feat(predicates): add adjacent predicate

lua/nvim-treesitter/query_predicates.lua

@@ -1,4 +1,5 @@
 local utils = require'nvim-treesitter.utils'
+local ts_utils = require'nvim-treesitter.ts_utils'
 
 local M = {}
 
@@ -12,6 +13,42 @@ local function get_node(query, match, pred_item)
   return utils.get_at_path(match, query.captures[pred_item]..'.node')
 end
 
+local function create_adjacent_predicate(match_successive_nodes)
+  return function(query, match, pred)
+    if #pred < 3 then error("adjacent? must have at least two arguments!") end
+    local node = get_node(query, match, pred[2])
+    if not node then return true end
+
+    local adjacent_types = {unpack(pred, 3)}
+    local adjacent_node = ts_utils.get_next_node(node)
+
+    if match_successive_nodes then
+      -- Move to the last node in a series that doesn't match the node type
+      -- and use that node to compare with.
+      while adjacent_node and adjacent_node:type() == node:type() do
+        node = adjacent_node
+        adjacent_node = ts_utils.get_next_node(node)
+      end
+    end
+
+    if not adjacent_node then return false end
+
+    for _, adjacent_type in ipairs(adjacent_types) do
+      if type(adjacent_type) == "number" then
+        if get_node(query, match, adjacent_type) == adjacent_node then
+          return true
+        end
+      elseif type(adjacent_type) == "string" then
+        if adjacent_node:type() == adjacent_type then
+          return true
+        end
+      end
+    end
+
+    return false
+  end
+end
+
 function M.check_predicate(query, match, pred)
   local check_function = M[pred[1]]
   if check_function then
@@ -55,7 +92,7 @@ end
   end
 end
 
-M['has_ancestor?'] = function(query, match, pred)
+M['has-ancestor?'] = function(query, match, pred)
   if #pred ~= 3 then error("has-ancestor? must have exactly two arguments!") end
   local node = get_node(query, match, pred[2])
   local ancestor_type = pred[3]
@@ -71,4 +108,7 @@ M['has_ancestor?'] = function(query, match, pred)
   return false
 end
 
+M['adjacent?'] = create_adjacent_predicate(false)
+M['adjacent-block?'] = create_adjacent_predicate(true)
+
 return M