auto merge of #10854 : Kimundi/rust/result_compose_map_mutate_or, r=alexcrichton

This implements parts of the changes to `Option` I proposed and discussed in this thread: https://mail.mozilla.org/pipermail/rust-dev/2013-November/006254.html, and on IRC.

In short, the string "default" should not be used in any context that has nothing to do with the `std::default::Default` trait.

This PR consists of this change:
- Renamed `map_default -> map_or` and `mutate_default -> mutate_or_set`.

Author: bors

src/libextra/dlist.rs

@@ -191,7 +191,7 @@ impl<T> DList<T> {
     /// Remove the last Node and return it, or None if the list is empty
     #[inline]
     fn pop_back_node(&mut self) -> Option<~Node<T>> {
-        self.list_tail.resolve().map_default(None, |tail| {
+        self.list_tail.resolve().map_or(None, |tail| {
             self.length -= 1;
             self.list_tail = tail.prev;
             match tail.prev.resolve() {

src/libextra/glob.rs

@@ -100,7 +100,7 @@ pub fn glob_with(pattern: &str, options: MatchOptions) -> GlobIterator {
         root.push(pat_root.get_ref());
     }
 
-    let root_len = pat_root.map_default(0u, |p| p.as_vec().len());
+    let root_len = pat_root.map_or(0u, |p| p.as_vec().len());
     let dir_patterns = pattern.slice_from(root_len.min(&pattern.len()))
                        .split_terminator(is_sep).map(|s| Pattern::new(s)).to_owned_vec();
 
@@ -314,7 +314,7 @@ impl Pattern {
      */
     pub fn matches_path(&self, path: &Path) -> bool {
         // FIXME (#9639): This needs to handle non-utf8 paths
-        path.as_str().map_default(false, |s| {
+        path.as_str().map_or(false, |s| {
             self.matches(s)
         })
     }
@@ -332,7 +332,7 @@ impl Pattern {
      */
     pub fn matches_path_with(&self, path: &Path, options: MatchOptions) -> bool {
         // FIXME (#9639): This needs to handle non-utf8 paths
-        path.as_str().map_default(false, |s| {
+        path.as_str().map_or(false, |s| {
             self.matches_with(s, options)
         })
     }

src/libextra/num/bigint.rs

@@ -697,7 +697,7 @@ impl BigUint {
     #[inline]
     pub fn new(v: ~[BigDigit]) -> BigUint {
         // omit trailing zeros
-        let new_len = v.iter().rposition(|n| *n != 0).map_default(0, |p| p + 1);
+        let new_len = v.iter().rposition(|n| *n != 0).map_or(0, |p| p + 1);
 
         if new_len == v.len() { return BigUint { data: v }; }
         let mut v = v;

src/libextra/term.rs

@@ -122,7 +122,7 @@ impl<T: Writer> Terminal<T> {
         let inf = ti.unwrap();
         let nc = if inf.strings.find_equiv(&("setaf")).is_some()
                  && inf.strings.find_equiv(&("setab")).is_some() {
-                     inf.numbers.find_equiv(&("colors")).map_default(0, |&n| n)
+                     inf.numbers.find_equiv(&("colors")).map_or(0, |&n| n)
                  } else { 0 };
 
         return Ok(Terminal {out: out, ti: inf, num_colors: nc});
@@ -215,7 +215,7 @@ impl<T: Writer> Terminal<T> {
                 cap = self.ti.strings.find_equiv(&("op"));
             }
         }
-        let s = cap.map_default(Err(~"can't find terminfo capability `sgr0`"), |op| {
+        let s = cap.map_or(Err(~"can't find terminfo capability `sgr0`"), |op| {
             expand(*op, [], &mut Variables::new())
         });
         if s.is_ok() {

src/libextra/treemap.rs

@@ -820,7 +820,7 @@ impl<K: TotalOrd, V> TreeNode<K, V> {
 
 // Remove left horizontal link by rotating right
 fn skew<K: TotalOrd, V>(node: &mut ~TreeNode<K, V>) {
-    if node.left.as_ref().map_default(false, |x| x.level == node.level) {
+    if node.left.as_ref().map_or(false, |x| x.level == node.level) {
         let mut save = node.left.take_unwrap();
         swap(&mut node.left, &mut save.right); // save.right now None
         swap(node, &mut save);
@@ -831,8 +831,8 @@ fn skew<K: TotalOrd, V>(node: &mut ~TreeNode<K, V>) {
 // Remove dual horizontal link by rotating left and increasing level of
 // the parent
 fn split<K: TotalOrd, V>(node: &mut ~TreeNode<K, V>) {
-    if node.right.as_ref().map_default(false,
-      |x| x.right.as_ref().map_default(false, |y| y.level == node.level)) {
+    if node.right.as_ref().map_or(false,
+      |x| x.right.as_ref().map_or(false, |y| y.level == node.level)) {
         let mut save = node.right.take_unwrap();
         swap(&mut node.right, &mut save.left); // save.left now None
         save.level += 1;
@@ -938,8 +938,8 @@ fn remove<K: TotalOrd, V>(node: &mut Option<~TreeNode<K, V>>,
         };
 
         if rebalance {
-            let left_level = save.left.as_ref().map_default(0, |x| x.level);
-            let right_level = save.right.as_ref().map_default(0, |x| x.level);
+            let left_level = save.left.as_ref().map_or(0, |x| x.level);
+            let right_level = save.right.as_ref().map_or(0, |x| x.level);
 
             // re-balance, if necessary
             if left_level < save.level - 1 || right_level < save.level - 1 {

src/librustc/middle/check_match.rs

@@ -927,7 +927,7 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
         // check legality of moving out of the enum
 
         // x @ Foo(..) is legal, but x @ Foo(y) isn't.
-        if sub.map_default(false, |p| pat_contains_bindings(def_map, p)) {
+        if sub.map_or(false, |p| pat_contains_bindings(def_map, p)) {
             tcx.sess.span_err(
                 p.span,
                 "cannot bind by-move with sub-bindings");

src/librustc/middle/dead.rs

@@ -300,8 +300,8 @@ impl DeadVisitor {
     fn symbol_is_live(&mut self, id: ast::NodeId,
                       ctor_id: Option<ast::NodeId>) -> bool {
         if self.live_symbols.contains(&id)
-           || ctor_id.map_default(false,
-                                  |ctor| self.live_symbols.contains(&ctor)) {
+           || ctor_id.map_or(false,
+                             |ctor| self.live_symbols.contains(&ctor)) {
             return true;
         }
         // If it's a type whose methods are live, then it's live, too.

src/librustc/middle/privacy.rs

@@ -256,7 +256,7 @@ impl<'a> Visitor<()> for EmbargoVisitor<'a> {
                     _ => true,
                 };
                 let tr = ty::impl_trait_ref(self.tcx, local_def(item.id));
-                let public_trait = tr.map_default(false, |tr| {
+                let public_trait = tr.map_or(false, |tr| {
                     !is_local(tr.def_id) ||
                      self.exported_items.contains(&tr.def_id.node)
                 });

src/librustc/middle/typeck/check/_match.rs

@@ -165,7 +165,7 @@ pub fn check_pat_variant(pcx: &pat_ctxt, pat: &ast::Pat, path: &ast::Path,
                     // See [Note-Type-error-reporting] in middle/typeck/infer/mod.rs
                     fcx.infcx().type_error_message_str_with_expected(pat.span,
                                                        |expected, actual| {
-                                                       expected.map_default(~"", |e| {
+                                                       expected.map_or(~"", |e| {
                         format!("mismatched types: expected `{}` but found {}",
                              e, actual)})},
                              Some(expected), ~"a structure pattern",
@@ -214,7 +214,7 @@ pub fn check_pat_variant(pcx: &pat_ctxt, pat: &ast::Pat, path: &ast::Path,
             // See [Note-Type-error-reporting] in middle/typeck/infer/mod.rs
             fcx.infcx().type_error_message_str_with_expected(pat.span,
                                                |expected, actual| {
-                                               expected.map_default(~"", |e| {
+                                               expected.map_or(~"", |e| {
                     format!("mismatched types: expected `{}` but found {}",
                          e, actual)})},
                     Some(expected), ~"an enum or structure pattern",
@@ -530,7 +530,7 @@ pub fn check_pat(pcx: &pat_ctxt, pat: &ast::Pat, expected: ty::t) {
                // See [Note-Type-error-reporting] in middle/typeck/infer/mod.rs
                 fcx.infcx().type_error_message_str_with_expected(pat.span,
                                                                 |expected, actual| {
-                            expected.map_default(~"", |e| {
+                            expected.map_or(~"", |e| {
                                     format!("mismatched types: expected `{}` but found {}",
                                          e, actual)})},
                                          Some(expected), ~"a structure pattern",
@@ -578,7 +578,7 @@ pub fn check_pat(pcx: &pat_ctxt, pat: &ast::Pat, expected: ty::t) {
                 };
                 // See [Note-Type-error-reporting] in middle/typeck/infer/mod.rs
                 fcx.infcx().type_error_message_str_with_expected(pat.span, |expected, actual| {
-                expected.map_default(~"", |e| {
+                expected.map_or(~"", |e| {
                     format!("mismatched types: expected `{}` but found {}",
                                      e, actual)})}, Some(expected), ~"tuple", Some(&type_error));
                 fcx.write_error(pat.id);
@@ -628,7 +628,7 @@ pub fn check_pat(pcx: &pat_ctxt, pat: &ast::Pat, expected: ty::t) {
               fcx.infcx().type_error_message_str_with_expected(
                   pat.span,
                   |expected, actual| {
-                      expected.map_default(~"", |e| {
+                      expected.map_or(~"", |e| {
                           format!("mismatched types: expected `{}` but found {}",
                                e, actual)})},
                   Some(expected),
@@ -687,7 +687,7 @@ pub fn check_pointer_pat(pcx: &pat_ctxt,
             fcx.infcx().type_error_message_str_with_expected(
                 span,
                 |expected, actual| {
-                    expected.map_default(~"", |e| {
+                    expected.map_or(~"", |e| {
                         format!("mismatched types: expected `{}` but found {}",
                              e, actual)})},
                 Some(expected),

src/librustc/middle/typeck/check/vtable.rs

@@ -141,7 +141,7 @@ fn lookup_vtables_for_param(vcx: &VtableContext,
 
         // Substitute the values of the type parameters that may
         // appear in the bound.
-        let trait_ref = substs.as_ref().map_default(trait_ref, |substs| {
+        let trait_ref = substs.as_ref().map_or(trait_ref, |substs| {
             debug!("about to subst: {}, {}",
                    trait_ref.repr(tcx), substs.repr(tcx));
             trait_ref.subst(tcx, *substs)
@@ -334,7 +334,7 @@ fn search_for_vtable(vcx: &VtableContext,
         let trait_impls = tcx.trait_impls.borrow();
         trait_impls.get()
                    .find(&trait_ref.def_id)
-                   .map_default(@RefCell::new(~[]), |x| *x)
+                   .map_or(@RefCell::new(~[]), |x| *x)
     };
     // impls is the list of all impls in scope for trait_ref.
     let impls = impls.borrow();

src/librustc/middle/typeck/infer/mod.rs

@@ -747,13 +747,13 @@ impl InferCtxt {
                                                 err: Option<&ty::type_err>) {
         debug!("hi! expected_ty = {:?}, actual_ty = {}", expected_ty, actual_ty);
 
-        let error_str = err.map_default(~"", |t_err| {
+        let error_str = err.map_or(~"", |t_err| {
             format!(" ({})", ty::type_err_to_str(self.tcx, t_err))
         });
         let resolved_expected = expected_ty.map(|e_ty| {
             self.resolve_type_vars_if_possible(e_ty)
         });
-        if !resolved_expected.map_default(false, |e| { ty::type_is_error(e) }) {
+        if !resolved_expected.map_or(false, |e| { ty::type_is_error(e) }) {
             match resolved_expected {
                 None => self.tcx.sess.span_err(sp,
                             format!("{}{}", mk_msg(None, actual_ty), error_str)),

src/librustpkg/tests.rs

@@ -384,7 +384,7 @@ fn executable_exists(repo: &Path, short_name: &str) -> bool {
 fn test_executable_exists(repo: &Path, short_name: &str) -> bool {
     debug!("test_executable_exists: repo = {}, short_name = {}", repo.display(), short_name);
     let exec = built_test_in_workspace(&CrateId::new(short_name), repo);
-    exec.map_default(false, |exec| exec.exists() && is_rwx(&exec))
+    exec.map_or(false, |exec| exec.exists() && is_rwx(&exec))
 }
 
 fn remove_executable_file(p: &CrateId, workspace: &Path) {
@@ -600,8 +600,8 @@ fn test_install_valid() {
 
     let lib = installed_library_in_workspace(&temp_pkg_id.path, temp_workspace);
     debug!("lib = {:?}", lib);
-    assert!(lib.as_ref().map_default(false, |l| l.exists()));
-    assert!(lib.as_ref().map_default(false, |l| is_rwx(l)));
+    assert!(lib.as_ref().map_or(false, |l| l.exists()));
+    assert!(lib.as_ref().map_or(false, |l| is_rwx(l)));
 
     // And that the test and bench executables aren't installed
     assert!(!target_test_in_workspace(&temp_pkg_id, temp_workspace).exists());
@@ -652,8 +652,8 @@ fn test_install_valid_external() {
 
     let lib = installed_library_in_workspace(&temp_pkg_id.path, temp_workspace);
     debug!("lib = {:?}", lib);
-    assert!(lib.as_ref().map_default(false, |l| l.exists()));
-    assert!(lib.as_ref().map_default(false, |l| is_rwx(l)));
+    assert!(lib.as_ref().map_or(false, |l| l.exists()));
+    assert!(lib.as_ref().map_or(false, |l| is_rwx(l)));
 
     // And that the test and bench executables aren't installed
     assert!(!target_test_in_workspace(&temp_pkg_id, temp_workspace).exists());
@@ -947,7 +947,7 @@ fn rustpkg_clean_no_arg() {
     assert_built_executable_exists(&tmp, "foo");
     command_line_test([~"clean"], &package_dir);
     let res = built_executable_in_workspace(&CrateId::new("foo"), &tmp);
-    assert!(!res.as_ref().map_default(false, |m| m.exists()));
+    assert!(!res.as_ref().map_or(false, |m| m.exists()));
 }
 
 #[test]

src/librustuv/addrinfo.rs

@@ -72,7 +72,7 @@ impl GetAddrInfoRequest {
                 ai_next: null(),
             }
         });
-        let hint_ptr = hint.as_ref().map_default(null(), |x| x as *uvll::addrinfo);
+        let hint_ptr = hint.as_ref().map_or(null(), |x| x as *uvll::addrinfo);
         let mut req = Request::new(uvll::UV_GETADDRINFO);
 
         return match unsafe {

src/libstd/iter.rs

@@ -1600,8 +1600,8 @@ impl<'a, A, T: Iterator<A>, B, U: Iterator<B>> Iterator<B> for FlatMap<'a, A, T,
 
     #[inline]
     fn size_hint(&self) -> (uint, Option<uint>) {
-        let (flo, fhi) = self.frontiter.as_ref().map_default((0, Some(0)), |it| it.size_hint());
-        let (blo, bhi) = self.backiter.as_ref().map_default((0, Some(0)), |it| it.size_hint());
+        let (flo, fhi) = self.frontiter.as_ref().map_or((0, Some(0)), |it| it.size_hint());
+        let (blo, bhi) = self.backiter.as_ref().map_or((0, Some(0)), |it| it.size_hint());
         let lo = flo.saturating_add(blo);
         match (self.iter.size_hint(), fhi, bhi) {
             ((0, Some(0)), Some(a), Some(b)) => (lo, a.checked_add(&b)),

src/libstd/option.rs

@@ -164,7 +164,7 @@ impl<T> Option<T> {
 
     /// Applies a function to the contained value or returns a default.
     #[inline]
-    pub fn map_default<U>(self, def: U, f: |T| -> U) -> U {
+    pub fn map_or<U>(self, def: U, f: |T| -> U) -> U {
         match self { None => def, Some(t) => f(t) }
     }
 
@@ -179,7 +179,7 @@ impl<T> Option<T> {
 
     /// Apply a function to the contained value or set it to a default.
     /// Returns true if the contained value was mutated, or false if set to the default.
-    pub fn mutate_default(&mut self, def: T, f: |T| -> T) -> bool {
+    pub fn mutate_or_set(&mut self, def: T, f: |T| -> T) -> bool {
         if self.is_some() {
             *self = Some(f(self.take_unwrap()));
             true
@@ -695,12 +695,12 @@ mod tests {
         let mut x = Some(3i);
         assert!(x.mutate(|i| i+1));
         assert_eq!(x, Some(4i));
-        assert!(x.mutate_default(0, |i| i+1));
+        assert!(x.mutate_or_set(0, |i| i+1));
         assert_eq!(x, Some(5i));
         x = None;
         assert!(!x.mutate(|i| i+1));
         assert_eq!(x, None);
-        assert!(!x.mutate_default(0i, |i| i+1));
+        assert!(!x.mutate_or_set(0i, |i| i+1));
         assert_eq!(x, Some(0i));
     }
 

src/libstd/path/windows.rs

@@ -255,7 +255,7 @@ impl GenericPathUnsafe for Path {
             // if me is verbatim, we need to pre-normalize the new path
             let path_ = if is_verbatim(me) { Path::normalize__(path, None) }
                         else { None };
-            let pathlen = path_.as_ref().map_default(path.len(), |p| p.len());
+            let pathlen = path_.as_ref().map_or(path.len(), |p| p.len());
             let mut s = str::with_capacity(me.repr.len() + 1 + pathlen);
             s.push_str(me.repr);
             let plen = me.prefix_len();

src/libsyntax/diagnostic.rs

@@ -314,12 +314,11 @@ fn highlight_lines(cm: &codemap::CodeMap,
 
 fn print_macro_backtrace(cm: &codemap::CodeMap, sp: Span) {
     for ei in sp.expn_info.iter() {
-        let ss = ei.callee.span.as_ref().map_default(~"", |span| cm.span_to_str(*span));
+        let ss = ei.callee.span.as_ref().map_or(~"", |span| cm.span_to_str(*span));
         let (pre, post) = match ei.callee.format {
             codemap::MacroAttribute => ("#[", "]"),
             codemap::MacroBang => ("", "!")
         };
-
         print_diagnostic(ss, note,
                          format!("in expansion of {}{}{}", pre, ei.callee.name, post));
         let ss = cm.span_to_str(ei.call_site);

src/libsyntax/parse/parser.rs

@@ -402,7 +402,7 @@ impl Parser {
         fn tokens_to_str(tokens: &[token::Token]) -> ~str {
             let mut i = tokens.iter();
             // This might be a sign we need a connect method on Iterator.
-            let b = i.next().map_default(~"", |t| Parser::token_to_str(t));
+            let b = i.next().map_or(~"", |t| Parser::token_to_str(t));
             i.fold(b, |b,a| b + "`, `" + Parser::token_to_str(a))
         }
         if edible.contains(&self.token) {
@@ -467,7 +467,7 @@ impl Parser {
     pub fn commit_stmt(&mut self, s: @Stmt, edible: &[token::Token], inedible: &[token::Token]) {
         debug!("commit_stmt {:?}", s);
         let _s = s; // unused, but future checks might want to inspect `s`.
-        if self.last_token.as_ref().map_default(false, |t| is_ident_or_path(*t)) {
+        if self.last_token.as_ref().map_or(false, |t| is_ident_or_path(*t)) {
             let expected = vec::append(edible.to_owned(), inedible);
             self.check_for_erroneous_unit_struct_expecting(expected);
         }