visitor trait rewrite step 4 (of 5).

src/librustc/middle/borrowck/check_loans.rs

@@ -27,7 +27,8 @@ use syntax::ast::{m_mutbl, m_imm, m_const};
 use syntax::ast;
 use syntax::ast_util;
 use syntax::codemap::span;
-use syntax::oldvisit;
+use syntax::visit;
+use syntax::visit::Visitor;
 use util::ppaux::Repr;
 
 #[deriving(Clone)]
@@ -39,6 +40,27 @@ struct CheckLoanCtxt<'self> {
     reported: @mut HashSet<ast::NodeId>,
 }
 
+struct CheckLoanVisitor;
+
+impl<'self> Visitor<CheckLoanCtxt<'self>> for CheckLoanVisitor {
+    fn visit_expr<'a>(&mut self, ex:@ast::expr, e:CheckLoanCtxt<'a>) {
+        check_loans_in_expr(self, ex, e);
+    }
+    fn visit_local(&mut self, l:@ast::Local, e:CheckLoanCtxt) {
+        check_loans_in_local(self, l, e);
+    }
+    fn visit_block(&mut self, b:&ast::Block, e:CheckLoanCtxt) {
+        check_loans_in_block(self, b, e);
+    }
+    fn visit_pat(&mut self, p:@ast::pat, e:CheckLoanCtxt) {
+        check_loans_in_pat(self, p, e);
+    }
+    fn visit_fn(&mut self, fk:&visit::fn_kind, fd:&ast::fn_decl,
+                b:&ast::Block, s:span, n:ast::NodeId, e:CheckLoanCtxt) {
+        check_loans_in_fn(self, fk, fd, b, s, n, e);
+    }
+}
+
 pub fn check_loans(bccx: @BorrowckCtxt,
                    dfcx_loans: &LoanDataFlow,
                    move_data: move_data::FlowedMoveData,
@@ -54,15 +76,8 @@ pub fn check_loans(bccx: @BorrowckCtxt,
         reported: @mut HashSet::new(),
     };
 
-    let vt = oldvisit::mk_vt(@oldvisit::Visitor {
-        visit_expr: check_loans_in_expr,
-        visit_local: check_loans_in_local,
-        visit_block: check_loans_in_block,
-        visit_pat: check_loans_in_pat,
-        visit_fn: check_loans_in_fn,
-        .. *oldvisit::default_visitor()
-    });
-    (vt.visit_block)(body, (clcx, vt));
+    let mut vt = CheckLoanVisitor;
+    vt.visit_block(body, clcx);
 }
 
 enum MoveError {
@@ -626,27 +641,27 @@ impl<'self> CheckLoanCtxt<'self> {
     }
 }
 
-fn check_loans_in_fn<'a>(fk: &oldvisit::fn_kind,
+fn check_loans_in_fn<'a>(visitor: &mut CheckLoanVisitor,
+                         fk: &visit::fn_kind,
                          decl: &ast::fn_decl,
                          body: &ast::Block,
                          sp: span,
                          id: ast::NodeId,
-                         (this, visitor): (CheckLoanCtxt<'a>,
-                                           oldvisit::vt<CheckLoanCtxt<'a>>)) {
+                         this: CheckLoanCtxt<'a>) {
     match *fk {
-        oldvisit::fk_item_fn(*) |
-        oldvisit::fk_method(*) => {
+        visit::fk_item_fn(*) |
+        visit::fk_method(*) => {
             // Don't process nested items.
             return;
         }
 
-        oldvisit::fk_anon(*) |
-        oldvisit::fk_fn_block(*) => {
+        visit::fk_anon(*) |
+        visit::fk_fn_block(*) => {
             check_captured_variables(this, id, sp);
         }
     }
 
-    oldvisit::visit_fn(fk, decl, body, sp, id, (this, visitor));
+    visit::walk_fn(visitor, fk, decl, body, sp, id, this);
 
     fn check_captured_variables(this: CheckLoanCtxt,
                                 closure_id: ast::NodeId,
@@ -689,16 +704,16 @@ fn check_loans_in_fn<'a>(fk: &oldvisit::fn_kind,
     }
 }
 
-fn check_loans_in_local<'a>(local: @ast::Local,
-                            (this, vt): (CheckLoanCtxt<'a>,
-                                         oldvisit::vt<CheckLoanCtxt<'a>>)) {
-    oldvisit::visit_local(local, (this, vt));
+fn check_loans_in_local<'a>(vt: &mut CheckLoanVisitor,
+                            local: @ast::Local,
+                            this: CheckLoanCtxt<'a>) {
+    visit::walk_local(vt, local, this);
 }
 
-fn check_loans_in_expr<'a>(expr: @ast::expr,
-                           (this, vt): (CheckLoanCtxt<'a>,
-                                        oldvisit::vt<CheckLoanCtxt<'a>>)) {
-    oldvisit::visit_expr(expr, (this, vt));
+fn check_loans_in_expr<'a>(vt: &mut CheckLoanVisitor,
+                           expr: @ast::expr,
+                           this: CheckLoanCtxt<'a>) {
+    visit::walk_expr(vt, expr, this);
 
     debug!("check_loans_in_expr(expr=%s)",
            expr.repr(this.tcx()));
@@ -749,19 +764,19 @@ fn check_loans_in_expr<'a>(expr: @ast::expr,
     }
 }
 
-fn check_loans_in_pat<'a>(pat: @ast::pat,
-                          (this, vt): (CheckLoanCtxt<'a>,
-                                       oldvisit::vt<CheckLoanCtxt<'a>>))
+fn check_loans_in_pat<'a>(vt: &mut CheckLoanVisitor,
+                          pat: @ast::pat,
+                          this: CheckLoanCtxt<'a>)
 {
     this.check_for_conflicting_loans(pat.id);
     this.check_move_out_from_id(pat.id, pat.span);
-    oldvisit::visit_pat(pat, (this, vt));
+    visit::walk_pat(vt, pat, this);
 }
 
-fn check_loans_in_block<'a>(blk: &ast::Block,
-                            (this, vt): (CheckLoanCtxt<'a>,
-                                         oldvisit::vt<CheckLoanCtxt<'a>>))
+fn check_loans_in_block<'a>(vt: &mut CheckLoanVisitor,
+                            blk: &ast::Block,
+                            this: CheckLoanCtxt<'a>)
 {
-    oldvisit::visit_block(blk, (this, vt));
+    visit::walk_block(vt, blk, this);
     this.check_for_conflicting_loans(blk.id);
 }

src/librustc/middle/entry.rs

@@ -15,9 +15,9 @@ use syntax::ast::{Crate, NodeId, item, item_fn};
 use syntax::ast_map;
 use syntax::attr;
 use syntax::codemap::span;
-use syntax::oldvisit::{default_visitor, mk_vt, vt, Visitor, visit_crate};
-use syntax::oldvisit::{visit_item};
 use syntax::parse::token::special_idents;
+use syntax::visit;
+use syntax::visit::Visitor;
 use std::util;
 
 struct EntryContext {
@@ -39,7 +39,13 @@ struct EntryContext {
     non_main_fns: ~[(NodeId, span)],
 }
 
-type EntryVisitor = vt<@mut EntryContext>;
+struct EntryVisitor;
+
+impl Visitor<@mut EntryContext> for EntryVisitor {
+    fn visit_item(&mut self, item:@item, ctxt:@mut EntryContext) {
+        find_item(item, ctxt, self);
+    }
+}
 
 pub fn find_entry_point(session: Session, crate: &Crate, ast_map: ast_map::map) {
 
@@ -65,15 +71,14 @@ pub fn find_entry_point(session: Session, crate: &Crate, ast_map: ast_map::map)
         non_main_fns: ~[],
     };
 
-    visit_crate(crate, (ctxt, mk_vt(@Visitor {
-        visit_item: |item, (ctxt, visitor)| find_item(item, ctxt, visitor),
-        .. *default_visitor()
-    })));
+    let mut v = EntryVisitor;
+
+    visit::walk_crate(&mut v, crate, ctxt);
 
     configure_main(ctxt);
 }
 
-fn find_item(item: @item, ctxt: @mut EntryContext, visitor: EntryVisitor) {
+fn find_item(item: @item, ctxt: @mut EntryContext, visitor: &mut EntryVisitor) {
     match item.node {
         item_fn(*) => {
             if item.ident == special_idents::main {
@@ -120,7 +125,7 @@ fn find_item(item: @item, ctxt: @mut EntryContext, visitor: EntryVisitor) {
         _ => ()
     }
 
-    visit_item(item, (ctxt, visitor));
+    visit::walk_item(visitor, item, ctxt);
 }
 
 fn configure_main(ctxt: @mut EntryContext) {

src/librustc/middle/freevars.rs

@@ -17,7 +17,10 @@ use middle::ty;
 
 use std::hashmap::HashMap;
 use syntax::codemap::span;
-use syntax::{ast, ast_util, oldvisit};
+use syntax::{ast, ast_util};
+use syntax::visit;
+use syntax::visit::Visitor;
+use syntax::ast::{item};
 
 // A vector of defs representing the free variables referred to in a function.
 // (The def_upvar will already have been stripped).
@@ -29,27 +32,27 @@ pub struct freevar_entry {
 pub type freevar_info = @~[@freevar_entry];
 pub type freevar_map = @mut HashMap<ast::NodeId, freevar_info>;
 
-// Searches through part of the AST for all references to locals or
-// upvars in this frame and returns the list of definition IDs thus found.
-// Since we want to be able to collect upvars in some arbitrary piece
-// of the AST, we take a walker function that we invoke with a visitor
-// in order to start the search.
-fn collect_freevars(def_map: resolve::DefMap, blk: &ast::Block)
-    -> freevar_info {
-    let seen = @mut HashMap::new();
-    let refs = @mut ~[];
+struct CollectFreevarsVisitor {
+    seen: @mut HashMap<ast::NodeId, ()>,
+    refs: @mut ~[@freevar_entry],
+    def_map: resolve::DefMap,
+}
+
+impl Visitor<int> for CollectFreevarsVisitor {
 
-    fn ignore_item(_i: @ast::item, (_depth, _v): (int, oldvisit::vt<int>)) { }
+    fn visit_item(&mut self, _:@item, _:int) {
+        // ignore_item
+    }
+
+    fn visit_expr(&mut self, expr:@ast::expr, depth:int) {
 
-    let walk_expr: @fn(expr: @ast::expr, (int, oldvisit::vt<int>)) =
-        |expr, (depth, v)| {
             match expr.node {
               ast::expr_fn_block(*) => {
-                oldvisit::visit_expr(expr, (depth + 1, v))
+                visit::walk_expr(self, expr, depth + 1)
               }
               ast::expr_path(*) | ast::expr_self => {
                   let mut i = 0;
-                  match def_map.find(&expr.id) {
+                  match self.def_map.find(&expr.id) {
                     None => fail!("path not found"),
                     Some(&df) => {
                       let mut def = df;
@@ -62,28 +65,58 @@ fn collect_freevars(def_map: resolve::DefMap, blk: &ast::Block)
                       }
                       if i == depth { // Made it to end of loop
                         let dnum = ast_util::def_id_of_def(def).node;
-                        if !seen.contains_key(&dnum) {
-                            refs.push(@freevar_entry {
+                        if !self.seen.contains_key(&dnum) {
+                            self.refs.push(@freevar_entry {
                                 def: def,
                                 span: expr.span,
                             });
-                            seen.insert(dnum, ());
+                            self.seen.insert(dnum, ());
                         }
                       }
                     }
                   }
               }
-              _ => oldvisit::visit_expr(expr, (depth, v))
+              _ => visit::walk_expr(self, expr, depth)
             }
-        };
+    }
 
-    let v = oldvisit::mk_vt(@oldvisit::Visitor {visit_item: ignore_item,
-                                          visit_expr: walk_expr,
-                                          .. *oldvisit::default_visitor()});
-    (v.visit_block)(blk, (1, v));
+
+}
+
+// Searches through part of the AST for all references to locals or
+// upvars in this frame and returns the list of definition IDs thus found.
+// Since we want to be able to collect upvars in some arbitrary piece
+// of the AST, we take a walker function that we invoke with a visitor
+// in order to start the search.
+fn collect_freevars(def_map: resolve::DefMap, blk: &ast::Block)
+    -> freevar_info {
+    let seen = @mut HashMap::new();
+    let refs = @mut ~[];
+
+    let mut v = CollectFreevarsVisitor {
+        seen: seen,
+        refs: refs,
+        def_map: def_map,
+    };
+
+    v.visit_block(blk, 1);
     return @(*refs).clone();
 }
 
+struct AnnotateFreevarsVisitor {
+    def_map: resolve::DefMap,
+    freevars: freevar_map,
+}
+
+impl Visitor<()> for AnnotateFreevarsVisitor {
+    fn visit_fn(&mut self, fk:&visit::fn_kind, fd:&ast::fn_decl,
+                blk:&ast::Block, s:span, nid:ast::NodeId, _:()) {
+        let vars = collect_freevars(self.def_map, blk);
+        self.freevars.insert(nid, vars);
+        visit::walk_fn(self, fk, fd, blk, s, nid, ());
+    }
+}
+
 // Build a map from every function and for-each body to a set of the
 // freevars contained in it. The implementation is not particularly
 // efficient as it fully recomputes the free variables at every
@@ -93,20 +126,11 @@ pub fn annotate_freevars(def_map: resolve::DefMap, crate: &ast::Crate) ->
    freevar_map {
     let freevars = @mut HashMap::new();
 
-    let walk_fn: @fn(&oldvisit::fn_kind,
-                     &ast::fn_decl,
-                     &ast::Block,
-                     span,
-                     ast::NodeId) = |_, _, blk, _, nid| {
-        let vars = collect_freevars(def_map, blk);
-        freevars.insert(nid, vars);
+    let mut visitor = AnnotateFreevarsVisitor {
+        def_map: def_map,
+        freevars: freevars,
     };
-
-    let visitor =
-        oldvisit::mk_simple_visitor(@oldvisit::SimpleVisitor {
-            visit_fn: walk_fn,
-            .. *oldvisit::default_simple_visitor()});
-    oldvisit::visit_crate(crate, ((), visitor));
+    visit::walk_crate(&mut visitor, crate, ());
 
     return freevars;
 }