Feat: Opt in vim buffers for previewers (#298)

Enable with:
require('telescope').setup {
  defaults = {
    file_previewer = previewers.vim_buffer_cat.new,
    grep_previewer = previewers.vim_buffer_vimgrep.new,
    qflist_previewer = previewers.vim_buffer_qflist.new,
  }
}

lua/telescope/builtin/files.lua

@@ -28,7 +28,7 @@ files.live_grep = function(opts)
   pickers.new(opts, {
     prompt_title = 'Live Grep',
     finder = live_grepper,
-    previewer = previewers.vimgrep.new(opts),
+    previewer = conf.grep_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end
@@ -48,7 +48,7 @@ files.grep_string = function(opts)
       flatten { conf.vimgrep_arguments, opts.word_match, search},
       opts
     ),
-    previewer = previewers.vimgrep.new(opts),
+    previewer = conf.grep_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end
@@ -87,7 +87,7 @@ files.find_files = function(opts)
       find_command,
       opts
     ),
-    previewer = previewers.cat.new(opts),
+    previewer = conf.file_previewer(opts),
     sorter = conf.file_sorter(opts),
   }):find()
 end
@@ -143,7 +143,7 @@ files.treesitter = function(opts)
       results = results,
       entry_maker = make_entry.gen_from_treesitter(opts)
     },
-    previewer = previewers.vimgrep.new(opts),
+    previewer = conf.grep_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end

lua/telescope/builtin/git.lua

@@ -22,7 +22,7 @@ git.files = function(opts)
       { "git", "ls-files", "--exclude-standard", "--cached", show_untracked and "--others" },
       opts
     ),
-    previewer = previewers.cat.new(opts),
+    previewer = conf.file_previewer(opts),
     sorter = conf.file_sorter(opts),
   }):find()
 end

lua/telescope/builtin/internal.lua

@@ -144,7 +144,7 @@ internal.quickfix = function(opts)
       results     = locations,
       entry_maker = make_entry.gen_from_quickfix(opts),
     },
-    previewer = previewers.qflist.new(opts),
+    previewer = conf.qflist_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end
@@ -167,7 +167,7 @@ internal.loclist = function(opts)
       results     = locations,
       entry_maker = make_entry.gen_from_quickfix(opts),
     },
-    previewer = previewers.qflist.new(opts),
+    previewer = conf.qflist_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end
@@ -179,7 +179,7 @@ internal.oldfiles = function(opts)
       return 0 ~= vim.fn.filereadable(val)
     end, vim.v.oldfiles)),
     sorter = conf.file_sorter(opts),
-    previewer = previewers.cat.new(opts),
+    previewer = conf.file_previewer(opts),
   }):find()
 end
 
@@ -422,7 +422,7 @@ internal.buffers = function(opts)
       results = buffers,
       entry_maker = make_entry.gen_from_buffer(opts)
     },
-    previewer = previewers.vim_buffer.new(opts),
+    previewer = conf.grep_previewer(opts),
     sorter = conf.generic_sorter(opts),
     default_selection_index = default_selection_idx,
   }):find()
@@ -464,7 +464,7 @@ internal.marks = function(opts)
       results = marks_table,
       entry_maker = make_entry.gen_from_marks(opts),
     },
-    previewer = previewers.vimgrep.new(opts),
+    previewer = conf.grep_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end

lua/telescope/builtin/lsp.lua

@@ -33,7 +33,7 @@ lsp.references = function(opts)
       results = locations,
       entry_maker = make_entry.gen_from_quickfix(opts),
     },
-    previewer = previewers.qflist.new(opts),
+    previewer = conf.qflist_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end
@@ -62,7 +62,7 @@ lsp.document_symbols = function(opts)
       results = locations,
       entry_maker = make_entry.gen_from_quickfix(opts)
     },
-    previewer = previewers.qflist.new(opts),
+    previewer = conf.qflist_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end
@@ -167,7 +167,7 @@ lsp.workspace_symbols = function(opts)
       results = locations,
       entry_maker = make_entry.gen_from_quickfix(opts)
     },
-    previewer = previewers.qflist.new(opts),
+    previewer = conf.qflist_previewer(opts),
     sorter = conf.generic_sorter(opts),
   }):find()
 end