GHash: BLI_ghash_reinsert_key utility function

Useful when ghash keys are reallocated.

source/blender/blenlib/BLI_ghash.h

@@ -90,6 +90,7 @@ void   BLI_ghash_free(GHash *gh, GHashKeyFreeFP keyfreefp, GHashValFreeFP valfre
 void   BLI_ghash_reserve(GHash *gh, const unsigned int nentries_reserve);
 void   BLI_ghash_insert(GHash *gh, void *key, void *val);
 bool   BLI_ghash_reinsert(GHash *gh, void *key, void *val, GHashKeyFreeFP keyfreefp, GHashValFreeFP valfreefp);
+void  *BLI_ghash_replace_key(GHash *gh, void *key);
 void  *BLI_ghash_lookup(GHash *gh, const void *key) ATTR_WARN_UNUSED_RESULT;
 void  *BLI_ghash_lookup_default(GHash *gh, const void *key, void *val_default) ATTR_WARN_UNUSED_RESULT;
 void **BLI_ghash_lookup_p(GHash *gh, const void *key) ATTR_WARN_UNUSED_RESULT;
@@ -248,6 +249,7 @@ void   BLI_gset_insert(GSet *gh, void *key);
 bool   BLI_gset_add(GSet *gs, void *key);
 bool   BLI_gset_ensure_p_ex(GSet *gs, const void *key, void ***r_key);
 bool   BLI_gset_reinsert(GSet *gh, void *key, GSetKeyFreeFP keyfreefp);
+void  *BLI_gset_replace_key(GSet *gs, void *key);
 bool   BLI_gset_haskey(GSet *gs, const void *key) ATTR_WARN_UNUSED_RESULT;
 bool   BLI_gset_pop(GSet *gs, GSetIterState *state, void **r_key) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL();
 bool   BLI_gset_remove(GSet *gs, const void *key, GSetKeyFreeFP keyfreefp);

source/blender/blenlib/intern/BLI_ghash.c

@@ -762,6 +762,28 @@ bool BLI_ghash_reinsert(GHash *gh, void *key, void *val, GHashKeyFreeFP keyfreef
 	return ghash_insert_safe(gh, key, val, true, keyfreefp, valfreefp);
 }
 
+/**
+ * Replaces the key of an item in the \a gh.
+ *
+ * Use when a key is re-allocated or it's memory location is changed.
+ *
+ * \returns The previous key or NULL if not found, the caller may free if it's needed.
+ */
+void *BLI_ghash_replace_key(GHash *gh, void *key)
+{
+	const unsigned int hash = ghash_keyhash(gh, key);
+	const unsigned int bucket_index = ghash_bucket_index(gh, hash);
+	GHashEntry *e = (GHashEntry *)ghash_lookup_entry_ex(gh, key, bucket_index);
+	if (e != NULL) {
+		void *key_prev = e->e.key;
+		e->e.key = key;
+		return key_prev;
+	}
+	else {
+		return NULL;
+	}
+}
+
 /**
  * Lookup the value of \a key in \a gh.
  *
@@ -1434,6 +1456,18 @@ bool BLI_gset_reinsert(GSet *gs, void *key, GSetKeyFreeFP keyfreefp)
 	return ghash_insert_safe_keyonly((GHash *)gs, key, true, keyfreefp);
 }
 
+/**
+ * Replaces the key to the set if it's found.
+ * Matching #BLI_ghash_replace_key
+ *
+ * \returns The old key or NULL if not found.
+ */
+void *BLI_gset_replace_key(GSet *gs, void *key)
+{
+	return BLI_ghash_replace_key((GHash *)gs, key);
+}
+
+
 bool BLI_gset_remove(GSet *gs, const void *key, GSetKeyFreeFP keyfreefp)
 {
 	return BLI_ghash_remove((GHash *)gs, key, keyfreefp, NULL);