use crate::expand::{AstFragment, AstFragmentKind}; use rustc_ast as ast; use rustc_ast::mut_visit::*; use rustc_ast::ptr::P; use rustc_span::source_map::DUMMY_SP; use rustc_span::symbol::Ident; use smallvec::{smallvec, SmallVec}; use rustc_data_structures::fx::FxHashMap; pub fn placeholder( kind: AstFragmentKind, id: ast::NodeId, vis: Option, ) -> AstFragment { fn mac_placeholder() -> ast::MacCall { ast::MacCall { path: ast::Path { span: DUMMY_SP, segments: Vec::new(), tokens: None }, args: P(ast::MacArgs::Empty), prior_type_ascription: None, } } let ident = Ident::empty(); let attrs = Vec::new(); let vis = vis.unwrap_or(ast::Visibility { span: DUMMY_SP, kind: ast::VisibilityKind::Inherited, tokens: None, }); let span = DUMMY_SP; let expr_placeholder = || { P(ast::Expr { id, span, attrs: ast::AttrVec::new(), kind: ast::ExprKind::MacCall(mac_placeholder()), tokens: None, }) }; let ty = || P(ast::Ty { id, kind: ast::TyKind::MacCall(mac_placeholder()), span, tokens: None }); let pat = || P(ast::Pat { id, kind: ast::PatKind::MacCall(mac_placeholder()), span, tokens: None }); match kind { AstFragmentKind::Crate => AstFragment::Crate(ast::Crate { attrs: Default::default(), items: Default::default(), spans: ast::ModSpans { inner_span: span, ..Default::default() }, id, is_placeholder: true, }), AstFragmentKind::Expr => AstFragment::Expr(expr_placeholder()), AstFragmentKind::OptExpr => AstFragment::OptExpr(Some(expr_placeholder())), AstFragmentKind::Items => AstFragment::Items(smallvec![P(ast::Item { id, span, ident, vis, attrs, kind: ast::ItemKind::MacCall(mac_placeholder()), tokens: None, })]), AstFragmentKind::TraitItems => AstFragment::TraitItems(smallvec![P(ast::AssocItem { id, span, ident, vis, attrs, kind: ast::AssocItemKind::MacCall(mac_placeholder()), tokens: None, })]), AstFragmentKind::ImplItems => AstFragment::ImplItems(smallvec![P(ast::AssocItem { id, span, ident, vis, attrs, kind: ast::AssocItemKind::MacCall(mac_placeholder()), tokens: None, })]), AstFragmentKind::ForeignItems => { AstFragment::ForeignItems(smallvec![P(ast::ForeignItem { id, span, ident, vis, attrs, kind: ast::ForeignItemKind::MacCall(mac_placeholder()), tokens: None, })]) } AstFragmentKind::Pat => AstFragment::Pat(P(ast::Pat { id, span, kind: ast::PatKind::MacCall(mac_placeholder()), tokens: None, })), AstFragmentKind::Ty => AstFragment::Ty(P(ast::Ty { id, span, kind: ast::TyKind::MacCall(mac_placeholder()), tokens: None, })), AstFragmentKind::Stmts => AstFragment::Stmts(smallvec![{ let mac = P(ast::MacCallStmt { mac: mac_placeholder(), style: ast::MacStmtStyle::Braces, attrs: ast::AttrVec::new(), tokens: None, }); ast::Stmt { id, span, kind: ast::StmtKind::MacCall(mac) } }]), AstFragmentKind::Arms => AstFragment::Arms(smallvec![ast::Arm { attrs: Default::default(), body: expr_placeholder(), guard: None, id, pat: pat(), span, is_placeholder: true, }]), AstFragmentKind::ExprFields => AstFragment::ExprFields(smallvec![ast::ExprField { attrs: Default::default(), expr: expr_placeholder(), id, ident, is_shorthand: false, span, is_placeholder: true, }]), AstFragmentKind::PatFields => AstFragment::PatFields(smallvec![ast::PatField { attrs: Default::default(), id, ident, is_shorthand: false, pat: pat(), span, is_placeholder: true, }]), AstFragmentKind::GenericParams => AstFragment::GenericParams(smallvec![{ ast::GenericParam { attrs: Default::default(), bounds: Default::default(), id, ident, is_placeholder: true, kind: ast::GenericParamKind::Lifetime, colon_span: None, } }]), AstFragmentKind::Params => AstFragment::Params(smallvec![ast::Param { attrs: Default::default(), id, pat: pat(), span, ty: ty(), is_placeholder: true, }]), AstFragmentKind::FieldDefs => AstFragment::FieldDefs(smallvec![ast::FieldDef { attrs: Default::default(), id, ident: None, span, ty: ty(), vis, is_placeholder: true, }]), AstFragmentKind::Variants => AstFragment::Variants(smallvec![ast::Variant { attrs: Default::default(), data: ast::VariantData::Struct(Default::default(), false), disr_expr: None, id, ident, span, vis, is_placeholder: true, }]), } } #[derive(Default)] pub struct PlaceholderExpander { expanded_fragments: FxHashMap, } impl PlaceholderExpander { pub fn add(&mut self, id: ast::NodeId, mut fragment: AstFragment) { fragment.mut_visit_with(self); self.expanded_fragments.insert(id, fragment); } fn remove(&mut self, id: ast::NodeId) -> AstFragment { self.expanded_fragments.remove(&id).unwrap() } } impl MutVisitor for PlaceholderExpander { fn flat_map_arm(&mut self, arm: ast::Arm) -> SmallVec<[ast::Arm; 1]> { if arm.is_placeholder { self.remove(arm.id).make_arms() } else { noop_flat_map_arm(arm, self) } } fn flat_map_expr_field(&mut self, field: ast::ExprField) -> SmallVec<[ast::ExprField; 1]> { if field.is_placeholder { self.remove(field.id).make_expr_fields() } else { noop_flat_map_expr_field(field, self) } } fn flat_map_pat_field(&mut self, fp: ast::PatField) -> SmallVec<[ast::PatField; 1]> { if fp.is_placeholder { self.remove(fp.id).make_pat_fields() } else { noop_flat_map_pat_field(fp, self) } } fn flat_map_generic_param( &mut self, param: ast::GenericParam, ) -> SmallVec<[ast::GenericParam; 1]> { if param.is_placeholder { self.remove(param.id).make_generic_params() } else { noop_flat_map_generic_param(param, self) } } fn flat_map_param(&mut self, p: ast::Param) -> SmallVec<[ast::Param; 1]> { if p.is_placeholder { self.remove(p.id).make_params() } else { noop_flat_map_param(p, self) } } fn flat_map_field_def(&mut self, sf: ast::FieldDef) -> SmallVec<[ast::FieldDef; 1]> { if sf.is_placeholder { self.remove(sf.id).make_field_defs() } else { noop_flat_map_field_def(sf, self) } } fn flat_map_variant(&mut self, variant: ast::Variant) -> SmallVec<[ast::Variant; 1]> { if variant.is_placeholder { self.remove(variant.id).make_variants() } else { noop_flat_map_variant(variant, self) } } fn flat_map_item(&mut self, item: P) -> SmallVec<[P; 1]> { match item.kind { ast::ItemKind::MacCall(_) => self.remove(item.id).make_items(), _ => noop_flat_map_item(item, self), } } fn flat_map_trait_item(&mut self, item: P) -> SmallVec<[P; 1]> { match item.kind { ast::AssocItemKind::MacCall(_) => self.remove(item.id).make_trait_items(), _ => noop_flat_map_assoc_item(item, self), } } fn flat_map_impl_item(&mut self, item: P) -> SmallVec<[P; 1]> { match item.kind { ast::AssocItemKind::MacCall(_) => self.remove(item.id).make_impl_items(), _ => noop_flat_map_assoc_item(item, self), } } fn flat_map_foreign_item( &mut self, item: P, ) -> SmallVec<[P; 1]> { match item.kind { ast::ForeignItemKind::MacCall(_) => self.remove(item.id).make_foreign_items(), _ => noop_flat_map_foreign_item(item, self), } } fn visit_expr(&mut self, expr: &mut P) { match expr.kind { ast::ExprKind::MacCall(_) => *expr = self.remove(expr.id).make_expr(), _ => noop_visit_expr(expr, self), } } fn filter_map_expr(&mut self, expr: P) -> Option> { match expr.kind { ast::ExprKind::MacCall(_) => self.remove(expr.id).make_opt_expr(), _ => noop_filter_map_expr(expr, self), } } fn flat_map_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> { let (style, mut stmts) = match stmt.kind { ast::StmtKind::MacCall(mac) => (mac.style, self.remove(stmt.id).make_stmts()), _ => return noop_flat_map_stmt(stmt, self), }; if style == ast::MacStmtStyle::Semicolon { // Implement the proposal described in // https://github.com/rust-lang/rust/issues/61733#issuecomment-509626449 // // The macro invocation expands to the list of statements. If the // list of statements is empty, then 'parse' the trailing semicolon // on the original invocation as an empty statement. That is: // // `empty();` is parsed as a single `StmtKind::Empty` // // If the list of statements is non-empty, see if the final // statement already has a trailing semicolon. // // If it doesn't have a semicolon, then 'parse' the trailing // semicolon from the invocation as part of the final statement, // using `stmt.add_trailing_semicolon()` // // If it does have a semicolon, then 'parse' the trailing semicolon // from the invocation as a new StmtKind::Empty // FIXME: We will need to preserve the original semicolon token and // span as part of #15701 let empty_stmt = ast::Stmt { id: ast::DUMMY_NODE_ID, kind: ast::StmtKind::Empty, span: DUMMY_SP }; if let Some(stmt) = stmts.pop() { if stmt.has_trailing_semicolon() { stmts.push(stmt); stmts.push(empty_stmt); } else { stmts.push(stmt.add_trailing_semicolon()); } } else { stmts.push(empty_stmt); } } stmts } fn visit_pat(&mut self, pat: &mut P) { match pat.kind { ast::PatKind::MacCall(_) => *pat = self.remove(pat.id).make_pat(), _ => noop_visit_pat(pat, self), } } fn visit_ty(&mut self, ty: &mut P) { match ty.kind { ast::TyKind::MacCall(_) => *ty = self.remove(ty.id).make_ty(), _ => noop_visit_ty(ty, self), } } fn visit_crate(&mut self, krate: &mut ast::Crate) { if krate.is_placeholder { *krate = self.remove(krate.id).make_crate(); } else { noop_visit_crate(krate, self) } } }