rust/src/librustc/front/config.rs

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// Copyright 2012 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 std::vec_ng::Vec;
use syntax::fold::Folder;
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use syntax::{ast, fold, attr};
use syntax::codemap;
struct Context<'a> {
in_cfg: 'a |attrs: &[ast::Attribute]| -> 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> {
fn fold_mod(&mut self, module: &ast::Mod) -> ast::Mod {
fold_mod(self, module)
}
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fn fold_block(&mut self, block: ast::P<ast::Block>) -> ast::P<ast::Block> {
fold_block(self, block)
}
fn fold_foreign_mod(&mut self, foreign_mod: &ast::ForeignMod) -> ast::ForeignMod {
fold_foreign_mod(self, foreign_mod)
}
fn fold_item_underscore(&mut self, item: &ast::Item_) -> ast::Item_ {
fold_item_underscore(self, item)
}
}
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)
}
fn filter_view_item<'r>(cx: &Context, view_item: &'r ast::ViewItem)
-> Option<&'r ast::ViewItem> {
if view_item_in_cfg(cx, view_item) {
Some(view_item)
} else {
None
}
}
fn fold_mod(cx: &mut Context, m: &ast::Mod) -> ast::Mod {
let filtered_items: Vec<&@ast::Item> = m.items.iter()
.filter(|&a| item_in_cfg(cx, *a))
.collect();
let flattened_items = filtered_items.move_iter()
.flat_map(|&x| cx.fold_item(x).move_iter())
.collect();
let filtered_view_items = m.view_items.iter().filter_map(|a| {
filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
}).collect();
ast::Mod {
view_items: filtered_view_items,
items: flattened_items
}
}
fn filter_foreign_item(cx: &Context, item: @ast::ForeignItem)
-> Option<@ast::ForeignItem> {
if foreign_item_in_cfg(cx, item) {
Some(item)
} else {
None
}
}
fn fold_foreign_mod(cx: &mut Context, nm: &ast::ForeignMod) -> ast::ForeignMod {
let filtered_items = nm.items
.iter()
.filter_map(|a| filter_foreign_item(cx, *a))
.collect();
let filtered_view_items = nm.view_items.iter().filter_map(|a| {
filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
}).collect();
ast::ForeignMod {
abis: nm.abis,
view_items: filtered_view_items,
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items: filtered_items
}
}
fn fold_item_underscore(cx: &mut Context, item: &ast::Item_) -> ast::Item_ {
let item = match *item {
ast::ItemImpl(ref a, ref b, c, ref methods) => {
let methods = methods.iter().filter(|m| method_in_cfg(cx, **m))
.map(|x| *x).collect();
ast::ItemImpl((*a).clone(), (*b).clone(), c, methods)
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}
ast::ItemTrait(ref a, ref b, ref methods) => {
let methods = methods.iter()
.filter(|m| trait_method_in_cfg(cx, *m) )
.map(|x| (*x).clone())
.collect();
ast::ItemTrait((*a).clone(), (*b).clone(), methods)
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}
ast::ItemStruct(def, ref generics) => {
ast::ItemStruct(fold_struct(cx, def), generics.clone())
}
ast::ItemEnum(ref def, ref generics) => {
let mut variants = def.variants.iter().map(|c| c.clone()).
filter_map(|v| {
if !(cx.in_cfg)(v.node.attrs.as_slice()) {
None
} else {
Some(match v.node.kind {
ast::TupleVariantKind(..) => v,
ast::StructVariantKind(def) => {
let def = fold_struct(cx, def);
@codemap::Spanned {
node: ast::Variant_ {
kind: ast::StructVariantKind(def),
..v.node.clone()
},
..*v
}
}
})
}
});
ast::ItemEnum(ast::EnumDef {
variants: variants.collect(),
}, generics.clone())
}
ref item => item.clone(),
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};
fold::noop_fold_item_underscore(&item, cx)
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}
fn fold_struct(cx: &Context, def: &ast::StructDef) -> @ast::StructDef {
let mut fields = def.fields.iter().map(|c| c.clone()).filter(|m| {
(cx.in_cfg)(m.node.attrs.as_slice())
});
@ast::StructDef {
fields: fields.collect(),
ctor_id: def.ctor_id,
}
}
fn retain_stmt(cx: &Context, stmt: @ast::Stmt) -> bool {
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match stmt.node {
ast::StmtDecl(decl, _) => {
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match decl.node {
ast::DeclItem(item) => {
item_in_cfg(cx, item)
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}
_ => true
}
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}
_ => true
}
}
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fn fold_block(cx: &mut Context, b: ast::P<ast::Block>) -> ast::P<ast::Block> {
let resulting_stmts: Vec<&@ast::Stmt> =
b.stmts.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 = b.view_items.iter().filter_map(|a| {
filter_view_item(cx, a).map(|x| cx.fold_view_item(x))
}).collect();
ast::P(ast::Block {
view_items: filtered_view_items,
stmts: resulting_stmts,
expr: b.expr.map(|x| cx.fold_expr(x)),
id: b.id,
rules: b.rules,
span: b.span,
})
}
fn item_in_cfg(cx: &Context, item: &ast::Item) -> bool {
return (cx.in_cfg)(item.attrs.as_slice());
}
fn foreign_item_in_cfg(cx: &Context, item: &ast::ForeignItem) -> bool {
return (cx.in_cfg)(item.attrs.as_slice());
}
fn view_item_in_cfg(cx: &Context, item: &ast::ViewItem) -> bool {
return (cx.in_cfg)(item.attrs.as_slice());
}
fn method_in_cfg(cx: &Context, meth: &ast::Method) -> bool {
return (cx.in_cfg)(meth.attrs.as_slice());
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}
fn trait_method_in_cfg(cx: &Context, meth: &ast::TraitMethod) -> bool {
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match *meth {
ast::Required(ref meth) => (cx.in_cfg)(meth.attrs.as_slice()),
ast::Provided(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
fn in_cfg(cfg: &[@ast::MetaItem], attrs: &[ast::Attribute]) -> bool {
attr::test_cfg(cfg, attrs.iter().map(|x| *x))
}