1 use crate::expand::{AstFragment, AstFragmentKind};
4 use rustc_ast::mut_visit::*;
6 use rustc_span::source_map::DUMMY_SP;
7 use rustc_span::symbol::Ident;
9 use smallvec::{smallvec, SmallVec};
11 use rustc_data_structures::fx::FxHashMap;
14 kind: AstFragmentKind,
16 vis: Option<ast::Visibility>,
18 fn mac_placeholder() -> ast::MacCall {
20 path: ast::Path { span: DUMMY_SP, segments: Vec::new(), tokens: None },
21 args: P(ast::MacArgs::Empty),
22 prior_type_ascription: None,
26 let ident = Ident::empty();
27 let attrs = Vec::new();
28 let vis = vis.unwrap_or(ast::Visibility {
30 kind: ast::VisibilityKind::Inherited,
34 let expr_placeholder = || {
38 attrs: ast::AttrVec::new(),
39 kind: ast::ExprKind::MacCall(mac_placeholder()),
44 || P(ast::Ty { id, kind: ast::TyKind::MacCall(mac_placeholder()), span, tokens: None });
46 || P(ast::Pat { id, kind: ast::PatKind::MacCall(mac_placeholder()), span, tokens: None });
49 AstFragmentKind::Crate => AstFragment::Crate(ast::Crate {
50 attrs: Default::default(),
51 items: Default::default(),
52 spans: ast::ModSpans { inner_span: span, ..Default::default() },
56 AstFragmentKind::Expr => AstFragment::Expr(expr_placeholder()),
57 AstFragmentKind::OptExpr => AstFragment::OptExpr(Some(expr_placeholder())),
58 AstFragmentKind::Items => AstFragment::Items(smallvec![P(ast::Item {
64 kind: ast::ItemKind::MacCall(mac_placeholder()),
67 AstFragmentKind::TraitItems => AstFragment::TraitItems(smallvec![P(ast::AssocItem {
73 kind: ast::AssocItemKind::MacCall(mac_placeholder()),
76 AstFragmentKind::ImplItems => AstFragment::ImplItems(smallvec![P(ast::AssocItem {
82 kind: ast::AssocItemKind::MacCall(mac_placeholder()),
85 AstFragmentKind::ForeignItems => {
86 AstFragment::ForeignItems(smallvec![P(ast::ForeignItem {
92 kind: ast::ForeignItemKind::MacCall(mac_placeholder()),
96 AstFragmentKind::Pat => AstFragment::Pat(P(ast::Pat {
99 kind: ast::PatKind::MacCall(mac_placeholder()),
102 AstFragmentKind::Ty => AstFragment::Ty(P(ast::Ty {
105 kind: ast::TyKind::MacCall(mac_placeholder()),
108 AstFragmentKind::Stmts => AstFragment::Stmts(smallvec![{
109 let mac = P(ast::MacCallStmt {
110 mac: mac_placeholder(),
111 style: ast::MacStmtStyle::Braces,
112 attrs: ast::AttrVec::new(),
115 ast::Stmt { id, span, kind: ast::StmtKind::MacCall(mac) }
117 AstFragmentKind::Arms => AstFragment::Arms(smallvec![ast::Arm {
118 attrs: Default::default(),
119 body: expr_placeholder(),
124 is_placeholder: true,
126 AstFragmentKind::ExprFields => AstFragment::ExprFields(smallvec![ast::ExprField {
127 attrs: Default::default(),
128 expr: expr_placeholder(),
133 is_placeholder: true,
135 AstFragmentKind::PatFields => AstFragment::PatFields(smallvec![ast::PatField {
136 attrs: Default::default(),
142 is_placeholder: true,
144 AstFragmentKind::GenericParams => AstFragment::GenericParams(smallvec![{
146 attrs: Default::default(),
147 bounds: Default::default(),
150 is_placeholder: true,
151 kind: ast::GenericParamKind::Lifetime,
155 AstFragmentKind::Params => AstFragment::Params(smallvec![ast::Param {
156 attrs: Default::default(),
161 is_placeholder: true,
163 AstFragmentKind::FieldDefs => AstFragment::FieldDefs(smallvec![ast::FieldDef {
164 attrs: Default::default(),
170 is_placeholder: true,
172 AstFragmentKind::Variants => AstFragment::Variants(smallvec![ast::Variant {
173 attrs: Default::default(),
174 data: ast::VariantData::Struct(Default::default(), false),
180 is_placeholder: true,
186 pub struct PlaceholderExpander {
187 expanded_fragments: FxHashMap<ast::NodeId, AstFragment>,
190 impl PlaceholderExpander {
191 pub fn add(&mut self, id: ast::NodeId, mut fragment: AstFragment) {
192 fragment.mut_visit_with(self);
193 self.expanded_fragments.insert(id, fragment);
196 fn remove(&mut self, id: ast::NodeId) -> AstFragment {
197 self.expanded_fragments.remove(&id).unwrap()
201 impl MutVisitor for PlaceholderExpander {
202 fn flat_map_arm(&mut self, arm: ast::Arm) -> SmallVec<[ast::Arm; 1]> {
203 if arm.is_placeholder {
204 self.remove(arm.id).make_arms()
206 noop_flat_map_arm(arm, self)
210 fn flat_map_expr_field(&mut self, field: ast::ExprField) -> SmallVec<[ast::ExprField; 1]> {
211 if field.is_placeholder {
212 self.remove(field.id).make_expr_fields()
214 noop_flat_map_expr_field(field, self)
218 fn flat_map_pat_field(&mut self, fp: ast::PatField) -> SmallVec<[ast::PatField; 1]> {
219 if fp.is_placeholder {
220 self.remove(fp.id).make_pat_fields()
222 noop_flat_map_pat_field(fp, self)
226 fn flat_map_generic_param(
228 param: ast::GenericParam,
229 ) -> SmallVec<[ast::GenericParam; 1]> {
230 if param.is_placeholder {
231 self.remove(param.id).make_generic_params()
233 noop_flat_map_generic_param(param, self)
237 fn flat_map_param(&mut self, p: ast::Param) -> SmallVec<[ast::Param; 1]> {
238 if p.is_placeholder {
239 self.remove(p.id).make_params()
241 noop_flat_map_param(p, self)
245 fn flat_map_field_def(&mut self, sf: ast::FieldDef) -> SmallVec<[ast::FieldDef; 1]> {
246 if sf.is_placeholder {
247 self.remove(sf.id).make_field_defs()
249 noop_flat_map_field_def(sf, self)
253 fn flat_map_variant(&mut self, variant: ast::Variant) -> SmallVec<[ast::Variant; 1]> {
254 if variant.is_placeholder {
255 self.remove(variant.id).make_variants()
257 noop_flat_map_variant(variant, self)
261 fn flat_map_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
263 ast::ItemKind::MacCall(_) => self.remove(item.id).make_items(),
264 _ => noop_flat_map_item(item, self),
268 fn flat_map_trait_item(&mut self, item: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
270 ast::AssocItemKind::MacCall(_) => self.remove(item.id).make_trait_items(),
271 _ => noop_flat_map_assoc_item(item, self),
275 fn flat_map_impl_item(&mut self, item: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
277 ast::AssocItemKind::MacCall(_) => self.remove(item.id).make_impl_items(),
278 _ => noop_flat_map_assoc_item(item, self),
282 fn flat_map_foreign_item(
284 item: P<ast::ForeignItem>,
285 ) -> SmallVec<[P<ast::ForeignItem>; 1]> {
287 ast::ForeignItemKind::MacCall(_) => self.remove(item.id).make_foreign_items(),
288 _ => noop_flat_map_foreign_item(item, self),
292 fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {
294 ast::ExprKind::MacCall(_) => *expr = self.remove(expr.id).make_expr(),
295 _ => noop_visit_expr(expr, self),
299 fn filter_map_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
301 ast::ExprKind::MacCall(_) => self.remove(expr.id).make_opt_expr(),
302 _ => noop_filter_map_expr(expr, self),
306 fn flat_map_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
307 let (style, mut stmts) = match stmt.kind {
308 ast::StmtKind::MacCall(mac) => (mac.style, self.remove(stmt.id).make_stmts()),
309 _ => return noop_flat_map_stmt(stmt, self),
312 if style == ast::MacStmtStyle::Semicolon {
313 // Implement the proposal described in
314 // https://github.com/rust-lang/rust/issues/61733#issuecomment-509626449
316 // The macro invocation expands to the list of statements. If the
317 // list of statements is empty, then 'parse' the trailing semicolon
318 // on the original invocation as an empty statement. That is:
320 // `empty();` is parsed as a single `StmtKind::Empty`
322 // If the list of statements is non-empty, see if the final
323 // statement already has a trailing semicolon.
325 // If it doesn't have a semicolon, then 'parse' the trailing
326 // semicolon from the invocation as part of the final statement,
327 // using `stmt.add_trailing_semicolon()`
329 // If it does have a semicolon, then 'parse' the trailing semicolon
330 // from the invocation as a new StmtKind::Empty
332 // FIXME: We will need to preserve the original semicolon token and
333 // span as part of #15701
335 ast::Stmt { id: ast::DUMMY_NODE_ID, kind: ast::StmtKind::Empty, span: DUMMY_SP };
337 if let Some(stmt) = stmts.pop() {
338 if stmt.has_trailing_semicolon() {
340 stmts.push(empty_stmt);
342 stmts.push(stmt.add_trailing_semicolon());
345 stmts.push(empty_stmt);
352 fn visit_pat(&mut self, pat: &mut P<ast::Pat>) {
354 ast::PatKind::MacCall(_) => *pat = self.remove(pat.id).make_pat(),
355 _ => noop_visit_pat(pat, self),
359 fn visit_ty(&mut self, ty: &mut P<ast::Ty>) {
361 ast::TyKind::MacCall(_) => *ty = self.remove(ty.id).make_ty(),
362 _ => noop_visit_ty(ty, self),
366 fn visit_crate(&mut self, krate: &mut ast::Crate) {
367 if krate.is_placeholder {
368 *krate = self.remove(krate.id).make_crate();
370 noop_visit_crate(krate, self)