(&mut self, use_tree: &UseTree) {
        match use_tree {
            UseTree::Path(use_path) => self.use_path(use_path),
            UseTree::Name(use_name) => self.use_name(use_name),
            UseTree::Rename(use_rename) => self.use_rename(use_rename),
            UseTree::Glob(use_glob) => self.use_glob(use_glob),
            UseTree::Group(use_group) => self.use_group(use_group),
        }
    }

    fn use_path(&mut self, use_path: &UsePath) {
        self.ident(&use_path.ident);
        self.word("::");
        self.use_tree(&use_path.tree);
    }

    fn use_name(&mut self, use_name: &UseName) {
        self.ident(&use_name.ident);
    }

    fn use_rename(&mut self, use_rename: &UseRename) {
        self.ident(&use_rename.ident);
        self.word(" as ");
        self.ident(&use_rename.rename);
    }

    fn use_glob(&mut self, use_glob: &UseGlob) {
        let _ = use_glob;
        self.word("*");
    }

    fn use_group(&mut self, use_group: &UseGroup) {
        if use_group.items.is_empty() {
            self.word("{}");
        } else if use_group.items.len() == 1 {
            self.use_tree(&use_group.items[0]);
        } else {
            self.cbox(INDENT);
            self.word("{");
            self.zerobreak();
            self.ibox(0);
            for use_tree in use_group.items.iter().delimited() {
                self.use_tree(&use_tree);
                if !use_tree.is_last {
                    self.word(",");
                    let mut use_tree = *use_tree;
                    while let UseTree::Path(use_path) = use_tree {
                        use_tree = &use_path.tree;
                    }
                    if let UseTree::Group(_) = use_tree {
                        self.hardbreak();
                    } else {
                        self.space();
                    }
                }
            }
            self.end();
            self.trailing_comma(true);
            self.offset(-INDENT);
            self.word("}");
            self.end();
        }
    }

    fn foreign_item(&mut self, foreign_item: &ForeignItem) {
        match foreign_item {
            ForeignItem::Fn(item) => self.foreign_item_fn(item),
            ForeignItem::Static(item) => self.foreign_item_static(item),
            ForeignItem::Type(item) => self.foreign_item_type(item),
            ForeignItem::Macro(item) => self.foreign_item_macro(item),
            ForeignItem::Verbatim(item) => self.foreign_item_verbatim(item),
            #[cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
            _ => unimplemented!("unknown ForeignItem"),
        }
    }

    fn foreign_item_fn(&mut self, foreign_item: &ForeignItemFn) {
        self.outer_attrs(&foreign_item.attrs);
        self.cbox(INDENT);
        self.visibility(&foreign_item.vis);
        self.signature(&foreign_item.sig);
        self.where_clause_semi(&foreign_item.sig.generics.where_clause);
        self.end();
        self.hardbreak();
    }

    fn foreign_item_static(&mut self, foreign_item: &ForeignItemStatic) {
        self.outer_attrs(&foreign_item.attrs);
        self.cbox(0);
        self.visibility(&foreign_item.vis);
        self.word("static ");
        if foreign_item.mutability.is_some() {
            self.word("mut ");
        }
        self.ident(&foreign_item.ident);
        self.word(": ");
        self.ty(&foreign_item.ty);
        self.word(";");
        self.end();
        self.hardbreak();
    }

    fn foreign_item_type(&mut self, foreign_item: &ForeignItemType) {
        self.outer_attrs(&foreign_item.attrs);
        self.cbox(0);
        self.visibility(&foreign_item.vis);
        self.word("type ");
        self.ident(&foreign_item.ident);
        self.word(";");
        self.end();
        self.hardbreak();
    }

    fn foreign_item_macro(&mut self, foreign_item: &ForeignItemMacro) {
        self.outer_attrs(&foreign_item.attrs);
        self.mac(&foreign_item.mac, None);
        self.mac_semi_if_needed(&foreign_item.mac.delimiter);
        self.hardbreak();
    }

    #[cfg(not(feature = "verbatim"))]
    fn foreign_item_verbatim(&mut self, foreign_item: &TokenStream) {
        if !foreign_item.is_empty() {
            unimplemented!("ForeignItem::Verbatim `{}`", foreign_item);
        }
        self.hardbreak();
    }

    #[cfg(feature = "verbatim")]
    fn foreign_item_verbatim(&mut self, tokens: &TokenStream) {
        use syn::parse::{Parse, ParseStream, Result};

        enum ForeignItemVerbatim {
            TypeAlias(ItemType),
        }

        impl Parse for ForeignItemVerbatim {
            fn parse(input: ParseStream) -> Result<Self> {
                input.parse().map(ForeignItemVerbatim::TypeAlias)
            }
        }

        let foreign_item: ForeignItemVerbatim = match syn::parse2(tokens.clone()) {
            Ok(foreign_item) => foreign_item,
            Err(_) => unimplemented!("ForeignItem::Verbatim `{}`", tokens),
        };

        match foreign_item {
            ForeignItemVerbatim::TypeAlias(item) => self.item_type(&item),
        }
    }

    fn trait_item(&mut self, trait_item: &TraitItem) {
        match trait_item {
            TraitItem::Const(item) => self.trait_item_const(item),
            TraitItem::Method(item) => self.trait_item_method(item),
            TraitItem::Type(item) => self.trait_item_type(item),
            TraitItem::Macro(item) => self.trait_item_macro(item),
            TraitItem::Verbatim(item) => self.trait_item_verbatim(item),
            #[cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
            _ => unimplemented!("unknown TraitItem"),
        }
    }

    fn trait_item_const(&mut self, trait_item: &TraitItemConst) {
        self.outer_attrs(&trait_item.attrs);
        self.cbox(0);
        self.word("const ");
        self.ident(&trait_item.ident);
        self.word(": ");
        self.ty(&trait_item.ty);
        if let Some((_eq_token, default)) = &trait_item.default {
            self.word(" = ");
            self.neverbreak();
            self.expr(default);
        }
        self.word(";");
        self.end();
        self.hardbreak();
    }

    fn trait_item_method(&mut self, trait_item: &TraitItemMethod) {
        self.outer_attrs(&trait_item.attrs);
        self.cbox(INDENT);
        self.signature(&trait_item.sig);
        if let Some(block) = &trait_item.default {
            self.where_clause_for_body(&trait_item.sig.generics.where_clause);
            self.word("{");
            self.hardbreak_if_nonempty();
            self.inner_attrs(&trait_item.attrs);
            for stmt in &block.stmts {
                self.stmt(stmt);
            }
            self.offset(-INDENT);
            self.end();
            self.word("}");
        } else {
            self.where_clause_semi(&trait_item.sig.generics.where_clause);
            self.end();
        }
        self.hardbreak();
    }

    fn trait_item_type(&mut self, trait_item: &TraitItemType) {
        self.outer_attrs(&trait_item.attrs);
        self.cbox(INDENT);
        self.word("type ");
        self.ident(&trait_item.ident);
        self.generics(&trait_item.generics);
        for bound in trait_item.bounds.iter().delimited() {
            if bound.is_first {
                self.word(": ");
            } else {
                self.space();
                self.word("+ ");
            }
            self.type_param_bound(&bound);
        }
        if let Some((_eq_token, default)) = &trait_item.default {
            self.word(" = ");
            self.neverbreak();
            self.ty(default);
        }
        self.where_clause_oneline_semi(&trait_item.generics.where_clause);
        self.end();
        self.hardbreak();
    }

    fn trait_item_macro(&mut self, trait_item: &TraitItemMacro) {
        self.outer_attrs(&trait_item.attrs);
        self.mac(&trait_item.mac, None);
        self.mac_semi_if_needed(&trait_item.mac.delimiter);
        self.hardbreak();
    }

    fn trait_item_verbatim(&mut self, trait_item: &TokenStream) {
        if !trait_item.is_empty() {
            unimplemented!("TraitItem::Verbatim `{}`", trait_item);
        }
        self.hardbreak();
    }

    fn impl_item(&mut self, impl_item: &ImplItem) {
        match impl_item {
            ImplItem::Const(item) => self.impl_item_const(item),
            ImplItem::Method(item) => self.impl_item_method(item),
            ImplItem::Type(item) => self.impl_item_type(item),
            ImplItem::Macro(item) => self.impl_item_macro(item),
            ImplItem::Verbatim(item) => self.impl_item_verbatim(item),
            #[cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
            _ => unimplemented!("unknown ImplItem"),
        }
    }

    fn impl_item_const(&mut self, impl_item: &ImplItemConst) {
        self.outer_attrs(&impl_item.attrs);
        self.cbox(0);
        self.visibility(&impl_item.vis);
        if impl_item.defaultness.is_some() {
            self.word("default ");
        }
        self.word("const ");
        self.ident(&impl_item.ident);
        self.word(": ");
        self.ty(&impl_item.ty);
        self.word(" = ");
        self.neverbreak();
        self.expr(&impl_item.expr);
        self.word(";");
        self.end();
        self.hardbreak();
    }

    fn impl_item_method(&mut self, impl_item: &ImplItemMethod) {
        self.outer_attrs(&impl_item.attrs);
        self.cbox(INDENT);
        self.visibility(&impl_item.vis);
        if impl_item.defaultness.is_some() {
            self.word("default ");
        }
        self.signature(&impl_item.sig);
        if impl_item.block.stmts.len() == 1 {
            if let Stmt::Item(Item::Verbatim(verbatim)) = &impl_item.block.stmts[0] {
                if verbatim.to_string() == ";" {
                    self.where_clause_semi(&impl_item.sig.generics.where_clause);
                    self.end();
                    self.hardbreak();
                    return;
                }
            }
        }
        self.where_clause_for_body(&impl_item.sig.generics.where_clause);
        self.word("{");
        self.hardbreak_if_nonempty();
        self.inner_attrs(&impl_item.attrs);
        for stmt in &impl_item.block.stmts {
            self.stmt(stmt);
        }
        self.offset(-INDENT);
        self.end();
        self.word("}");
        self.hardbreak();
    }

    fn impl_item_type(&mut self, impl_item: &ImplItemType) {
        self.outer_attrs(&impl_item.attrs);
        self.cbox(INDENT);
        self.visibility(&impl_item.vis);
        if impl_item.defaultness.is_some() {
            self.word("default ");
        }
        self.word("type ");
        self.ident(&impl_item.ident);
        self.generics(&impl_item.generics);
        self.word(" = ");
        self.neverbreak();
        self.ibox(-INDENT);
        self.ty(&impl_item.ty);
        self.end();
        self.where_clause_oneline_semi(&impl_item.generics.where_clause);
        self.end();
        self.hardbreak();
    }

    fn impl_item_macro(&mut self, impl_item: &ImplItemMacro) {
        self.outer_attrs(&impl_item.attrs);
        self.mac(&impl_item.mac, None);
        self.mac_semi_if_needed(&impl_item.mac.delimiter);
        self.hardbreak();
    }

    fn impl_item_verbatim(&mut self, impl_item: &TokenStream) {
        if !impl_item.is_empty() {
            unimplemented!("ImplItem::Verbatim `{}`", impl_item);
        }
        self.hardbreak();
    }

    fn maybe_variadic(&mut self, arg: &FnArg) -> bool {
        let pat_type = match arg {
            FnArg::Typed(pat_type) => pat_type,
            FnArg::Receiver(receiver) => {
                self.receiver(receiver);
                return false;
            }
        };

        match pat_type.ty.as_ref() {
            Type::Verbatim(ty) if ty.to_string() == "..." => {
                match pat_type.pat.as_ref() {
                    Pat::Verbatim(pat) if pat.to_string() == "..." => {
                        self.outer_attrs(&pat_type.attrs);
                        self.word("...");
                    }
                    _ => self.pat_type(pat_type),
                }
                true
            }
            _ => {
                self.pat_type(pat_type);
                false
            }
        }
    }

    fn signature(&mut self, signature: &Signature) {
        if signature.constness.is_some() {
            self.word("const ");
        }
        if signature.asyncness.is_some() {
            self.word("async ");
        }
        if signature.unsafety.is_some() {
            self.word("unsafe ");
        }
        if let Some(abi) = &signature.abi {
            self.abi(abi);
        }
        self.word("fn ");
        self.ident(&signature.ident);
        self.generics(&signature.generics);
        self.word("(");
        self.neverbreak();
        self.cbox(0);
        self.zerobreak();
        let mut last_is_variadic = false;
        for input in signature.inputs.iter().delimited() {
            last_is_variadic = self.maybe_variadic(&input);
            if last_is_variadic {
                self.zerobreak();
            } else {
                let is_last = input.is_last && signature.variadic.is_none();
                self.trailing_comma(is_last);
            }
        }
        if signature.variadic.is_some() && !last_is_variadic {
            self.word("...");
            self.zerobreak();
        }
        self.offset(-INDENT);
        self.end();
        self.word(")");
        self.cbox(-INDENT);
        self.return_type(&signature.output);
        self.end();
    }

    fn receiver(&mut self, receiver: &Receiver) {
        self.outer_attrs(&receiver.attrs);
        if let Some((_ampersand, lifetime)) = &receiver.reference {
            self.word("&");
            if let Some(lifetime) = lifetime {
                self.lifetime(lifetime);
                self.nbsp();
            }
        }
        if receiver.mutability.is_some() {
            self.word("mut ");
        }
        self.word("self");
    }
}