124 lines
4.5 KiB
Rust
124 lines
4.5 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// A pass that annotates for each loops and functions with the free
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// variables that they contain.
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use core::prelude::*;
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use middle::resolve;
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use middle::ty;
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use core::hashmap::HashMap;
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use core::vec;
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use syntax::codemap::span;
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use syntax::{ast, ast_util, visit};
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// A vector of defs representing the free variables referred to in a function.
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// (The def_upvar will already have been stripped).
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#[deriving(Encodable, Decodable)]
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pub struct freevar_entry {
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def: ast::def, //< The variable being accessed free.
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span: span //< First span where it is accessed (there can be multiple)
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}
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pub type freevar_info = @~[@freevar_entry];
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pub type freevar_map = @mut HashMap<ast::node_id, freevar_info>;
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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_freevars(def_map: resolve::DefMap, blk: &ast::blk)
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-> freevar_info {
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let seen = @mut HashMap::new();
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let refs = @mut ~[];
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fn ignore_item(_i: @ast::item, _depth: int, _v: visit::vt<int>) { }
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let walk_expr: @fn(expr: @ast::expr, depth: int, v: visit::vt<int>) =
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|expr, depth, v| {
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match expr.node {
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ast::expr_fn_block(*) => visit::visit_expr(expr, depth + 1, v),
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ast::expr_path(*) | ast::expr_self => {
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let mut i = 0;
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match def_map.find(&expr.id) {
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None => fail!("path not found"),
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Some(&df) => {
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let mut def = df;
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while i < depth {
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match def {
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ast::def_upvar(_, inner, _, _) => { def = *inner; }
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_ => break
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}
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i += 1;
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}
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if i == depth { // Made it to end of loop
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let dnum = ast_util::def_id_of_def(def).node;
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if !seen.contains_key(&dnum) {
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refs.push(@freevar_entry {
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def: def,
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span: expr.span,
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});
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seen.insert(dnum, ());
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}
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}
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}
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}
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}
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_ => visit::visit_expr(expr, depth, v)
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}
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};
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let v = visit::mk_vt(@visit::Visitor {visit_item: ignore_item,
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visit_expr: walk_expr,
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.. *visit::default_visitor()});
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(v.visit_block)(blk, 1, v);
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return @/*bad*/copy *refs;
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}
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// Build a map from every function and for-each body to a set of the
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// freevars contained in it. The implementation is not particularly
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// efficient as it fully recomputes the free variables at every
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// node of interest rather than building up the free variables in
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// one pass. This could be improved upon if it turns out to matter.
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pub fn annotate_freevars(def_map: resolve::DefMap, crate: @ast::crate) ->
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freevar_map {
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let freevars = @mut HashMap::new();
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let walk_fn: @fn(&visit::fn_kind,
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&ast::fn_decl,
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&ast::blk,
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span,
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ast::node_id) = |_, _, blk, _, nid| {
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let vars = collect_freevars(def_map, blk);
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freevars.insert(nid, vars);
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};
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let visitor =
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visit::mk_simple_visitor(@visit::SimpleVisitor {
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visit_fn: walk_fn,
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.. *visit::default_simple_visitor()});
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visit::visit_crate(crate, (), visitor);
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return freevars;
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}
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pub fn get_freevars(tcx: ty::ctxt, fid: ast::node_id) -> freevar_info {
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match tcx.freevars.find(&fid) {
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None => fail!("get_freevars: %d has no freevars", fid),
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Some(&d) => return d
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}
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}
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pub fn has_freevars(tcx: ty::ctxt, fid: ast::node_id) -> bool {
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return vec::len(*get_freevars(tcx, fid)) != 0u;
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}
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