92 lines
3.0 KiB
Rust
92 lines
3.0 KiB
Rust
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// A pass that annotates for each loops with the free variables that
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// they contain.
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import std::map;
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import std::map::*;
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import syntax::ast;
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import syntax::walk;
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import driver::session;
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import middle::ty;
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import syntax::codemap::span;
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// Searches through part of the AST for all references to locals or
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// upvars in this frame and returns the list of definition IDs thus found.
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// Since we want to be able to collect upvars in some arbitrary piece
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// of the AST, we take a walker function that we invoke with a visitor
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// in order to start the search.
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fn collect_upvars(&ty::ctxt tcx, &fn (&walk::ast_visitor) walker,
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ast::node_id[] initial_decls) -> ast::node_id[] {
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type env =
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@rec(mutable ast::node_id[] refs,
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hashmap[ast::node_id, ()] decls,
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resolve::def_map def_map,
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session::session sess);
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fn walk_fn(env e, &ast::_fn f, &ast::ty_param[] tps, &span sp,
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&ast::fn_ident i, ast::node_id nid) {
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for (ast::arg a in f.decl.inputs) { e.decls.insert(a.id, ()); }
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}
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fn walk_expr(env e, &@ast::expr expr) {
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alt (expr.node) {
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case (ast::expr_path(?path)) {
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if (! e.def_map.contains_key(expr.id)) {
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e.sess.span_fatal(expr.span,
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"internal error in collect_upvars");
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}
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alt (e.def_map.get(expr.id)) {
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case (ast::def_arg(?did)) { e.refs += ~[did._1]; }
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case (ast::def_local(?did)) { e.refs += ~[did._1]; }
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case (ast::def_binding(?did)) { e.refs += ~[did._1]; }
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case (_) { /* no-op */ }
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}
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}
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case (_) { }
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}
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}
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fn walk_local(env e, &@ast::local local) {
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e.decls.insert(local.node.id, ());
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}
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fn walk_pat(env e, &@ast::pat p) {
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alt (p.node) {
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case (ast::pat_bind(_)) {
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e.decls.insert(p.id, ());
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}
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case (_) {}
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}
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}
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let hashmap[ast::node_id, ()] decls = new_int_hash[()]();
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for (ast::node_id decl in initial_decls) { decls.insert(decl, ()); }
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let env e =
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@rec(mutable refs=~[],
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decls=decls,
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def_map=tcx.def_map,
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sess=tcx.sess);
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auto visitor =
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@rec(visit_fn_pre=bind walk_fn(e, _, _, _, _, _),
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visit_local_pre=bind walk_local(e, _),
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visit_expr_pre=bind walk_expr(e, _),
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visit_pat_pre=bind walk_pat(e, _)
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with walk::default_visitor());
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walker(*visitor);
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// Calculate (refs - decls). This is the set of captured upvars.
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let ast::node_id[] result = ~[];
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for (ast::node_id ref_id_ in e.refs) {
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auto ref_id = ref_id_;
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if (!decls.contains_key(ref_id)) { result += ~[ref_id]; }
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}
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ret result;
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}
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// Local Variables:
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// mode: rust
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// fill-column: 78;
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// indent-tabs-mode: nil
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// c-basic-offset: 4
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// buffer-file-coding-system: utf-8-unix
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// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
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// End:
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