feat: support get_bufnrs for the buffer source (#411)

* feat: support specifies the bufnrs for the buffer source

as [cmp-buffer](https://github.com/hrsh7th/cmp-buffer?tab=readme-ov-file#get_bufnrs-type-fun-number)

* feat: deduplicate get_bufnrs, default to normal visible buffers

* style: get_buf_text return type

---------

Co-authored-by: Liam Dyer <liamcdyer@gmail.com>

README.md

@@ -598,6 +598,16 @@ MiniDeps.add({
         name = 'Buffer',
         module = 'blink.cmp.sources.buffer',
         fallback_for = { 'lsp' },
+        opts = {
+          -- default to all visible buffers
+          get_bufnrs = function()
+            return vim
+              .iter(vim.api.nvim_list_wins())
+              :map(function(win) return vim.api.nvim_win_get_buf(win) end)
+              :filter(function(buf) return vim.bo[buf].buftype ~= 'nofile' end)
+              :totable()
+          end,
+        }
       },
     },
   },

lua/blink/cmp/lib/utils.lua

@@ -28,6 +28,18 @@ function utils.union_keys(t1, t2)
   return vim.tbl_keys(t3)
 end
 
+--- Returns a list of unique values from the input array
+--- @generic T
+--- @param arr T[]
+--- @return T[]
+function utils.deduplicate(arr)
+  local hash = {}
+  for _, v in ipairs(arr) do
+    hash[v] = true
+  end
+  return vim.tbl_keys(hash)
+end
+
 --- Determines whether the current buffer is a "special" buffer or if the filetype is in the list of ignored filetypes
 --- @return boolean
 function utils.is_blocked_buffer()

lua/blink/cmp/sources/buffer.lua

@@ -4,9 +4,9 @@
 
 local uv = vim.uv
 
----@return string
-local function get_buf_text()
-  local bufnr = vim.api.nvim_get_current_buf()
+--- @param bufnr integer
+--- @return string
+local function get_buf_text(bufnr)
   local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
 
   -- exclude word under the cursor
@@ -62,19 +62,38 @@ local function run_async(buf_text, callback)
   worker:queue(buf_text)
 end
 
+--- @class blink.cmp.BufferOpts
+--- @field get_bufnrs fun(): integer[]
+
 --- Public API
 
---- @class blink.cmp.Source
 local buffer = {}
 
-function buffer.new() return setmetatable({}, { __index = buffer }) end
+function buffer.new(opts)
+  opts = opts or {} ---@type blink.cmp.BufferOpts
+  local self = setmetatable({}, { __index = buffer })
+  self.get_bufnrs = opts.get_bufnrs
+    or function()
+      return vim
+        .iter(vim.api.nvim_list_wins())
+        :map(function(win) return vim.api.nvim_win_get_buf(win) end)
+        :filter(function(buf) return vim.bo[buf].buftype ~= 'nofile' end)
+        :totable()
+    end
+  return self
+end
 
 function buffer:get_completions(_, callback)
   local transformed_callback = function(items)
     callback({ is_incomplete_forward = false, is_incomplete_backward = false, items = items })
   end
 
-  local buf_text = get_buf_text()
+  local bufnrs = require('blink.cmp.lib.utils').deduplicate(self.get_bufnrs())
+  local buf_texts = {}
+  for _, buf in ipairs(bufnrs) do
+    table.insert(buf_texts, get_buf_text(buf))
+  end
+  local buf_text = table.concat(buf_texts, '\n')
   -- should take less than 2ms
   if #buf_text < 20000 then
     run_sync(buf_text, transformed_callback)