API: Refactor vim_{get,set}_var

- Change in dict_set_value: Passing 'nil' as value will delete the
  variable.
- Change in dict_get_value: Removed 'pop' parameter, now values can be popped
  by passing 'nil' to dict_set_value
- Update {buffer,window,tabpage}_get_var to reflect the changes

src/api/buffer.c

@@ -231,7 +231,7 @@ Object buffer_get_var(Buffer buffer, String name, Error *err)
     return rv;
   }
 
-  return dict_get_value(buf->b_vars, name, false, err);
+  return dict_get_value(buf->b_vars, name, err);
 }
 
 Object buffer_set_var(Buffer buffer, String name, Object value, Error *err)

src/api/buffer.h

@@ -78,7 +78,7 @@ void buffer_set_slice(Buffer buffer,
 /// @return The variable value
 Object buffer_get_var(Buffer buffer, String name, Error *err);
 
-/// Sets a buffer variable
+/// Sets a buffer variable. Passing 'nil' as value deletes the variable.
 ///
 /// @param buffer The buffer handle
 /// @param name The variable name

src/api/helpers.c

@@ -82,7 +82,7 @@ bool try_end(Error *err)
   return err->set;
 }
 
-Object dict_get_value(dict_T *dict, String key, bool pop, Error *err)
+Object dict_get_value(dict_T *dict, String key, Error *err)
 {
   Object rv;
   hashitem_T *hi;
@@ -99,16 +99,6 @@ Object dict_get_value(dict_T *dict, String key, bool pop, Error *err)
   di = dict_lookup(hi);
   rv = vim_to_object(&di->di_tv);
 
-  if (pop) {
-    if (dict->dv_lock) {
-      set_api_error("Dictionary is locked", err);
-      return rv;
-    }
-
-    hash_remove(&dict->dv_hashtab, hi);
-    dictitem_free(di);
-  }
-
   return rv;
 }
 
@@ -127,24 +117,45 @@ Object dict_set_value(dict_T *dict, String key, Object value, Error *err)
   }
 
   dictitem_T *di = dict_find(dict, (uint8_t *)key.data, key.size);
-  typval_T tv;
 
-  if (!object_to_vim(value, &tv, err)) {
-    return rv;
-  }
-
-  if (di == NULL) {
-    char *k = xstrndup(key.data, key.size);
-    di = dictitem_alloc((uint8_t *)k);
-    free(k);
-    dict_add(dict, di);
+  if (value.type == kObjectTypeNil) {
+    // Delete the key
+    if (di == NULL) {
+      // Doesn't exist, fail
+      set_api_error("Key doesn't exist", err);
+    } else {
+      // Return the old value
+      rv = vim_to_object(&di->di_tv);
+      // Delete the entry
+      hashitem_T *hi = hash_find(&dict->dv_hashtab, di->di_key);
+      hash_remove(&dict->dv_hashtab, hi);
+      dictitem_free(di);
+    }
   } else {
-    rv = vim_to_object(&di->di_tv);
-    clear_tv(&di->di_tv);
-  }
+    // Update the key
+    typval_T tv;
 
-  copy_tv(&tv, &di->di_tv);
-  clear_tv(&tv);
+    // Convert the object to a vimscript type in the temporary variable
+    if (!object_to_vim(value, &tv, err)) {
+      return rv;
+    }
+
+    if (di == NULL) {
+      // Need to create an entry
+      char *k = xstrndup(key.data, key.size);
+      di = dictitem_alloc((uint8_t *)k);
+      free(k);
+      dict_add(dict, di);
+    } else {
+      // Return the old value
+      clear_tv(&di->di_tv);
+    }
+
+    // Update the value
+    copy_tv(&tv, &di->di_tv);
+    // Clear the temporary variable
+    clear_tv(&tv);
+  }
 
   return rv;
 }

src/api/helpers.h

@@ -26,12 +26,11 @@ bool try_end(Error *err);
 ///
 /// @param dict The vimscript dict
 /// @param key The key
-/// @param bool If true it will pop the value from the dict
 /// @param[out] err Details of an error that may have occurred
-Object dict_get_value(dict_T *dict, String key, bool pop, Error *err);
+Object dict_get_value(dict_T *dict, String key, Error *err);
 
 /// Set a value in a dict. Objects are recursively expanded into their
-/// vimscript equivalents.
+/// vimscript equivalents. Passing 'nil' as value deletes the key.
 ///
 /// @param dict The vimscript dict
 /// @param key The key

src/api/tabpage.c

@@ -38,7 +38,7 @@ Object tabpage_get_var(Tabpage tabpage, String name, Error *err)
     return rv;
   }
 
-  return dict_get_value(tab->tp_vars, name, false, err);
+  return dict_get_value(tab->tp_vars, name, err);
 }
 
 Object tabpage_set_var(Tabpage tabpage, String name, Object value, Error *err)

src/api/tabpage.h

@@ -21,7 +21,7 @@ int64_t tabpage_get_window_count(Tabpage tabpage, Error *err);
 /// @return The variable value
 Object tabpage_get_var(Tabpage tabpage, String name, Error *err);
 
-/// Sets a tabpage variable
+/// Sets a tabpage variable. Passing 'nil' as value deletes the variable.
 ///
 /// @param tabpage handle
 /// @param name The variable name

src/api/vim.c

@@ -142,11 +142,9 @@ void vim_del_current_line(Error *err)
   buffer_del_line(curbuf->b_fnum, curwin->w_cursor.lnum - 1, err);
 }
 
-Object vim_get_var(bool special, String name, bool pop, Error *err)
+Object vim_get_var(String name, Error *err)
 {
-  return dict_get_value(special ? &vimvardict : &globvardict, name,
-                        special ? false : pop,
-                        err);
+  return dict_get_value(&globvardict, name, err);
 }
 
 Object vim_set_var(String name, Object value, Error *err)

src/api/vim.h

@@ -61,15 +61,14 @@ void vim_del_current_line(Error *err);
 /// @param[out] err Details of an error that may have occurred
 void vim_set_current_line(String line, Error *err);
 
-/// Gets a global or special variable
+/// Gets a global variable
 ///
-/// @param special If it's a special(:v) variable
 /// @param name The variable name
 /// @param[out] err Details of an error that may have occurred
 /// @return The variable value
-Object vim_get_var(bool special, String name, bool pop, Error *err);
+Object vim_get_var(String name, Error *err);
 
-/// Sets a global variable
+/// Sets a global variable. Passing 'nil' as value deletes the variable.
 ///
 /// @param name The variable name
 /// @param value The variable value

src/api/window.c

@@ -119,7 +119,7 @@ Object window_get_var(Window window, String name, Error *err)
     return rv;
   }
 
-  return dict_get_value(win->w_vars, name, false, err);
+  return dict_get_value(win->w_vars, name, err);
 }
 
 Object window_set_var(Window window, String name, Object value, Error *err)

src/api/window.h

@@ -65,7 +65,7 @@ void window_set_width(Window window, int64_t width, Error *err);
 /// @return The variable value
 Object window_get_var(Window window, String name, Error *err);
 
-/// Sets a window variable
+/// Sets a window variable. Passing 'nil' as value deletes the variable.
 ///
 /// @param window The window handle
 /// @param name The variable name