1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use attr::AttrMetaMethods;
12 use diagnostic::SpanHandler;
14 use {ast, fold, attr};
15 use codemap::{Spanned, respan};
18 use util::small_vector::SmallVector;
20 /// A folder that strips out items that do not belong in the current
22 struct Context<F> where F: FnMut(&[ast::Attribute]) -> bool {
26 // Support conditional compilation by transforming the AST, stripping out
27 // any items that do not belong in the current configuration
28 pub fn strip_unconfigured_items(diagnostic: &SpanHandler, krate: ast::Crate) -> ast::Crate {
29 let krate = process_cfg_attr(diagnostic, krate);
30 let config = krate.config.clone();
31 strip_items(krate, |attrs| in_cfg(diagnostic, &config, attrs))
34 impl<F> fold::Folder for Context<F> where F: FnMut(&[ast::Attribute]) -> bool {
35 fn fold_mod(&mut self, module: ast::Mod) -> ast::Mod {
36 fold_mod(self, module)
38 fn fold_block(&mut self, block: P<ast::Block>) -> P<ast::Block> {
39 fold_block(self, block)
41 fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
42 fold_foreign_mod(self, foreign_mod)
44 fn fold_item_underscore(&mut self, item: ast::Item_) -> ast::Item_ {
45 fold_item_underscore(self, item)
47 fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
50 fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
51 fold::noop_fold_mac(mac, self)
53 fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
58 pub fn strip_items<F>(krate: ast::Crate, in_cfg: F) -> ast::Crate where
59 F: FnMut(&[ast::Attribute]) -> bool,
61 let mut ctxt = Context {
64 ctxt.fold_crate(krate)
67 fn fold_mod<F>(cx: &mut Context<F>,
68 ast::Mod {inner, items}: ast::Mod)
70 F: FnMut(&[ast::Attribute]) -> bool
74 items: items.into_iter().flat_map(|a| {
75 cx.fold_item(a).into_iter()
80 fn filter_foreign_item<F>(cx: &mut Context<F>,
81 item: P<ast::ForeignItem>)
82 -> Option<P<ast::ForeignItem>> where
83 F: FnMut(&[ast::Attribute]) -> bool
85 if foreign_item_in_cfg(cx, &*item) {
92 fn fold_foreign_mod<F>(cx: &mut Context<F>,
93 ast::ForeignMod {abi, items}: ast::ForeignMod)
94 -> ast::ForeignMod where
95 F: FnMut(&[ast::Attribute]) -> bool
99 items: items.into_iter()
100 .filter_map(|a| filter_foreign_item(cx, a))
105 fn fold_item<F>(cx: &mut Context<F>, item: P<ast::Item>) -> SmallVector<P<ast::Item>> where
106 F: FnMut(&[ast::Attribute]) -> bool
108 if item_in_cfg(cx, &*item) {
109 SmallVector::one(item.map(|i| cx.fold_item_simple(i)))
115 fn fold_item_underscore<F>(cx: &mut Context<F>, item: ast::Item_) -> ast::Item_ where
116 F: FnMut(&[ast::Attribute]) -> bool
118 let item = match item {
119 ast::ItemImpl(u, o, a, b, c, impl_items) => {
120 let impl_items = impl_items.into_iter()
121 .filter(|ii| (cx.in_cfg)(&ii.attrs))
123 ast::ItemImpl(u, o, a, b, c, impl_items)
125 ast::ItemTrait(u, a, b, methods) => {
126 let methods = methods.into_iter()
127 .filter(|ti| (cx.in_cfg)(&ti.attrs))
129 ast::ItemTrait(u, a, b, methods)
131 ast::ItemStruct(def, generics) => {
132 ast::ItemStruct(fold_struct(cx, def), generics)
134 ast::ItemEnum(def, generics) => {
135 let variants = def.variants.into_iter().filter_map(|v| {
136 if !(cx.in_cfg)(&v.node.attrs) {
139 Some(v.map(|Spanned {node: ast::Variant_ {id, name, attrs, kind,
140 disr_expr, vis}, span}| {
142 node: ast::Variant_ {
147 ast::TupleVariantKind(..) => kind,
148 ast::StructVariantKind(def) => {
149 ast::StructVariantKind(fold_struct(cx, def))
152 disr_expr: disr_expr,
160 ast::ItemEnum(ast::EnumDef {
161 variants: variants.collect(),
167 fold::noop_fold_item_underscore(item, cx)
170 fn fold_struct<F>(cx: &mut Context<F>, def: P<ast::StructDef>) -> P<ast::StructDef> where
171 F: FnMut(&[ast::Attribute]) -> bool
173 def.map(|ast::StructDef { fields, ctor_id }| {
175 fields: fields.into_iter().filter(|m| {
176 (cx.in_cfg)(&m.node.attrs)
183 fn retain_stmt<F>(cx: &mut Context<F>, stmt: &ast::Stmt) -> bool where
184 F: FnMut(&[ast::Attribute]) -> bool
187 ast::StmtDecl(ref decl, _) => {
189 ast::DeclItem(ref item) => {
190 item_in_cfg(cx, &**item)
199 fn fold_block<F>(cx: &mut Context<F>, b: P<ast::Block>) -> P<ast::Block> where
200 F: FnMut(&[ast::Attribute]) -> bool
202 b.map(|ast::Block {id, stmts, expr, rules, span}| {
203 let resulting_stmts: Vec<P<ast::Stmt>> =
204 stmts.into_iter().filter(|a| retain_stmt(cx, &**a)).collect();
205 let resulting_stmts = resulting_stmts.into_iter()
206 .flat_map(|stmt| cx.fold_stmt(stmt).into_iter())
210 stmts: resulting_stmts,
211 expr: expr.map(|x| cx.fold_expr(x)),
218 fn fold_expr<F>(cx: &mut Context<F>, expr: P<ast::Expr>) -> P<ast::Expr> where
219 F: FnMut(&[ast::Attribute]) -> bool
221 expr.map(|ast::Expr {id, span, node}| {
222 fold::noop_fold_expr(ast::Expr {
225 ast::ExprMatch(m, arms, source) => {
226 ast::ExprMatch(m, arms.into_iter()
227 .filter(|a| (cx.in_cfg)(&a.attrs))
237 fn item_in_cfg<F>(cx: &mut Context<F>, item: &ast::Item) -> bool where
238 F: FnMut(&[ast::Attribute]) -> bool
240 return (cx.in_cfg)(&item.attrs);
243 fn foreign_item_in_cfg<F>(cx: &mut Context<F>, item: &ast::ForeignItem) -> bool where
244 F: FnMut(&[ast::Attribute]) -> bool
246 return (cx.in_cfg)(&item.attrs);
249 // Determine if an item should be translated in the current crate
250 // configuration based on the item's attributes
251 fn in_cfg(diagnostic: &SpanHandler, cfg: &[P<ast::MetaItem>], attrs: &[ast::Attribute]) -> bool {
252 attrs.iter().all(|attr| {
253 let mis = match attr.node.value.node {
254 ast::MetaList(_, ref mis) if attr.check_name("cfg") => mis,
259 diagnostic.span_err(attr.span, "expected 1 cfg-pattern");
263 attr::cfg_matches(diagnostic, cfg, &*mis[0])
267 struct CfgAttrFolder<'a> {
268 diag: &'a SpanHandler,
269 config: ast::CrateConfig,
272 // Process `#[cfg_attr]`.
273 fn process_cfg_attr(diagnostic: &SpanHandler, krate: ast::Crate) -> ast::Crate {
274 let mut fld = CfgAttrFolder {
276 config: krate.config.clone(),
278 fld.fold_crate(krate)
281 impl<'a> fold::Folder for CfgAttrFolder<'a> {
282 fn fold_attribute(&mut self, attr: ast::Attribute) -> Option<ast::Attribute> {
283 if !attr.check_name("cfg_attr") {
284 return fold::noop_fold_attribute(attr, self);
287 let attr_list = match attr.meta_item_list() {
288 Some(attr_list) => attr_list,
290 self.diag.span_err(attr.span, "expected `#[cfg_attr(<cfg pattern>, <attr>)]`");
294 let (cfg, mi) = match (attr_list.len(), attr_list.get(0), attr_list.get(1)) {
295 (2, Some(cfg), Some(mi)) => (cfg, mi),
297 self.diag.span_err(attr.span, "expected `#[cfg_attr(<cfg pattern>, <attr>)]`");
302 if attr::cfg_matches(self.diag, &self.config[..], &cfg) {
303 Some(respan(mi.span, ast::Attribute_ {
304 id: attr::mk_attr_id(),
305 style: attr.node.style,
307 is_sugared_doc: false,
314 // Need the ability to run pre-expansion.
315 fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
316 fold::noop_fold_mac(mac, self)