Merge pull request #31 from Brugarolas/objecthash

Objecthash

doc/site/modules/core/object.markdown

@@ -29,6 +29,10 @@ Compares two objects using built-in equality. This compares [value
 types](../../values.html) by value, and all other objects are compared by
 identity—two objects are equal only if they are the exact same object.
 
+### **hash**
+
+Returns a hash of the object.
+
 ### **is**(class) operator
 
 Returns `true` if this object's class or one of its superclasses is `class`.

src/vm/wren_core.c

@@ -989,6 +989,11 @@ DEF_PRIMITIVE(object_is)
   RETURN_BOOL(false);
 }
 
+DEF_PRIMITIVE(object_hash)
+{
+  RETURN_NUM(wrenHash(args[0]));
+}
+
 DEF_PRIMITIVE(object_toString)
 {
   Obj* obj = AS_OBJ(args[0]);
@@ -1355,6 +1360,7 @@ void wrenInitializeCore(WrenVM* vm)
   PRIMITIVE(vm->objectClass, "==(_)", object_eqeq);
   PRIMITIVE(vm->objectClass, "~~(_)", object_eqeq);
   PRIMITIVE(vm->objectClass, "!=(_)", object_bangeq);
+  PRIMITIVE(vm->objectClass, "hash", object_hash);
   PRIMITIVE(vm->objectClass, "!~(_)", object_bangeq);
   PRIMITIVE(vm->objectClass, "is(_)", object_is);
   PRIMITIVE(vm->objectClass, "toString", object_toString);

src/vm/wren_value.c

@@ -426,14 +426,13 @@ static uint32_t hashObject(Obj* object)
       return ((ObjString*)object)->hash;
 
     default:
-      ASSERT(false, "Only immutable objects can be hashed.");
-      return 0;
+      return hashBits((uintptr_t)object);
   }
 }
 
 // Generates a hash code for [value], which must be one of the built-in
 // immutable types: null, bool, class, num, range, or string.
-static uint32_t hashValue(Value value)
+uint32_t wrenHash(Value value)
 {
   // TODO: We'll probably want to randomize this at some point.
 
@@ -470,7 +469,7 @@ static bool findEntry(MapEntry* entries, uint32_t capacity, Value key,
 
   // Figure out where to insert it in the table. Use open addressing and
   // basic linear probing.
-  uint32_t startIndex = hashValue(key) % capacity;
+  uint32_t startIndex = wrenHash(key) % capacity;
   uint32_t index = startIndex;
 
   // If we pass a tombstone and don't end up finding the key, its entry will

src/vm/wren_value.h

@@ -722,6 +722,8 @@ ObjMap* wrenNewMap(WrenVM* vm);
 // This separation exists to aid the API in surfacing errors to the developer as well.
 static inline bool wrenMapIsValidKey(Value arg);
 
+uint32_t wrenHash(Value value);
+
 // Looks up [key] in [map]. If found, returns the value. Otherwise, returns
 // `UNDEFINED_VAL`.
 Value wrenMapGet(ObjMap* map, Value key);