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import syntax::{ast, fold, attr};
export strip_unconfigured_items;
export metas_in_cfg;
export strip_items;
type in_cfg_pred = fn@(~[ast::attribute]) -> bool;
type ctxt = @{
in_cfg: in_cfg_pred
};
// Support conditional compilation by transforming the AST, stripping out
// any items that do not belong in the current configuration
fn strip_unconfigured_items(crate: @ast::crate) -> @ast::crate {
do strip_items(crate) |attrs| {
in_cfg(crate.node.config, attrs)
}
}
fn strip_items(crate: @ast::crate, in_cfg: in_cfg_pred)
-> @ast::crate {
let ctxt = @{in_cfg: in_cfg};
let precursor =
@{fold_mod: |a,b| fold_mod(ctxt, a, b),
fold_block: fold::wrap(|a,b| fold_block(ctxt, a, b) ),
fold_foreign_mod: |a,b| fold_foreign_mod(ctxt, a, b)
with *fold::default_ast_fold()};
let fold = fold::make_fold(precursor);
let res = @fold.fold_crate(*crate);
ret res;
}
fn filter_item(cx: ctxt, &&item: @ast::item) ->
option<@ast::item> {
if item_in_cfg(cx, item) { option::some(item) } else { option::none }
}
fn filter_view_item(cx: ctxt, &&view_item: @ast::view_item
)-> option<@ast::view_item> {
if view_item_in_cfg(cx, view_item) {
option::some(view_item)
} else {
option::none
}
}
fn fold_mod(cx: ctxt, m: ast::_mod, fld: fold::ast_fold) ->
ast::_mod {
let item_filter = |a| filter_item(cx, a);
let filtered_items = vec::filter_map(m.items, item_filter);
let view_item_filter = |a| filter_view_item(cx, a);
let filtered_view_items = vec::filter_map(m.view_items, view_item_filter);
ret {view_items: vec::map(filtered_view_items, |x| fld.fold_view_item(x)),
items: vec::filter_map(filtered_items, |x| fld.fold_item(x))};
}
fn filter_foreign_item(cx: ctxt, &&item: @ast::foreign_item) ->
option<@ast::foreign_item> {
if foreign_item_in_cfg(cx, item) {
option::some(item)
} else { option::none }
}
fn fold_foreign_mod(cx: ctxt, nm: ast::foreign_mod,
fld: fold::ast_fold) -> ast::foreign_mod {
let item_filter = |a| filter_foreign_item(cx, a);
let filtered_items = vec::filter_map(nm.items, item_filter);
let view_item_filter = |a| filter_view_item(cx, a);
let filtered_view_items = vec::filter_map(
nm.view_items, view_item_filter);
ret {view_items: vec::map(filtered_view_items, |x| fld.fold_view_item(x)),
items: filtered_items};
}
fn filter_stmt(cx: ctxt, &&stmt: @ast::stmt) ->
option<@ast::stmt> {
alt stmt.node {
ast::stmt_decl(decl, _) {
alt decl.node {
ast::decl_item(item) {
if item_in_cfg(cx, item) {
option::some(stmt)
} else { option::none }
}
_ { option::some(stmt) }
}
}
_ { option::some(stmt) }
}
}
fn fold_block(cx: ctxt, b: ast::blk_, fld: fold::ast_fold) ->
ast::blk_ {
let filter = |a| filter_stmt(cx, a);
let filtered_stmts = vec::filter_map(b.stmts, filter);
ret {view_items: b.view_items,
stmts: vec::map(filtered_stmts, |x| fld.fold_stmt(x)),
expr: option::map(b.expr, |x| fld.fold_expr(x)),
id: b.id,
rules: b.rules};
}
fn item_in_cfg(cx: ctxt, item: @ast::item) -> bool {
ret cx.in_cfg(item.attrs);
}
fn foreign_item_in_cfg(cx: ctxt, item: @ast::foreign_item) -> bool {
ret cx.in_cfg(item.attrs);
}
fn view_item_in_cfg(cx: ctxt, item: @ast::view_item) -> bool {
ret cx.in_cfg(item.attrs);
}
// Determine if an item should be translated in the current crate
// configuration based on the item's attributes
fn in_cfg(cfg: ast::crate_cfg, attrs: ~[ast::attribute]) -> bool {
metas_in_cfg(cfg, attr::attr_metas(attrs))
}
fn metas_in_cfg(cfg: ast::crate_cfg, metas: ~[@ast::meta_item]) -> bool {
// The "cfg" attributes on the item
let cfg_metas = attr::find_meta_items_by_name(metas, "cfg");
// Pull the inner meta_items from the #[cfg(meta_item, ...)] attributes,
// so we can match against them. This is the list of configurations for
// which the item is valid
let cfg_metas = vec::concat(vec::filter_map(cfg_metas,
|&&i| attr::get_meta_item_list(i) ));
let has_cfg_metas = vec::len(cfg_metas) > 0u;
if !has_cfg_metas { ret true; }
for cfg_metas.each |cfg_mi| {
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
// End:
|
