128 lines
4.6 KiB
Rust
128 lines
4.6 KiB
Rust
import syntax::{ast, ast_util};
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import driver::session::session;
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import syntax::codemap::span;
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import std::map;
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import std::map::hashmap;
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export capture_mode;
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export capture_var;
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export capture_map;
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export check_capture_clause;
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export compute_capture_vars;
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export cap_copy;
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export cap_move;
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export cap_drop;
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export cap_ref;
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enum capture_mode {
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cap_copy, // Copy the value into the closure.
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cap_move, // Move the value into the closure.
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cap_drop, // Drop value after creating closure.
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cap_ref, // Reference directly from parent stack frame (block fn).
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}
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type capture_var = {
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def: ast::def, // Variable being accessed free
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span: span, // Location of access or cap item
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cap_item: Option<ast::capture_item>, // Capture item, if any
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mode: capture_mode // How variable is being accessed
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};
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type capture_map = map::hashmap<ast::def_id, capture_var>;
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// checks the capture clause for a fn_expr() and issues warnings or
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// errors for any irregularities which we identify.
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fn check_capture_clause(tcx: ty::ctxt,
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fn_expr_id: ast::node_id,
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cap_clause: ast::capture_clause) {
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let freevars = freevars::get_freevars(tcx, fn_expr_id);
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let seen_defs = map::int_hash();
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for (*cap_clause).each |cap_item| {
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let cap_def = tcx.def_map.get(cap_item.id);
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if !vec::any(*freevars, |fv| fv.def == cap_def ) {
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tcx.sess.span_warn(
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cap_item.span,
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fmt!("captured variable `%s` not used in closure",
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tcx.sess.str_of(cap_item.name)));
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}
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let cap_def_id = ast_util::def_id_of_def(cap_def).node;
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if !seen_defs.insert(cap_def_id, ()) {
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tcx.sess.span_err(
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cap_item.span,
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fmt!("variable `%s` captured more than once",
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tcx.sess.str_of(cap_item.name)));
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}
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}
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}
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fn compute_capture_vars(tcx: ty::ctxt,
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fn_expr_id: ast::node_id,
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fn_proto: ty::fn_proto,
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cap_clause: ast::capture_clause) -> ~[capture_var] {
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let freevars = freevars::get_freevars(tcx, fn_expr_id);
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let cap_map = map::int_hash();
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// first add entries for anything explicitly named in the cap clause
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for (*cap_clause).each |cap_item| {
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debug!("Doing capture var: %s (%?)",
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tcx.sess.str_of(cap_item.name), cap_item.id);
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let cap_def = tcx.def_map.get(cap_item.id);
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let cap_def_id = ast_util::def_id_of_def(cap_def).node;
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if cap_item.is_move {
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// if we are moving the value in, but it's not actually used,
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// must drop it.
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if vec::any(*freevars, |fv| fv.def == cap_def ) {
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cap_map.insert(cap_def_id, {def:cap_def,
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span: cap_item.span,
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cap_item: Some(cap_item),
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mode:cap_move});
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} else {
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cap_map.insert(cap_def_id, {def:cap_def,
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span: cap_item.span,
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cap_item: Some(cap_item),
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mode:cap_drop});
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}
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} else {
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// if we are copying the value in, but it's not actually used,
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// just ignore it.
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if vec::any(*freevars, |fv| fv.def == cap_def ) {
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cap_map.insert(cap_def_id, {def:cap_def,
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span: cap_item.span,
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cap_item: Some(cap_item),
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mode:cap_copy});
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}
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}
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}
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// now go through anything that is referenced but was not explicitly
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// named and add that
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let implicit_mode;
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if ty::is_blockish(fn_proto) {
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implicit_mode = cap_ref;
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} else {
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implicit_mode = cap_copy;
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}
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do vec::iter(*freevars) |fvar| {
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let fvar_def_id = ast_util::def_id_of_def(fvar.def).node;
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match cap_map.find(fvar_def_id) {
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option::Some(_) => { /* was explicitly named, do nothing */ }
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option::None => {
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cap_map.insert(fvar_def_id, {def:fvar.def,
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span: fvar.span,
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cap_item: None,
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mode:implicit_mode});
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}
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}
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}
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let mut result = ~[];
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for cap_map.each_value |cap_var| { vec::push(result, cap_var); }
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return result;
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}
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