rust/src/librustc/front/config.rs

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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use syntax::fold::Folder;
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use syntax::{ast, fold, attr};
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use syntax::codemap::Spanned;
use syntax::ptr::P;
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/// A folder that strips out items that do not belong in the current
/// configuration.
struct Context<'a> {
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in_cfg: |attrs: &[ast::Attribute]|: 'a -> bool,
}
// Support conditional compilation by transforming the AST, stripping out
// any items that do not belong in the current configuration
pub fn strip_unconfigured_items(krate: ast::Crate) -> ast::Crate {
let config = krate.config.clone();
strip_items(krate, |attrs| in_cfg(config.as_slice(), attrs))
}
impl<'a> fold::Folder for Context<'a> {
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fn fold_mod(&mut self, module: ast::Mod) -> ast::Mod {
fold_mod(self, module)
}
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fn fold_block(&mut self, block: P<ast::Block>) -> P<ast::Block> {
fold_block(self, block)
}
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fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
fold_foreign_mod(self, foreign_mod)
}
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fn fold_item_underscore(&mut self, item: ast::Item_) -> ast::Item_ {
fold_item_underscore(self, item)
}
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fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
fold_expr(self, expr)
}
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fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
fold::noop_fold_mac(mac, self)
}
}
pub fn strip_items(krate: ast::Crate,
in_cfg: |attrs: &[ast::Attribute]| -> bool)
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-> ast::Crate {
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let mut ctxt = Context {
in_cfg: in_cfg,
};
ctxt.fold_crate(krate)
}
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fn filter_view_item(cx: &mut Context, view_item: ast::ViewItem) -> Option<ast::ViewItem> {
if view_item_in_cfg(cx, &view_item) {
Some(view_item)
} else {
None
}
}
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fn fold_mod(cx: &mut Context, ast::Mod {inner, view_items, items}: ast::Mod) -> ast::Mod {
ast::Mod {
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inner: inner,
view_items: view_items.move_iter().filter_map(|a| {
filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
}).collect(),
items: items.move_iter().filter_map(|a| {
if item_in_cfg(cx, &*a) {
Some(cx.fold_item(a))
} else {
None
}
}).flat_map(|x| x.move_iter()).collect()
}
}
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fn filter_foreign_item(cx: &mut Context, item: P<ast::ForeignItem>)
-> Option<P<ast::ForeignItem>> {
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if foreign_item_in_cfg(cx, &*item) {
Some(item)
} else {
None
}
}
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fn fold_foreign_mod(cx: &mut Context, ast::ForeignMod {abi, view_items, items}: ast::ForeignMod)
-> ast::ForeignMod {
ast::ForeignMod {
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abi: abi,
view_items: view_items.move_iter().filter_map(|a| {
filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
}).collect(),
items: items.move_iter()
.filter_map(|a| filter_foreign_item(cx, a))
.collect()
}
}
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fn fold_item_underscore(cx: &mut Context, item: ast::Item_) -> ast::Item_ {
let item = match item {
ast::ItemImpl(a, b, c, impl_items) => {
let impl_items = impl_items.move_iter()
.filter(|ii| impl_item_in_cfg(cx, ii))
.collect();
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ast::ItemImpl(a, b, c, impl_items)
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}
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ast::ItemTrait(a, b, c, methods) => {
let methods = methods.move_iter()
.filter(|m| trait_method_in_cfg(cx, m))
.collect();
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ast::ItemTrait(a, b, c, methods)
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}
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ast::ItemStruct(def, generics) => {
ast::ItemStruct(fold_struct(cx, def), generics)
}
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ast::ItemEnum(def, generics) => {
let mut variants = def.variants.move_iter().filter_map(|v| {
if !(cx.in_cfg)(v.node.attrs.as_slice()) {
None
} else {
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Some(v.map(|Spanned {node: ast::Variant_ {id, name, attrs, kind,
disr_expr, vis}, span}| {
Spanned {
node: ast::Variant_ {
id: id,
name: name,
attrs: attrs,
kind: match kind {
ast::TupleVariantKind(..) => kind,
ast::StructVariantKind(def) => {
ast::StructVariantKind(fold_struct(cx, def))
}
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},
disr_expr: disr_expr,
vis: vis
},
span: span
}
}))
}
});
ast::ItemEnum(ast::EnumDef {
variants: variants.collect(),
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}, generics)
}
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item => item,
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};
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fold::noop_fold_item_underscore(item, cx)
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}
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fn fold_struct(cx: &mut Context, def: P<ast::StructDef>) -> P<ast::StructDef> {
def.map(|ast::StructDef {fields, ctor_id, super_struct, is_virtual}| {
ast::StructDef {
fields: fields.move_iter().filter(|m| {
(cx.in_cfg)(m.node.attrs.as_slice())
}).collect(),
ctor_id: ctor_id,
super_struct: super_struct,
is_virtual: is_virtual,
}
})
}
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fn retain_stmt(cx: &mut Context, stmt: &ast::Stmt) -> bool {
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match stmt.node {
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ast::StmtDecl(ref decl, _) => {
match decl.node {
ast::DeclItem(ref item) => {
item_in_cfg(cx, &**item)
}
_ => true
}
}
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_ => true
}
}
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fn fold_block(cx: &mut Context, b: P<ast::Block>) -> P<ast::Block> {
b.map(|ast::Block {id, view_items, stmts, expr, rules, span}| {
let resulting_stmts: Vec<P<ast::Stmt>> =
stmts.move_iter().filter(|a| retain_stmt(cx, &**a)).collect();
let resulting_stmts = resulting_stmts.move_iter()
.flat_map(|stmt| cx.fold_stmt(stmt).move_iter())
.collect();
let filtered_view_items = view_items.move_iter().filter_map(|a| {
filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
}).collect();
ast::Block {
id: id,
view_items: filtered_view_items,
stmts: resulting_stmts,
expr: expr.map(|x| cx.fold_expr(x)),
rules: rules,
span: span,
}
})
}
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fn fold_expr(cx: &mut Context, expr: P<ast::Expr>) -> P<ast::Expr> {
expr.map(|ast::Expr {id, span, node}| {
fold::noop_fold_expr(ast::Expr {
id: id,
node: match node {
ast::ExprMatch(m, arms) => {
ast::ExprMatch(m, arms.move_iter()
.filter(|a| (cx.in_cfg)(a.attrs.as_slice()))
.collect())
}
_ => node
},
span: span
}, cx)
})
}
fn item_in_cfg(cx: &mut Context, item: &ast::Item) -> bool {
return (cx.in_cfg)(item.attrs.as_slice());
}
fn foreign_item_in_cfg(cx: &mut Context, item: &ast::ForeignItem) -> bool {
return (cx.in_cfg)(item.attrs.as_slice());
}
fn view_item_in_cfg(cx: &mut Context, item: &ast::ViewItem) -> bool {
return (cx.in_cfg)(item.attrs.as_slice());
}
fn trait_method_in_cfg(cx: &mut Context, meth: &ast::TraitItem) -> bool {
match *meth {
ast::RequiredMethod(ref meth) => (cx.in_cfg)(meth.attrs.as_slice()),
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ast::ProvidedMethod(ref meth) => (cx.in_cfg)(meth.attrs.as_slice())
}
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}
fn impl_item_in_cfg(cx: &mut Context, impl_item: &ast::ImplItem) -> bool {
match *impl_item {
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ast::MethodImplItem(ref meth) => (cx.in_cfg)(meth.attrs.as_slice()),
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}
}
// Determine if an item should be translated in the current crate
// configuration based on the item's attributes
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fn in_cfg(cfg: &[P<ast::MetaItem>], attrs: &[ast::Attribute]) -> bool {
attr::test_cfg(cfg, attrs.iter())
}