---

yaml
---
r: 60405
b: refs/heads/master
c: 2264c79
h: refs/heads/master
i:
  60403: 097e2ea
v: v3

Author: tmmcguire

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: 17970a91115dd30dd6ee445ef344153f46f0a946
+refs/heads/master: 2264c7927dbfc6124b9b756de47200ded1ca76ac
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 2d28d645422c1617be58c8ca7ad9a457264ca850
 refs/heads/try: c50a9d5b664478e533ba1d1d353213d70c8ad589

trunk/src/libcore/vec.rs

@@ -1445,6 +1445,46 @@ pub fn reverse<T>(v: &mut [T]) {
     }
 }
 
+/**
+ * Reverse part of a vector in place.
+ *
+ * Reverse the elements in the vector between `start` and `end - 1`.
+ *
+ * # Arguments
+ *
+ * * `v` - The mutable vector to be modified
+ *
+ * * `start` - Index of the first element of the slice
+ *
+ * * `end` - Index one past the final element to be reversed.
+ *
+ * # Example
+ *
+ * Assume a mutable vector `v` contains `[1,2,3,4,5]`. After the call:
+ *
+ * ~~~
+ *
+ * reverse_part(v, 1, 4);
+ *
+ * ~~~
+ *
+ * `v` now contains `[1,4,3,2,5]`.
+ *
+ * # Safety note
+ *
+ * Behavior is undefined if `start` or `end` do not represent valid
+ * positions in `v`.
+ */
+pub fn reverse_part<T>(v: &mut [T], start: uint, end : uint) {
+    let mut i = start;
+    let mut j = end - 1;
+    while i < j {
+        v[i] <-> v[j];
+        i += 1;
+        j -= 1;
+    }
+}
+
 /// Returns a vector with the order of elements reversed
 pub fn reversed<T:Copy>(v: &const [T]) -> ~[T] {
     let mut rs: ~[T] = ~[];
@@ -1739,31 +1779,75 @@ pub fn each2_mut<U, T>(v1: &mut [U], v2: &mut [T], f: &fn(u: &mut U, t: &mut T)
  *
  * The total number of permutations produced is `len(v)!`.  If `v` contains
  * repeated elements, then some permutations are repeated.
+ *
+ * See [Algorithms to generate
+ * permutations](http://en.wikipedia.org/wiki/Permutation).
+ *
+ *  # Arguments
+ *
+ *  * `values` - A vector of values from which the permutations are
+ *  chosen
+ *
+ *  * `fun` - The function to iterate over the combinations
  */
 #[cfg(not(stage0))]
-pub fn each_permutation<T:Copy>(v: &[T], put: &fn(ts: &[T]) -> bool) -> bool {
-    let ln = len(v);
-    if ln <= 1 {
-        put(v);
-    } else {
-        // This does not seem like the most efficient implementation.  You
-        // could make far fewer copies if you put your mind to it.
-        let mut i = 0u;
-        while i < ln {
-            let elt = v[i];
-            let mut rest = slice(v, 0u, i).to_vec();
-            rest.push_all(const_slice(v, i+1u, ln));
-            for each_permutation(rest) |permutation| {
-                if !put(append(~[elt], permutation)) {
-                    return false;
-                }
-            }
-            i += 1u;
+pub fn each_permutation<T:Copy>(values: &[T], fun: &fn(perm : &[T]) -> bool) {
+    let length = values.len();
+    let mut permutation = vec::from_fn(length, |i| values[i]);
+    if length <= 1 {
+        fun(permutation);
+        return;
+    }
+    let mut indices = vec::from_fn(length, |i| i);
+    loop {
+        if !fun(permutation) { return; }
+        // find largest k such that indices[k] < indices[k+1]
+        // if no such k exists, all permutations have been generated
+        let mut k = length - 2;
+        while k > 0 && indices[k] >= indices[k+1] {
+            k -= 1;
+        }
+        if k == 0 && indices[0] > indices[1] { return; }
+        // find largest l such that indices[k] < indices[l]
+        // k+1 is guaranteed to be such
+        let mut l = length - 1;
+        while indices[k] >= indices[l] {
+            l -= 1;
+        }
+        // swap indices[k] and indices[l]; sort indices[k+1..]
+        // (they're just reversed)
+        indices[k] <-> indices[l];
+        unsafe {
+            reverse_part(indices, k+1, length);
+        }
+        // fixup permutation based on indices
+        for uint::range(k, length) |i| {
+            permutation[i] = values[indices[i]];
         }
     }
     return true;
 }
 
+/**
+ * Iterate over all permutations of vector `values`.
+ *
+ * This is an alternative to each_permutation that uses references to
+ * avoid copying the elements of the values vector.
+ *
+ * To avoid copying, the iterator will be passed a reference to a vector
+ * containing references to the elements in the original `values` vector.
+ *
+ * # Arguments
+ *
+ * * `values` - A vector of values from which the permutations are chosen
+ *
+ * * `fun` - The function to iterate over the permutations
+ */
+#[cfg(not(stage0))]
+pub fn each_permutation_ref<T>(values : &'v[T], fun : &fn(perm : &[&'v T]) -> bool) {
+    each_permutation(vec::from_fn(values.len(), |i| &values[i]), fun);
+}
+
 /**
  * Iterate over all contiguous windows of length `n` of the vector `v`.
  *
@@ -4730,6 +4814,97 @@ mod tests {
         }
     }
 
+    fn dup<T:Copy>(values : &[&T]) -> ~[T] {
+        from_fn(values.len(), |i| *values[i])
+    }
+
+    #[test]
+    fn test_reverse_part() {
+        let mut values = [1,2,3,4,5];
+        reverse_part(values,1,4);
+        assert values == [1,4,3,2,5];
+    }
+
+    #[test]
+    fn test_permutations0() {
+        let values = [];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation(values) |p| {
+            v.push(vec::from_slice(p));
+        }
+        assert v == ~[~[]];
+    }
+
+    #[test]
+    fn test_permutations0_ref() {
+        let values = [];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation_ref(values) |p| {
+            v.push(dup(p));
+        }
+        assert v == ~[~[]];
+    }
+
+    #[test]
+    fn test_permutations1() {
+        let values = [1];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation(values) |p| {
+            v.push(vec::from_slice(p));
+        }
+        assert v == ~[~[1]];
+    }
+
+    #[test]
+    fn test_permutations1_ref() {
+        let values = [1];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation_ref(values) |p| {
+            v.push(dup(p));
+        }
+        assert v == ~[~[1]];
+    }
+
+    #[test]
+    fn test_permutations2() {
+        let values = [1,2];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation(values) |p| {
+            v.push(vec::from_slice(p));
+        }
+        assert v == ~[~[1,2],~[2,1]];
+    }
+
+    #[test]
+    fn test_permutations2_ref() {
+        let values = [1,2];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation_ref(values) |p| {
+            v.push(dup(p));
+        }
+        assert v == ~[~[1,2],~[2,1]];
+    }
+
+    #[test]
+    fn test_permutations3() {
+        let values = [1,2,3];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation(values) |p| {
+            v.push(vec::from_slice(p));
+        }
+        assert v == ~[~[1,2,3],~[1,3,2],~[2,1,3],~[2,3,1],~[3,1,2],~[3,2,1]];
+    }
+
+    #[test]
+    fn test_permutations3_ref() {
+        let values = [1,2,3];
+        let mut v : ~[~[int]] = ~[];
+        for each_permutation_ref(values) |p| {
+            v.push(dup(p));
+        }
+        assert v == ~[~[1,2,3],~[1,3,2],~[2,1,3],~[2,3,1],~[3,1,2],~[3,2,1]];
+    }
+
     #[test]
     fn test_each_val() {
         use old_iter::CopyableNonstrictIter;

trunk/src/librustc/metadata/csearch.rs

@@ -234,13 +234,14 @@ pub fn get_field_type(tcx: ty::ctxt, class_id: ast::def_id,
     }
 }
 
-// Given a def_id for an impl, return the trait it implements,
-// if there is one.
-pub fn get_impl_trait(tcx: ty::ctxt,
-                      def: ast::def_id) -> Option<@ty::TraitRef> {
+// Given a def_id for an impl or class, return the traits it implements,
+// or the empty vector if it's not for an impl or for a class that implements
+// traits
+pub fn get_impl_traits(tcx: ty::ctxt,
+                       def: ast::def_id) -> ~[@ty::TraitRef] {
     let cstore = tcx.cstore;
     let cdata = cstore::get_crate_data(cstore, def.crate);
-    decoder::get_impl_trait(cdata, def.node, tcx)
+    decoder::get_impl_traits(cdata, def.node, tcx)
 }
 
 pub fn get_impl_method(cstore: @mut cstore::CStore,

trunk/src/librustc/metadata/decoder.rs

@@ -415,20 +415,19 @@ pub fn get_type_param_count(data: @~[u8], id: ast::node_id) -> uint {
     item_ty_param_count(lookup_item(id, data))
 }
 
-pub fn get_impl_trait(cdata: cmd,
+pub fn get_impl_traits(cdata: cmd,
                        id: ast::node_id,
-                       tcx: ty::ctxt) -> Option<@ty::TraitRef>
+                       tcx: ty::ctxt) -> ~[@ty::TraitRef]
 {
     let item_doc = lookup_item(id, cdata.data);
-    let mut result = None;
+    let mut results = ~[];
     for reader::tagged_docs(item_doc, tag_item_trait_ref) |tp| {
         let trait_ref =
             @parse_trait_ref_data(tp.data, cdata.cnum, tp.start, tcx,
                                   |_, did| translate_def_id(cdata, did));
-        result = Some(trait_ref);
-        break;
+        results.push(trait_ref);
     };
-    result
+    results
 }
 
 pub fn get_impl_method(intr: @ident_interner, cdata: cmd, id: ast::node_id,

trunk/src/librustc/middle/trans/base.rs

@@ -2228,7 +2228,8 @@ pub fn register_fn_fuller(ccx: @CrateContext,
         mangle_exported_name(ccx, /*bad*/copy path, node_type)
     };
 
-    let llfn: ValueRef = decl_fn(ccx.llmod, ps, cc, llfty);
+    // XXX: Bad copy.
+    let llfn: ValueRef = decl_fn(ccx.llmod, copy ps, cc, llfty);
     ccx.item_symbols.insert(node_id, ps);
 
     // FIXME #4404 android JNI hacks

trunk/src/librustc/middle/trans/datum.rs

@@ -101,6 +101,7 @@ use middle::ty;
 use util::common::indenter;
 use util::ppaux::ty_to_str;
 
+use core::container::Set; // XXX: this should not be necessary
 use core::to_bytes;
 use syntax::ast;
 use syntax::codemap::span;

trunk/src/librustc/middle/trans/meth.rs

@@ -795,11 +795,8 @@ pub fn make_impl_vtable(ccx: @CrateContext,
     let _icx = ccx.insn_ctxt("impl::make_impl_vtable");
     let tcx = ccx.tcx;
 
-    let trt_id = match ty::impl_trait_ref(tcx, impl_id) {
-        Some(t_id) => t_id.def_id,
-        None       => ccx.sess.bug("make_impl_vtable: don't know how to \
-                                    make a vtable for a type impl!")
-    };
+    // XXX: This should support multiple traits.
+    let trt_id = ty::impl_trait_refs(tcx, impl_id)[0].def_id;
 
     let has_tps =
         !ty::lookup_item_type(ccx.tcx, impl_id).generics.type_param_defs.is_empty();

trunk/src/librustc/middle/ty.rs

@@ -3883,23 +3883,23 @@ pub fn trait_method_def_ids(cx: ctxt, id: ast::def_id) -> @~[def_id] {
         || @csearch::get_trait_method_def_ids(cx.cstore, id))
 }
 
-pub fn impl_trait_ref(cx: ctxt, id: ast::def_id) -> Option<@TraitRef> {
+pub fn impl_trait_refs(cx: ctxt, id: ast::def_id) -> ~[@TraitRef] {
     if id.crate == ast::local_crate {
-        debug!("(impl_trait_ref) searching for trait impl %?", id);
+        debug!("(impl_traits) searching for trait impl %?", id);
         match cx.items.find(&id.node) {
            Some(&ast_map::node_item(@ast::item {
                         node: ast::item_impl(_, opt_trait, _, _),
                         _},
                     _)) => {
                match opt_trait {
-                   Some(t) => Some(ty::node_id_to_trait_ref(cx, t.ref_id)),
-                   None => None
+                   Some(t) => ~[ty::node_id_to_trait_ref(cx, t.ref_id)],
+                   None => ~[]
                }
            }
-           _ => None
+           _ => ~[]
         }
     } else {
-        csearch::get_impl_trait(cx, id)
+        csearch::get_impl_traits(cx, id)
     }
 }
 

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

@@ -261,14 +261,24 @@ fn lookup_vtable(vcx: &VtableContext,
                         }
                         impls_seen.insert(im.did);
 
-                        // ty::impl_traits gives us the trait im implements,
-                        // if there is one (there's either zero or one).
+                        // ty::impl_traits gives us the list of all
+                        // traits that im implements. Again, usually
+                        // there's just one.
                         //
-                        // If foo implements a trait t, and if t is the
-                        // same trait as trait_ref, we need to
+                        // For example, if im represented the struct
+                        // in:
+                        //
+                        //   struct foo : baz<int>, bar, quux { ... }
+                        //
+                        // then ty::impl_traits would return
+                        //
+                        //   ~[baz<int>, bar, quux]
+                        //
+                        // For each of the traits foo implements, if
+                        // it's the same trait as trait_ref, we need to
                         // unify it with trait_ref in order to get all
                         // the ty vars sorted out.
-                        for ty::impl_trait_ref(tcx, im.did).each |&of_trait_ref|
+                        for ty::impl_trait_refs(tcx, im.did).each |&of_trait_ref|
                         {
                             if of_trait_ref.def_id != trait_ref.def_id { loop; }
 
@@ -446,12 +456,8 @@ fn connect_trait_tps(vcx: &VtableContext,
 {
     let tcx = vcx.tcx();
 
-    let impl_trait_ref = match ty::impl_trait_ref(tcx, impl_did) {
-        Some(t) => t,
-        None => vcx.tcx().sess.span_bug(location_info.span,
-                                  "connect_trait_tps invoked on a type impl")
-    };
-
+    // XXX: This should work for multiple traits.
+    let impl_trait_ref = ty::impl_trait_refs(tcx, impl_did)[0];
     let impl_trait_ref = (*impl_trait_ref).subst(tcx, impl_substs);
     relate_trait_refs(vcx, location_info, &impl_trait_ref, trait_ref);
 }