rust/src/comp/front/config.rs

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Rust
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import std::option;
import std::vec;
import ast;
import fold;
import attr;
export strip_unconfigured_items;
// Support conditional compilation by transforming the AST, stripping out
// any items that do not belong in the current configuration
fn strip_unconfigured_items(@ast::crate crate) -> @ast::crate {
auto cfg = crate.node.config;
auto precursor = rec(fold_mod = bind fold_mod(cfg, _, _)
with *fold::default_ast_fold());
auto fold = fold::make_fold(precursor);
auto res = @fold.fold_crate(*crate);
// FIXME: This is necessary to break a circular reference
fold::dummy_out(fold);
ret res;
}
fn filter_item(&ast::crate_cfg cfg,
&@ast::item item) -> option::t[@ast::item] {
if (in_cfg(cfg, item)) {
option::some(item)
} else {
option::none
}
}
fn fold_mod(&ast::crate_cfg cfg, &ast::_mod m,
fold::ast_fold fld) -> ast::_mod {
auto filter = bind filter_item(cfg, _);
auto filtered_items = vec::filter_map(filter, m.items);
ret rec(view_items=vec::map(fld.fold_view_item, m.view_items),
items=vec::map(fld.fold_item, filtered_items));
}
// Determine if an item should be translated in the current crate
// configuration based on the item's attributes
fn in_cfg(&ast::crate_cfg cfg, &@ast::item item) -> bool {
auto item_cfg_attrs = attr::find_attrs_by_name(item.attrs, "cfg");
auto item_has_cfg_attrs = vec::len(item_cfg_attrs) > 0u;
if (!item_has_cfg_attrs) { ret true; }
auto item_cfg_metas = attr::attr_metas(item_cfg_attrs);
for (@ast::meta_item cfg_mi in item_cfg_metas) {
if (attr::contains(cfg, cfg_mi)) {
ret true;
}
}
ret false;
}
// Local Variables:
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End: