Finally implemented stack_iterator(), a way to iterate over objects in

a stack without all that o = mitm[o].link stuff. Redid Ely's destroy
weapons power to use it.


git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@5875 c06c8d41-db1a-0410-9941-cceddc491573

3 files changed, 81 insertions, 17 deletions

diff --git a/crawl-ref/source/religion.cc b/crawl-ref/source/religion.cc
index 0bbdd9de6f..df5340db9d 100644
--- a/crawl-ref/source/religion.cc
+++ b/crawl-ref/source/religion.cc
@@ -3021,35 +3021,30 @@ bool ely_destroy_weapons()
     god_acting gdact;
 
     bool success = false;
-    int i = igrd[you.x_pos][you.y_pos];
-    while (i != NON_ITEM)
+    for ( stack_iterator si(you.pos()); si; ++si )
     {
-        const int next = mitm[i].link;  // In case we can't get it later.
-
-        if (mitm[i].base_type != OBJ_WEAPONS
-                && mitm[i].base_type != OBJ_MISSILES
-            || item_is_stationary(mitm[i])) // Held in a net?
+        item_def& item(*si);
+        if ( (item.base_type != OBJ_WEAPONS
+              && item.base_type != OBJ_MISSILES)
+             || item_is_stationary(item)) // Held in a net?
         {
-            i = next;
             continue;
         }
 
-        if (!check_warning_inscriptions(mitm[i], OPER_DESTROY))
+        if (!check_warning_inscriptions(item, OPER_DESTROY))
         {
             mpr("Won't destroy {!D} inscribed item.");
-            i = next;
             continue;
         }
 
-        const int value = item_value( mitm[i], true );
+        const int value = item_value( item, true );
 #ifdef DEBUG_DIAGNOSTICS
         mprf(MSGCH_DIAGNOSTICS, "Destroyed weapon value: %d", value);
 #endif
 
         piety_gain_t pgain = PIETY_NONE;
-        bool is_evil_weapon = is_evil_item(mitm[i]);
-        if (is_evil_weapon
-            || _destroyed_valuable_weapon(value, mitm[i].base_type))
+        const bool is_evil_weapon = is_evil_item(item);
+        if (is_evil_weapon || _destroyed_valuable_weapon(value, item.base_type))
         {
             pgain = PIETY_SOME;
             gain_piety(1);
@@ -3057,7 +3052,7 @@ bool ely_destroy_weapons()
 
         // Elyvilon doesn't care about item sacrifices at altars, so
         // I'm stealing _Sacrifice_Messages.
-        _print_sacrifice_message(GOD_ELYVILON, mitm[i], pgain);
+        _print_sacrifice_message(GOD_ELYVILON, item, pgain);
         if (is_evil_weapon)
         {
             // Print this is addition to the above!
@@ -3065,9 +3060,8 @@ bool ely_destroy_weapons()
                                GOD_ELYVILON);
         }
 
-        destroy_item(i);
+        destroy_item( si.link() );
         success = true;
-        i = next;
     }
 
     if (!success)
diff --git a/crawl-ref/source/stuff.cc b/crawl-ref/source/stuff.cc
index d2e1fbb52e..ea171db473 100644
--- a/crawl-ref/source/stuff.cc
+++ b/crawl-ref/source/stuff.cc
@@ -77,6 +77,55 @@
 #include "tutorial.h"
 #include "view.h"
 
+stack_iterator::stack_iterator(const coord_def& pos)
+{
+    cur_link = igrd(pos);
+    if ( cur_link != NON_ITEM )
+        next_link = mitm[cur_link].link;
+    else
+        next_link = NON_ITEM;
+}
+
+stack_iterator::stack_iterator(int start_link)
+{
+    cur_link = start_link;
+    if ( cur_link != NON_ITEM )
+        next_link = mitm[cur_link].link;
+    else
+        next_link = NON_ITEM;
+}
+
+stack_iterator::operator bool() const
+{
+    return ( cur_link != NON_ITEM );
+}
+
+item_def& stack_iterator::operator*() const
+{
+    ASSERT( cur_link != NON_ITEM );
+    return mitm[cur_link];
+}
+
+int stack_iterator::link() const
+{
+    return cur_link;
+}
+
+const stack_iterator& stack_iterator::operator ++ ()
+{
+    cur_link = next_link;
+    if ( cur_link != NON_ITEM )
+        next_link = mitm[cur_link].link;
+    return *this;
+}
+
+stack_iterator stack_iterator::operator++(int dummy)
+{
+    const stack_iterator copy = *this;
+    ++(*this);
+    return copy;
+}
+
 radius_iterator::radius_iterator( const coord_def& _center, int _radius,
                                   bool _roguelike_metric, bool _require_los,
                                   bool _exclude_center )
diff --git a/crawl-ref/source/stuff.h b/crawl-ref/source/stuff.h
index 66e492c7ca..3bb0221fca 100644
--- a/crawl-ref/source/stuff.h
+++ b/crawl-ref/source/stuff.h
@@ -48,6 +48,27 @@ int roll_dice( int num, int size );
 int roll_dice( const struct dice_def &dice );
 void scale_dice( dice_def &dice, int threshold = 24 );
 
+// stack_iterator guarantees validity so long as you don't manually
+// mess with item_def.link: i.e., you can kill the item you're
+// examining but you can't kill the item linked to it.
+class stack_iterator : public std::iterator<std::forward_iterator_tag,
+                                            item_def>
+{
+public:
+    stack_iterator( const coord_def& pos );
+    stack_iterator( int start_link );
+
+    operator bool() const;
+    item_def& operator *() const;
+    int link() const;
+
+    const stack_iterator& operator ++ ();
+    stack_iterator operator ++ (int);
+private:
+    int cur_link;
+    int next_link;
+};
+
 class radius_iterator : public std::iterator<std::bidirectional_iterator_tag,
                         coord_def>
 {